STBC21 Datasheet, PDF (21/54 Pages) STMicroelectronics – LI+ battery charger with thermal regulation

STBC21
Detailed description
Using an integrated resistor partition and a very low-offset comparator, it's possible to detect
a battery temperature value that doesn't depend on reference voltage, but is affected by an
internal resistor divider matching only.
As regards NTC, the components suggested are:
1. NTC1 PANASONIC R₂₅ = 100 kΩ ±1% B_25/85=4700 K ±1% (code ERTJ0EV104F)
2. NTC2 PANASONIC R₂₅ = 10 kΩ ±1% B_25/85=3435 K ±1% (code ERTJ0EG103FA)
Two resistor networks are proposed to implement linearization of these two NTCs, as written
below.
NTC1: R₁ = 100 kΩ - R₂ = 700 kΩ - R₃ = 17.8 kΩ
NTC2: R₁ = 9.1 kΩ - R₂ = 160 kΩ - R₃ = 0.22 kΩ
In this way, voltage thresholds of similar value for both NTCs are obtained. The STBC21
automatically recognizes these voltage thresholds.
T_LO (-2 °C)
2.128 V
T_L (10 °C)
1.74 V - 1.95 V
T_H (45 °C)
0.89 V - 1.1 V
T_HH (50 °C)
0.79 V - 1.002 V
T_HO (60 °C)
0.75 V
5.6
PHC pin functionality
The time diagram of the charging process can be summarized in the image below:
Figure 11. Charging process diagram
As shown, in fast-charge phase the power dissipation can be important and supposing V_IN =
9.0 V and I_BAT = 1.1 A:
Doc ID 023256 Rev 1
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