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SC804A

Fully Integrated 4.4V Lithium-Ion

Battery Charger System with Timer

PRELIMINARY

POWER MANAGEMENT

October 4, 2005

Typical Application Circuit

Applications

Description

Features

The SC804A is a fully integrated full-feature, single cell
constant-current/constant-voltage (CC/CV) 4.4V Lithium-
Ion battery charger. With an integrated timer and
complete charge control algorithm, the SC804A is ideal for
stand-alone charger applications. The SC804A contains
programmable pre-charge, fast-charge and termination
current settings. The SC804A can be programmed to
terminate charging based on the output current or the
time-out of the programmable timer. The fast charge
current is typically set with an external resistor, but it can
also be adjusted by applying an analog voltage to the AFC
pin. This feature allows use of a microcontroller to set
charging current via a DAC output.

The SC804A's 14V input voltage range eliminates the
need for additional protection circuitry required by other
5V chargers to protect against faulty adapters. The
SC804A also incorporates an under-voltage lockout falling
threshold of 3V so that charging will continue if the input
supply goes into a current-limited mode.

Reference ground and battery sense inputs are provided
to eliminate voltage drops during charging due to high
charging currents.

The output voltage to the battery is controlled to within
1% of the programmed voltage. The SC804A can also
function as a general purpose current source or as a
current source for charging nickel-cadmium (NiCd) and
nickel-metal-hydride (NiMH) batteries.

Typical Application Circuit

Fully integrated charger with FET pass transistor,
reverse-blocking diode, sense resistor, timer, and
thermal protection

Battery voltage controlled to 1% accuracy

Programmable precharge, fastcharge & termination
current over wide range, with analog current control
reference input for design fl exibility

Up to 1.5A continuous charge current

Input voltage range from 3V to 14V

Soft-start reduces start-of-charge adapter

load transients

NTC thermistor sense input and adjustable cold
temperature threshold

Adjustable 2 - 6 hour programmable charge timer

0.1A battery drain current in shutdown and monitor
modes

Small 4mm x 4mm 16 lead MLPQ package

Over-current protection in all modes

Over-voltage protection

Remote Kelvin sensing at the battery terminals

Status indicators for charger-present, charger-active,
over-voltage fault, and error notifi cation

Cellular phones

PDAs

Handheld meters

Charging stations

Handheld computers

Digital cameras

Programmable current
source

VCC

OVPB

IPRGM

NTC

CPB

CHRGB

RTIM

CTO

11
10
12

ITERM

FLTB

8
6

GND

RGND

BSEN

VOUT
VOUT

AFC

16
15

SC804A

2.2

Battery

Red

Green

Charger VIN

NTC

DAC ISET

C2
2.2

ERROR

OV_FLT

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

Electrical Characteristics

Unless otherwise noted: VCC = 4.75V - 5.25V. Typical values are at T

= 25°C Min and Max are for -40°C < T

< +85°C unless noted.

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Operating Voltage

VCC

4.28

5.0

6.22

(1)

VCC UVLO Rising Threshold

UVLOR

Charging begins when

threshold is exceeded

3.88

4.08

4.28

VCC UVLO Falling Threshold

UVLOF

Charging continues until

threshold is reached

2.86

3.06

3.26

VCC OVP
Rising Threshold

OVPR

6.63

6.94

7.40

VCC OVP
Falling Threshold

OVPF

6.22

6.63

7.00

VCC OVP Hysteresis

OVPH

200

350

600

Operating Current

ICC

DIS

Shutdown Mode - CHRGB, CPB,

OVPB, FLTB off NTC = 0V

1.9

ICC

CHG

Charging Mode - CHRGB, CPB,

OVPB, FLTB off NTC = 2.5V

2.0

Exceeding the specifi cations below may result in permanent damage to the device or device malfunction. Operation outside of the parameters specifi ed in the
Electrical Characteristics section is not implied.

Parameter

Symbol

Maximum

Units

VCC, CTO, NTC to GND

-0.3 to 14.0

VOUT, BSEN, RTIM, AFC, IPRGM, CPB, CHRGB, OVPB,
ITERM, FLTB, to GND

-0.3 to +6.0

RGND to GND

-0.3 to 0.3

VOUT Output Current

VOUT

1.5

Power Dissipation MLP (Derate 20mW/°C above 85°C)

Thermal Impedance, Junction to Ambient

(1)

°C/W

Junction Temperature

150

°C

Operating Ambient Temperature Range

-40 to +85

°C

IR Refl ow Temperature

LEAD

260

°C

Storage Temperature Range

STG

-65 to 150

°C

VOUT short to GND

Continuous

ESD Protection Level

(2)

ESD

Absolute Maximum Ratings

Notes:
1) Calculated from package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
2) Tested according to JEDEC standard JESD22-A11 4-B.

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SC804A

POWER MANAGEMENT

Electrical Characteristics (Cont.)

