
2009 Microchip Technology Inc.
DS40044G-page 13
PIC16F627A/628A/648A
TABLE 3-2:
PIC16F627A/628A/648A PINOUT DESCRIPTION
Name
Function
Input Type Output Type
Description
RA0/AN0
RA0
ST
CMOS
Bidirectional I/O port
AN0
AN
—
Analog comparator input
RA1/AN1
RA1
ST
CMOS
Bidirectional I/O port
AN1
AN
—
Analog comparator input
RA2/AN2/VREF
RA2
ST
CMOS
Bidirectional I/O port
AN2
AN
—
Analog comparator input
VREF
—AN
VREF output
RA3/AN3/CMP1
RA3
ST
CMOS
Bidirectional I/O port
AN3
AN
—
Analog comparator input
CMP1
—
CMOS
Comparator 1 output
RA4/T0CKI/CMP2
RA4
ST
OD
Bidirectional I/O port
T0CKI
ST
—
Timer0 clock input
CMP2
—
OD
Comparator 2 output
RA5/MCLR/VPP
RA5
ST
—
Input port
MCLR
ST
—
Master clear. When configured as MCLR, this
pin is an active low Reset to the device.
Voltage on MCLR/VPP must not exceed VDD
during normal device operation.
VPP
—
Programming voltage input
RA6/OSC2/CLKOUT
RA6
ST
CMOS
Bidirectional I/O port
OSC2
—
XTAL
Oscillator crystal output. Connects to crystal
or resonator in Crystal Oscillator mode.
CLKOUT
—
CMOS
In RC/INTOSC mode, OSC2 pin can output
CLKOUT, which has 1/4 the frequency of
OSC1.
RA7/OSC1/CLKIN
RA7
ST
CMOS
Bidirectional I/O port
OSC1
XTAL
—
Oscillator crystal input
CLKIN
ST
—
External clock source input. RC biasing pin.
RB0/INT
RB0
TTL
CMOS
Bidirectional I/O port. Can be software
programmed for internal weak pull-up.
INT
ST
—
External interrupt
RB1/RX/DT
RB1
TTL
CMOS
Bidirectional I/O port. Can be software
programmed for internal weak pull-up.
RX
ST
—
USART receive pin
DT
ST
CMOS
Synchronous data I/O
RB2/TX/CK
RB2
TTL
CMOS
Bidirectional I/O port. Can be software
programmed for internal weak pull-up.
TX
—
CMOS
USART transmit pin
CK
ST
CMOS
Synchronous clock I/O
RB3/CCP1
RB3
TTL
CMOS
Bidirectional I/O port. Can be software
programmed for internal weak pull-up.
CCP1
ST
CMOS
Capture/Compare/PWM I/O
Legend:
O = Output
CMOS = CMOS Output
P
= Power
— = Not used
I
= Input
ST = Schmitt Trigger Input
TTL = TTL Input
OD
= Open Drain Output
AN = Analog