Document Outline
- DESCRIPTION
- FEATURES
- APPLICATIONS
- SIMPLIFIED SYSTEM DIAGRAM
- ORDERING INFORMATION
- PIN CONFIGURATION
- PIN DESCRIPTION
- MAXIMUM RATINGS
- ELECTRICAL CHARACTERISTICS
- TECHNICAL DISCUSSION
- Lithium cell safety
- Charging control versus battery protection
- Lithium cell operating characteristics
- Charging Lithium cells
- NE57611 CHARACTERISTICS
- APPLICATION INFORMATION
- PACKING METHOD
- REVISION HISTORY
- Data sheet status
- Definitions
- Disclaimers
Philips
Semiconductors
NE57611
Single cell Li-ion battery charger
Product data
Supersedes data of 2002 Dec 10
2003 Oct 15
INTEGRATED CIRCUITS
Philips Semiconductors
Product data
NE57611
Single cell Li-ion battery charger
2
2003 Oct 15
DESCRIPTION
The NE57611 is a one-cell, Li-ion battery charger controller which
includes constant-current and constant voltage charging, a precise
charge termination, and precharging of undervoltage cells.
It contains the minimum circuitry needed to safely charge a
lithium-ion or lithium-polymer cell. This makes it good for very
compact, portable applications.
FEATURES
30 mV per cell charging accuracy from 0
C to +50
C
Low quiescent current (250
A ON; 2
A OFF)
Undervoltage precharge detector
Self-discharge maintenance charging
APPLICATIONS
Cellular telephones
Personal Digital Assistants
Other 1-cell Li-ion portable applications
SIMPLIFIED SYSTEM DIAGRAM
SL01661
V
CC
8
1
ON/OFF
LV
3
DRV
V
CELL
7
6
4
2
5
V
SS
LVEN
CS
1 k
150
R
CS
PBYR
240CT
BCP51
NE57611
10
F
V+
V
Li-ION
CELL
BATTERY PACK
R
UV
BAL74
BC807
10 k
10
F
+V
IN
V
IN
Figure 1.
Simplified system diagram.
Philips Semiconductors
Product data
NE57611
Single cell Li-ion battery charger
2003 Oct 15
3
ORDERING INFORMATION
TYPE NUMBER
PACKAGE
TEMPERATURE
TYPE NUMBER
NAME
DESCRIPTION
RANGE
NE57611BDH
VSOP-8A (TSSOP)
plastic thin shrink small outline package; 8 leads; body width 4.4 mm
20 to +70
C
PIN CONFIGURATION
SL01660
1
2
3
4
8
7
6
5
TOP VIEW
V
SS
LV
LVEN
ON/OFF
CS
V
CELL
DRV
V
CC
Figure 2.
Pin configuration.
PIN DESCRIPTION
PIN
SYMBOL
DESCRIPTION
1
ON/OFF
ON/OFF control input pin for the IC.
ON/OFF = V
CC
: OFF
ON/OFF = GND: ON
2
LVEN
Low voltage detection circuit ON/OFF control.
LVEN = V
CC
: OFF
LVEN = GND: ON
3
LV
Low cell voltage detection circuit output pin.
Open collector; Active-LOW.
4
V
SS
Connect to negative pole of battery.
5
CS
Current detection pin.
Detects current by drop in external resistor
voltage and controls rated current.
Current value can be set at 0.1 V/R1 typ.
6
V
CELL
Battery voltage input pin.
Detects battery voltage and controls rated
voltage to the prescribed voltage value.
7
DRV
Charging control output pin drives external
PNP-Transistor to control charging.
8
V
CC
Power supply input pin.
MAXIMUM RATINGS
SYMBOL
PARAMETER
MIN.
MAX.
