STPMIC25 datasheet(33/145 Pages) STMICROELECTRONICS

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Figure 8. Buck dynamic voltage scaling (DVS)

OCP and Hiccup management: Each buck converter supports OCP and can operate in Hiccup mode. When the

output load of the buck exceeds the IOUT max output current (related to inductor peak current limit threshold

IBKLIM), the PWM pulse is immediately stopped, and the buck starts to decrease output voltage, limiting the output

current. If the overcurrent lasts more than tOCPDB_BUCK:

•

An interrupt is generated (if the interrupt has been unmasked by software).

•

Default behavior: the buck is turned OFF for tHICCUP_DLY duration and then turned ON again.

•

Alternative behavior: the PMIC is turned OFF for tHICCUP_DLY duration and then turned ON again (or goes

to FAIL_SAFE_LOCK state).

See Section 5.4.9 for details on OCP & hiccup management.

All buck converters have a programmable IOUT max current threshold. IOUT thresholds are programmed in the

NVM_BUCKS_IOUT_SHR NVM register.

Output discharge: when the buck is disabled, a configurable pull-down (PD) discharge is automatically enabled.

The buck output voltage discharges in tSD_BKtime duration (with typical recommended BOM) so that the buck

converter output voltage is low before disabling the next regulators in the next ranking slot. Four values are

configurable by software at runtime: no pull-down, slow-PD, fast-PD and forced slow-PD by setting

BUCKS_PD_CR1/2. Fast discharge output can be modified by software in fast-PD when the buck is disabled, or it

can be disabled by software to make the buck converter output in high impedance when it is disabled. See

Figure 9 which shows fast-PD and slow-PD behavior.

Startup sequence: when a buck is enabled, a startup delay (tSU_BCK) occurs before the output voltage starts to

rise, and is followed by a soft-start voltage ramp (tSS_BCK). See Figure 9

STPMIC25

Power regulator descriptions

DS14278 - Rev 3

page 33/145

STPMIC25 Datasheet(PDF) 33 Page - STMicroelectronics