INTEGRATED CIRCUITS
NE57607
Two-cell Lithium-ion battery protection
with overcurrent, over- and under-voltage
protection
Product data
2001 Oct 03
Philips
Semiconductors
Philips Semiconductors
Product data
Two-cell Lithium-ion battery protection with
overcurrent, over- and under-voltage protection
NE57607
GENERAL DESCRIPTION
The NE57607 is a family of 2-cell Li-ion protection ICs. Its over- and
under-voltage accuracy is trimmed to within
±25
mV (5%) and is
available to match the requirements of all lithium-ion cells
manufactured in the market today.
The NE57607 comes in the small VSOP-8A package.
FEATURES
•
Trimmed overvoltage trip point to within
±25
mV
•
Programmable overvoltage trip time delay
•
Trimmed undervoltage trip point to within
±25
mV
•
Very low undervoltage sleep quiescent current 0.05 mA
•
Discharge overcurrent cutoff
•
Low operating current (10 mA)
•
Very small package VSOP-8A
SIMPLIFIED DEVICE DIAGRAM
APPLICATIONS
•
Cellular phones
•
Palmtop computers
+
8
Li-ION CELL
6
7
5
CHARGER
OR
LOAD
NE57607
Li-ION CELL
4
2
3
1
–
SL01564
Figure 1. Simplified device diagram.
2001 Oct 03
2
853-2297 27198
Philips Semiconductors
Product data
Two-cell Lithium-ion battery protection with
overcurrent, over- and under-voltage protection
NE57607
ORDERING INFORMATION
TYPE NUMBER
NE57607XDH
PACKAGE
NAME
VSOP-8A
DESCRIPTION
8-pin surface mount small outline package
TEMPERATURE RANGE
–20 to +70
°C
NOTE:
The device has six protection parameter options, indicated by the
X
on the order code, and defined in the following table.
TYPICAL PROTECTION PARAMETERS IN THE NE57600 FAMILY
T
amb
= 0
°C
to 50
°C
Part Number
NE57607Y
NE57607C
NE57607E
NE57607G
NE57607H
NE57607K
Overcharge
detection voltage
(V)
4.350
4.295
4.250
4.300
4.225
4.350
Overcharge detection
hysteresis voltage
(mV)
220
±
50
TBD
300
±
50
220
±
50
TBD
220
±
50
Over-discharge
detection voltage
(V)
2.3
±
0.1
2.3
±
0.1
2.3
±
0.1
2.0
±
0.1
2.3
±
0.1
2.3
±
0.1
Over-discharge
resumption voltage
(V)
3.5
±
0.2
3.5
±
0.2
3.5
±
0.2
3.1
±
0.2
3.5
±
0.2
3.5
±
0.2
Overcurrent
detection voltage
(mV)
150
±
15
150
±
15
150
±
15
140
±
15
150
±
15
100
±
15
Part number marking
Each device is marked with a four letter code. The first three letters
in the top line of markings designate the product. The fourth letter,
represented by “x”, is a date code. The remaining markings are
manufacturing codes.
Part Number
NE57607YDH
NE57607CDH
NE57607EDH
NE57607GDH
NE57607HDH
NE57607KDH
Marking
AGDx
AGFx
AGHx
AGKx
AGLx
AGNx
PIN DESCRIPTION
PIN
1
SYMBOL
CF
DESCRIPTION
Charge FET drive pin, must have common
emitter NPN to drive FET gate.
Overcharge detection output pin
PNP open collector output
Discharge control FET (N-ch) control output
pin.
Overcurrent detection input pin.
Monitors discharge current equivalently by
the voltage drop between discharge FET
source and drain. Stops discharge when
voltage between CS pin and GND pin goes
above overcurrent detection threshold value,
and holds until load is released.
Ground pin, or lower cell (C1) negative pin.
Overcharge detection dead time setting pin.
Dead time can be set by adding a capacitor
between TD and GND pins.
Voltage input for positive terminal of bottom
cell (C10).
Connection pin for lower cell (C1) positive
electrode side and upper cell (C2) negative
electrode side.
Power supply input pin.
Voltage input for top terminal of upper cell
(C2).
