TheTTL - Al Kossow's Bitsavers

TIBPAL20L 10, TIBPAL20X4, TIBPAL20X8, TIBPAL20X10
HIGH·PERFORMANCE EXCLUSIVE·OR IMPACyrM PAL CIRCUITS
programming procedure for array fuses
Array fuses are programmed by executing the following programming sequence. Each fuse can be opened
by selecting the appropriate (one of 40) input line and (one of 80) product line. The levels for selecting
input lines and product lines are shown in Tables 1 and 2.
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 8
Step 9
Raise PGM ENABLE to VIHH.
Select an input line by applying appropriate logic levels to PI pins.
Select a product line group by applying appropriate logic levels to PA pins. The actual product
line selected will be determined by the PO pin (described in Step 5).
Raise OE to VIH.
Raise the selected PO pin to VIHH.
Program the fuse by pulsing Vee to VIHH.
Remove the voltage from the selected PO pin.
Lower OE to VIL to enable device
Verify the blowing of the fuse by checking for a VOL, at the selected PO pin. Register devices
require a position pulse on the PGM verify pin.
Steps 1 through 9 may be repeated if the verification does not indicate that the fuse was successfully
programmed (blown), but no more than four times. Verification is possible only with the verify·protect
fuse intact.
programming waveforms
PGMENABLE ~
PIO-PI5iE
SELECT INPUT LINE
PA8-PA10~
SELECT PRODUCT LINE GROUP
OE _______ ~I I \~---.:.- - - - ---- ~::
SELECTED ~ II.
I+-tsu~ . ~~h=+!. ____________ VIHH
POPIN_' j4.tw1+1
tsu~ ~th I
PGM VERIFY
VCC I 1\'"".-I----d
------------ . I I
1\ nnnxxlxxxn. ~ AIIIIi1ifiIIIII VOH
~~VOL
.. ~td2 - ---- - --- :I;H
ld1-.! I+-
---------------------.-.I--! I4- t
w2
n - - -- - ------- VIH
I I
VIL
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TEXAS ..
INSTRUMENTS
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