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Battery Leakage Current
(VOUT and BSEN)

ILEAK

BAT

VCC = 0V,

VOUT = BSEN = 4.5V

0.1

Regulated Constant
Voltage

0°C T

125°C

4.314

4.357

4.40

RGND Output Accuracy
VOUT = VOUT

NOM

+ RGND

RGND

RGND - GND = 30mV

RGND Current

RGND

RGND = 0V

Battery Pre-Charge Current

PREQ

ITERM

= 499, 0°C T

125°C

270

300

330

Battery Termination
Current

TERM

ITERM

= 499, 0°C T

125°C

270

300

330

Battery Fast-Charge
Current

FAST

PRGM

= 1.87k, VOUT = 3.8V

0°C T

125°C

753

815

878

AFC DAC
Fast-Charge Current

DACADJ

PRGM

= 1.87k, V(AFC) = 0.75V

0°C T

125°C

364

405

447

AFC Enable/Disable
Threshold

AFC

VCC - V

AFC

> VT

AFC

disables

Analog Fast Charge

ITERM Regulated
Voltage

ITERM

1.45

1.557

1.66

IPROG Regulated
Voltage

IPRGM

1.45

1.557

1.66

BAT

Precharge

Threshold

PreQ

0°C T

125°C

2.9

3.01

3.11

BAT

Recharge

Threshold

ReQ

- V

BSEN

, 0°C T

85°C

100

140

Over-Temperature
Shutdown

Hysteresis = 10°C

150

°C

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

Electrical Characteristics (Cont.)

Parameter

Symbol

Conditions

Min

Typ

Max

Units

NTC Thresholds

NTCDIS

SC804A Disabled

0.3

0.6

0.8

NTCH

NTC Hot V

Applies to falling threshold

4.3V VCC 6.5V

at VCC = 5V

1.45

1.50

1.55

% of

VCC

NTCC

NTC Cold V

, V

CTO

= 0V

Applies to rising threshold

4.3V VCC 6.5V

at VCC = 5V

73.4

3.67

74.4

3.72

75.4

3.77

% of

VCC

NTCHYS

NTC Hot & Cold VT

NTCx

hysteresis

(VT

NTCx

Rising - VT

NTCx

Falling)

Applies to internal NTC thresholds

CTO

CTO Voltage (Adjustable NTC

Cold Rising Threshold) Setting

Range

(2)

, -40°C T

25°C

(NTC

Cold Rising Threshold is VT

NTCC

when CTO tied to GND)

% of

VCC

Threshold Error

(3)

-40°C T

25°C

-70

CTOHYS

Internal hysteresis on CTO

CTO

Rising - V

CTO

Falling)

Applies to externally set

NTC cold threshold

Adjust Mode BSEN Voltage

BSEN-ADJ

3.5V VOUT VCC - 150mV

0°C T

125°C

3.189

3.217

3.253

Adjust Mode Enable Voltage,
VOUT-BSEN

ADJEN

3.5V VOUT VCC - 150mV

400

Adjust Mode Disable
Voltage, VOUT-BSEN

ADJDIS

3.5V VOUT VCC - 150mV

150

External RTIM
Regulation Voltage

RTIM

= 37.4k

1.450

1.557

1.660

Timer Disable
Threshold

TIMER

RTIM

TIMER

disables internal timer

0.65

0.85

Internal Timer Select

INTTS

VCC-V

RTIM

> VT

INTTS

selects internal timer

1.1

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SC804A

POWER MANAGEMENT

Electrical Characteristics (Cont.)

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Pre-Charge Fault
Time-out

PreQF

RTIM

= 37.4k

RTIM pulled to VCC

-20%
-35%

51
44

+20%
+35%

min

Complete Charge
Time-out

QCOMP

RTIM

= 37.4k

RTIM pulled to VCC

-20%
-35%

3.37
2.89

+20%
+35%

CHRGB On

CHRGB

Load = 5mA

0.5

CHRGB Off

CHRGB

Leakage Current, V = 5V

CPB On

CPB

Load = 5mA

0.5

CPB Off

CPB

Leakage Current, V = 5V

OVPB On

OVPB

Load = 5mA

0.5

OVPB Off

OVPB

Leakage Current, V = 5V

FLTB On

FLTB

Load = 5mA

0.5

FLTB Off

FLTB

Leakage Current, V = 5V

Notes:
1)

VCC_OP Max is the "Maximum Vsupply" as defi ned in EIA/JEDEC Standard No. 78, paragraph 2.11.

2) The absolute voltage on CTO must not exceed 6.0V to ensure normal operation.
3) The threshold error is tested at V

CTO

min and max only.

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

DEVICE

PACKAGE

SC804AMLTRT

(1)

MLPQ -16

(2)

SC804EVB

Evaluation Board

(2)

Pin Descriptions

Pin Confi guration

Notes:
1) Available in tape and reel packaging only. A reel contains 3000

devices.

2) Available in lead-free packaging only. This product is fully WEEE
and RoHS compliant.

Pin #

Pin Name

Pin Function

BSEN

Battery voltage sense. Connect to battery positive terminal for Kelvin voltage sensing, VOUT otherwise.
Do not leave open.

