MCP4921 datasheet(15/40 Pages) MICROCHIP

15 / 40 page

 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 (VDD)

VDD is the positive power supply input. The input power

supply is relative to AVSS and can range from 2.7V to

5.5V. A decoupling capacitor on VDD 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

DACx Outputs (VOUTA, VOUTB)

VOUTA and VOUTB are DAC outputs. The DAC output

amplifier drives these pins with a range of AVSS to VDD.

3.8

DACX Voltage Reference Inputs

(VREFA, VREFB)

VREFA and VREFB 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 AVSS to VDD.

3.9

Analog Ground (AVSS)

AVSS is the analog ground pin.

MCP4921

Pin No.

MCP4922

Pin No.

Symbol

Function

VDD

Positive Power Supply Input (2.7V to 5.5V)

—

No Connection

Chip Select Input

SCK

Serial Clock Input

SDI

Serial Data Input

—

No Connection

—

No Connection

LDAC

Syncronization input used to transfer DAC settings from serial

latches to the output latches.

—

SHDN

Hardware Shutdown Input

—10

VOUTB

DACB Output

—11

VREFB

DACB Voltage Input (AVSS to VDD)

712

AVSS

Analog ground

613

VREFA

DACA Voltage Input (AVSS to VDD)

814

VOUTA

DACA Output

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