MCP41XXX/42XXX
3.9
Shutdown (SHDN)
3.0
PIN DESCRIPTIONS
(MCP42XXX devices only)
3.1
PA0, PA1
The Shutdown pin has a Schmitt Trigger input. Pulling
this pin low will put the device in a power-saving mode
where A terminal is opened and the B and W terminals
are connected for all potentiometers. This pin should
not be toggled low when the CS pin is low. In order to
minimize power consumption, this pin has an active
pull-up circuit. The performance of this circuit is shown
in Figure 2-12. This pin will draw negligible current at
logic level ‘0’ and logic level ‘1’. Do not leave this pin
floating.
Potentiometer Terminal A Connection.
3.2
PB0, PB1
Potentiometer Terminal B Connection.
3.3
PW0, PW1
Potentiometer Wiper Connection.
3.4
Chip Select (CS)
TABLE 3-1:
Pin # Name
MCP41XXX Pins
Function
This is the SPI port chip select pin and is used to exe-
cute a new command after it has been loaded into the
shift register. This pin has a Schmitt Trigger input.
1
2
3
4
5
6
7
8
CS Chip Select
SCK Serial Clock
SI Serial Data Input
3.5
Serial Clock (SCK)
This is the SPI port clock pin and is used to clock-in
new register data. Data is clocked into the SI pin on the
rising edge of the clock and out the SO pin on the falling
edge of the clock. This pin is gated to the CS pin (i.e.,
the device will not draw any more current if the SCK pin
is toggling when the CS pin is high). This pin has a
Schmitt Trigger input.
VSS Ground
PA0 Terminal A Connection For Pot 0
PW0 Wiper Connection For Pot 0
PB0 Terminal B Connection For Pot 0
VDD Power
3.6
Serial Data Input (SI)
TABLE 3-2:
Pin # Name
MCP42XXX Pins
Function
This is the SPI port serial data input pin. The command
and data bytes are clocked into the shift register using
this pin. This pin is gated to the CS pin (i.e., the device
will not draw any more current if the SI pin is toggling
when the CS pin is high). This pin has a Schmitt Trigger
input.
1
2
CS Chip Select
SCK Serial Clock
SI Serial Data Input
3
4
VSS Ground
3.7
Serial Data Output (SO)
5
PB1 Terminal B Connection For Pot 1
PW1 Wiper Connection For Pot 1
PA1 Terminal A Connection For Pot 1
PA0 Terminal A Connection For Pot 0
PW0 Wiper Connection For Pot 0
PB0 Terminal B Connection For Pot 0
RS Reset Input
(MCP42XXX devices only)
6
This is the SPI port serial data output pin used for
daisy-chaining more than one device. Data is clocked
out of the SO pin on the falling edge of clock. This is a
push-pull output and does not go to a high-impedance
state when CS is high. It will drive a logic-low when CS
is high.
7
8
9
10
11
12
13
14
3.8
Reset (RS)
SHDN Shutdown Input
(MCP42XXX devices only)
SO Data Out for Daisy-Chaining
VDD Power
The Reset pin will set all potentiometers to mid-scale
(Code 80h) if this pin is brought low for at least 150 ns.
This pin should not be toggled low when the CS pin is
low. It is possible to toggle this pin when the SHDN pin
is low. In order to minimize power consumption, this pin
has an active pull-up circuit. The performance of this
circuit is shown in Figure 2-12. This pin will draw negli-
gible current at logic level ‘0’ and logic level ‘1’. Do not
leave this pin floating.
DS11195C-page 12
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
