BQ3285ESS datasheet(2/29 Pages) TI

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Block Diagram

Pin Descriptions

MOT

Bus type select input

MOT selects bus timing for either Motorola

or Intel architecture.

This pin should be

tied to VCC for Motorola timing or to VSS for

Intel timing (see Table 1).

The setting

should not be changed during system opera-

tion.

MOT is internally pulled low by a

30K

Ω resistor.

AD0–AD7

Multiplexed address/data input/

output

The bq3285E/L bus cycle consists of two

phases: the address phase and the data-

transfer phase.

The address phase pre-

cedes the data-transfer phase. During the

address phase, an address placed on

AD0–AD7 and EXTRAM is latched into the

bq3285E/L on the falling edge of the AS sig-

nal. During the data-transfer phase of the

bus cycle, the AD0–AD7 pins serve as a bidi-

rectional data bus.

Address strobe input

AS serves to demultiplex the address/data

bus. The falling edge of AS latches the ad-

dress on AD0–AD7 and EXTRAM. This de-

multiplexing process is independent of the

CS signal. For DIP and SOIC packages with

MOT=VSS, the AS input is provided a signal

similar to ALE in an Intel-based system.

Bus

Type

MOT

Level

Equivalent

R/W

Equivalent

Motorola

VCC

DS, E, or

Φ2

R/W

Intel

VSS

RD,

MEMR, or

I/OR

WR,

MEMW, or

I/OW

ALE

Table 1. Bus Setup

bq3285E/L

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