MCP4821 datasheet(15/50 Pages) MICROCHIP

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DS20002249B-page 15

MCP4802/4812/4822

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

3.1

Supply Voltage Pins (VDD, VSS)

VDD is the positive supply voltage input pin. The input

supply voltage is relative to VSS and can range from

2.7V to 5.5V. The power supply at the VDD pin should

be as clean as possible for a good DAC performance.

It is recommended to use an appropriate bypass

capacitor of about 0.1 µF (ceramic) to ground. An

additional 10 µF capacitor (tantalum) in parallel is also

recommended to further attenuate high-frequency

noise present in application boards.

VSS is the analog ground pin and the current return path

of the device. The user must connect the VSS pin to a

ground plane through a low-impedance connection. If

an analog ground path is available in the application

Printed Circuit Board (PCB), it is highly recommended

that the VSS pin be tied to the analog ground path or

isolated within an analog ground plane of the circuit

board.

3.2

Chip Select (CS)

CS is the Chip Select input pin, which requires an

active-low to enable serial clock and data functions.

3.3

Serial Clock Input (SCK)

SCK is the SPI compatible serial clock input pin.

3.4

Serial Data Input (SDI)

SDI is the SPI compatible serial data input pin.

3.5

Latch DAC Input (LDAC)

LDAC (latch DAC synchronization input) pin is used to

transfer the input latch registers to their corresponding

DAC registers (output latches, VOUT). When this pin is

low, both VOUTA and VOUTB are updated at the same

time with their input register contents. This pin can be

tied to low (VSS) if the VOUT update is desired at the

rising edge of the CS pin. This pin can be driven by an

external control device such as an MCU I/O pin.

3.6

Analog Outputs (VOUTA, VOUTB)

VOUTA is the DAC A output pin, and VOUTB is the DAC

B output pin. Each output has its own output amplifier.

The full-scale range of the DAC output is from

VSS to G* VREF, where G is the gain selection option

(1x or 2x). The DAC analog output cannot go higher

than the supply voltage (VDD).

TABLE 3-1:

PIN FUNCTION TABLE FOR MCP4802/4812/4822

MCP4802/4812/4822

Symbol

Description

MSOP, PDIP, SOIC

1VDD

Supply Voltage Input (2.7V to 5.5V)

2CS

Chip Select Input

SCK

Serial Clock Input

SDI

Serial Data Input

5LDAC

Synchronization Input. This pin is used to transfer DAC settings

(Input Registers) to the output registers (VOUT)

6VOUTB

DACB Output

7VSS

Ground reference point for all circuitry on the device

8VOUTA

DACA Output

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