1
LTC4069
4069f
DESCRIPTIO
U
Wireless PDAs
Cellular Phones
Portable Electronics
Standalone 750mA Li-Ion
Battery Charger in 2
2 DFN
with NTC Thermistor Input
Complete Linear Charger in 2mm
2mm DFN
Package
C/10 Charge Current Detection Output
Timer Charge Termination
Charge Current Programmable up to 750mA with
5% Accuracy
No External MOSFET, Sense Resistor or Blocking
Diode Required
NTC Thermistor Input for Temperature Qualified
Charging
Preset 4.2V Float Voltage with 0.6% Accuracy
Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charge Rate
Without Risk of Overheating
Charge Current Monitor Output for Gas Gauging
Automatic Recharge
Charges Single Cell Li-Ion Batteries Directly from
USB Port
20
A Supply Current in Shutdown Mode
Soft-Start Limits Inrush Current
Tiny 6-Lead (2mm
2mm) DFN Package
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
The LTC
4069 is a complete constant-current/constant-
voltage linear charger for single-cell lithium-ion batteries.
The 2mm
2mm DFN package and low external compo-
nent count make the LTC4069 especially well-suited for
portable applications. Furthermore, LTC4069 is specifi-
cally designed to work within USB power specifications.
The CHRG pin indicates when charge current has dropped
to ten percent of its programmed value (C/10). An internal
timer terminates charging according to battery manufac-
turer specifications.
No external sense resistor or blocking diode is required
due to the internal MOSFET architecture. Thermal feed-
back regulates charge current to limit the die temperature
during high power operation or high ambient temperature
conditions.
When the input supply (wall adapter or USB supply) is
removed, the LTC4069 automatically enters a low current
state, dropping battery drain current to less than 1
A. With
power applied, LTC4069 can be put into shutdown mode,
reducing the supply current to less than 20
A.
The LTC4069 also includes automatic recharge, low-
battery charge conditioning (trickle charging), soft-start
(to limit inrush current) and an NTC thermistor input used
to monitor battery temperature.
The LTC4069 is available in a tiny 6-lead, low profile
(0.75mm) 2mm
2mm DFN package.
Standalone Li-Ion Battery Charger
+
V
CC
R1
510
500mA
R
PROG
2k
4069 TA01
4.2V
Li-Ion
BATTERY
V
IN
4.3V TO 5.5V
1
F
LTC4069
CHRG
NTC
BAT
PROG
GND
R
NOM
100k
R
NTC
100k
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6522118, 6700364.
TIME (HOURS)
0
CHARGE CURRENT (mA)
200
400
600
100
300
500
1
2
3
4
4069 TA01b
3.00
BATTREY VOLTAGE (V)
3.50
4.00
4.50
3.25
3.75
4.25
5
0.5
0
1.5
2.5
3.5
4.5
CONSTANT
CURRENT
CONSTANT
VOLTAGE
V
CC
= 5V
R
PROG
= 2k
CHARGE
TRANSITION
CHARGE
TERMINATION
Complete Charge Cycle (1000mAh Battery)
2
LTC4069
4069f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
V
CC
Supply Voltage
(Note 4)
3.75
5.5
V
I
CC
Quiescent V
CC
Supply Current
V
BAT
= 4.5V (Forces I
BAT
and I
PROG
= 0)
120
250
A
I
CCMS
V
CC
Supply Current in Shutdown
Float PROG
20
40
A
I
CCUV
V
CC
Supply Current in Undervoltage
V
CC
< V
BAT
, V
CC
= 3.5V, V
BAT
= 4V
6
11
A
Lockout
V
FLOAT
V
BAT
Regulated Output Voltage
I
BAT
= 2mA
4.175
4.2
4.225
V
I
BAT
= 2mA, 0
C < T
A
< 85
C
4.158
4.2
4.242
V
I
BAT
BAT Pin Current
R
PROG
= 10k (0.1%), Current Mode
88
100
112
mA
R
PROG
= 2k (0.1%), Current Mode
475
500
525
mA
I
BMS
Battery Drain Current in Shutdown
Floating PROG, V
CC
> V
BAT
1
0
1
A
Mode
I
BUV
Battery Drain Current in Undervoltage V
CC
= 3.5V, V
BAT
= 4V
0
1
4
A
Lockout
V
UVLO
V
CC
Undervoltage Lockout Voltage
V
CC
Rising
3.4
3.6
3.8
V
V
CC
Falling
2.8
3.0
3.2
V
V
PROG
PROG Pin Voltage
R
PROG
= 2k, I
PROG
= 500
A
0.98
1
1.02
V
R
PROG
= 10k, I
PROG
= 100
A
0.98
1
1.02
V
V
ASD
Automatic Shutdown Threshold
(V
CC
V
BAT
), V
CC
Low to High
60
82
100
mV
Voltage
(V
CC
V
BAT
), V
CC
High to Low
15
32
45
mV
I
PROG
PROG Pin Pull-Up Current
V
PROG
> 1V
3
A
V
CC
t < 1ms and Duty Cycle < 1% ................. 0.3V to 7V
Steady State ........................................... 0.3V to 6V
BAT, CHRG ................................................. 0.3V to 6V
PROG, NTC ..................................... 0.3V to V
CC
+ 0.3V
BAT Short-Circuit Duration ........................... Continuous
BAT Pin Current ................................................. 800mA
PROG Pin Current ............................................... 800
A
Junction Temperature (Note 6) ............................ 125
C
Operating Temperature Range (Note 2) .. 40
C to 85C
Storage Temperature Range ................ 65
C to 125C
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
LTC4069EDC
T
JMAX
= 125
C,
JA
= 60
C/W (NOTE 3)
EXPOSED PAD (PIN 7) IS GND
MUST BE SOLDERED TO PCB
The
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25
C.
