8XC51RARBRC

ONCE MODE

The ONCE (‘‘On-Circuit Emulation’’) Mode facilitates

testing

and

debugging

of

systems

using

the

8XC51RX without the 8XC51RX 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

PSEN is high

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 8XC51RX is in this mode an emulator

or test CPU can be used to drive the circuit Normal

operation is restored when a normal reset is applied

8XC51RX 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

standards

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 Cto a70 C With the ex-

tended temperature range option operational char-

acteristics are guaranteed over the range of b40 C

to a85 C

The optional burn-in is dynamic for a minimum time

following guidelines in MIL-STD-883 Method 1015

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

Table 3 Prefix Identification

Prefix

Package

Temperature

Burn-In

Type

Range

P

Plastic

Commercial

No

N

PLCC

Commercial

No

S

QFP

Commercial

No

TP

Plastic

Extended

No

TN

PLCC

Extended

No

TS

QFP

Extended

No

LP

Plastic

Extended

Yes

LN

PLCC

Extended

Yes

LS

QFP

Extended

Yes

NOTE

Contact distributor or local sales office to match EXPRESS prefix with proper device

EXAMPLES

P80C51RA indicates 80C51RA in a plastic package and specified for commercial temperature range without burn-in

TS87C51RC indicates 87C51RC in a QFP package and specified for extended temperature range without burn-in

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