CTO

Cold Temperature Offset. Adjustable NTC input high voltage (cold temperature) threshold. When the pin
is connected to GND the NTC high voltage threshold defaults to VT

NTCC

×V

VCC

IPRGM

Charger current program pin for fast-charge mode. Requires a resistor to GND to program fast-charge current.

ITERM

Charger termination current program pin. Requires a resistor to GND to program pre-charge and termination current.

RGND

Reference ground. Connect to battery's negative terminal for Kelvin voltage sensing, GND otherwise. Do not leave open.

GND

Ground.

NTC

Input for battery NTC thermistor network. Voltage between VT

NTCH

×V

VCC

, normally the hot threshold, and the CTO voltage

(VT

NTCC

×V

VCC

if CTO is tied to GND), normally the cold threshold, enables charging. Voltages outside this range suspend

charging and drive FLTB pin active (low). Voltage below VT

NTCDIS

(nominally 0.6V) disables the SC804A and resets the

charge timer (with FLTB pin inactive).

FLTB

Open drain fault indicator. Active low when a fault condition occurs.

AFC

Analog Fast Charge input. Connect to a DAC for analog control of fast charge current level, connect to VCC
to disable this feature. Do not leave open.

CHRGB

Open drain charge status indicator. Active low when the charger is on and the output current exceeds the
termination current setting, high impedance when I

VOUT

< ITERM.

CPB

Open drain charger-present indicator. Active low when VCC exceeds UVLO.

RTIM

Programmable timer input pin. Connect to VCC to select the default time-out of 3 hrs., connect to GND

to disable timer, or connect an external resistor to GND to program the time-out period.

OVPB

Open drain over-voltage indicator. Active low when an input over-voltage fault occurs.

VCC

Input supply pin. Connect to adapter power.

VOUT

Charger output. Connect to battery.

VOUT

Charger output. Connect to battery.

THERMAL

PAD

Thermal-conduction pad on bottom of the package. Solder directly to the ground plane with multiple
thermal vias to all other ground planes.

Ordering Information

TOP VIEW

MLPQ16: 4X4 16 LEAD

VOU

OVP

AFC

CHRGB

CPB

RTIM

BSEN

CTO

IPRGM

ITERM

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

Fast-Charge Mode (CC)

The fast-charge CC (Constant Current) mode is active when
the battery voltage is above VT

PreQ

and less than V

The

fast-charge current can be set to a maximum of 1.5A and
is selected by the program resistor on the IPRGM pin. The
voltage on this pin will represent the current through the
battery, enabling a microprocessor via an analog-to-digital
converter (ADC) to monitor battery current by sensing the
voltage on the IPRGM pin. The equation to set the fast-
charge current is given by:

The superior fast-charge current accuracy of the SC804A
is obtained by use of a patented* polarity-switched
(i.e., chopped) current sense amplifi er to nullify current
measurement offset errors.

Compliance with the absolute maximum output current
I

VOUTMAX

, allowing for current regulation tolerance, requires

that R

IPRGM

be no smaller than 1.05k

nominal. R

IPRGM

can

be as large as 15k

, for a nominal FCI as small as 100

mA. Note that for a given program resistor the current
through the battery in CV mode can be determined by
replacing V

IPRGM_Typ

with the actual voltage on the IPRGM

pin in the above equation. The CC current can also be
modifi ed by applying an analog voltage to the AFC pin as
described below.

Analog Fast Charge (AFC Pin)

Many applications require more than one current setting
for fast-charge. This behavior is obtained in the SC804A
using the AFC function. When the AFC pin is connected
to VCC the device behaves as described in the previous
section. When the AFC pin is driven by an analog voltage
between 0V and (V

VCC

-1.0)V, the SC804A automatically

uses this pin voltage to set the maximum fast-charge
current according to the following equation:

This adjustment to the fast charge current is obtained
by replacing the fi xed V

IPRGM

reference voltage with the

General Operation

The SC804A can be confi gured independently with respect
to fast-charge and termination current, output voltage,
and timing, depending on the application. A typical
charging cycle is described below. Details on alternative
applications and output programmability are covered in
the individual sections.

The charging cycle begins when the power adapter is
connected to the device. The SC804A performs glitch
fi ltering on the VCC input and initiates a charge cycle
when V

VCC

is greater than the under-voltage lockout (UVLO)

rising threshold voltage. If the battery voltage is less than
the pre-charge threshold level, the SC804A will output the
pre-charge current. Once the pre-charge threshold voltage
is exceeded, the SC804A enters fast-charge constant
current (CC) mode. When the battery voltage reaches its
fi nal value, the charger enters the constant voltage (CV)
mode. In this mode the output current decreases as the
battery continues to charge until the termination current
level is reached. The CHRGB output turns off when IOUT
drops below the termination current. If the charge timer
is active, the SC804A continues to hold the battery in
CV charge mode until the timer expires. When the timer
expires the charger enters the monitor mode where the
output remains off until the voltage at VOUT drops by
VT

ReQ

. At this point a new charge cycle is initiated.