V
CC
= 5V, V
BAT
= 3.8V, V
NTC
= 0V unless otherwise specified. (Note 2)
ELECTRICAL CHARACTERISTICS
ORDER PART NUMBER
DC PART MARKING
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
TOP VIEW
7
DC PACKAGE
6-LEAD (2mm
2mm) PLASTIC DFN
4
5
6
3
2
1
GND
CHRG
BAT
PROG
NTC
V
CC
LBZX
3
LTC4069
4069f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
MS,PROG
PROG Shutdown Threshold Voltage
V
PROG
Rising
3.7
4
4.3
V
t
SS
Soft-Start Time
170
s
I
TRKL
Trickle Charge Current
V
BAT
= 2V, R
PROG
= 2k (0.1%)
35
50
65
mA
V
TRKL
Trickle Charge Threshold Voltage
V
BAT
Rising
2.7
2.9
3.05
V
V
TRHYS
Trickle Charge Hysteresis Voltage
90
mV
V
RECHRG
Recharge Battery Threshold Voltage
V
FLOAT
V
RECHRG
, 0
C < T
A
< 85
C
70
100
130
mV
V
UVCL1
(V
CC
V
BAT
) Undervoltage Current
I
BAT
= 90% Programmed Charge Current
180
220
330
mV
V
UVCL2
Limit
I
BAT
= 10% Programmed Charge Current
90
125
150
mV
t
TIMER
Termination Timer
3
4.5
6
Hrs
Recharge Timer
1.5
2.25
3
Hrs
Low-Battery Trickle Charge Time
V
BAT
= 2.5V
0.75
1.125
1.5
Hrs
V
CHRG
CHRG Pin Output Low Voltage
I
CHRG
= 5mA
60
105
mV
I
CHRG
CHRG Pin Leakage Current
V
BAT
= 4.5V, V
CHRG
= 5V
0
1
A
I
C/10
End of Charge Indication Current
R
PROG
= 2k (Note 5)
0.08
0.095
0.11
mA/mA
Level
T
LIM
Junction Temperature in Constant
115
C
Temperature Mode
R
ON
Power FET "ON" Resistance
I
BAT
= 350mA
450
m
(Between V
CC
and BAT)
f
BADBAT
Defective Battery Detection CHRG
2
Hz
Pulse Frequency
D
BADBAT
Defective Battery Detection CHRG
80
%
Pulse Frequency Duty Ratio
I
NTC
NTC PIN Current
V
NTC
= 2.5V
1
A
V
COLD
Cold Temperature Fault Threshold
Rising Voltage Threshold
0.76 V
CC
V
Voltage
Hysteresis
0.015 V
CC
V
V
HOT
Hot Temperature Fault Threshold
Falling Voltage Threshold
0.35 V
CC
V
Voltage
Hysteresis
0.017 V
CC
V
V
NTC-DIS
NTC Disable Threshold Voltage
Falling Threshold; V
CC
= 5V
82
mV
V
DIS-HYS
NTC Disable Hysteresis Voltage
50
mV
f
NTC
Fault Temperature CHRG Pulse
2
Hz
Frequency
D
NTC
Fault Temperature CHRG Pulse
20
%
Frequency Duty Ratio
The
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25
C.
V
CC
= 5V, V
BAT
= 3.8V, V
NTC
= 0V unless otherwise specified. (Note 2)
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC4069 is guaranteed to meet performance specifications
from 0
C to 70C. Specifications over the 40C to 85C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
rated.
Note 4: Although the LTC4069 functions properly at 3.75V, full charge
current requires an input voltage greater than the desired final battery
voltage per the
V
UVCL1
specification.
Note 5: I
C/10
is expressed as a fraction of measured full charge current
with indicated PROG resistor.
Note 6: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125
C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
4
LTC4069
4069f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Battery Regulation (Float) Voltage
vs Battery Charge Current
I
BAT
(mA)
0
V
FLOAT
(V)
4.19
4.20
4.21
300
500
4069 G01
4.18
4.17
4.16
100
200
400
4.22
4.23
4.24
V
CC
= 5V
T
A
= 25
C
R
PROG
= 2k
TEMPERATURE (
C)
50
V
FLOAT
(V)
4.23
25
4069 G02
4.20
4.18
25
0
50
4.17
4.16
4.24
4.22
4.21
4.19
75
100
SUPPLY VOLTAGE (V)
4
V
FLOAT
(V)
4.20
4.21
4.22
6
4069 G03
4.19
4.18
4.16
4.5
5
5.5
4.17
4.24
4.23
T
A
= 25
C
I
BAT
= 2mA
R
PROG
= 2k
Battery Regulation (Float) Voltage
vs Temperature
Battery Regulation (Float) Voltage
vs Supply Voltage
Charge Current vs Supply Voltage
(Constant Current Mode)
Charge Current vs Battery Voltage
Charge Current vs Ambient
Temperature with Thermal
Regulation (Constant Current Mode)
SUPPLY VOLTAGE (V)
4
0
I
BAT
(mA)
25
50
75
100
125
150
175
200
4.5
5
5.5
6
4069 G04
R
PROG
= 10k
V
BAT
= 3.8V
T
A
= 25
C
V
BAT
(V)
0
0
I
BAT
(mA)
100
200
300
400
500
600
1
2
3
4
4069 G05
5
V
CC
= 5V
T
A
= 25
C
R
PROG
= 2k
PROG Pin Voltage vs Temperature
(Constant Current Mode)
PROG Pin Voltage
vs Charge Current
Power FET On Resistance
vs Temperature
TEMPERATURE (
C)
50
V
PROG
(V)
1.01
1.02
25
75
4069 G07
1.00
25
0
50
100
0.99
0.98
V
CC
= 5V
V
BAT
= 3.8V
R
PROG
= 10k
I
BAT
(mA)
0
0
V
PROG
(V)
0.2
0.4
0.6
0.8
1.0
1.2
100
200
300
400
4069 G08
500
V
CC
= 5V
T
A
= 25
C
R
PROG
= 2k
TEMPERATURE (
C)
50
300
R
DS
(m
)
350
400
450
500
550
25
0
25
50
4069 G09
75
100
V
CC
= 4V
I
BAT
= 400mA
TEMPERATURE (
C)
50
0
I
BAT
(mA)
100
200
300
400
0
50
100
150
4069 G06
500
600
THERMAL CONTROL
LOOP IN OPERATION
V
CC
= 5V
V
BAT
= 3.8V
R
PROG
= 2k
5
LTC4069
4069f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
CHRG Pin Output Low Voltage
