AIC AIC1802CCS Two-cell lithium-ion battery protection ic Datasheet

AIC1802
Two-Cell Lithium-Ion Battery Protection IC
n FEATURES
l
l
n DESCRIPTION
Ultra-Low Quiescent Current at 10µA (V CC =7V,
The AIC1802 battery protection IC is designed
VC =3.5V).
to protect lithium-ion batteries from damage due
Ultra-Low Power-Down Current at 0.2µA (V CC
to
overcharging,
overdischarging,
and
=3.8V, VC =1.9V).
overcurrent for two series cells in portable
l
Wide Supply Range: 2 to 18V.
phones and laptop computers. It can be a part of
l
Precision Overcharge Protection Voltage
the low-cost charge control system within a two-
4.35V ± 30mV for the AIC1802A
cell lithium-ion battery pack.
4.30V ± 30mV for the AIC1802B
Safe and full utilization charging is ensured by
4.25V ± 30mV for the AIC1802C
l
l
l
Built-in Delay Circuits for Overcharge, Over-
the accurate ±30mV overcharge detection.
discharge and Overcurrent Protection.
Three
Overcharge and Overdischarge Delay Time
overcharge protection voltage are provided for
can be Extended by External Capacitors.
various protection requirements. The very low
Built-in Cell-balancing Bleeding Network under
standby current drains little current from the
Overcharge Condition.
cells while in storage.
different
specification
values
for
n APPLICATIONS
l
Protection IC for Two-Cell Lithium-Ion Battery
Pack.
n TYPICAL APPLICATION CIRCUIT
V BAT+
**R1
8
BATTERY 1
C1
1µ F
BATTERY 2
C2
1µ F
VCC
TC
5
TD
3
*CTC
6 VC
*CTD
4
GND
OC
1
**R2
M1
CEM9926
2 OD
CS
AIC1802
R3
1M
7
Q1
R6
1K
M2
R4
1M
R5
C3
0.01µF 1M
CEM9926
VBAT-
*CTC & CTD are optional for delay time adjustment.
**R1 & R2: Refer application informations.
Protection Circuit for Two-Cell Lithium-Ion Battery Pack
DS-1802-03
July 13, 00
www.analog.com.tw
1
AIC1802
n
ORDERING INFORMATION
AIC1802 XCX
PIN CONFIGURATION
ORDER NUMBER
PACKAGE TYPE
S: SOP-8
AIC1802ACS
AIC1802BCS
AIC1802CCS
(PLASTIC SO8)
OVERCHARGE
PROTECTION VOLTAGE
A: 4.35V
B: 4.30V
C: 4.25V
TOP VIEW
OC 1
OD 2
8 VC
7 CS
6 VC
TD 3
GND 4
5 TC
n ABSOLUTE MAXIMUM RATINGS
Supply Voltage
....................................… … … … … ..................................................... 18V
DC Voltage Applied on VC, CS, OC, OD Pins ...............… … … … … ..............................
18V
DC Voltage Applied on TC, TD Pins ...............… … … … … … … ..… … ..............................
5V
Operating Temperature Range
Storage Temperature Range
.......................................… .… … … … .............. -40°C~85°C
.........................… … … … … … … .....................
- 65°C~150°C
n TEST CIRCUIT
ICO
1
OC
VCC
ICC
8
VCC
VCS
VOD
2
OD
CS 7
TD
VC 6
4 GND
TC 5
3
+
CTD
AIC1802
IC
VC
+
CTC
2
AIC1802
n ELECTRICAL CHARACTERISTICS (Ta=25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS SYMBOL
MIN.
TYP.
MAX.