Pre-Charge Mode

Pre-charge mode is automatically enabled whenever
the battery voltage is below the pre-charge threshold
voltage, VT

PreQ

. It is used to limit the power dissipation and

precondition the battery for fast charging. The pre-charge
current value is determined by the resistor on the ITERM
pin. The pre-charge current is programmable from 50mA
to 350mA. The equation to select the pre-charge current
is given by:

where V

ITERM_Typ

designates the typical value of V

ITERM

. When

the timer is enabled there is also a maximum allowed pre-
charge duration. If the pre-charge time exceeds 25% of
the total charge cycle the charger will turn off due to a
pre-charge fault. This fault is cleared when VCC is toggled
or the output voltage rises above VT

PreQ

Applications Information

PCI =

ITERM_Typ

× 100

ITERM

FCI =

AFC

× 1000

IPRGM

*US Patent 6,836,095.

× 1000

FCI =

IPRGM

IPRGM_Typ

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SC804A

POWER MANAGEMENT

internal timer, and to GND to disable the timer.

Connecting a resistor between RTIM and GND will program
the total charge time according to the following equation:

RTIM

Charge time =

(

--------

)

------

3.08

3600

With charge time expressed in hours. The timer is
programmable over the range of 2 to 6 hours. The internal
timer selection results in a charge time of 3 hours. The
SC804A will automatically turn off the output when the
charge timer times out.

NTC Interface

The NTC pin provides an interface to a battery pack
Negative Temperature Coeffi cient (NTC) thermistor. The
typical NTC network has a fi xed resistor from VCC to the
NTC pin, and the battery pack NTC thermistor connected
from the NTC pin to ground. In this confi guration, an
increasing battery temperature produces a decreasing
NTC pin voltage, and a decreasing battery temperature
produces an increasing NTC pin voltage.

This confi guration is shown in the typical application
schematic on page 1 of this datasheet. When the NTC
voltage from the divider is greater than the high (cold)
threshold or less than the low (hot) threshold, the SC804A
suspends the charge cycle by turning off the output, halting
(but not resetting) the charge timer, and indicating a fault
on the FLTB pin. Hysteresis is included for both high and
low NTC thresholds to avoid chatter at the NTC trip points.
When the NTC pin voltage returns to the valid range, the
SC804A automatically resumes the charge cycle. The
charge timer will time-out when the SC804A output on-
time exceeds the timer setting regardless of how long it
has been disabled due to the NTC temperature.

An input voltage between

NTCH

×V

VCC

and the CTO input

voltage V

CTO

(

NTCC

×V

VCC

if CTO is tied to GND) enables

charging. An input voltage outside this range suspends
charging and drives FLTB pin active (low). The internal
NTC thresholds of

NTCH

and

NTCC

were designed to

work with standard thermistors available from numerous
vendors.

NTC pin voltage below VT

NTCDIS

(nominally 0.6V) disables

the SC804A and resets the charge timer (with the FLTB
pin inactive). The NTC pin can be pulled down to ground

Applications Information (Cont.)

AFC voltage. (Note that AFC voltages above VIPRGM will

produce I

VOUT

exceeding that specifi ed in the Fast-Charge

Mode (CC) section.)

Termination Current

Once the battery voltage reaches V

the SC804A will

transition from constant current mode to constant voltage
mode. The current through the battery will decrease while
the voltage remains constant as the battery becomes fully
charged. When the current falls below the programmed
termination current set by the termination resistor
connected to the ITERM pin, the SC804A will disable
CHRGB. If the timer is enabled the output will continue
to fl oat-charge in CV mode until the timer expires. If the
timer is disabled, the output will turn off as soon as the
termination current level is reached. The equation to set
the termination current is given by:

ITERM can be programmed to be as high as 300mA or as
low as 50mA, though accuracy is not guaranteed below
100mA. ITERM must be programmed to be less than FCI
for correct operation of the charge cycle.

Monitor Mode

When a charge cycle is complete, the SC804A output
turns off and the device enters monitor mode. If the
voltage of the battery falls below the recharge threshold
(V

- V

ReQ

), the charger will clear the charge timer and

re-initiate a charge cycle. The maximum current drain of
the battery during monitor mode will be no more than 1

over temperature. The status of the charger output as a
function of the timer and IOUT is tabulated below.