vs Temperature
TEMPERATURE (
C)
50
80
100
140
25
75
4069 G10
60
40
25
0
50
100
20
0
120
V
CHRG
(mV)
V
CC
= 5V
I
CHRG
= 5mA
Trickle Charge Current
vs Supply Voltage
SUPPLY VOLTAGE (V)
4
0
I
BAT
(mA)
10
20
30
40
50
60
4.5
5
5.5
6
4069 G14
R
PROG
= 2k
R
PROG
= 10k
V
BAT
= 2V
T
A
= 25
C
Trickle Charge Current
vs Temperature
TEMPERATURE (
C)
50
I
BAT
(mA)
40
50
60
25
75
4069 G15
30
20
25
0
50
100
10
0
R
PROG
= 2k
R
PROG
= 10k
V
CC
= 5V
V
BAT
= 2V
Undervoltage Lockout Threshold
Voltage vs Temperature
TEMPERATURE (
C)
50
2.50
V
CC
(V)
2.75
3.00
3.25
3.50
4.00
25
0
25
RISE
FALL
50
4069 G16
75
100
3.75
Timer Accuracy vs Temperature
Timer Accuracy vs Supply Voltage
TEMPERATURE (
C)
50
TIMER ACCURACY (%)
4
3
2
25
75
4069 G18
5
6
7
25
0
50
1
0
1
100
V
CC
= 5V
SUPPLY VOLTAGE (V)
4
TIMER ACCURACY (%)
0
1.0
6
4069 G19
1.0
2.0
4.5
5
5.5
2.0
0.5
0.5
1.5
1.5
T
A
= 25
C
PROG Pin Shutdown Voltage
Threshold vs Temperature
PROG Pin Shutdown Voltage vs
Supply Voltage
TEMPERATURE (
C)
50
3.0
V
MS(PROG)
(V)
3.5
4.0
4.5
5.0
25
0
25
50
4069 G20
75
100
V
CC
= 5V
SUPPLY VOLTAGE (V)
4
V
MS(PROG)
(V)
2.0
3.0
4.0
5.0
2.5
3.5
4.5
4.5
5
5.5
4069 G21
6
T
A
= 25
C
6
LTC4069
4069f
U
U
U
PI FU CTIO S
GND (Pin 1): Ground.
CHRG (Pin 2): Open-Drain Charge Status Output. The
charge status indicator pin has three states: pull-down,
pulse at 2Hz and high impedance state. This output can be
used as a logic interface or as an LED driver. When the
battery is being charged, the CHRG pin is pulled low by an
internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current, the CHRG pin is
forced to a high impedance state. If the battery voltage
remains below 2.9V for one quarter of the charge time, the
battery is considered defective and the CHRG pin pulses at
a frequency of 2Hz (80% duty cycle). When the NTC pin
voltage rises above 0.76 V
CC
or drops below 0.35 V
CC
,
the CHRG pin pulses at a frequency of 2Hz (20% duty
cycle).
BAT (Pin 3): Charge Current Output. Provides charge
current to the battery and regulates the final float voltage
to 4.2V. An internal precision resistor divider on this pin
sets the float voltage and is disconnected in shutdown
mode.
V
CC
(Pin 4): Positive Input Supply Voltage. This pin
provides power to the charger. V
CC
can range from 3.75V
to 5.5V. This pin should be bypassed with at least a 1
F
capacitor. When V
CC
is within 32mV of the BAT pin
voltage, the LTC4069 enters shutdown mode, dropping
I
BAT
to about 1
A.
NTC (Pin 5): Input to the NTC (Negative Temperature
Coefficient) Thermistor Temperature Monitoring Circuit.
Under normal operation, connect a thermistor from the
NTC pin to ground and a resistor of equal value from the
NTC pin to V
CC
. When the voltage at this pin drops below
0.35 V
CC
at hot temperatures or rises above 0.76 V
CC
at
cold, charging is suspended, the internal timer is frozen
and the CHRG pin output will start to pulse at 2Hz. Pulling
this pin below 0.016 V
CC
disables the NTC feature. There
is approximately 3
C of temperature hysteresis associ-
ated with each of the input comparator's thresholds.
PROG (Pin 6): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor, R
PROG
, to
ground programs the charge current. When charging in
constant-current mode, this pin servos to 1V. In all modes,
the voltage on this pin can be used to measure the charge
current using the following formula:
I
V
R
BAT
PROG
PROG
=
1000
Floating the PROG pin puts the charger in shutdown mode.
In shutdown mode, the LTC4069 has less than 20
A
supply current and about 1
A battery drain current.
Exposed Pad (Pin 7): Ground. The Exposed Pad must be
soldered to the PCB ground to provide both electrical con-
tact and rated thermal performance.
7
LTC4069
4069f
Figure 1. LTC4069 Block Diagram
OPERATIO
U
The LTC4069 is a linear battery charger designed primarily
for charging single cell lithium-ion batteries. Featuring an
internal P-channel power MOSFET, the charger uses a
constant-current/constant-voltage charge algorithm with
programmable current. Charge current can be programmed
up to 750mA with a final float voltage accuracy of
0.6%.
The CHRG open-drain status output indicates if C/10 has
been reached. No blocking diode or external sense resistor
is required; thus, the basic charger circuit requires only
two external components. An internal termination timer
and trickle charge low-battery conditioning adhere to
battery manufacturer safety guidelines. Furthermore, the
LTC4069 is capable of operating from a USB power
source.
