STBC02JR datasheet(23/39 Pages) STMICROELECTRONICS

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STBC02

Functional pin description

DocID029261 Rev 2

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If not used, it is recommended both the nRESET and the RESET_NOW pins are pulled

down via a 100 kΩ resistor connected to GND.

6.13.2

Watchdog section control pins

The watchdog functionality can be enabled or disabled by using SWIRE commands (#27

enabled, #26 disabled).

If enabled by asserting the SWIRE command, the RESET_CLEAR function, implemented

using the RESET_NOW pin, allows the nRESET pulses to be skipped when in a high logic

level state.

It is recommended a proper RESET_CLEAR signal is applied at least 100 µs before the

next scheduled nReset transition to a low level (it occurs every 4000 ms).

Should the watchdog function be enabled at least after having detected a valid VIN plus a

delay of 150 ms, an nRESET signal transitioning to a low level occurs after 4000 ms

starting from the RST_PENDING transitioning to a high level. To skip this nRESET pulse, a

high level RESET_CLEAR signal must be generated prior to (at least 100 µs) the expiration

of the 4000 ms counter triggered by the RST_PENDING transitioning to a high level.

The watchdog function can be disabled anytime through an SWIRE command (#26) and if

so, the relevant circuit block goes back to the smart reset functionality default state. For

more details refer to the following timing diagram.

The watchdog function works when the STBC02 is in battery mode too.

Figure 20: Watchdog timing diagram

6.14

SW1_OA, SW1_OB, SW1_I, SW2_OA, SW2_OB, SW2_I

SPDT load switches pins. Both of SPDT load switches are controlled by an internal

of 3 Ω. SPDT

load switches can be paralleled to reduce the series resistor as well as to increase the

allowable flowing current.

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