ADM1168ASTZ datasheet(21/28 Pages) AD

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ADM1168

Rev. 0 | Page 21 of 28

POWER-UP

(VCC > 2.5V)

EEPROM

SMBus

DEVICE

CONTROLLER

LATCH A

LATCH B

FUNCTION

(OV THRESHOLD

ON VP1)

Figure 24. Configuration Update Flow Diagram

UPDATING THE SEQUENCING ENGINE

SE functions are not updated in the same way as regular

configuration latches. The SE has its own dedicated 512-byte

EEPROM for storing state definitions, providing 63 individual

states, each with a 64-bit word (one state is reserved). At power-up,

the first state is loaded from the SE EEPROM into the engine

itself. When the conditions of this state are met, the next state is

loaded from the EEPROM into the engine and so on. The loading

of each new state takes approximately 10 μs.

To alter a state, the required changes must be made directly to

the EEPROM. RAM for each state does not exist. The relevant

alterations must be made to the 64-bit word, which is then

uploaded directly to the EEPROM.

INTERNAL REGISTERS

The ADM1168 contains a large number of data registers. The

principal registers are the address pointer register and the

configuration registers.

Address Pointer Register

The address pointer register contains the address that selects one

of the other internal registers. When writing to the ADM1168, the

first byte of data is always a register address that is written to the

address pointer register.

Configuration Registers

The configuration registers provide control and configuration

for various operating parameters of the ADM1168. See the

AN-721 Application Note.

EEPROM

The ADM1168 has two 512-byte cells of nonvolatile, electrically

erasable, programmable, read-only memory (EEPROM), from

Address 0xF800 to Register Address 0xFBFF. The EEPROM is

used for permanent storage of data that is not lost when the

ADM1168 is powered down. One EEPROM cell, 0xF800 to

0xF9FF, contains the configuration data, user information and,

if enabled, any fault records of the device; the other section, 0xFA00

to 0xFBFF, contains the state definitions for the SE. Although

referred to as read-only memory, the EEPROM can be written to,

as well as read from, using the serial bus in exactly the same way

as the other registers.

The major differences between the EEPROM and other registers

are as follows:

•

An EEPROM location must be blank before it can be

written to. If it contains data, the data must first be erased.

•

Writing to the EEPROM is slower than writing to the RAM.

•

Writing to the EEPROM should be restricted because it has

a limited write/cycle life of typically 10,000 write operations

due to the usual EEPROM wear-out mechanisms.

The first EEPROM is split into 16 (0 to 15) pages of 32 bytes each.

Page 0 to Page 4, from Address 0xF800 to Address 0xF89F, hold

the configuration data for the applications on the ADM1168

(such as the SFDs and PDOs). These EEPROM addresses are

the same as the RAM register addresses, prefixed by F8. Page 5

to Page 7, from Address 0xF8A0 to Address 0xF8FF, are reserved.

Page 8 to Page 11 are available for customer use to store any

information that may be required by the customer in their

application. Customers can store information on Page 12 to

Page 15, or these pages can store the fault records written by

the sequencing engine if users have decided to enable writing

of the fault records for different states.

Data can be downloaded from the EEPROM to the RAM in one

of the following ways:

•

At power-up, when Page 0 to Page 4 are downloaded.

•

By setting Bit 0 of the UDOWNLD register (0xD8), which

performs a user download of Page 0 to Page 4.

When the sequence engine is enabled, it is not possible to access

the section of EEPROM from Address 0xFA00 to Address 0xFBFF.

The sequence engine must be halted before it is possible to read

or write to this range. Attempting to read or write to this range if

the sequence engine is not halted generates a no acknowledge,

or NACK.

Read/write access to the configuration and user EEPROM ranges

from Address 0xF800 to Address 0xF89F and Address 0xF900 to

Address 0xF9FF depends on whether the black box fault recorder

is enabled. If the fault recorder is enabled and one or more states

have been set as fault record trigger states, then it is not possible

to access any EEPROM location in this range without first halting

the black box. Attempts to read or write to this EEPROM range

while the fault recorder is operating are acknowledged by the

device but do not return any useful data or modify the EEPROM in

any way.

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