An internal thermal limit reduces the programmed charge
current if the die temperature attempts to rise above a
preset value of approximately 115
C. This feature protects
the LTC4069 from excessive temperature and allows the
user to push the limits of the power handling capability of
a given circuit board without risk of damaging the LTC4069
or external components. Another benefit of the LTC4069
thermal limit is that charge current can be set according to
typical, not worst-case, ambient temperatures for a given
+
+
+
+
2
+
MP
M2
1
M1
1000
V
CC
V
CC
R1
R2
MIN
ENABLE
R3
R4
R5
2.9V
CHRG
6
PROG
1
GND
4069 F01
R
PROG
BAT
1V
PROG
C/10
C1
+
TA
T
DIE
115
C
0.1V
1.2V
SUSPEND
D3
TOO
HOT
TOO
COLD
NTC_EN
0.1V
D2
3.6V
D1
1.2V
+
REF
CA
MA
LOBAT
5
R7
NTC
R8
R9
R10
V
CC
V
CC
+
UVLO
3
4
BAT
LOGIC
COUNTER
OSCILLATOR
CHARGE CONTROL
+
+
C3
+
C2
C5
VA
4V
+
SHUTDOWN
SUSPEND
OR
AND
R
NOM
R
NTC
C4
SI PLIFIED
W
BLOCK DIAGRA
W
8
LTC4069
4069f
OPERATIO
U
application with the assurance that the charger will auto-
matically reduce the current in worst-case conditions.
The charge cycle begins when the voltage at the V
CC
pin
rises above 3.5V and approximately 80mV above the BAT
pin voltage, a 1% program resistor is connected from the
PROG pin to ground and the NTC pin voltage stays
between 0.76 V
CC
and 0.35 V
CC
or below 0.016 V
CC
.
If the BAT pin voltage is below 2.9V, the charger goes into
trickle charge mode, charging the battery at one-tenth the
programmed charge current to bring the cell voltage up to
a safe level for charging. If the BAT pin voltage is above
4.1V, the charger will not charge the battery as the cell is
near full capacity. Otherwise, the charger goes into the fast
charge constant-current mode.
When the BAT pin approaches the final float voltage
(4.2V), the LTC4069 enters constant-voltage mode and
the charge current begins to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator turns off the N-channel MOSFET on the CHRG
pin and the pin assumes a high impedance state.
An internal timer sets the total charge time, t
TIMER
(typi-
cally 4.5 hours). When this time elapses, the charge cycle
terminates and the CHRG pin assumes a high impedance
state. The charge cycle will automatically restart if the BAT
pin voltage falls below V
RECHRG
(typically 4.1V). To manu-
ally restart the charge cycle, remove the input voltage and
reapply it, or momentarily float the PROG pin and recon-
nect it.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The battery charge current
is 1000 times the current out of the PROG pin. The
program resistor and the charge current are calculated
using the following equations:
R
V
I
I
V
R
PROG
CHG
CHG
PROG
=
=
1000
1
1000
,
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage and using
the following equation:
I
V
R
BAT
PROG
PROG
=
1000
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input
voltage and keeps the charger in undervoltage lockout
until V
CC
rises above 3.6V
and approximately 80mV above
the BAT pin voltage. The 3.6V UVLO circuit has a built-in
hysteresis of approximately 0.6V and the automatic shut-
down threshold has a built-in hysteresis of approximately
50mV. During undervoltage lockout conditions, maxi-
mum battery drain current is 4
A and maximum supply
current is 11
A.
Shutdown Mode
The LTC4069 can be disabled by floating the PROG pin. In
shutdown mode, the battery drain current is reduced to
less than 1
A and the supply current to about 20A.
Timer and Recharge
The LTC4069 has an internal termination timer that starts
when an input voltage greater than the undervoltage
lockout threshold is applied to V
CC
, or when leaving
shutdown and the battery voltage is less than the recharge
threshold.
At power-up or when exiting shutdown, if the battery
voltage is less than the recharge threshold, the charge
time is set to 4.5 hours. If the battery temperature is either
too high or too low, the timer will pause until the battery
returns to normal temperature. If the battery is greater
than the recharge threshold at power-up or when exiting
shutdown, the timer will not start and charging is pre-
vented since the battery is at or near full capacity.
Once the charge cycle terminates, the LTC4069 continu-
ously monitors the BAT pin voltage using a comparator
with a 2ms filter time. When the battery voltage falls below
4.1V (which corresponds to 80% to 90% battery capac-
ity), a new charge cycle is initiated and a 2.25 hour timer
begins. This ensures that the battery is kept at, or near, a
fully charged condition and eliminates the need for peri-
odic charge cycle initiations. Also, if the battery voltage
9
LTC4069
4069f
OPERATIO
U
does not exceed the recharge threshold voltage when the
timer ends, the timer resets and a 2.25 hour recharge cycle
begins. The CHRG output assumes a strong pull-down
state during recharge cycles until C/10 is reached when it
transitions to a high impendance state.
Trickle Charge and Defective Battery Detection
At the beginning of a charge cycle, if the battery voltage is
low (below 2.9V), the charger goes into trickle charge,
reducing the charge current to 10% of the full-scale
current. If the low-battery voltage persists for one quarter
of the total time (1.125 hour), the battery is assumed to be
defective, the charge cycle is terminated and the CHRG pin
output pulses at a frequency of 2Hz with a 80% duty cycle.
If for any reason the battery voltage rises above 2.9V, the
charge cycle will be restarted. To restart the charge cycle
(i.e., when the defective battery is replaced with a dis-
charged battery), simply remove the input voltage and
reapply it or momentarily float the PROG pin and
reconnect it.
CHRG Status Output Pin
The charge status indicator pin has three states: pull-
down, pulse at 2Hz (see Trickle Charge and Defective
Battery Detection and Battery Temperature Monitoring)
and high impedance. The pull-down state indicates that
the LTC4069 is in a charge cycle. A high impedance state
indicates that the charge current has dropped below 10%
of the full-scale current or the LTC4069 is disabled. Figure
2 shows the CHRG status under various conditions.