Charge Timer

The timer on the SC804A has two functions: to protect
in the event of a faulty battery and to maximize charging
capacity. The RTIM pin is connected to VCC to select the

Timer

Iout

Output State

T < Timeout

N/A

T > Timeout

N/A

Off

Disabled

< Itermination

Off

ITERM_Typ

ITERM =

× 100

ITERM

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SC804A

PRELIMINARY

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DRAFT

or R3 = 2.333×R

HOT

= 13.624k

exactly. The closest 1%

standard nominal value is R3 = 13.7k

Step 2:

Verify acceptable thermistor self heating.

general, lower values of RT provide more noise immunity
for the NTC voltage, but at the expense of bias current
from the input adapter and power dissipation in the NTC
network. The dissipation constant is the power rating of
the thermistor resulting in a 1

C self heating error. The

greatest self-heating occurs at low thermistor resistance
(at high temperature). Since temperature sensing
accuracy matters only at the charging temperature range
thresholds, self heating is assessed only at the worst case
high temperature threshold of +40

For V

VCC

= 5V, the 40

C NTC network current I

NTC_HOT

VCC

/(R3 + R

HOT

) = 0.246mA. Power dissipation in the

thermistor at this temperature, P

HOT

= R

HOT

× (I

NTC_HOT

)

0.38mW, for self heating of approximately 0.13

C. The

actual high temperature threshold will thus be lower by
0.13

C. This self-heating error is usually acceptable. If

it is not, then a thermistor with a greater R

HOT

must be

chosen.

Step 3:

Determine the desired high (cold) threshold

Compute the NTC network resistor divider voltage, as a
function of V

VCC

, at the cold temperature threshold.

Step 4:

Confi gure CTO.

If NTC

COLD

is suffi ciently close

to the default cold threshold (

NTCC

×V

VCC

), then simply

connect CTO to ground, disabling the CTO function, to
complete the design. But in this example it is not, so the
voltage on CTO must be set to 0.6591×V

VCC

. The simple

resistive voltage divider network of Figure 2 can be used
to obtain the desired CTO voltage.

Applications Information (Cont.)

by an external n-channel FET transistor or processor GPIO
to disable or reset the SC804A.

Note that the response of the SC804A to NTC pin voltage
above the high threshold and below the low threshold
is the same. Thus it is possible to confi gure the NTC
network with the battery pack thermistor between NTC
and VCC, and a fi xed resistor between NTC and ground.
This confi guration may be useful if it is desired to reset the
charge timer (and the CHRGB output) when the battery
pack is removed (so the fi xed resistor pulls the NTC pin to
ground) while VCC is present.

Cold Temperature Offset (CTO)

The voltage applied to the CTO pin sets the NTC high
voltage (normally the cold temperature threshold) for the
NTC input. The default NTC high threshold (

NTCC

×V

VCC

)

can be selected by connecting the CTO pin to ground. If
it is desired to change this threshold, the voltage on the
CTO pin can be set between 0.5×V

VCC

and 0.9×V

VCC

This feature is especially useful if a single PCB design
is needed to satisfy similar applications with different
requirements. The temperature range for normal charging
can be adjusted by adjusting resistor values on a divider
network without changing the NTC thermistor, which
is often enclosed in the battery pack. An example of a
typical application is shown in Figure 2.

NTC/CTO Design Example

The following example assumes the NTC network
confi guration of Figure 2, with a fi xed resistor R3 connected
between NTC and VCC, and a battery NTC thermistor
RT connected between NTC and ground. The battery
temperature range over which charging is permitted is
specifi ed to be 0

C through 40

C. The datasheet for the

selected NTC thermistor indicates that RT = 5.839k

C, at RT = 26.49k

at 0

C, with a dissipation constant

DC = 3mW. Designate R

HOT

= 5.839k

and R

COLD

26.49k

Step 1:

Select R3.

For the normal (NTC thermistor to

ground) confi guration, solve the NTC network voltage
divider for R3 to place the NTC voltage at 0.3×VCC when
RT = R

HOT

0.3 × VCC =

VCC × R

HOT

R3 + R

HOT

NTC

COLD

VCC × R

COLD

= 0.6591 × VCC

R3 + R

COLD

CTO

= NTC

COLD

= 0.6591 × VCC =

VCC × R

CT2

CT1

+ R

CT2

CT1

1 0.6591

= 0.5172

CT2

0.6591

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SC804A

POWER MANAGEMENT

Applications Information (Cont.)

The choice of R

CT1

and R

CT2

is somewhat arbitrary. The

simplest approach is to pick one and compute the other.
A good choice here is R

CT1

= 115k

, and R

CT2

= 221k

, as

these standard 1% tolerance values produce the closest
match to the desired voltage divider ratio. With these
resistor nominal values,

which is, nominally, only 0.2% below the target value of
0.6591×V

VCC

. The CTO network will present a load of only

15A to a 5V charging adapter. The nominal impedance
presented to the CTO pin is R

CT1

|| R

CT2

= 75.6k

. Any

impedance on the order of 100k

(or less) is acceptable.

Remote Kelvin Sensing at the Battery

The BSEN pin provides the positive Kelvin sensing voltage
feedback to the CV amplifi er and should be connected as
close to the battery + terminal as possible. Likewise, the
RGND pin should be connected directly to the negative
terminal of the battery. This allows the designer great
fl exibility in PCB layout and achieves greater accuracy
by sensing the battery voltage directly at the battery
terminals. When laying out the PCB, the designer should
route the BSEN and RGND trace directly to the battery
connection terminals, rather than just to the VOUT and
GND pins on the device.

