L9758

Operating modes

Doc ID 14273 Rev 3

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rate of the common voltage reference so the slew is different for each regulator because all

start together and reach the steady-state at the same time but with different voltage levels.

6.3

Power down

The power down sequence starts when both IGN and PSU_EN signal are low. In this phase

there is no control of the linear regulator output voltages. The falling slew-rate is defined

from load currents and load capacitors. A voltage comparator controls VDDL voltage and

ensures that the VDDL supply voltage will drop below 2V before initiating a new power-up

sequence.

Figure 4.

Power up/down sequence

6.4

Low voltage operation

When L9758 is up and running it is fully operational with the VBAT and VBAT_SW pin

operational. If only the buck regulator is used the L9758 operates as follow:

●

Switching regulator runs at 100% duty cycle

●

VKAM and VSTBY regulators are fully operational

●

VDDL fully operational

●

VCORE fully operational

●

VDD5 out of range with output voltage no less than 3.2V

●

Tracking regulators out of range with output voltages no less than 3.2V

●

Reset monitor RST5 and RSTL fully operational, with reset at RST5 pin in allowed

IGN

or

PSU_EN

VB

Vth_Start

VDD5

VDDL

Inductor

current

Soft start

Slew rate

control

Current

limitation

VCORE

RST5

RSTL