UNIT
Supply Current in Normal Mode
VCC =7V, VC =3.5V
ICC
10
15
µA
Supply Current in Power-Down
Mode
VCC =4.8V, VC =2.4V
IPD
0.8
1.2
µA
VC Pin Input Current
VCC =7V, VC =3.5V
IC
400
600
nA
4.32
4.35
4.38
4.27
4.30
4.33
4.22
4.25
4.28
AIC1802A
Overcharge Protection Voltage
AIC1802B
VOCP
AIC1802C
V
Overcharge Release Voltage
VOCR
3.85
4.0
4.15
V
Overdischarge Protection
Voltage
VODP
2.25
2.4
2.55
V
Overdischarge Release Voltage
VODR
2.85
3.0
3.15
V
Overcurrent Protection Voltage
VCC =7V
VOIP
135
150
165
mV
Overcharge Delay Time (1)
VCC =8.6V, VC =4.3V,
CTC =0µF
TOC1
12
25
38
mS
Overcharge Delay Time (2)
VCC =8.6V, VC =4.3V,
CTC =0.47µF
TOC2
0.7
1.1
1.5
S
Overdischarge Delay Time (1)
VCC =4.8V, VC =2.4V,
CTD =0µF
TOD1
12
25
38
mS
Overdischarge Delay Time (2)
VCC =4.8V, VC =2.4V,
CTD =0.47µF
TOD2
0.7
1.1
1.5
S
Overcurrent Delay Time (1)
VCC =7V, VC =3.5V,
VCS=0.15V
TOI1
4
9
14
mS
Overcurrent Delay Time (2)
VCC =7V, VC =3.5V,
VCS=0.36V
TOI2
1.0
2.0
3.0
mS
OC Pin Source Current
VCC =8.6V, VC =4.3V,
OC Pin Short to GND
ICO
270
400
530
µA
OD Pin Output “H” Voltage
VDL
VCC -0.1 VCC -0.02
V
3
AIC1802
n ELECTRICAL CHARACTERISTICS (Continued)
PARAMETER
TEST CONDITIONS SYMBOL
OD Pin Output “L” Voltage
MIN.
TYP.
MAX.
UNIT
0.01
0.1
V
VDH
Charge Detection Threshold
Voltage
VCC =4.8V
VCH
-0.55
-0.4
Unbalance Discharge Current
VCC =8.3V, VC =4V
IUD
5.4
7.7
V
10
mA
n TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs. Supply Voltage
Power-down Current vs. Supply Voltage
10.7
Power-Down Current (µA)
VC=1/2VC C
TA=25°C
Supply Current (µA)
10.5
0.8
0.65
10.3
10.1
VC=1/2VCC
TA=25°C
0.5
0.35
9.9
0.2
9.7
5.5
6.5
7.5
3.8
8.5
4.3
Supply Voltage (V)
Overcharge Protection Voltage vs. Temperature
Overcurrent Protection Voltage (mV)
Overcharge Protection Voltage (V)
4.32
4.315
AIC1802B
4.31
4.305
4.3
-20
-10
0
10
20
30
Temperature (°C)
4.8
5.3
5.8
Supply Voltage (V)
40
50
60
70
Overcurrent Protection Voltage vs. Temperature
150
VCC=7V
VC=3.5V
147.5
145
142.5
140
-20
-10
0
10
20
30
40
50
60
70
Temperature (°C)
4
AIC1802
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Supply Current vs. Temperature
Power-Down Current vs. Temperature
1.1
VCC=7V
VC=3.5V
Power-Down Current (µA)
Supply Current (µA)
12.5
11.5
VCC=4.8V
VC=2.4V
0.9
10.5
0.7
9.5
0.5
8.5
-20
-10
0
10
20
30
Temperature (°C)
40
50
60
0
10
20
30
40
50
60
70
Overcharge Release Voltage vs. Temperature
Overdischarge Protection Voltage vs. Temperature
4.025
Overcharge Release Voltage (V)
Overdischarge Protection Voltage
(V)
2.415
4.020
2.410
4.015
2.405
4.010
2.400
-10
0
10
20
30
Temperature (°C)
40
50
60
70
4.005
-20
-10
0
10
20
30
40
50
60
70
Temperature (°C)
Overdischarge Release Voltage vs. Temperature
Overdischarge Release Voltage (V)
3.025
-10
Temperature (°C)
2.420
2.395
-20
-20
70
3.020
3.015
3.010
3.005
-20
-10
0
10
20
30
40
50
60
70
Temperature (°C)
5
AIC1802
n BLOCK DIAGRAM
VCC 8
OVERCHARGE
DETECTOR 1
450
OVERDISCHARGE
DETECTOR 1
VC
6
OVERDISCHARGE
DELAY CIRCUIT
3
LOGIC
CONTROL
OVERDISCHARGE
DETECTOR 2
4
OVERCURRENT
DELAY CIRCUIT
OVERCURRENT
DETECTOR
POWERDOWN
TD
VCC
WAKEUP
450
OD
TC
UNBALANCE
DISCHARGE
OVERCHARGE
DETECTOR 2
GND
5
OVERCHARGE
DELAY CIRCUIT
TIMING
GENERATION
1
OC
CHARGE
DETECTION
7
2
CS
n PIN DESCRIPTIONS
PIN 1: OC
- PMOS open drain output for
control of the charge control
MOSFET M2. When overcharge
occurs, this pin sources current to
switch the external NPN Q1 on,
and charging is inhibited by
turning off the charge control
MOSFET M2.