Dropout Voltage

Dropout voltage is the smallest achievable difference
voltage between VCC and VOUT under a particular
operating condition. Dropout voltage is encountered
during CC charging whenever the current limit of the
charging adapter is less than the SC804A FCI programmed
current. In this case, the adapter voltage (the SC804A
input voltage) will be pulled down to the battery voltage
(the SC804A output voltage) plus the dropout voltage.

Dropout voltage is the larger of two values: (1) the I-R
component, which is the output current multiplied by the
minimum VCC-to-VOUT path resistance (which is highly
temperature dependent), and (2) a regulated minimum
difference voltage, which is output voltage dependent
but is independent of the output current. The regulated
minimum dropout voltage results from the collapse of

internal voltage references as VOUT pulls VCC down to
near, or below, V

, creating a reduced output regulation

voltage approximately 200mV below VCC. Thus VCC
cannot be pulled down below VOUT + 200mV. The dropout
voltage will be larger than 200mV whenever the minimum
path resistance multiplied by the output current exceeds
200mV, but it cannot be smaller than 200mV.

This greatest-of-two-limit dropout voltage behavior is
evident in the dropout voltage typical performance plot.

When operating in Adjust Mode (next section), the
regulated minimum dropout voltage depends on the
programmed VOUT regulation voltage, and dropout also
varies with the actual output voltage during CC charging.
See Figure 4 for an illustration of dropout voltage data.

Adjust Mode

The SC804A can be confi gured for an output voltage
other than V

using Adjust (ADJ) Mode. In Adjust Mode

the output voltage is determined by an external resistor
divider from VOUT to BSEN. When BSEN is connected in
this fashion, V

VOUT

(during Constant Voltage (CV) charging)

will be controlled such that the voltage at the BSEN pin
(V

BSEN

) is the reference voltage V

BSEN-ADJ

The output voltage can be set to any voltage desired by
an appropriate choice of divider network resistors, within
the following limits. When the SC804A is programmed for
adjust mode, V

VOUT

is required to be 150mV less than V

VCC

and V

VOUT

is required to be 400mV greater than V

BSEN

VOUT

within 150mV of V

BSEN

guarantees normal mode

operation. This implies that, for BSEN used as a Kelvin
sense of battery voltage, the product of the fast charge
current and the charge path resistance from VOUT to the
Kelvin sense point should not exceed 150mV to ensure
normal mode operation.

The SC804A Adjust Mode schematic is shown in Figures
3a and 3b. Referring to these schematics, the equation
for setting the output voltage is:

The capacitor C3 across R8 in the feedback network
introduces zero-pole frequency compensation for stability.
Place the zero according to the following equation to
ensure stability:

CTO

VCC × R

CT2

= 0.6577 × VCC

CT1

+ R

CT2

R11

× C3 = 1

2 × 100kHz

VOUT = V

BSEN-ADJ_TYP

(

1 +

R11

)

R12

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

VCC

OVP

IPRGM

NTC

CPB

CHRGB

RTIM

CTO

11
10
12

ITERM

FLTB

8
6

GND

RGND

BSEN

VOUT
VOUT

AFC

16
15

SC804A

2.2

Red

Green

Charger VIN

NTC

C2
2.2

ERROR

CT1

CT2

OV_FLT

VCC

OVP

IPRGM

NTC

CPB

CHRGB

RTIM

CTO

11
10
12

ITERM

FLTB

8
6

GND

RGND

BSEN

VOUT
VOUT

AFC

16
15

SC804A

2.2

Red

Green

Charger VIN

NTC

C2
2.2

ERROR

R11

R12

OV_FLT

VCC

OVP

IPRGM

NTC

CPB

CHRGB

RTIM

CTO

11
10
12

ITERM

FLTB

8
6

GND

RGND

BSEN

VOUT
VOUT

AFC

16
15

SC804A

2.2

Red

Green

Charger VIN

NTC

C2
2.2

ERROR

R11

R12

OV_FLT

Applications Information (Cont.)

Figure 2 - Application Circuit with AFC Disabled, and with NTC and CTO Resistor Networks

Figure 3a - Application Circuit for Adjust Mode

Figure 3b - Application Circuit for Adjust Mode, with Adapter-only Voltage Sensing

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SC804A

POWER MANAGEMENT

The actual dropout voltage is the greater of the Minimum Dropout
Voltage at various programmed V

and instantaneous VOUT

voltages (shown here, with several programmed V

voltages

indicated in the fi gure by `o'), and the IR drop due to the product
of IOUT and R

DS-ON

(not shown here). Adjust mode operation is

ensured for any IOUT current at programmed V

voltages up to

approximately 4.41V.

Applications Information (Cont.)

FLAG

OFF

CPB

UVLO < VCC < OVP

Input out of range

CHRGB

IOUT > ITERM

IOUT < ITERM

OVPB

VCC > OVP

VCC < OVP

FLTB

VCC > OVP

VCC UVLO

NTC Temp Fault

Pre-Charge Time-out

(OT (Tj > 150°C)

Normal Operation or

NTC Disable

NOTE: When using Adjust Mode to program a CV regulation
voltage greater than V

, care must be taken when CC

charging with a charging adapter operating in current
limit. Adapter current-limited operation occurs when
the adapter current limit is less than the programmed
SC804A fast charge current, such that the adapter voltage
is pulled down to V

VOUT

plus the SC804A dropout voltage.

