TS2208A/B
Li-Ion Battery Protector
Pin assignment
1. D
OUT
2. V
-
3. C
OUT
4. C
EXT
5. V
DD
6. V
SS
Ideal for One-Cell Rechargeable
Li-Ion Battery
General Description
The TS2208A/B series are over-charge/discharge protection ICs for rechargeable one-cell Lithium-ion batteries. They
bear an over-charge/over-discharge threshold for the battery cell voltage during charging/discharging process, and also
provide on-time protection when excess current or short circuit occurs.
The TS2208A/B series are essentially composed of a reference unit and three voltage detectors. During charging
process, when the cell voltage/V
DD
crosses the over-charge threshold voltage V
C1
, the over charge detector (COM1) will
switch the output pin (C
OUT
) to a low level within a delay time (t
C1
), and thus turning off the MOSFET connected to the
charging path. The C
OUT
pin may change to high level again when the V
DD
voltage falls below “V
C1
-V
HYS
”, or when V
DD
falls below V
C1
while the charger is disconnected from the battery pack.
During the discharging process, when the V
DD
voltage crosses the over-discharge threshold voltage (V
D1
), the
over-discharge detector (COM2) will switch D
OUT
to low level within a delay time (t
D1
), and thus turning off the MOSFET
connecting the discharging path. In the mean time, the TS2208A/B series will enter a low current standby mode. Once
into standby mode, it can only be released from standby after the battery pack is connected to a charger.
The conditions of excess current and short circuit protection are both determined according to the voltage at the V- pin.
As the voltage of V- pin reaches a greater value than V
OC
, which means an undesirable large current is flowing through
the path, D
OUT
will be switched to a low level and the path is cutoff after internally pre-set delay time (t
OC
) elapses. In the
case of short circuit, i.e. V- rises above V
SHORT
, the path will also be cutoff but with almost no delay time. Once the excess
current or short circuit fault is removed, the built-in resistor at the V- pin, typically 100kohm, will pull V- down to V
SS
and
bringing the IC back to normal operation.
Together with the application circuit, the TS2208A/B will function as a consummate protector for Li-ion battery packs
which leads to safety and long lifetime.
Features
Low current consumption
Supply current 3uA (typ) and standby current 0.1uA
High withstand voltage up to 22V (VDD ~ V-)
High accuracy voltage detection
Over charge detector
Over discharge detector
Over current and short circuit protection
Small package of SOT-26
Ordering Information
Part No.
TS2208ACX6
TS2208BCX6
Note: Marking BXX,
XX
is wafer and assembly lot code (A~Z and 1~9)
Threshold Voltage
4.33V ~ 4.37V
4.26V ~ 4.30V
Reel
Black
White
Pin Description
No.
1
2
3
4
Symbol
D
OUT
V
-
C
OUT
C
EXT
Description
Output of over discharge detection
Pin for charger negative input
Output of over charge detection
Pin for external capacitor Setting
COM1 delay time
Applications
Over-charge and over-discharge protection for Li-ion
cell pack
High precision protectors for cell-phones and other
gadget using on board Li-ion cell battery
5
6
V
DD
V
SS
Power supply
Ground
TS2208A/B series
1-6
2003/12 rev. B
Absolute Maximum Rating
Supply Voltage
Input Voltage
V
-
pin
V
CT
pin
Output Voltage
Power Dissipation
Operating Temperature Range
Storage Temperature Range
C
OUT
pin
D
OUT
pin
V
DD
V-
VCext
VC
OUT
VD
OUT
P
D
T
OPT
T
STG
-0.3 to 12
V
DD
-22 to V
DD
+0.3
V
DD
-0.3 to V
DD
+0.3
V
DD
-22 to V
DD
+0.3
V
DD
-0.3 to V
DD
+0.3
150
-40 to +85
-50 to +120
V
V
V
V
V
mW
o
o
C
C
Note:
Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any
conditions. Operation above these absolute maximum ratings may cause degradation or permanent damage to the
device. These are stress ratings only and do not necessarily functional operation below these limits.
Electrical Characteristics
(Ta = 25
o
C, unless otherwise specified.)
