AUTOMOTIVE 87C5487C54-20

AC TESTING INPUT OUTPUT WAVEFORMS

270849 – 17

FLOAT WAVEFORMS

270849 – 18

For timing purposes a port pin is no longer floating when a

100 mV change from load voltage occurs and begins to float

EPROM CHARACTERISTICS

Table 3 shows the logic levels for programming the Program Memory the Encryption Table and the Lock Bits

and for reading the signature bytes

Table 3 EPROM Programming Modes

Mode

RST

PSEN

ALE

EA

P26

P27

P33

P36

P37

PROG

Program Code Data

H

L

1275V

L

H

H

H

H

Verify Code Data

H

L

H

H

L

L

L

H

H

Program Encryption

H

L

1275V

L

H

H

L

H

Array Address 0 – 3FH

Program Lock

Bit 1

H

L

1275V

H

H

H

H

H

Bits

Bit 2

H

L

1275V

H

H

H

L

L

Bit 3

H

L

1275V

H

L

H

H

L

Read Signature Byte

H

L

H

H

L

L

L

L

L

DEFINITION OF TERMS

ADDRESS LINES

P10 – P17 P20 – P25 respec-

tively for A0 – A13

DATA LINES

P00 – P07 for D0 – D7

CONTROL SIGNALS

RST PSEN P26 P27 P33

P36 P37

PROGRAM SIGNALS

PROGRAMMING THE EPROM

To be programmed the part must be running with a

4 MHz to 6 MHz oscillator (The reason the oscillator

needs to be running is that the internal bus is being

used to transfer address and program data to appro-

priate internal EPROM locations) The address of an

EPROM location to be programmed is applied to

Port 1 and pins P20 – P25 of Port 2 while the code

byte to be programmed into that location is applied

to Port 0 The other Port 2 and 3 pins RST PSEN

indicated in Table 3 ALEPROG is pulsed low to

program the code byte into the addressed EPROM

location The setup is shown in Figure 11

14