DFE252012P-2R2M datasheet(22/44 Pages) MICROCHIP

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MCP16501

DS20006388A-page 22

 2020 Microchip Technology Inc.

4.4.2

POWER-UP SEQUENCE

FLOWCHART

The start-up sequence is divided into three steps and

each Buck regulator is assigned to a specific sequence

step:

• Step 1 (Buck1) regulator is started after a delay

(t1) from the start-up event. If the start-up event is

no longer valid as the instant t1 expires, the

start-up sequence is aborted before the first regu-

lator is started.

• Step 2 (Buck2) regulator is started after a delay

(t2) since the completion of the sequence Step 1

(regulator enabled at Step 1 has been powered up

correctly).

• Step 3 (Buck3) regulator is started after a delay

(t3) from the completion of the sequence Step 2

(regulator enabled at Step 2 has been powered up

correctly).

The subsequent assertion of nRSTO is determined by

the status of all regulators that have been turned on

during the power-up sequence Their status is checked

before starting counter t4 and again checked at the

expiration of t4 to have nRSTO deasserted.

After the completion of the power-up sequence (i.e., at

the time instant nRSTO is deasserted), the MCP16501

will enter the Power Modes state machine operation

defined by the LPM and PWRHLD signals, and the cor-

responding device setting.

Some regulators which are supposed to turn on in the

power-up sequence may fail to power up correctly.

In this case, the sequencing engine adds a 32 ms

waiting time to allow the affected regulators to recover.

After the expiration of the 32 ms period, if the affected

regulators have still not recovered, the start-up

sequence is aborted and the MCP16501 returns to its

OFF state.

The start-up sequence flowchart is described in

Figure 4-6 on the next page.

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