Charge Current Soft-Start and Soft-Stop
The LTC4069 includes a soft-start circuit to minimize the
inrush current at the start of a charge cycle. When a charge
cycle is initiated, the charge current ramps from zero to the
full-scale current over a period of approximately 170
s.
Likewise, internal circuitry slowly ramps the charge cur-
rent from full-scale to zero when the charger is shut off or
self terminates. This has the effect of minimizing the
transient current load on the power supply during start-up
and charge termination.
Constant-Current/Constant-Voltage/
Constant-Temperature
The LTC4069 uses a unique architecture to charge a
battery in a constant-current, constant-voltage and con-
stant-temperature fashion. Figure 1 shows a Simplified
Block Diagram of the LTC4069. Three of the amplifier
feedback loops shown control the constant-current (CA),
constant-voltage (VA), and constant-temperature (TA)
modes. A fourth amplifier feedback loop (MA) is used to
increase the output impedance of the current source pair,
M1 and M2 (note that M1 is the internal P-channel power
MOSFET). It ensures that the drain current of M1 is exactly
1000 times greater than the drain current of M2.
Amplifiers CA and VA are used in separate feedback loops
to force the charger into constant-current or constant-
voltage mode, respectively. Diodes D1 and D2 provide
priority to either the constant-current or constant-voltage
loop, whichever is trying to reduce the charge current the
most. The output of the other amplifier saturates low
which effectively removes its loop from the system. When
in constant-current mode, CA servos the voltage at the
PROG pin to be precisely 1V. VA servos its inverting input
to an internal reference voltage when in constant-voltage
mode and the internal resistor divider, made up of R1 and
R2, ensures that the battery voltage is maintained at 4.2V.
The PROG pin voltage gives an indication of the charge
current during constant-voltage mode as discussed in
"Programming Charge Current".
Transconductance amplifier, TA, limits the die tempera-
ture to approximately 115
C when in constant-tempera-
ture mode. Diode D3 ensures that TA does not affect the
charge current when the die temperature is below approxi-
mately 115
C. The PROG pin voltage continues to give an
indication of the charge current.
In typical operation, the charge cycle begins in constant-
current mode with the current delivered to the battery
equal to 1000V/R
PROG
. If the power dissipation of the
LTC4069 results in the junction temperature approaching
115
C, the amplifier (TA) will begin decreasing the charge
current to limit the die temperature to approximately
115
C. As the battery voltage rises, the LTC4069 either
returns to constant-current mode or enters constant-
voltage mode straight from constant-temperature mode.
10
LTC4069
4069f
OPERATIO
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Figure 2. State Diagram of LTC4069 Operation
Regardless of mode, the voltage at the PROG pin is
proportional to the current delivered to the battery.
Battery Temperature Monitoring via NTC
The battery temperature is measured by placing a negative
temperature coefficient (NTC) thermistor close to the
battery pack. The NTC circuitry is shown in Figure 3.
To use this feature, connect the NTC thermistor, R
NTC
,
between the NTC pin and ground and a resistor, R
NOM
,
from the NTC pin to V
CC
. R
NOM
should be a 1% resistor
with a value equal to the value of the chosen NTC ther-
mistor at 25
C (this value is 10k for a Vishay
NTHS0603NO1N1002J thermistor). The LTC4069 goes
into hold mode when the value of the NTC thermistor drops
to 0.53 times the value of R
NOM
, which corresponds to
approximately 40
C, and when the value of the NTC
thermistor increases to 3.26 times the value of R
NOM
,
which corresponds to approximately 0
C. Hold mode
freezes the timer and stops the charge cycle until the
thermistor indicates a return to a valid temperature. For a
Vishay NTHS0603NO1N1002J thermistor, this value is
32.6k which corresponds to approximately 0
C. The hot
and cold comparators each have approximately 3
C of
hysteresis to prevent oscillation about the trip point.
When the charger is in Hold mode (battery temperature is
either too hot or too cold) the CHRG pin pulses in a 2Hz,
20% duty cycle frequency unless the charge task is
finished or the battery is assumed to be defective. If the
NTC pin is grounded, the NTC function will be disabled.
IF V
CC
> 3.6V AND
V
CC
> V
BAT
+ 80mV?
UVLO
UVLO MODE
1/10 FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
TRICKLE CHARGE MODE
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
FAST CHARGE MODE
IS V
BAT
< 2.9V?
DEFECTIVE BATTERY
IS V
BAT
< 4.1V?
RECHARGE
NO CHARGE CURRENT
CHRG PULSES (2Hz)
BAD BATTERY MODE
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
RECHARGE MODE
CHRG HIGH IMPEDANCE
YES
YES
NO
NO
4069 F02
V
BAT
2.9V
1/4 CHARGE CYCLE
(1.125 HOURS)
V
CC
< 3V
CHARGE CYCLE
(4.5 HOURS)
1/2 CHARGE CYCLE
(2.25 HOURS)
2.9V < V
BAT
< 4.1V
V
BAT
> 4.1V
YES
NO
NO CHARGE CURRENT
CHRG HIGH IMPEDANCE
STANDBY MODE
POWER
ON
BATTERY CHARGING SUSPENDED
CHRG PULSES (2Hz)
NTC FAULT
TEMPERATURE OK
TEMPERATURE
NOT OK
TEMPERATURE NOT OK
11
LTC4069
4069f
Undervoltage Charge Current Limiting (UVCL)
The LTC4069 includes undervoltage charge (
V
UVCL1
)
current limiting that prevents full charge current until the
input supply voltage exceeds approximately 200mV above
the battery voltage. This feature is particularly useful if the
LTC4069 is powered from a supply with long leads (or any
relatively high output impedance).
For example, USB-powered systems tend to have highly
variable source impedances (due primarily to cable quality
and length). A transient load combined with such imped-
ance can easily trip the UVLO threshold and turn the
charger off unless undervoltage charge current limiting is
implemented.
