ADM1063ASU datasheet(18/36 Pages) AD

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ADM1063

Rev. 0 | Page 18 of 36

SEQUENCING ENGINE APPLICATION EXAMPLE

The application in this section demonstrates the operation of

the SE. Figure 27 shows how the simple building block of a

single SE state can be used to build a power-up sequence for a

3-supply system.

Table 7 lists the PDO outputs for each state in the same SE

implementation. In this system, the triggers required to start a

power-up sequence are the presence of a good 5 V supply on VP1

and the VX1 pin held low. The sequence intends to turn on the

3.3 V supply next, then the 2.5 V supply (assuming successful

turn-on of the 3.3 V supply). Once all three supplies are good,

the POWER_GOOD state is entered, where the SE remains until

a fault occurs on one of the three supplies, or until it is instructed

to go through a power-down sequence by VX1 going high.

Faults are dealt with throughout the power-up sequence on a

case-by-case basis. The following sections, which describe the

individual blocks, use this sample application to demonstrate

the state machine’s actions.

IDLE1

IDLE2

EN3V3

DIS3V3

DIS2V5

PWRGD

FSEL1

FSEL2

SEQUENCE

STATES

MONITOR FAULT

STATES

TIMEOUT

STATES

VX1 = 0

VP1 = 1

VP1 = 0

(VP1 + VP2) = 0

(VP1 + VP2 + VP3) = 0

(VP1 +

VP2) = 0

VP2 = 1

VP3 = 1

VP2 = 0

VX1 = 1

VP3 = 0

VP2 = 0

VP1 = 0

VX1 = 1

10ms

20ms

EN2V5

Figure 27. Sample Application Flow Diagram

Table 7. PDO Outputs for Each State

PDO Outputs

IDLE1

IDLE2

EN3V3

EN2V5

DIS3V3

DIS2V5

PWRGD

FSEL1

FSEL2

PDO1 = 3V3ON

PDO2 = 2V5ON

PDO3 = FAULT

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