ADM1067ASU datasheet(19/32 Pages) AD

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ADM1067

Rev. B | Page 19 of 32

SEQUENCING ENGINE

OVERVIEW

The ADM1067’s sequencing engine (SE) provides the user with

powerful and flexible control of sequencing. The SE implements

a state machine control of the PDO outputs, with state changes

conditional on input events. SE programs can enable complex

control of boards such as power-up and power-down sequence

control, fault event handling, interrupt generation on warnings,

among others. A watchdog function that verifies the continued

operation of a processor clock can be integrated into the SE

program. The SE can also be controlled via the SMBus, giving

software or firmware control of the board sequencing.

The SE state machine comprises 63 state cells. Each state has the

following attributes:

•

Monitors signals indicating the status of the 10 input pins,

VP1 to VP4, VH, and VX1 to VX5.

•

Can be entered from any other state.

•

Three exit routes move the state machine onto a next state:

sequence detection, fault monitoring, and timeout.

•

Delay timers for the sequence and timeout blocks can be

programmed independently and changed with each state

change. The range of timeouts is from 0 ms to 400 ms.

•

Output condition of the 10 PDO pins is defined and fixed

within a state.

•

Transition from one state to the next is made in less than

20 μs, which is the time needed to download a state

definition from EEPROM to the SE.

SEQUENCE

TIMEOUT

MONITOR

FAULT

STATE

Figure 23. State Cell

The ADM1067 offers up to 63 state definitions. The signals

monitored to indicate the status of the input pins are the

outputs of the SFDs.

WARNINGS

The SE also monitors warnings. These warnings can be

generated when the ADC readings violate their limit register

value or when secondary voltage monitors on VPn or VH are

triggered. The warnings are OR’ed together and are available as

a single warning input to each of the three blocks that enable

exiting from a state.

SMBus JUMP/UNCONDITIONAL JUMP

The SE can be forced to advance to the next state uncondition-

ally. This enables the user to force the SE to advance. Examples

of where this could be used include moving to a margining state

or debugging a sequence. The SMBus jump or go-to command

can be seen as another input to sequence and timeout blocks,

which provide an exit from each state.

Table 7. Sample Sequence State Entries

State

Sequence

Timeout

Monitor

IDLE1

If VX1 is low , go to state IDLE2.

IDLE2

If VP1 is okay, go to state EN3V3.

EN3V3

If VP2 is okay, go to state EN2V5.

If VP2 is not okay after 10 ms, go to

state DIS3V3.

If VP1 is not okay, go to state IDLE1.

DIS3V3

If VX1 is high, go to state IDLE1.

EN2V5

If VP3 is okay, go to state PWRGD.

If VP3 is not okay after 20 ms, go to

state DIS2V5.

If VP1 or VP2 is not okay, go to state FSEL2.

DIS2V5

If VX1 is high, go to state IDLE1.

FSEL1

If VP3 is not okay, go to state DIS2V5.

If VP1 or VP2 is not okay, go to state FSEL2.

FSEL2

If VP2 is not okay, go to state DIS3V3.

If VP1 is not okay, go to state IDLE1.

PWRGD

If VX1 is high, go to state DIS2V5.

If VP1, VP2, or VP3 is not okay, go to state

FSEL1.

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