ADM1266ACPZ-R7 datasheet(22/62 Pages) AD

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ADM1266

Data Sheet

Rev. A | Page 22 of 62

BLACK BOX (EEPROM) FAULT RECORDING

The ADM1266 has a configurable black box feature. Using this

feature, the device is capable of recording to nonvolatile flash

memory the vital data about the system status that caused the

system to perform a black box write.

BLACK BOX WRITES WHEN EXTERNAL SUPPLY IS

POWERING DOWN

When all the input supplies fail, the state machine can be

programmed to trigger a write into the black box flash. Provided

that the AVDD_CAP voltage remains above 3.0 V during the

memory write, the entire fault record is written to the EEPROM.

To ensure a complete black box write, it is recommended to place

a capacitor of at least 68 µF on the AVDD_CAP pin.

TRIGGERING A BLACK BOX WRITE

Black box information can be captured in the loop action or

enter action of a state, when the black box action is triggered.

If the black box action is triggered in the loop action, the device

takes a snapshot immediately and writes it to the flash memory

at the end of the enter actions of the next state.

If the black box action is triggered in the enter actions, the

device takes a snapshot immediately and writes it at the end of

the enter actions of the same state.

When multiple ADM1266 devices are connected though the

IDB, a black box write trigger in each device initiates a black

box write to ensure that the status of the entire system is

captured. Each black box record has a unique ID that is the

same across all the devices, which enables combining

information together from multiple devices.

BLACK BOX RECORD MODE

There are two types of black box record mode: single mode and

cyclic mode. Four pages of flash memory are reserved for a

single mode black box record, and five pages of flash memory

for cyclic mode. Each black box record has 64 bytes. The black

box mode can be changed without power cycling the device.

Single Mode

In single mode, the black box can write up to 32 fault records.

When the 32 records are filled, the ADM1266 black box does

not write anymore until the records are erased. Single mode is

useful for keeping the initial fault records and preventing them

from being overwritten.

Cyclic Mode

In cyclic mode, the black box operates in a circular recording

mode, and after writing the eighth record of any page, the next

page is automatically erased to allow continuous black box

recording. In cyclic mode, there can be up to 32 records at a

time. Cyclic mode is useful to keep the most recent black box

information.

POWER-UP COUNTER

The power-up counter in the ADM1266 keeps a record of the

number of times the ADM1266 has been powered up. It is stored in

nonvolatile memory. The power-up counter is 2 bytes and has a

maximum count up to 65,535 power cycles. The counter

increments automatically at every power cycle of ADM1266

and cannot be reset by the user.

BLACK BOX WRITE TIME

Writing 4 bytes of data to the flash memory takes 46 µs, and

each fault record has 64 bytes of data. The total time taken to

write one fault record is approximately 736 µs.

BLACK BOX CONTENTS

The total number of black box records in the device can be read

from the record count byte of the BLACKBOX_INFORMATION

box is pointed by the logic index byte of the BLACKBOX_

INFORMATION register. The value is only valid when the

record count is greater than zero.

The last black box record number can be read back by the

READ_BLACKBOX register.

The black box record data can be read by READ_BLACKBOX.

The record number and the last record index can be read back

by BLACKBOX_INFORMATION.

ADM1266ACPZ-R7 数据表(PDF) 22 Page - Analog Devices

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