PIN 2: OD
- Output pin for control of
discharge control MOSFET
When overdischarge occurs,
pin goes low to turn off
discharge control MOSFET
and discharging is inhibited.
the
M1.
this
the
M1
PIN 3: TD
- Overdischarge delay time setting
pin.
PIN 4: GND - Ground pin. This pin is to be
connected to the negative terminal
of the lower battery cell.
PIN 5: TC
- Overcharge delay time setting
pin.
PIN 6: VC
- To be connected to the positive
terminal of the lower cell and
the negative terminal of the
upper cell.
PIN 7: CS
- Input pin for current sensing.
Using the drain-source voltage
of
the
discharge
control
MOSFET M1 (voltage between
CS and GND), it senses
discharge current during normal
mode and detects whether
charging current is present
during power down mode.
PIN 8: VCC - Power supply pin. It is to be
connected to the positive
terminal of the upper cell.
6
AIC1802
n APPLICATION INFORMATIONS
THE OPERATION
detection circuits except the overcharge detection
circuit for the cell under overcharge condition.
Overcharge Protection
When the voltage of either of the battery cells
exceeds VOCP (overcharge protection voltage)
Charge Detection after Overdischarge
period,
When overcharge occurs, the discharge control
charging is inhibited by the turning-off of the
MOSFET M1 turns off and discharging is inhibited.
charge control MOSFET M2. The overcharge
However, charging is still permitted through the
delay time (TOC ) defaults to 25mS and can be
parasitic diode of M1. Once the charger is
extended by adding a capacitor CTC . Inhibition of
connected to the battery pack, the AIC1802
charging is immediately released when the
immediately turns on all the timing generation and
voltage of the overcharged cell becomes lower
detection circuitry and goes into normal mode.
than VOCR (overcharge release voltage) through
Charging is determined to be in progress if the
discharge.
voltage between CS and GND is below –0.4V
beyond
the
overcharge
delay
time
(charge detection threshold voltage VCH )
Overdischarge Protection
When the voltage of either of the battery cells
Overcurrent Protection
goes
protection
In normal mode, the AIC1802 continuously
voltage) beyond the overdischarge delay time
monitors the discharge current by sensing the
period, discharging is inhibited by the turning-off
voltage of CS pin. If the voltage of CS pin
of the discharge control MOSFET M1. The
exceeds VOIP (overcurrent protection voltage)
overdischarge delay time (TOD ) defaults to 25mS
beyond overcurrent delay time TOI period, the
and can be extended by adding a capacitor CTD .
overcurrent
Inhibition of discharging is immediately released
discharging is inhibited by turning-off of the
when the voltage of the overdischarged cell
discharge control MOSFET M1. Discharging must
becomes
be inhibited for at least 256mS after overcurrent
below
VODP
higher
(overdischarge
than
VODR
(overdischarge
protection
circuit
operates
and
takes place to avoid damage to external control
release voltage) through charging.
MOSFETs due to rapidly switching transient
between
Power-Down after Overdischarge
When overdischarge occurs, the AIC1802 will go
into power-down mode, turning off all the timing
generation and detection circuitry to reduce the
quiescent current to 0.8µA (V CC =4.8V). In the
unusual
case
where
one
battery
cell
is
overdischarged while the other under overcharge
condition, the AIC1802 will turn off all the
VBAT+
and
VBAT-
terminals.
The
overcurrent condition returns to the normal mode
when the load is released and the impedance
between the VBAT+ and VBAT- terminals is 10MΩ or
higher. For the sake of protection of the external
MOSFETs, the larger the CS pin voltage (which
means the larger discharge current) the shorter
the overcurrent delay time. The relationship
between voltage of CS pin and overcurrent delay
7
AIC1802
time TOI is tabulated as below.
