STPMIC25 datasheet(44/145 Pages) STMICROELECTRONICS

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5.4

Feature descriptions

5.4.1

VIN monitoring

The main input supply pin VIN is monitored permanently by the PMIC state machine. There are different threshold

triggers on VIN. The lowest to the highest thresholds are: VINPOR, VINOK, and VINLOW as presented in the

Figure 13.

Figure 13. VIN monitoring thresholds

Christophe Belet

VIN

VINPOR_Rise

VINOK_Rise (NVM)

VINLOW_Fall

VINLOW_Rise

VINOK_Fall

VINPOR_Fall

VINLOW_FA Interrupt

VINLOW_RI Interrupt

200 mV

VINOK_HYST (NVM)

VINLOW_HYST

5.4.1.1

VINPOR

VINPOR is the minimum voltage required to supply the PMIC internal circuitry. It is specified by two hardcoded

thresholds with 200 mV hysteresis:

Below VINPOR_Fall, the PMIC is considered as not supplied.

Above VINPOR_Rise, the PMIC internal circuitry is functional.

Note:

Once VIN rises above VINPOR_Rise, PMIC internal circuitry remains functional until VIN falls below VINPOR_Fall.

Refer to Section 3.4.1 for threshold values.

5.4.1.2

VINOK

VINOK is the minimal voltage required to allow the PMIC to work in the POWER_ON state.

It is specified by VINOK_Rise threshold and VINOK_HYST hysteresis values that can be adjusted in the NVM,

respectively by the VINOK_RISE[1:0] and VINOK_HYST[1:0] bits field.

If VIN falls below VINOK_Fall (VINOK_Fall = VINOK_Rise – VINOK_HYST), then it is considered as a hard-fault turn-OFF

condition and the PMIC immediately starts the POWER_DOWN sequence (see Section 5.4.4.). Following this

condition, the PMIC waits for the tVINOK_Fall delay before it can restart, even if VIN goes back higher than

VINOK_Rise before the tVINOK_Fall delay ends.

Definition: The VIN > VINOK condition means that if VIN rises above VINOK_Rise then VIN remains higher than

VINOK_Fall. Reciprocally, VIN < VINOK means that VIN < VINOK_Fall or VIN is less than the VINOK_Rise threshold (this

definition is just to simplify the state machine description).

5.4.1.3

VINLOW

VINLOW operates as a flag: VINLOW_Fall and VINLOW_Rise are configurable software thresholds that notify the AP

(via an interrupt line) when the VIN voltage crosses one of those two thresholds.

VINLOW can be enabled and configured by programming the register VINLOW_CR.

VINLOW_Rise and VINLOW_Fall thresholds generate respectively VINLOW_RI and VINLOW_FA interrupts, allowing the

application processor to take relevant actions. They can be unmasked independently.

The VINLOW_RI interrupt is asserted once VIN goes below the VINLOW_Rise threshold.

The VINLOW_FA interrupt is asserted once VIN goes higher than the VINLOW_Fall threshold.

STPMIC25

Feature descriptions

DS14278 - Rev 3

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