STBC21 datasheet(21/54 Pages) STMICROELECTRONICS

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STBC21

Detailed description

Doc ID 023256 Rev 1

21/54

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:

NTC1 PANASONIC R25 = 100 kΩ ±1% B25/85=4700 K ±1% (code ERTJ0EV104F)

NTC2 PANASONIC R25 = 10 kΩ ±1% B25/85=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.

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 VIN =

9.0 V and IBAT = 1.1 A:

TLO (-2 °C)

TL (10 °C)

TH (45 °C)

THH (50 °C)

THO (60 °C)

2.128 V

1.74 V - 1.95 V

0.89 V - 1.1 V

0.79 V - 1.002 V

0.75 V

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