PM6675AS datasheet(31/48 Pages) STMICROELECTRONICS

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PM6675AS

Device description

31/48

The Under-Voltage Protection circuit is enabled only at the end of the soft-start. Once an

UVP has taken part, a toggle on SWEN pin or a Power-On-Reset is necessary to clear the

fault state and restart the section.

7.1.12

Device thermal protection

The internal control circuitry of the PM6675AS self-monitors the junction temperature and

turns all outputs off when the 150 °C limit has been overran. This event causes the switching

section to be immediately disabled and both switches to be opened. The controller performs

a soft-end and both the outputs are eventually kept to ground, then the low side MOSFET is

turned on when the voltage of the switching section is lower than 400 mV.

The thermal fault is a latched protection and normal operating condition is restored by a

Power-On Reset or toggling SWEN and LEN pins at the same time.

7.2

LDO linear regulator section

The independent Low-Drop-Out (LDO) linear regulator has been designed to sink and

source up to 2 A peak current and 1 A continuously. The LDO output voltage can be

adjusted in the range 0.6 V to 3.3 V simply connecting a resistor divider as shown in

Figure 34 on page 32

Equation 23

Table 9.

Switching section OV, UV and OT faults management

Fault

Conditions

Action

Over voltage

VOUT > 115 % of the

nominal value

LGATE pin is forced high and the device latches off.

Exit by a Power-On Reset or toggling SWEN

Under voltage

VOUT < 70 % of the nominal

value

LGATE pin is forced high after the soft-end, then the

device latches off. Exit by a Power-On Reset or

toggling SWEN.

Junction over

temperature

TJ > +150 °C

LGATE pin is forced high after the soft-end, then the

device latches off. Exit by a Power-On Reset or

toggling SWEN and LEN after temperature drop.

VLDOADJ

⋅

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