Philips Semiconductors

Product specification

80C451/83C451/87C451

80C51 8-bit microcontroller family

4K/128 OTP/ROM/ROMless, expanded I/O

1998 May 01

9

Table 3. Control Status Register (CSR)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

MB1

MB0

MA1

MA0

OBFC

IDSM

OBF

IBF

BFLAG Mode Select

AFLAG Mode Select

Output Buffer

Flag Clear

Mode

Input Data

Strobe Mode

Output Buffer

Flag Full

Input Buffer

Flag Full

0/0 = Logic 0 output*

0/1 = Logic 1 output*

1/0 = IBF output

1/1 = PE input

(0 = Select)

(1 = Disable I/O)

0/0 = Logic 0 output*

0/1 = Logic 1 output*

1/0 = OBF output

1/1 = SEL input

(0 = Select)

(1 = Control/status)

0 = Negative

edge of ODS

1 = Positive

edge o ODS

0 = Positive

edge of IDS

1 = Low level

of IDS

0 = Output

data buffer

empty

1 = Output

data buffer full

0 = Input data

buffer empty

1 = Input data

buffer full

NOTE:

*

Output-always mode: MB1 = 0, MA1 = 1, and MA0 = 0. In this mode, port 6 is always enabled for output. ODS only clears the OBF flag.

PARAMETER

RATING

UNIT

Operating temperature under bias

0 to +70

°C

Storage temperature range

–65 to +150

°C

–0.5 to +6.5

V

Power dissipation (based on package heat transfer limitations, not device power consumption)

1.5

W

NOTES:

1. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and

functional operation of the device at these or any conditions other than those described in the AC and DC Electrical Characteristics section

of this specification is not implied.

2. This product includes circuitry specifically designed for the protection of its internal devices from the damaging effects of excessive static

charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying greater than the rated maxima.

noted.