VCS (V)
TOI (S)
150m
9.0m
200m
5.6m
300m
2.8m
360m
CTC (F)
TOC (S)
0µ
25m
0.1µ
320m
0.3µ
890m
0.47µ
1.12
0.57µ
1.43
2.0m
1V
540µ
3V
290µ
CTD (F)
TOD (S)
5V
270µ
0µ
25m
0.1µ
320m
0.3µ
820m
0.47µ
1.08
0.57µ
1.39
Unbalanced Discharge after Overcharge
When either of the battery cells is overcharged,
the AIC1802 will automatically discharge the
overcharged cell at about 7.7mA until the voltage
of the overcharged cell is equal to the voltage of
the other cell. If the voltage of the other cell is
Selection of External Control MOSFETs
below VOCR, the internal cell-balance “bleeding”
Because the overcurrent protection voltage is
will proceed until the voltage of the overcharged
cell decreases to VOCR.
preset, the threshold current for overcurrent
detection is determined by the turn-on resistance
of the discharge control MOSFET M1. The turnon resistance of the external control MOSFETs
can be determined by the equation: RON =VOIP/IT
DESIGN GUIDE
Adjustment
of
Overcharge
Overdischarge Delay Time
and
Both the overcharge and overdischarge delay
times default to 25mS and can be extended by
adding the external capacitors C TC and C TD ,
respectively. Increasing the capacitance value will
increase the delay time. The relationship between
capacitance of the external capacitors and delay
time is tabulated as below:
(I T is the overcurrent threshold current). For
example, if the overcurrent threshold current IT is
designed to be 5A, the turn-on resistance of the
external control MOSFETs must be 30mΩ. Users
should be aware that turn-on resistance of the
MOSFET changes with temperature variation due
to heat dissipation. It changes with the voltage
between gate and source as well. (Turn-on
resistance of a MOSFET increases as the voltage
between gate and source decreases). Once the
turn-on resistance of the external MOSFET
8
AIC1802
changes, the overcurrent threshold current will
release
voltage
and
bleeding
function.
The
change accordingly.
relationship among Vrelease1,Vrelease2, R1, and
R2 is shown as following equations:
Suppressing the Ripple and Disturbance
from Charger
Vrelease1=VOCR+IUD*R1
To suppress the ripple and disturbance from
where
Vrelease2=VOCR+IUD*R2
charger, connecting C1 to cell 1 and C2 to cell 2 is
Vrelease1 is Battery 1, real overcharge release
necessary.
voltage
Vrelease2 is Battery 2, real overcharge release
voltage
Controlling the Charge Control MOSFET
R3, R4, R5 and NPN transistor Q1 are used to
Therefore, resistance of R1 and R2 should not
switch the charge control MOSFET M2. If
higher than 30Ω. Otherwise, overcharge release
overcharge does not occur, no current flows out
voltage
from OC pin and Q1 are turned off, then M2 is
protection voltage and the charging current may
turned on. When overcharge occurs, current flows
oscillate. In addition, if overcharge protection
out from OC pin and Q1 is turned on, which turns
function occurs, AIC1802 will discharge the
off M2 in turn. High resistance for R3, R4, and R5
overcharged cell and will stop bleeding function
is recommended for reducing loading of the
even if the voltage is not equal to the other. The
batteries.
recommended resistance of R1 and R2 is from 20
would
be
higher
than
overcharge
to 30Ω.
Latch-Up Protraction at CS Pin
R6 is used for latch-up protection when charger is
connected under overdischarge condition, and
also for overstress protection when charger is
connected in reverse. The charge detection
function after overdischarge is possibly disabled
by larger value of R6. Resistance of 1KΩ is
recommended.
Effect of C3
C3 has to be applied to the circuit. Because C3
will
keep
AIC1802
to
be
charged
after
overdischarge occurred. In addition, when the
differential voltage between charger and battery
pack
is
higher
than
2.1V
and
overcharge
protection function work, C3 will avoid battery
pack from being charged even if the battery
Selection of R1 and R 2
voltage lower than 4V (To avoid battery pack from
R1 and R2 are used to avoid large current flow
being
through the battery pack under the situation of IC
situation). The battery pack can be charged again
damage or pin short. On the other hand,
till remove it from charger.
charged
under
charger
malfunction
resistance of R1 and R2 will affect overcharge
9
AIC1802
PHYSICAL DIMENSIONS
l
8 LEAD PLASTIC SO (unit: mm)
D
H
E
e
C
B
SYMBOL
MIN
MAX
A
1.35
1.75
A1
0.10
0.25
B
0.33
0.51
C
0.19
0.25
D
4.80
5.00
E
3.80
4.00
e
A
A1
n
1.27(TYP)
H
5.80
6.20
L
0.40
1.27
L
10
Similar pages