Consider a situation where the LTC4069 is operating
under normal conditions and the input supply voltage
begins to droop (e.g., an external load drags the input
supply down). If the input voltage reaches
V
BAT
+
V
UVCL1
(approximately 220mV above the battery voltage),
undervoltage charge current limiting will begin to reduce
the charge current in an attempt to maintain
V
UVCL1
between the V
CC
input and the BAT output of the IC. The
LTC4069 will continue to operate at the reduced charge
current until the input supply voltage is increased or
constant voltage mode reduces the charge current further.
Operation from Current Limited Wall Adapter
By using a current limited wall adapter as the input supply,
the LTC4069 dissipates significantly less power when
programmed for a current higher than the limit of the
supply as compared to using a non-current limited supply
at the same charge current.
Consider a situation where an application demands a
600mA charge current for an 800mAh Li-Ion battery. If a
typical 5V (non-current limited) input supply is used, the
charger's peak power dissipation can exceed 1W.
Now consider the same scenario, but with a 5V input
supply with a 600mA current limit. To take advantage of
the current limited supply, it is necessary to program the
LTC4069 to charge at a current above 600mA. Assume
that the LTC4069 is programmed for 750mA (i.e., R
PROG
= 1.33k) to ensure that part tolerances maintain a pro-
grammed current higher than 600mA. Since the LTC4069
APPLICATIO S I FOR ATIO
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Figure 3. NTC Circuit Information
OPERATIO
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4069 F03
R
NOM
R
NTC
V
CC
+
+
+
TOO COLD
TOO HOT
NTC_ENABLE
0.76 V
CC
0.35 V
CC
0.016 V
CC
6
NTC
12
LTC4069
4069f
will demand a charge current higher than the current limit
of the voltage supply, the supply voltage will drop to the
battery voltage plus 600mA times the "on" resistance of
the internal PFET. The "on" resistance of the LTC4069
power device is approximately 450m
with a 5V supply.
The actual "on" resistance will be slightly higher due to the
fact that the input supply will drop to less than 5V. The
power dissipated during this phase of charging is less than
240mW. That is a 76% improvement over the non-current
limited supply power dissipation.
USB and Wall Adapter Power
Although the LTC4069 allows charging from a USB port,
a wall adapter can also be used to charge Li-Ion batteries.
Figure 4 shows an example of how to combine wall adapter
and USB power inputs. A P-channel MOSFET, MP1, is
used to prevent back conducting into the USB port when
a wall adapter is present and Schottky diode, D1, is used
to prevent USB power loss through the 1k pull-down
resistor.
Typically a wall adapter can supply significantly more
current than the 500mA-limited USB port. Therefore, an
N-channel MOSFET, MN1, and an extra program resistor
are used to increase the charge current to 750mA when the
wall adapter is present.
Stability Considerations
The LTC4069 contains two control loops: constant-volt-
age and constant-current. The constant-voltage loop is
stable without any compensation when a battery is con-
nected with low impedance leads. Excessive lead length,
however, may add enough series inductance to require a
bypass capacitor of at least 1
F from BAT to GND. Further-
more, a 4.7
F capacitor with a 0.2 to 1 series resistor
from BAT to GND is required to keep ripple voltage low
when the battery is disconnected.
High value capacitors with very low ESR (especially ce-
ramic) may reduce the constant-voltage loop phase mar-
gin. Ceramic capacitors up to 22
F may be used in parallel
with a battery, but larger ceramics should be decoupled
with 0.2
to 1 of series resistance.
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. Because of the additional pole
created by the PROG pin capacitance, capacitance on this
pin must be kept to a minimum. With no additional
capacitance on the PROG pin, the charger is stable with
program resistor values as high as 25k. However, addi-
tional capacitance on this node reduces the maximum
allowed program resistor. The pole frequency at the PROG
pin should be kept above 100kHz. Therefore, if the PROG
pin is loaded with a capacitance, C
PROG
, the following
equation should be used to calculate the maximum resis-
tance value for R
PROG
:
R
C
PROG
PROG
1
2
10
5
Average, rather than instantaneous, battery current may
be of interest to the user. For example, if a switching power
supply operating in low current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
instantaneous current pulses. In such a case, a simple RC
filter can be used on the PROG pin to measure the average
Figure 5. Isolating Capacitive Load on the PROG Pin and Filtering
APPLICATIO S I FOR ATIO
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Figure 4. Combining Wall Adapter and USB Power
V
CC
MP1
MN1
1k
2k
4.02k
I
CHG
D1
Li-Ion
BATTERY
SYSTEM
LOAD
4069 F04
LTC4069
BAT
USB
POWER
500mA
I
CHG
5V WALL
ADAPTER
750mA
I
CHG
PROG
+
4069 F05
C
FILTER
CHARGE
CURRENT
MONITOR
CIRCUITRY
R
PROG
LTC4069
PROG
GND
10k
13
LTC4069
4069f
battery current as shown in Figure 5. A 10K resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
Power Dissipation
The conditions that cause the LTC4069 to reduce charge
current through thermal feedback can be approximated by
considering the power dissipated in the IC. For high charge
currents, the LTC4069 power dissipation is approximately:
P
D
= (V
CC
V
BAT
) I
BAT
where P
D
is the power dissipated, V
CC
is the input supply
voltage, V
BAT
is the battery voltage and I
BAT
is the charge
current. It is not necessary to perform any worst-case
power dissipation scenarios because the LTC4069 will
automatically reduce the charge current to maintain the
die temperature at approximately 115
C. However, the
approximate ambient temperature at which the thermal
feedback begins to protect the IC is:
T
A
= 115
C P
D
JA
T
A
= 115
C (V
CC
V
BAT
) I
BAT
JA
Example: Consider an LTC4069 operating from a 5V wall
adapter providing 750mA to a 3.6V Li-Ion battery. The
ambient temperature above which the LTC4069 will begin
to reduce the 750mA charge current is approximately:
T
A
= 115
C (5V 3.6V) (750mA) 60C/W
T
A
= 115
C (1.05W 60C/W) = 115C 63C
T
A
= 52
C
The LTC4069 can be used above 70
C, but the charge
current will be reduced from 750mA. The approximate
current at a given ambient temperature can be calculated:
I
C T
V
V
BAT
A
CC
BAT
JA
=
(
)
115
APPLICATIO S I FOR ATIO
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Using the previous example with an ambient temperature
of 73
C, the charge current will be reduced to approxi-
mately:
I
C
C
V
V
C W
C
C A
mA
BAT
=
(
)
=
=
115
73
5
3 6
60
42
84
500
.