A low adapter current limit multiplied by the low minimum
path resistance of the main pass transistor and current
sense resistor (as low as 290m

total at extremely low

temperature) can result in a voltage drop from VCC to
VOUT of less than 150mV if the Adjust Mode CV regulation
voltage is programmed above V

+ 50mV. If V

VCC

- V

VOUT

< 150mV, Adjust Mode may not operate correctly. Adjust
Mode will operate correctly whenever the programmed
VOUT CV voltage is less than V

+ 50mV, regardless of the

adapter current limit, because the regulated minimum
dropout voltage is always greater than 150mV in this
case. It will also operate correctly with an adapter current
limit greater than 550 mA, regardless of the programmed
output voltage, because the I-R dropout voltage will
exceed 150mV at even the lowest specifi ed operating
temperature. Normal mode (that is, not

Adjust Mode) has

a regulated minimum dropout voltage of approximately
200mV, which is constant for any V

VOUT

, and so operates

correctly for any adapter current limit.

Overcurrent and Max Temperature Protection

Overcurrent protection is inherent in all modes of operation.
When the device is in charge mode the output is current-
limited to either the pre-charge current limit value or the
fast charge current limit value depending on the voltage
at the output. Max die temperature protection is also
included. This feature allows the SC804A to operate
with maximum power dissipation by disabling the output
current when the die temperature reaches the maximum
operating temperature. The result is that the SC804A will
operate as a pulse charger in extreme power dissipation
applications, delivering the maximum allowable output
current while regulating the internal die temperature to a
safe level.

Indicator Flags

There are four indicator outputs/LED drivers ont he
SC804A; CPB (Charger Present), CHRGB (Charge Active),
OVPB (Over Voltage Fault), and FLTB (Fault). These outputs
are all active-low; open drain NMOS drivers capable of
sinking up to 10mA. The following table defi nes each
indicator's output state.

The CPB output can be used as a VCC-present indicator.
Regardless of teh state of NTC, the CPB output refl ects
the VCC voltage. When V

is between the UVLO and OVP

thresholds the CPB output is low. If V

is outside these

limits, this output is high impedance.

The CHRGB output indicates the charging status. When
the output current is greater than ITERM, CHRGB is low.
CHRGB is high impedance when IOUT is less than ITERM.
The CHRGB output is latched during the charge cycle
when the output current is less than ITERM. This latch is
reset when the battery enters a recharge cycle, or if NTC
or VCC are toggled.

3.2

3.4

3.6

3.8

4.2

4.4

4.6

0.2

0.4

0.6

0.8

Output voltage, V

Minimum dropout voltage, V

Figure 4 - Adjust Mode Minimum Dropout Voltage

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

Charge Mode Timing Diagram

VCC

VOUT

IOUT

CPB

CHRGB

TIMER

FLTB

NTC

UVLO

PreQ

Pre-Charge

Soft Start

Fast Charge

Termination

Current

Re-Charge

Threshold

CC Mode

CV Mode

Off

Fault

Hold

Figure 5 - Charge Mode Timing

The OVPB signal is an active-low output that signals when
the input voltage exceeds the OVP threshold. When the
voltage on VCC is less than the OVP threshold voltage
this output is high impedance.

The FLTB output is activated when the device experiences
a fault condition. This output can be used to notify the
system controller of a fault condition when connected to
an interrupt input, or it can be used like CPB and CHRGB
to drive an indicator LED. There are fi ve fault modes
signaled by FLTB: input over-voltage, input under-voltage,
NTC temperature out of range, max die temperature (OT),

and pre-charge timeout. When any of these conditions
occurs the FLTB output goes low; otherwise it remains
high impedance.

Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and
X7R dielectric material types are recommended for use with
the SC804A. The output capacitance range is 1F to 4.7F.
The input capacitor is typically between 0.1F to 2.2F, but
larger values will not degrade performance

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SC804A

POWER MANAGEMENT

State Diagram

Over-Voltage, Under-Voltage or
Over-Temperature will force the
SC804A into Shutdown Mode
from any state.

Soft Start CC Mode

Yes

OUT

= I

FAST

Yes

OUT

< I

TERM

OUT

< V

- V

ReQ

low temp > NTC Temp

> high temp

Yes

Start Timer

Start CV Mode

Timer

Enabled?

CC = Constant Current
CV = Constant Voltage

Yes

OVP > VCC > UVLO

En = Hi

Soft Start Vout

CHRGB Low

Timer

Enabled?

Start Pre- Charge

OUT

= I

PREQ

Time > T

MAX

Pre- Charge

Timeout Fault

FLTB goes low.

