80C31BH Datasheet, PDF (14/16 Pages) Intel Corporation – CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

AUTOMOTIVE 80C31BH 80C51BH 87C51
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Figure 12 PROG Waveforms
Quick-Pulse Programming
(EPROM Only)
The setup for Microcontroller Quick-Pulse Program-
ming is shown in Figure 11 Note that the 87C51 is
running with a 4 to 6 MHz oscillator The reason the
oscillator needs to be running is that the device is
executing internal address and program data trans-
fers
The address of the EPROM location to be pro-
grammed is applied to Ports 1 and 2 as shown in
Figure 11 The code byte to be programmed into
that location is applied to Port 0 RST PSEN and
pins of Ports 2 and 3 specified in Table 3 are held at
the ‘‘Program Code Data’’ levels indicated in Table
2 Then ALE PROG is pulsed low 25 times as
shown in Figure 12
To program the Encryption Table repeat the 25-
pulse programming sequence for addresses 0
through 1FH using the ‘‘Pgm Encryption Table’’ lev-
els Don’t forget that after the Encryption Table is
programmed verify cycles will produce only encrypt-
ed data
To program the Lock Bits repeat the 25-pulse pro-
gramming sequence using the ‘‘Pgm Lock Bit’’ lev-
els After one Lock Bit is programmed further pro-
gramming of the Code Memory and Encryption Ta-
ble is disabled However the other Lock Bit can still
be programmed
Note that the EA V_PP pin must not be allowed to go
above the maximum specified V_PP level for any
amount of time Even a narrow glitch above that volt-
age level can cause permanent damage to the de-
vice The V_PP source should be well regulated and
free of glitches and overshoot
Figure 13 Program Verification
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