Parameter
Operating input voltage
Conditions
Voltage defined as V
DD
-V
SS
Detect rising
Over-charge threshold voltage
edge of supply
voltage
Over-charge threshold hysteresis
range
Over-charge delay time
C
3
= 0.01µF,
V
DD
= 3.6V to 4.4V
Detect falling edge of supply
voltage
V
DD
= 3.6V to 2.4V
Detect rising edge of “V-” pin
voltage
V
DD
= 3.0V
V
DD
= 3.0V
V
DD
= 3.0V
V
DD
= 3.6V,V-=1.0V
I
OL
= 50µA, V
DD
= 4.4V
I
OH
= -50µA, V
DD
= 3.9V
I
OH
= 50µA, V
DD
= 2.4V
I
OH
= -50µA, V
DD
= 3.9V
V
DD
= 3.9V,V-= 0V
V
DD
= 2.0V
TS2208B
V
HYS
TS2208A
V
C1
4.26
0.15
4.28
0.20
4.30
0.25
V
Symbol
V
DD1
Min
1.5
4.33
Typ
--
4.35
Max
10
4.37
V
Unit
V
t
C1
60
75
90
ms
Over-discharge threshold voltage
Over-discharge delay time
Over current detection voltage
Over current detection delay time
Short circuit detection voltage
Short circuit detection delay time
Reset resistance for excess
current protection
Nch ON voltage of C
OUT
Pch ON voltage of C
OUT
Nch ON voltage of C
OUT
Pch ON voltage of C
OUT
Supply current
Standby current
V
D1
t
D1
V
OC
t
OC
Vshort
tshort
Rshort
V
OL1
V
OH1
V
OL2
V
OH2
I
DD
I
standby
2.437
7
0.17
9
V
DD
-1.2
--
50
--
3.4
--
3.4
--
--
2.500
10
0.20
14
V
DD
-0.9
5
100
0.3
3.8
0.2
3.7
3
--
2.563
13
0.23
17
V
DD
-0.6
50
150
0.5
--
0.5
--
5
0.1
V
ms
V
ms
V
µS
KΩ
V
V
V
V
µA
µA
TS2208A/B series
3-6
2003/12 rev. B
Operation Description
COM1 (Over-Charge Detector)
COM1 is the monitor of the voltage at the V
DD
pin. COM1 senses an over charging condition and if this condition
continues longer than the delay time (t
C1
), When the voltage at V
DD
exceeds the over charge detector threshold V
C1
.
the C
OUT
pin goes to a “L” level thus turns off the external charge control N-ch MOSFET. An internal level shifter is
incorporated in the buffer driver at the C
OUT
pin to drive the “L” level of C
OUT
equal to the V- pin voltage. By the way,
the “H” level of C
OUT
is set equal to V
DD
.
The delay time (t
C1
) of over-charging is decided by the external capacitor C
3
connected between the Vss and Cext pin,
-6
it can be estimated as
t
C1
= [C
3
x (V
DD
-0.7)] / (0.48 x 10 )
. However, if the over-charge condition doesn’t last long
enough to cover the time delay window, C
OUT
will not go “L” and the charging process continues.
Required Conditions to Reset COM1 from Over Charging
After the MOSFET, the charge control is turns off, COM1 can be reset under two conditions. As resetting COM1
means C
OUT
returns to “H” again and the charging path is reconnected to restart of charging process. One of the
condition to reset COM1 is when V
DD
falls to lower than “V
C1
- V
HYS
” as a result of battery cell internal discharge.
Disconnecting the battery pack from the charger can also reset COM1 even when V
DD
is still within the hysteresis
window (V
C1
- V
HYS
≤V
DD
< V
C1
).
After the battery pack is disconnected from the charger, connecting a system load to the battery pack allows current to
flow through the parasitic diode of external charge control MOSFET. This discharging current will bring V
DD
down a
little over some time and once V
DD
drops below V
C1
, C
OUT
will become “H”.
COM2 (Over-Discharge Detector)
COM2 monitors the cell voltage at the V
DD
pin. When V
DD
drops below the over-discharge threshold V
D2
during the
discharging process, COM1 senses an over-charging condition and after delay time (t
D1
), the D
OUT
pin goes to a “L”
level and thus turning off the external discharge control N-ch MOSFET. As soon as this happens, the V- pin will be
pulled “H” by an internal PMOS and TS2208A/B series will be enter a standby mode.
Connecting the battery pack to a charger is a necessary condition for TS2208A/B series to recover from standby
mode. With the charger connected, the charge current can flow through the parasitic diode of the external discharge
control N-ch MOSFET while V
DD
is still lower than the over-discharge threshold. Once V
DD
is charged up to a value
higher than V
D1
, the D
OUT
pin goes “H”. This leads to the “ON” state of both the charge and discharge control
MOSFETs, and the charge process proceeds on as long as the charger is connected. Connecting a charger to the
battery pack when V
DD
voltage is already higher then V
D1
will make D
OUT
instantaneously “H”.
COM3 (Over Current Detector, Short Circuit Protector)
The over current detector and short circuit protector can work when both the charge and discharge control N-ch
MOSFETs are “ON”.
Under normal operation, the V- pin voltage will be either slightly higher or lower than Vss (dependent on the
impedance of the two MOSFETs). However, when the V- pin voltage rises to a value between the short protection
voltage Vshort and over current threshold V
OC
, the TS2208A/B series detect an excess current condition. As a result,
the external discharge control N-ch MOSFET goes “OFF” with the D
OUT
pin being at “L”. An output delay time for the
over current detection is internally fixed. A quick recovery of V- from a value between Vshort and V
OC
to the normal
value within the delay time keeps the discharge control FET staying at the “ON” state.
Short circuit may as well be explained as a “serious” over current condition. When the V- pin voltage rises to a value
not only higher than V
OC
but also higher than Vshort, the short circuit protector will shut the discharge MOSFET down
immediately to protect battery pack from being damaged or exploding.
The V- pin has a built-in pull down resistor. Thus once the cause of over current or short circuit is removed, the V- pin
will be pulled down to the ground level through the internal resistor. Therefore, with V- lower than the over current and
short circuit protection threshold, D
OUT
will be turned back on and the TS2208A/B series can continue normal charge
or discharge operation.
Notice that when over current or short circuit occurs, the TS2208A/B series will not enter a standby mode.
TS2208A/B series
4-6
2003/12 rev. B
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