Cleared by

VBAT > VT

PreQ

or Re- cycle VCC

Yes

OUT

= V

CHRGB High Z

Monitor Mode

OUT

off

Time > T

MAX

Float Charge Mode

OUT

= V

NTC out of Range Fault

FLTB goes active low

Timer is frozen

Charge resumes when NTC

Temperature is valid

OUT

> VT

PreQ

Shutdown Mode:

OUT

& I

OUT

off,

CHRGB High Z,

CPB Low.

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

Typical Charge Cycle

Evaluation Board confi gured for internal timer, 1.5V on IPRGM = 843mA, 1.5V on ITERM = 300mA, VCC = 5.0V, Li-Ion
battery capacity = 850mAh. A 237 load resistor (18mA at a battery voltage of 4.36V) was applied to the battery fol-
lowing completion of precharge, to slowly discharge the battery following charge timer timeout to illustrate a recharge
cycle. The alphabetic markers indicate the following: (a) precharge; (b) fast charge, or Constant Current (CC) charg-
ing; (c) Constant Voltage (CV) charging; (d) termination; (e) CV ("fl oat") charging until charge timer timeout; (f) charge
timer timeout; (g) discharge of the battery due to 18mA load; (h) recharge cycle initiated when battery voltage drops
below the recharge threshold.

120

150

180

210

240

270

300

330

360

0.5

1.5

2.5

3.5

4.36

120

150

180

210

240

270

300

330

360

100

200

300

400

500

600

700

800

900

Time (minutes)

VOUT

BATTERY

CHRGB

(V)

Time (minutes)

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SC804A

POWER MANAGEMENT

VOUT V

Line Regulation vs. Load, T = +25°C

VOUT V

Load Regulation vs. Line, T = +25°C

VOUT V

Regulation vs. Temperature,

VCC = 5.0V, IOUT = 800mA

IOUT Line Regulation vs. Temperature,

RPRGM = 1.87k

IOUT vs. IPRGM Resistance, T = +25°C

Precharge and Termination Current vs.

ITERM Resistance

Typical Characteristics

4.338

4.340

4.342

4.344

4.346

4.348

4.350

4.352

4.354

4.356

500

750

1000

1250

1500

IOUT (mA)

VOUT (V)

VCC = 5.0V

VCC = 5.5V

VCC = 6.0V

VCC = 6.5V

4.348

4.350

4.352

4.354

4.356

4.358

4.360

-50

-25

100

Ambient Temperature, °C

VOUT,V

816

820

824

828

832

836

840

5.00

5.25

5.50

5.75

6.00

6.25

6.50

VCC, V

IOUT, mA

T = +85°C

T = +25°C

T = -40°C

4.338

4.340

4.342

4.344

4.346

4.348

4.350

4.352

4.354

4.356

5.00

5.20

5.40

5.60

5.80

6.00

6.20

6.40

VIN (V)

VOUT (V)

Iout = 500mA

Iout = 750mA

Iout = 1000mA

Iout = 1500mA

400

600

800

1000

1200

1400

1600

1800

0.3

0.5

0.7

0.9

1.1

1/Riprgm, 1/k

IOUT, mA

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

0.5

1.5

2.5

1/RIPRGM, 1/k

IOUT, mA

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SC804A

POWER MANAGEMENT

Evaluation Board Schematic

Evaluation Board Gerber Plot,Top/Bottom Views

390

GND

RGND

390

R15

37.4k

R15

37.4k

CHARGER+

BSEN

CTO

IPRGM

ITERM

RGND

GND

CPB

RTIM

OVPB

VOUT

CHRGB

NTC

AFC

FLTB

SC804A

ITERM

390

RTIM

GND

<NM>

CTO

10k

JP5

R11

<NM>

R14

<NM>

C2
2.2u

VOUT

R13

100k

R13

100k

R16

POT_3296W-105

R16

POT_3296W-105

2.2u

NTC

JP4

JP6

GND

JP2

R12

<NM>

R12

<NM>

JP1

JP7

IPRGM

R10

<NM>

R10

<NM>

1.87k

CHARGER-

JP3

499

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SC804A

PRELIMINARY

POWER MANAGEMENT

DRAFT

INDICATOR

(LASER MARK)

PIN 1

DIMENSIONS

NOM

INCHES

bbb

aaa

DIM

MIN

MAX

MILLIMETERS

MIN

MAX

NOM

.153

.157

.161

3.90

4.00

4.10

.153

.157

.161

3.90

4.00

4.10

.003

.010

.079

.012

.085

.000

.031

(.008)

0.08

0.30

.014

.089

0.25

2.00

.040

.002

0.00

0.80

2.25

0.35

2.15

0.05

1.00

(0.20)

.004

0.10

2.00

2.15

2.25

0.65 BSC

.026 BSC

0.30

.012

.020

.016

0.40

0.50

.089

.085

.079

D/2

LxN

bbb

C A B

bxN

SEATING

PLANE

E/2

e/2

aaa C

CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).

COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.

NOTES:

-
-

Outline Drawing - MLPQ-16

Marking Information

804A

yyww

xxxxx

xxxx

yyww = Date Code (Example: 0552)
xxxxx xxxx = Semtech Lot Number
(Example: E9010 01-1)

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