/
/
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in the
Programming Charge Current section.
It is important to remember that LTC4069 applications do
not need to be designed for worst-case thermal conditions
since the IC will automatically limit power dissipation
when the junction temperature reaches approximately
115
C.
Board Layout Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on the
backside of the LTC4069 package is soldered to the PC
board copper and extending out to relatively large copper
areas or internal copper layers connected using vias.
Correctly soldered to a 2500mm
2
double-sided 1 oz.
copper board the LTC4069 has a thermal resistance of
approximately 60
C/W. Failure to make thermal contact
between the Exposed Pad on the backside of the package
and the copper board will result in thermal resistances far
greater than 60
C/W. As an example, a correctly soldered
LTC4069 can deliver over 750mA to a battery from a 5V
supply at room temperature. Without a backside thermal
connection, this number could drop to less than 500mA.
V
CC
Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-
layer ceramic capacitors. Because of the self-resonant and
high Q characteristics of some types of ceramic capaci-
tors, high voltage transients can be generated under some
start-up conditions, such as connecting the charger input
to a live power source. For more information, refer to
Application Note 88.
14
LTC4069
4069f
Thermistors
The LTC4069 NTC trip points are designed to work with
thermistors whose resistance-temperature characteris-
tics follow Vishay Dale's "R-T Curve 1." The Vishay
NTHS0603NO1N1002J is an example of such a ther-
mistor. However, Vishay Dale has many thermistor prod-
ucts that follow the "R-T Curve 1" characteristic in a variety
of sizes. Furthermore, any thermistor whose ratio of
R
COLD
to R
HOT
is about 5 will also work (Vishay Dale R-T
Curve 1 shows a ratio of R
COLD
to R
HOT
of 3.266/0.5325 =
6.13).
Power conscious designs may want to use thermistors
whose room temperature value is greater than 10k. Vishay
Dale has a number of values of thermistor from 10k to
100k that follow the "R-T Curve 1." Using different R-T
curves, such as Vishay Dale "R-T Curve 2", is also pos-
sible. This curve, combined with LTC4069 internal thresh-
olds, gives temperature trip points of approximately 0
C
(falling) and 40
C (rising), a delta of 40C. This delta in
temperature can be moved in either direction by changing
the value of R
NOM
with respect to R
NTC
. Increasing R
NOM
will move both trip points to higher temperatures. To
calculate R
NOM
for a shift to lower temperature for ex-
ample, use the following equation:
R
R
R
at
C
NOM
COLD
NTC
=
3 266
25
.
where R
COLD
is the resistance ratio of R
NTC
at the desired
cold temperature trip point. If you want to shift the trip
points to higher temperatures use the following equation:
R
R
R
at
C
NOM
HOT
NTC
=
0 5325
25
.
where R
HOT
is the resistance ratio of R
NTC
at the desired
hot temperature trip point.
Here is an example using a 100k R-T Curve 2 thermistor
from Vishay Dale. The difference between the trip points is
40
C, from before, and we want the cold trip point to be
0
C, which would put the hot trip point at 40C. The R
NOM
needed is calculated as follows:
R
R
R
at
C
NOM
COLD
NTC
=
=
3 266
25
2 816
3
.
.
.
.
.
266
10
8 62
k
k
=
The nearest 1% value for R
NOM
is 8.66k. This is the value
used to bias the NTC thermistor to get cold and hot trip
points of approximately 0
C and 40C respectively. To
extend the delta between the cold and hot trip points, a
resistor, R1, can be added in series with R
NTC
(see Figure
6). The values of the resistors are calculated as follows:
R
R
R
R
NOM
COLD
HOT
=
-
-
=
3 266 0 5325
0 5325
3 266
1
.
.
.
.
-
-
-
(
)
-
0 5325
.
R
R
R
COLD
HOT
HOT
where R
NOM
is the value of the bias resistor and R
HOT
and
R
COLD
are the values of R
NTC
at the desired temperature
trip points. Continuing the example from before with a
desired trip point of 50
C:
4069 F06
R
NOM
8.87k
R
NTC
10k
V
CC
+
+
+
TOO COLD
TOO HOT
NTC_ENABLE
R1
604
0.76 V
CC
0.35 V
CC
0.016 V
CC
6
NTC
Figure 6. NTC Circuits
APPLICATIO S I FOR ATIO
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15
LTC4069
4069f
U
PACKAGE DESCRIPTIO
DC Package
6-Lead Plastic DFN (2mm
2mm)
(Reference LTC DWG # 05-08-1703)
2.00
0.10
(4 SIDES)
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
0.38
0.05
BOTTOM VIEW--EXPOSED PAD
0.56
0.05
(2 SIDES)
0.75
0.05
R = 0.115
TYP
1.37
0.05
(2 SIDES)
1
3
6
4
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 0.05
(DC6) DFN 1103
0.25
0.05
0.50 BSC
0.25
0.05
1.42
0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.61
0.05
(2 SIDES)
1.15
0.05
0.675
0.05
2.50
0.05
PACKAGE
OUTLINE
0.50 BSC
PIN 1
CHAMFER OF
EXPOSED PAD
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
R
R
R
k
NOM
COLD
HOT
=
-
-
=
-
3 266 0 5325
10
2 816 0
.
.
.
.44086
3 266 0 5325
8 8 8 87
(
)
-
=
.
.
. , .
k
k is
%
.
.
