Analog Devices AN723 Application Notes

AN-723

APPLICATION NOTE

One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106 • Tel: [phone] • Fax: [phone] • www.analog.com

Interrupt Generation Using The ADM106x

by Peter Canty

INTRODUCTION

The ADM106x family of fully programmable supply
sequencers can be used as complete supply man­agement solutions in systems with multiple voltage
supplies. Applications include line cards in telecommu­nications infrastructure equipment (central offi ce, base
stations) and blade cards in ser vers.

One of the most powerful features of the ADM106x is
its 63-state sequencing engine (SE). The SE is used to
sequence the power-up and power- down of supplies. It
can do this autonomously, independent of a processor.
However, there may be circumstances where the user
wants an intervention by a processor. Examples include
fault reporting, recording supply measurements if one
fails, and performing margining on supplies. This appli­cation note briefl y describes how this can be achieved
using the ADM106x.

EXTERNAL

TEMP

SENSOR

DC/DC

CONVERTER

OUT

D1P

D1N

ADM1062

VP1

DAC1

SW CONTINUE

A function is built into the SE that can halt the ADM106x,
enabling a processor to take meaningful readings from
the device. The processor can then reinstate sequencing
and monitoring control to the ADM106x. This function
is called SW CONTINUE. It is a bit that can be set as
an “end of step” condition in any of the 63 states of the
SE. Once a state with this exit condition is entered, the
ADM106x cannot continue on to the next state until the
processor sends the SMBus instruction that sets the SW
CONTINUE bit to 1. The bit self- clears to 0 after the state
change has happened. Its use is best demonstrated by
an applications example.

SMBus

PDO1

MICRO-

PROCESSOR

INT

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FB

Figure 1. Functional Block Diagram

AN-723

Consider a system where multiple supplies are being
monitored by the ADM106x. If one of these were to fail,
the user may want to interrogate the ADM106x to fi nd
which supply faulted. This could be done as follows:

1. The user programs a PWRGD state.

a. All supplies are up and being monitored in this

state.

b. One of the PDOs is set up as a PWRGD signal,

indicating that all supplies are in tolerance. This
PDO could then be used as an interrupt signal to
the processor. The PWRGD state enables the PDO.

c. If one of the supplies being monitored fails, the SE

will move on to another state, e.g., the PWRFAIL
state.

2. The user programs the PWRFAIL state.

a. The PWRGD PDO changes, generating an interrupt

to the processor.

b. The end of step condition is programmed as

follows:

IF <SW CONTINUE> THEN GOTO CLR_INT AFTER

100ms.

3. The user programs the CLR_INT state.

a. The CLR_INT or CLEAR INTERRUPT state is where

the PDO is reasserted, thus clearing the interrupt to
the processor. The user can then choose to defi ne
another state, e.g., POWER_DOWN, RESUME.

4. The ADM106x starts the s e quenc e of the supplies and
enters the PWRGD state. Subsequently, one of the
supplies fails and the ADM106x enters the PWRFAIL
state.

a. The ADM106x SE is now halted and cannot move

on to the next state until it receives the < SW CON­TINUE> command from the processor.

b. The processor can now read the fault, i.e., the reg-

isters that indicate which inputs are faulting. Thus
the failing supply is identifi ed.

c. The processor now issues a SW CONTINUE com -

mand. A < CONTINUE> button is provided in the
ADM106x software. This is merely to write a 1 to
Bit 2 of Register 0x93 (SECTRL).

d. The ADM106x SE now moves on to CLR_INT.

PROGRAMMING THE SW CONTINUE FUNCTION IN THE ADM106x EVALUATION SOFTWARE

Figure 2 shows the SE programming window of the
ADM106x software.

AN04841–0–4/04(0)

Figure 2. SE Window

Figure 3. SW Continue

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