2
3
DF
CS
4
GND
C
DLY
PIN CONFIGURATION
CF
DF
CS
GND
1
2
3
4
TOP VIEW
8
7
6
5
V
C2
V
CC
V
C1
C
DLY
5
6
V
C1
7
SL01565
V
CC
V
C2
8
Figure 2. Pin configuration.
2001 Oct 03
3
Philips Semiconductors
Product data
Two-cell Lithium-ion battery protection with
overcurrent, over- and under-voltage protection
NE57607
MAXIMUM RATINGS
SYMBOL
V
IN(max)
V
CF(max)
V
CS(max)
T
opr
T
stg
P
D
Input voltage
Maximum CF pin voltage
Maximum CS pin voltage
Operating ambient temperature range
Storage temperature
Power dissipation
PARAMETER
Min.
–0.3
–
–
–20
–40
–
Max.
+18
V
IN
–0.6
V
IN
–0.6
+70
+125
300
UNIT
V
V
V
°C
°C
mW
ELECTRICAL CHARACTERISTICS
T
amb
= 25
°C;
V
CEL
= V4–V3 = V3–V2 = V2–V1 = V1–GND; V
CC
= 4V
CEL
, except where noted otherwise.
SYMBOL
V
OC
V
OC
V
OD
I
VC2(1)
I
VC2(2)
I
VC23
I
VC24
I
VC1
V
DF
V
GDH
V
GDL
I
CFH
V
CS1
V
CS2
t
OC1
t
OC2
t
OD
t
OCH
V
ST
PARAMETER
Overcharge detection voltage
Overcharge detection hysteresis
voltage
Overdischarge detection voltage
Consumption current 1
Consumption current 2
Consumption current 3
Consumption current 4
V
C1
pin input current
Overdischarge release voltage
GD pin HIGH output voltage
GD pin LOW output voltage
CF pin output current
Overcurrent detection threshold value
Short circuit threshold value
Overcurrent release
Overcurrent detection delay time 1
Overcurrent detection delay time 2
Overdischarge detection delay time
Overcharge detection dead time
Start-up voltage
C
DLY
= 0.18
µF;
Note 2
V
C2
= V
C1
= 2.5 V
Note 1
When both battery pack pins are shorted
V
C2
= V
C1
= 1.0 V; V
CS
= 1.4 V
V
C2
= V
C1
= 1.9 V; V
CS
= 3.2 V
V
C2
= V
C1
= 3.5 V
V
C2
= V
C1
= 4.5 V; R
OC
= 270 kΩ
V
C2
= V
C1
= 3.5 V
Discharge resume by voltage rise
V
C2
= V
C1
= 3.5 V; I
L
= –10
µA
V
C2
= V
C1
= 3.5 V; I
L
= 10
µA
V
C2
= V
C1
= 4.5 V
CONDITIONS
T
amb
= 0
°C ∼
50
°C
Min.
4.325
170
2.20
–
–
–
–
–0.3
3.30
V
C2
–0.3
–
–
135
0.35
7
–
8
0.5
–0.24
Typ.
4.350
220
2.30
–
0.5
15.0
–
0
3.50
V
C2
–0.2
0.2
30
150
0.45
12
30
13
1.0
–0.12
Max.
4.375
270
2.40
0.1
0.8
20.0
150
0.3
3.70
–
0.3
150
165
0.55
18
100
20
1.5
–0.04
UNIT
V
mV
V
µA
µA
µA
µA
µA
V
V
V
µA
mV
V
ms
µs
ms
s
V
Load release: Load of 5MEG& or more between both battery pack pins
NOTES:
1. The short-circuit delay time is for the IC only. This time will increase with the discharge FET gate capacitance. The short-circuit condition
may cause the cell voltage to collapse and lengthen the delay.
2. Calculate overcharge dead time according to the following formula: T
alm
– 5.55
×
C
TD
(time expressed in seconds, capacitance in
µF)
2001 Oct 03
4
Philips Semiconductors
Product data
Two-cell Lithium-ion battery protection with
overcurrent, over- and under-voltage protection
NE57607
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 SA57611. This provides two levels of
overcharge protection, with the primary protection of the external
charge control circuit and the backup 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 mΩ range,
compared to the 5–20 mΩ 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 VOLTAGE (V)
4.0
V
OV
3.0
V
UV
2.0
50
NORMALIZED CELL CAPACITY (%)
100
SL01553
Figure 3. Lithium discharge curve.
2001 Oct 03
5
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