UNIT
V
CC(max)
Power supply voltage
0.3
+18
V
V
CEL(max)
Maximum cell voltage
0.3
+13
V
V
LVEN
LVEN input voltage
0.3
V
CC
+ 0.3
V
V
ON/OFF
ON/OFF input voltage
0.3
V
CC
+ 0.3
V
T
opr
Operating ambient temperature
20
+70
C
T
stg
Storage temperature
40
+125
C
P
D
Power dissipation
300
mW
Philips Semiconductors
Product data
NE57611
Single cell Li-ion battery charger
2003 Oct 15
4
ELECTRICAL CHARACTERISTICS
T
amb
= 25
C, V
IN
= 5 V, unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
I
CC1
Consumption current 1
ON/OFF = LVEN = 0 V (Charge: ON)
250
400
A
I
CC2
Consumption current 2
ON/OFF = LVEN = V
CC
(Charge: OFF)
2
10
A
V
OV1
Output voltage 1
T
amb
= 25
C
4.100
4.125
4.150
V
V
OV2
Output voltage 2
T
amb
= 0
C to 50
C
4.095
4.125
4.155
V
V
CL
Current limit
90
100
110
mV
I
CEL1
Leakage current between V
CELL
-CS
during operation
3.0
5.0
7.0
A
I
CEL2
Leak current between V
CELL
-CS
V
CC
= 0 V or OPEN
0.01
1
A
I
ON/OFF
ON/OFF input current
20
30
A
V
L1
ON/OFF input voltage L
Charge: ON
0.3
2.0
V
V
H1
ON/OFF input voltage H
Charge: OFF
V
CC
1.0
V
CC
+ 0.3
V
V
UV(CELL)
Low voltage detection voltage
2.0
2.15
2.3
V
I
LVEN
LVEN input current
20
30
A
V
L2
LVEN input voltage L
Low voltage detection circuit: ON
0.3
2.0
V
V
H2
LVEN input voltage H
Low voltage detection circuit: OFF
V
CC
1.0
V
CC
+ 0.3
V
I
LV
Low voltage detection
0.5
A
V
LV
output leak current Low voltage
detection
I
SINK
= 1 mA
0.2
0.4
V
I
DRV
output saturation voltage DRV pin
inflow current
10
20
mA
V
DRV
DRV pin output voltage
For no load
0.3
V
CC
0.3
V
NOTES:
1. Please insert a capacitor of several
F between power supply and ground when using.
2. Be sure that CS pin potential does not fall below 0.5 V.
3. If the IC is damaged and control is no longer possible, its safety cannot be guaranteed. Please protect with something other than this IC.
Philips Semiconductors
Product data
NE57611
Single cell Li-ion battery charger
2003 Oct 15
5
TECHNICAL DISCUSSION
Lithium cell safety
Lithium-ion and lithium-polymer cells have a higher energy density
than that of nickel-cadmium or nickel metal hydride cells and have a
much lighter weight. This makes the lithium cells attractive for use in
portable products. However, lithium cells require a protection circuit
within the battery pack because certain operating conditions can be
hazardous to the battery or the operator, if allowed to continue.
Lithium cells have a porous carbon or graphite anode where lithium
ions can lodge themselves in the pores. The lithium ions are
separated, which avoids the hazards of metallic lithium.
If the lithium cell is allowed to become overcharged, metallic lithium
plates out onto the surface of the anode and volatile gas is
generated within the cell. This creates a rapid-disassembly hazard
(the battery ruptures). If the cell is allowed to over-discharge (V
CELL
less than approximately 2.3 V), then the copper metal from the
cathode goes into the electrolyte solution. This shortens the cycle
life of the cell, but presents no safety hazard. If the cell experiences
excessive charge or discharge currents, as happens if the wrong
charger is used, or if the terminals short circuit, the internal series
resistance of the cell creates heating and generates the volatile gas
which could rupture the battery.
The protection circuit continuously monitors the cell voltage for an
overcharged condition or an overdischarged condition. It also
continuously monitors the output for an overcurrent condition. If
any of these conditions are encountered, the protection circuit opens
a series MOSFET switch to terminate the abnormal condition. The
lithium cell protection circuit is placed within the battery pack very
close to the cell.
Charging control versus battery protection
The battery pack industry does not recommend using the pack's
internal protection circuit to end the charging process. The external
battery charger should have a charge termination circuit in it, such
as that provided by the NE57611. This provides two levels of
overcharge protection, with the primary protection of the external
charge control circuit and the back-up protection from the battery
pack's protection circuit. The charge termination circuit will be set to
stop charging at a level around 50 mV less than the overvoltage
threshold voltage of the battery pack's own protection circuit.
Lithium cell operating characteristics
The internal resistance of lithium cells is in the 100 m
range,
compared to the 520 m
of the nickel-based batteries. This makes
the Lithium-ion and polymer cells better for lower battery current
applications (less than 1 ampere) as found in cellular and wireless
telephones, palmtop and laptop computers, etc.
The average operating voltage of a lithium-ion or polymer cell is
3.6 V as compared to the 1.2 V of NiCd and NiMH cells. The typical
discharge curve for Lithium cell is shown in Figure 3.
OPEN-CIRCUIT
CELL
VOL
T
AGE
(V)
SL01662
NORMALIZED CELL CAPACITY (%)
100
50
2.0
V
UV
3.0
4.0
V
OV
Figure 3.
Lithium discharge curve.
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