87C51 Intel Corporation, 87C51 Datasheet - Page 7

• Manufacturer Part Number: 87C51
• Description: CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
• Manufacturer: Intel Corporation

ONCE MODE
The ONCE (‘‘On-Circuit Emulation’’) mode facilitates
testing and debugging of systems using the
87C51 BH without the 87C51 BH having to be re-
moved from the circuit The ONCE mode is invoked
by
1 Pull ALE low while the device is in reset and
2 Hold ALE low as RST is deactivated
While the device is in ONCE mode the Port 0 pins
float and the other port pins and ALE and PSEN are
weakly pulled high The oscillator circuit remains ac-
tive While the 87C51 BH is in this mode an emula-
tor or test CPU can be used to drive the circuit Nor-
mal operation is restored when a normal reset is ap-
plied
87C51 BH EXPRESS
The Intel EXPRESS system offers enhancements to
the operational specifications of the MCS-51 family
of microcontrollers These EXPRESS products are
designed to meet the needs of those applications
whose operating requirements exceed commercial
temperature
The EXPRESS program includes the commercial
standard temperature range with burn-in and an ex-
tended temperature range with or without burn-in
With the commercial standard temperature range
operational characteristics are guaranteed over the
temperature range of 0 C to 70 C With the extend-
ed temperature range option operational character-
istics are guaranteed over the range of
The optional burn-in is dynamic for a minimum time
of 160 hours at 125 C with V
following guidelines in MIL-STD-883 Method 1015
a
85 C
PSEN is high
CC
e
6 9V
b
g
40 C to
0 25V
Package types and EXPRESS versions are identified
by a one- or two-letter prefix to the part number The
prefixes are listed in Table 3
For the extended temperature range option this
data sheet specifies the parameters which deviate
from their commercial temperature range limits
NOTE
Contact distributor or local sales office to match EXPRESS
prefix to proper device
Examples
P87C51 indicates 87C51 in a plastic package and
specified for commercial temperature range without
burn-in
LD87C51 indicates 87C51 in a cerdip package and
specified for extended temperature range with burn-
in
Prefix
TP
TD
TN
TS
LD
LN
LP
D
N
P
S
Table 3 Prefix Identification
Package
Plastic
Cerdip
Plastic
Cerdip
Plastic
Cerdip
PLCC
PLCC
PLCC
Type
QFP
QFP
87C51 80C51BH 80C31BH
Temperature
Commercial
Commercial
Commercial
Commercial
Extended
Extended
Extended
Extended
Extended
Extended
Extended
Range
Burn-in
Yes
Yes
Yes
No
No
No
No
No
No
No
No
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