4

CAT93HC46

Doc. No. 1008, Rev. G

DEVICE OPERATION

The CAT93HC46 is a 1024-bit nonvolatile memory

intended for use with industry standard microprocessors.

The CAT93HC46 can be organized as registers of either

16 bits or 8 bits. When organized as X16, seven 9-bit

instructions control the reading, writing and erase

operations of the device. When organized as X8, seven

10-bit instructions control the operation of the device.

The CAT93HC46 operates on a single power supply and

will generate on chip the high voltage required during

write operation.

Instructions, addresses, and data are clocked into the DI

pin on the rising edge of the clock (SK). The DO pin is

normally in a high impedance state, except when reading

data from the device, or when checking the ready/busy

status after a write operation.

The ready/busy status can be determined after the start

of a write operation by selecting the device (CS high) and

polling the DO pin; DO low indicates that the write

operation is not completed, while DO high indicates that

the device is ready for the next instruction. If necessary,

the DO pin may be placed back into a high impedance

state by shifting a dummy “1” into the DI pin. The DO pin

will enter the high impedance state on the falling edge of

the clock (SK). Placing the DO pin into the high impedance

state is recommended in applications where the DI pin

and the DO pin are to be tied together to form a common

DI/O pin.

The format for all instructions sent to the device is a

logical "1" start bit, a 2-bit (or 4-bit) opcode, 6-bit byte/

word address (an additional bit when organized X8) and

for write operations a 16-bit data field (8-bit for X8

organization).

Figure 1. Sychronous Data Timing

SK

DI

CS

DO

tDIS

tPD0,tPD1

tCSMIN

tCSS

tDIS

tDIH

tSKHI

tCSH

VALID

VALID

DATA VALID

tSKLOW

INSTRUCTION SET

Start

Address

Data

Instruction

Bit

Opcode

x8

x16

x8

x16

Comments

READ

1

10

A6-A0

A5-A0

Read Address AN–A0

ERASE

1

11

A6-A0

A5-A0

Clear Address AN–A0

WRITE

1

01

A6-A0

A5-A0

D7-D0

D15-D0 Write Address AN–A0

EWEN

1

00

11XXXXX

11XXXX

Write Enable

EWDS

1

00

00XXXXX

00XXXX

Write Disable

ERAL

1

00

10XXXXX

10XXXX

Clear All Addresses

WRAL

1

00

01XXXXX

01XXXX

D7-D0

D15-D0 Write All Addresses