
AUTOMOTIVE 80C31BH/80C51BH/87C51
Program Verification
(EPROM Only)
If Lock Bit 2 has not been programmed, the on-chip
Program Memory can be read out for program verifi-
cation. The address of the Program Memory location
to be read is applied to Ports 1 and 2 as shown in
Figure 13. The other pins are held at the ‘‘Verify
Code Data’’ levels indicated in Table 3. The con-
tents of the addressed location will be emitted on
Port 0. External pullups are required on Port 0 for
this operation. Detailed timing specifications are
shown in later sections of this datasheet.
If the Encryption Table has been programmed, the
data presented at Port 0 will be the Exclusive NOR
of the program byte with one of the encryption bytes.
The user will have to know the Encryption Table
contents in order to correctly decode the verification
data. The Encryption Table itself can not be read
out.
Reading the Signature Bytes
(EPROM Only)
The signature bytes are read by the same procedure
as a normal verification of locations 030H and 031H,
except that P3.6 and P3.7 need to be pulled to a
logic low. The values returned are:
(030H)
e
89H indicates manufactured by Intel
(031H)
e
57H indicates 87C51
Program/Verify Algorithms
(EPROM Only)
Any algorithm in agreement with the conditions list-
ed in Table 3, and which satisfies the timing specifi-
cations, is suitable.
Erasure Characteristics
(EPROM Only)
Erasure of the EPROM begins to occur when the
chip is exposed to light with wavelengths shorter
than approximately 4,000 Angstroms. Since sunlight
and fluorescent lighting have wavelengths in this
range, exposure to these light sources over an ex-
tended time (about 1 week in sunlight, or 3 years in
room level fluorescent lighting) could cause inadver-
tent erasure. If an application subjects the device to
this type of exposure, it is suggested that an opaque
label be placed over the window.
The recommended erasure procedure is exposure
to ultraviolet light (at 2537 Angstroms) to an integrat-
ed dose of at least 15 W-sec/cm
2
. Exposing the
EPROM to an ultraviolet lamp of 12,000
m
W/cm
2
rating for 30 minutes, at a distance of about 1 inch,
should be sufficient.
Erasure leaves the array in an all 1s state.
EPROM PROGRAMMING AND VERIFICATION CHARACTERISTICS:
(T
A
e
21
§
C to 27
§
C, V
CC
e
5V
g
20%, V
SS
e
0V)
Symbol
Parameter
Min
Max
Units
V
PP
Programming Supply Voltage
12.5
13.0
V
I
PP
Programming Supply Current
50
mA
1/T
CLCL
Oscillator Frequency
4
6
MHz
T
AVGL
Address Setup to PROG Low
48T
CLCL
T
GHAX
Address Hold After PROG
48T
CLCL
T
DVGL
Data Setup to PROG Low
48T
CLCL
T
GHDX
Data Hold After PROG
48T
CLCL
T
EHSH
P2.7 (ENABLE) High to V
PP
48T
CLCL
T
SHGL
V
PP
Setup to PROG Low
10
m
s
T
GHSL
V
PP
Hold After PROG
10
m
s
T
GLGH
PROG Width
90
110
m
s
T
AVQV
Address to Data Valid
48T
CLCL
T
ELQV
ENABLE Low to Data Valid
48T
CLCL
T
EHQZ
Data Float After ENABLE
0
48T
CLCL
T
GHGL
PROG High to PROG Low
10
m
s
15