MCP4011-103ESLASHMS datasheet(29/60 Pages) MICROCHIP

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DS21978C-page 29

MCP4011/2/3/4

5.0

SERIAL INTERFACE

5.1

Overview

The MCP4011/2/3/4 utilizes a simple 2-wire interface to

increment or decrement the digital potentiometer’s

wiper terminal (W). This interface uses the CS and U/D

pins. The CS pin is the Chip Select input, while the U/D

pin is the Up/Down input.

The Increment/Decrement protocol enables the device

to move one step at a time through the range of

possible resistance values. The wiper value is

initialized with the “default” value upon power-up.

A wiper value of 00h connects the wiper to terminal B.

A wiper value of 3Fh connects the wiper to terminal A.

Increment commands move the wiper toward terminal

A, but will not increment to a value greater than 3Fh.

Decrement commands move the wiper toward terminal

B, but will not decrement below 00h.

Refer to Section 1.0 “Electrical Characteristics”,

AC/DC Electrical Characteristics table for detailed input

threshold and timing specifications.

Communication is unidirectional. Therefore, the value

of the current wiper setting cannot be read out of the

MCP401X device.

5.2

Serial Commands

The MCP401X devices support eight serial commands.

Six of these commands are for support and to ease

migration with the MCP402X family of devices. The

commands can be grouped into the following types:

• Serial Commands

• High-voltage Serial Commands

All the commands are shown in Table 5-1.

The command type is determined by the voltage level

the CS pin is driven to. The initial state that the CS pin

must be driven is VIH. From VIH, the two levels that the

CS pin can be driven are:

•VIL

•VIHH

If the CS pin is driven from VIH to VIL, a serial

command is selected. If the CS pin is driven from VIH to

VIHH, a high-voltage serial command is selected.

Support of the high-voltage serial commands is for

compatiblity with the MCP402X devices.

TABLE 5-1:

COMMANDS

Command Name

High Voltage

on CS pin?

Increment

—

Increment (for MCP402X Compatibility)

—

Decrement

—

Decrement (for MCP402X Compatibility)

—

High-Voltage Increment 1 (for MCP402X Compatibility)

Yes

High-Voltage Increment 2 (for MCP402X Compatibility)

Yes

High-Voltage Decrement 1 (for MCP402X Compatibility)

Yes

High-Voltage Decrement 2 (for MCP402X Compatibility)

Yes

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