
Philips Semiconductors
Preliminary specification
83C754/87C754
80C51 8-bit microcontroller family
4K/256 OTP/ROM, DAC, comparator, UART, reference
1998 Apr 23
4
PIN DESCRIPTION
MNEMONIC
DIP
PIN NO.
TYPE
NAME AND FUNCTION
V
SS
8
I
Circuit Ground Potential.
V
CC
P1.0–P1.2
22
I
Supply voltage during normal, idle, and power-down operation.
21, 23, 24
I/O
Port 1:
Port 1 is a 3-bit bidirectional I/O port with internal pull-ups on P1.0 and P1.1. Port 1 pins that
have 1s written to them can be used as inputs. As inputs, port 1 pins that are externally pulled low will
source current because of the internal pull-ups (P1.0, P1.1). (See DC Electrical Characteristics: I
IL
).
Port 1 also serves the special function features listed below (Note: P1.0 does
not
have the strong
pullup that is on for 2 oscillator periods.):
INT0 (P1.0):
External interrupt 0.
CEX (P1.1):
PCA clock output.
V
PP
(P1.2):
Programming voltage input (open drain).
Port 3:
Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s written to
them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 3 pins that are
externally being pulled low will source current because of the pull-ups. (See DC Electrical
Characteristics: I
IL
). Port 3 also functions as the data input for the EPROM memory location to be
programmed (or verified). (Note: P3.5 does
not
have the strong pullup that is on for 2 oscillator
periods.)
Port 3 also serves the special function as listed below:
ECI (P3.6):
External PCA clock input.
RxD/T0 (P3.4):
Serial port receiver data input.
Timer 0 external clock input.
INT1:
External interrupt 1.
TxD/T1 (P3.5):
Serial port transmitter data.
Timer 1 external clock input.
24
23
21
I
O
I
P3.0–P3.7
1–4,
25–28
I/O
3
1
I
I
4
2
I
I
RST
5
I
Reset:
A high on this pin for two machine cycles while the oscillator is running resets the device. After
the device is reset, a 10-bit serial sequence, sent LSB first, applied to RESET, places the device in the
programming state allowing programming address, data and V
PP
to be applied for programming or
verification purposes. The RESET serial sequence must be synchronized with the X1 input. (Note: The
83/87C754 does not have an internal reset resistor.)
X1
7
I
Crystal 1:
Input to the inverting oscillator amplifier and input to the internal clock generator circuits. X1
also serves as the clock to strobe in a serial bit stream into RESET to place the device in the
programming state.
X2
AV
CC 1
AV
SS 1
ZIN
6
O
Crystal 2:
Output from the inverting oscillator amplifier.
14
I
Analog supply voltage and reference input.
13
I
Analog supply and reference ground.
9
I
ZIN:
Input to analog multiplexer.
YIN
10
I
YIN:
Input to analog multiplexer.
XIN
11
I
XIN:
Input to analog multiplexer.
XYZRAMP
12
O
XYZRAMP:
Provides a low impedance pulldown to V
SS
under S/W control.
Decouple:
Output from regulated supply for connection of decoupling capacitors.
DECOUPLE
15
O
VREG
16
O
VREG:
Provides regulated analog supply output.
XYDACBIAS
17
O
XYDACBIAS:
Provides source voltage for bias of external circuitry.
–
Input which specifies verify mode (output enable) or the program mode.
/PGM = 1 output enabled (verify mode).
/PGM = 0 program mode.
XYSOURCE
18
O
XYSOURCE:
Provides source voltage from regulated analog supply.
ZDAC
19
O
ZDAC:
Switchable outp from the internal DAC.
ASEL (P0.0) –
Input which indicates which bits of the EPROM address are applied to port 3.
ASEL = 0 low address byte available on port 3.
ASEL = 1 high address byte available on port 3 (only the three least significant bits are used).
XYDAC
NOTE:
1. AV
SS
(reference ground) must be connected to 0V (ground). AV
CC
(reference input) cannot differ from V
CC
by more than
±
0.2V, and must be
in the range 4.5V to 5.5V.
20
O
XYDAC:
Non-switchable output from the internal DAC.