Datasheet

 2004 Microchip Technology Inc. DS21897A-page 15
MCP4921/4922
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1: PIN FUNCTION TABLE
3.1 Positive Power Supply Input (V
DD
)
V
DD
is the positive power supply input. The input power
supply is relative to AV
SS
and can range from 2.7V to
5.5V. A decoupling capacitor on V
DD
is recommended
to achieve maximum performance.
3.2 Chip Select (CS)
CS is the chip select input, which requires an active-low
signal to enable serial clock and data functions.
3.3 Serial Clock Input (SCK)
SCK is the SPI compatible serial clock input.
3.4 Serial Data Input (SDI)
SDI is the SPI compatible serial data input.
3.5 Latch DAC Input (LDAC)
LDAC (the latch DAC syncronization input) transfers
the input latch registers to the DAC registers (output
latches) when low. Can also be tied low if transfer on
the rising edge of CS
is desired.
3.6 Hardware Shutdown Input (SHDN)
SHDN is the hardware shutdown input that requires an
active-low input signal to configure the DACs in their
low-power Standby mode.
3.7 DAC
x
Outputs (V
OUTA
, V
OUTB
)
V
OUTA
and V
OUTB
are DAC outputs. The DAC output
amplifier drives these pins with a range of AV
SS
to V
DD
.
3.8 DAC
X
Voltage Reference Inputs
(V
REFA
, V
REFB
)
V
REFA
and V
REFB
are DAC voltage reference inputs.
The analog signal on these pins is utilized to set the ref-
erence voltage on the string DAC. The input signal can
range from AV
SS
to V
DD
.
3.9 Analog Ground (AV
SS
)
AV
SS
is the analog ground pin.
MCP4921
Pin No.
MCP4922
Pin No.
Symbol Function
11V
DD
Positive Power Supply Input (2.7V to 5.5V)
— 2 NC No Connection
23CS
Chip Select Input
3 4 SCK Serial Clock Input
4 5 SDI Serial Data Input
— 6 NC No Connection
— 7 NC No Connection
58LDAC
Syncronization input used to transfer DAC settings from serial
latches to the output latches.
— 9 SHDN
Hardware Shutdown Input
—10V
OUTB
DAC
B
Output
—11V
REFB
DAC
B
Voltage Input (AV
SS
to V
DD
)
712AV
SS
Analog ground
613V
REFA
DAC
A
Voltage Input (AV
SS
to V
DD
)
814V
OUTA
DAC
A
Output