Datasheet
0 °C
(T1)
10 °C
(T2)
45 °C
(T3)
50°C
(T4)
60 °C
(T5)
Charge
Suspended
I
Charge
/2
I
Charge
Charge
Suspended
Charge Current
Temperature
V
FB
=2.05 V
V
FB
=2.025 V
Charge Voltage
V
FB
=2.1 V
Temperature
VREF COLD HOT
VREF VREF
HOT COLD
1 1
V RTH RTH
VT1 VT5
RT2 =
V V
RTH 1 RTH 1
VT5 VT1
æ ö
´ ´ ´ -
ç ÷
è ø
æ ö æ ö
´ - - ´ -
ç ÷ ç ÷
è ø è ø
VREF
COLD
V
1
VT1
RT1 =
1 1
+
RT2 RTH
-
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SLUSA49B –APRIL 2010– REVISED OCTOBER 2011
Temperature Qualification and JEITA Guideline
The controller continuously monitors battery temperature by measuring the voltage between the TS pin and
GND. A negative-temperature-coefficient (NTC) thermistor and an external voltage divider typically develop this
voltage. The controller compares this voltage against its internal thresholds to determine if charging is allowed.
To initiate a charge cycle, the voltage on the TS pin must be within the V
T1
to V
T5
thresholds. If V
TS
is outside of
this range, the controller suspends charge and waits until the battery temperature is within the V
T1
to V
T5
range.
During the charge cycle, the battery temperature must be within the V
T1
to V
T5
thresholds. If battery temperature
is outside of this range, the controller suspends charge and waits until the battery temperature is within the V
T1
to
V
T5
range. The controller suspends charge by turning off the PWM charge FETs. If V
TS
is within the range of V
T1
and V
T2
, charge voltage regulation on V
FB
pin is 2.1 V and the charge current is reduced to I
CHARGE
/2 (to avoid
early termination during V
T1
and V
T2
range, fast-charge current must be higher than 2 times the termination
current); if V
TS
is within the range of V
T2
and V
T3
, the charge voltage regulation on V
FB
pin is 2.1 V; if V
TS
is
within V
T3
and V
T4
, the charge voltage regulation on V
FB
pin is reduced back to 2.05 V; and if V
TS
is within V
T4
and V
T5
, the charge voltage regulation on the V
FB
pin is further reduced to 2.025 V. Figure 16 summarizes the
operation. See the "Li-ion battery-charger solutions for JEITA compliance" journal article (SLYT365).
Figure 16. Thermistor Sense Thresholds
Assuming a 103AT NTC thermistor on the battery pack as shown in Figure 1, the values of RT1 and RT2 can be
determined by using the following equations:
(8)
(9)
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