STPM066S datasheet(14/67 Pages) STMICROELECTRONICS

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Functional description

4.1

Programming by OTP

OTP cells are used to program all regulators output voltages and run frequencies, together with additional device

features. Programmable values are:

•

BUCK output values : 5.0 V, 3.6 V, 3.3 V, 1.5 V, 1.35 V, 1.2 V, 1.1 V or 1.0 V (3 bits)

•

BUCK current limit value: 1.35 A or 2.6 A (1 bit)

•

BUCK free running frequency: 0.4 or 2.4 MHz (1 bit)

•

LDO output values : 5.0 V, 3.3 V, 2.8 V, 2.5 V, 1.8 V, 1.3 V, 1.25 V or 1.2V (3 bits)

•

LDO output current limitation: 300 or 600 mA (1 bit)

•

BOOST output voltage: 7.0 V or 5.0 V (1 bit)

•

VREF output voltage: 4.1 V, 3.3 V, 2.5 V or 1.8 V (2 bits)

•

Watchdog selection: by WDI pin or through SPI (2 bits)

–

if OTP "WD_cfg" bits is "00" or "01": Use watchdog;

–

if OTP "WD_cfg" bits is "10" : No watchdog;

–

if OTP "WD_cfg" bits is "11": Use SPI as watchdog;

•

Effect of WD failure on FSM. If SPI_WD_REC_en=0 and OTP_WD_REC_en=0, a WD failure asserts

RESET_B but not FSM: the device keeps active state with regulators running. If one of these bits is “1”,

RESET_B is asserted and FSM goes to REC state.

•

Disabling or activation of a voltage regulator through the SPI

•

Regulators turning on order after the BUCK (2 bits per each regulator)

•

Regulators turning on delay after Power Good of the previous regulator: 0, 2, 5 or 10 ms (2 bits)

•

Reset activation after Power Good signal of a specific regulator (3 bits), with the possibility to add a delay

from 0 (no delay) to 10 ms (2 bits)

•

Reset activation by the over-voltage of regulators in reset activation list (1 bit)

The approach used in the STPM066S device is the following:

•

STPM066S OTP cells must be programmed before the first device turning on:

–

No default status is present for OTP programmed parameters

–

Customer can program OTP by himself

•

If all OTP cells are not written, the device automatically moves to OTP program mode.

•

OTP programming can be done only one time:

–

It is not possible an additional writing procedure after the first one:

◦

3 bits stored inside OTP means OTP written (USR Area Protection)

–

If the OTP programming procedure fails or it is wrong, the device is discarded

If a regulator is not used (disabled), it is recommended to set to “0” its enable and SeqId (post regulator

activation) bits. PGNDx and VBOOST pins should be connected to ground, while other pins can be left floating.

4.2

Voltage regulators and features description

4.2.1

Pre-regulator BUCK

The BUCK regulator operates using constant frequency peak current mode control. It works as Main BUCK

pre-regulator enabled by WKUP pin signal. The input voltage (VBAT2) is compatible with battery level (up to 32 V)

and the overvoltage detection of VBAT2 (typ 32 V, available via SPI and enabled by default) can be disabled via

SPI (enable by default condition). The switching frequency is set via OTP to 0.4/2.4 MHz with the possibility to

have Spread Spectrum (enabled by default and disabled via SPI). Output voltage is programmed with internal

OTP cells to 8 possible values (5.0 V, 3.6 V, 3.3 V, 1.5 V, 1.35 V, 1.2 V, 1.1 V or 1.0 V). Over current protection is

set via OTP to 1.35 or 2.5 A min peak. Soft start time and power stage driver slew rates (change in Trise and Tfall)

can be independently set via SPI. Compensation network is external.

The BUCK regulator provides the following diagnostics:

STPM066S

Functional description

DS12976 - Rev 2

page 14/67

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