L99LD21 datasheet(40/73 Pages) STMICROELECTRONICS

40 / 73 page

SPI functional description

L99LD21

40/73

DS11130 Rev 5

OVT1

Overtemperature for Buck1

(set when Tj ≥ TTSD for more than tOVT);

If this bit is set:

– in Active mode: Buck1 is latched OFF; reset is performed by

a R&C command, which will be successful only if Tj < TTSD -

TTSD_HYS (typ 140 °C). Then Buck1 is allowed to turn on

again.

– in LHM, after setting an OVT1, an auto restart procedure is

implemented: every tAUTORESTART OVT1 bit is automatically

cleared and, if Tj < TTSD - TTSD_HYS, then Buck1 is allowed

to turn on again, otherwise OVT1 bit is set again.

R/C

TW12

Thermal warning 2 for Buck1.

This bit is set if Tj ≥ TW2.

This is a read only and real time bit.

When Buck1 temperature decreases under a second threshold

(Tj < TW2 - TW2_HYS), this bit is cleared.

TW11

Thermal warning 1 for Buck1.

This bit is set if Tj ≥ TW1

This is a read only and real time bit.

When Buck1 temperature decreases under a second threshold

(TW1 - TW1_HYS), this bit is cleared.

TON_MIN_OP1

Operation at minimum on-time for Buck1.

This bit is set when Buck1 runs at an on-time shorter than

tON_MIN_BUCK for more than 32 (even not consecutive) cycles.

When TON_MIN_OP1 = 1, Buck1 is disabled until a read and

clear command of this bit has been acknowledged.

In LHM, an auto restart procedure cyclically clears this bit with

a period equal to tAUTORESTART.

R/C

TON_MIN_OP2

Operation at minimum on-time for Buck2.

This bit is set when Buck2 runs at an on-time shorter than

tON_MIN_BUCK for more than 32 (even not consecutive) cycles.

When TON_MIN_OP2 = 1, Buck2 is disabled until a read and

clear command of this bit has been acknowledged.

R/C

Parity Bit

ODD parity bit check

Table 22. SR#1: Status Register 1 (continued)

Bit

Default

Name

Description

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