Datasheet
1 1
0
( ) 25
B
T T
NTCR T R e
æ ö
æ ö
´ -
ç ÷
ç ÷
è ø
è ø
= ´
2.25V
RT1
NTC
TS
RT2
+
-
+
-
V (45)
HOT
V (0)
COLD
TPS65070, TPS65072, TPS65073
TPS650731, TPS650732, TPS650701, TPS650702, TPS650721
SLVS950G –JULY 2009–REVISED MAY 2013
www.ti.com
Input Capacitor Selection
A small ceramic input capacitor of 10 μF is needed at the input of the boost converter. If the inductor is directly
connected to the SYS output of TPS6507x, the capacitor can be shared. In this case the capacitance needs to
be 22μF or above. Only X5R or X7R ceramic capacitors should be used.
BATTERY CHARGER
Temperature Sensing
The battery charger integrated in TPS6507x has an over temperature protection for the Li-ion cell. The
temperature is sensed with a NTC located at the battery. Comparators in TPS6507x suspend charge at a
temperature below 0°C and above 45°C. The charger supports two different resistor values for the NTC. The
default is internally programmed to 10k. It is possible to change to a 100k NTC with the I2C interface.
Table 8. NTCs Supported
RESISTANCE AT 25°C CURVE / B VALUE RT2 NEEDED FOR MANUFACTURER
LINEARIZATION
10k Curve 2 / B=3477 75k Several
100k Curve 1 / B=3964 370k Several
For best performance, the NTC needs to be linearized by connecting a resistor (RT2) in parallel to the NTC as
shown in Figure 46. The resistor value of RT2 needed for linearization can be found in Table 8.
If the battery charger needs to be operated without a NTC connected, e.g. for test purposes, a resistor of 10k or
100k needs to be connected from TS to GND, depending for which NTC TPS6507x is configured to in register
CHCONFIG1.
Figure 45. Linearizing the NTC
Changing the Charging Temperature Range (Default 0°C to 45°C)
The battery charger is designed to operate with the two NTCs listed above. These will give a cold and hot
temperature threshold of 0°C and 45°C. If the charger needs to operate (charge) in a wider temperature range
e.g. –5°C to 50°C, the circuit can be modified accordingly. The NTC changes its resistance based on the
equation listed below:
(18)
With:
R25 = NTC resistance at 25°C
T = temperature in Kelvin
T0 = reference temperature (298K)
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