.
the nearest
value
R
k
1
10
0 5325
3 26
1
=
6
6 0 5325
2 816 0 4086
0 4086
-
-
(
)
-
.
.
.
.
,
%
.
= 604 604
1
is the nearest
value
NTC Trip Point Error
When a 1% resistor is used for R
HOT
, the major error in the
40
C trip point is determined by the tolerance of the NTC
thermistor. A typical 100k NTC thermistor has
10%
tolerance. By looking up the temperature coefficient of the
thermistor at 40
C, the tolerance error can be calculated in
degrees centigrade. Consider the Vishay
NTHS0603N01N1003J thermistor, which has a tempera-
ture coefficient of 4%/
C at 40C. Dividing the tolerance
by the temperature coefficient,
5%/(4%/C) = 1.25C,
gives the temperature error of the hot trip point.
The cold trip point error depends on the tolerance of the
NTC thermistor and the degree to which the ratio of its
value at 0
C and its value at 40C varies from 6.14 to 1.
Therefore, the cold trip point error can be calculated using
the tolerance, TOL, the temperature coefficient of the
thermistor at 0
C, TC (in %/C), the value of the thermistor
at 0
C, R
COLD
, and the value of the thermistor at 40
C,
R
HOT
. The formula is:
Temperature Error C
TOL
R
R
COLD
HOT
( )
.
=
+
1
6 14
-
-
1
100
TC
For example, the Vishay NTHS0603N01N1003J thermistor
with a tolerance of
5%, TC of 5%/C and R
COLD
/R
HOT
of
6.13, has a cold trip point error of:
Temperature Error C
( )
.
.
.
=
+
-
1 0 05
6 14
6 13 1
-
100
5
.
, .
= -
0 95
1 05
C
C
APPLICATIO S I FOR ATIO
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LTC4069
4069f
LINEAR TECHNOLOGY CORPORATION 2005
LT 1105 PRINTED IN THE USA
RELATED PARTS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
FAX: (408) 434-0507
www.linear.com
PART NUMBER
DESCRIPTION
COMMENTS
Battery Chargers
LTC1734
Lithium-Ion Linear Battery Charger in ThinSOT
TM
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
LTC1734L
Lithium-Ion Linear Battery Charger in ThinSOT
Low Current Version of LTC1734, 50mA
I
CHRG
180mA
LTC4002
Switch Mode Lithium-Ion Battery Charger
Standalone, 4.7V
V
IN
24V, 500kHz Frequency, 3 Hour Charge
Termination
LTC4050
Lithium-Ion Linear Battery Charger Controller
Features Preset Voltages, C/10 Charger Detection and Programmable
Timer, Input Power Good Indication, Thermistor Interface
LTC4052
Monolithic Lithium-Ion Battery Pulse Charger
No Blocking Diode or External Power FET Required,
1.5A Charge Current
LTC4053
USB Compatible Monolithic Li-Ion Battery Charger
Standalone Charger with Programmable Timer, Up to 1.25A Charge
Current
LTC4054
Standalone Linear Li-Ion Battery Charger
Thermal Regulation Prevents Overheating, C/10 Termination,
with Integrated Pass Transistor in ThinSOT
C/10 Indicator, Up to 800mA Charge Current
LTC4057
Lithium-Ion Linear Battery Charger
Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package
LTC4058
Standalone 950mA Lithium-Ion Charger in DFN
C/10 Charge Termination, Battery Kelvin Sensing,
7% Charge Accuracy
LTC4059/LTC4059A
900mA Linear Lithium-Ion Battery Charger
2mm
2mm DFN Package, Thermal Regulation, Charge Current Monitor
Output, Version A has ACPR Function
LTC4061
Standalone Li-Ion Charger with Thermistor Interface
4.2V,
0.35% Float Voltage, Up to 1A Charge Current, 3mm 3mm DFN
LTC4061-4.4
Standalone Li-Ion Charger with Thermistor Interface
4.4V (Max),
0.4% Float Voltage, Up to 1A Charge Current,
3mm
3mm DFN
LTC4062
Standalone Linear Li-Ion Battery Charger with
4.2V,
0.35% Float Voltage, Up to 1A Charge Current, 3mm 3mm DFN
Micropower Comparator
LTC4063
Li-Ion Charger with Linear Regulator
Up to 1A Charge Current, 100mA, 125mV LDO, 3mm
3mm DFN
LTC4065/LTC4065A
Standalone Li-Ion Battery Charger
4.2V,
0.6% Float Voltage, Up to 750mA Charge Current,
2mm
2mm DFN, Version A has ACPR Function
LTC4411/LTC4412
Low Loss PowerPath
TM
Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
Power Management
LTC3405/LTC3405A
300mA (I
OUT
), 1.5MHz, Synchronous Step-Down
95% Efficiency, V
IN
: 2.7V to 6V, V
OUT
= 0.8V, I
Q
= 20
A, I
SD
< 1
A,
DC/DC Converter
ThinSOT Package
LTC3406/LTC3406A
600mA (I
OUT
), 1.5MHz, Synchronous Step-Down
95% Efficiency, V
IN
: 2.5V to 5.5V, V
OUT
= 0.6V, I
Q
= 20
A, I
SD
< 1
A,
DC/DC Converter
ThinSOT Package
LTC3411
1.25A (I
OUT
), 4MHz, Synchronous Step-Down
95% Efficiency, V
IN
: 2.5V to 5.5V, V
OUT
= 0.8V, I
Q
= 60
A, I
SD
< 1
A,
DC/DC Converter
MS Package
LTC3440
600mA (I
OUT
), 2MHz, Synchronous Buck-Boost
95% Efficiency, V
IN
: 2.5V to 5.5V, V
OUT
= 2.5V, I
Q
= 25
A, I
SD
< 1
A,
DC/DC Converter
MS Package
LTC4413
Dual Ideal Diode in DFN
2-Channel Ideal Diode ORing, Low Forward ON Resistance, Low Regulated
Forward Voltage, 2.5V
V
IN
5.5V
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
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