MCP4716 datasheet(63/86 Pages) MICROCHIP

63 / 86 page

DS22272A-page 63

MCP4706/4716/4726

8.0

TYPICAL APPLICATIONS

The MCP47X6 family of devices are general purpose,

single channel voltage output DACs for various

applications

where

precision

operation

with

low-power and nonvolatile EEPROM memory is

needed.

Since the devices include a nonvolatile EEPROM

memory, the user can utilize these devices for

applications that require the output to return to the

previous set-up value on subsequent power-ups.

Applications generally suited for the devices are:

• Set Point or Offset Trimming

• Sensor Calibration

• Portable Instrumentation (Battery Powered)

• Motor Control

8.1

Connecting to I2C BUS using

Pull-Up Resistors

The SCL and SDA pins of the MCP47X6 devices are

open-drain configurations. These pins require a pull-up

resistor as shown in Figure 8-2.

The pull-up resistor values (R1 and R2) for SCL and

SDA pins depend on the operating speed (standard,

fast, and high speed) and loading capacitance of the

I2C bus line. A higher value of the pull-up resistor

consumes less power, but increases the signal

transition time (higher RC time constant) on the bus

line. Therefore, it can limit the bus operating speed.

The lower resistor value, on the other hand, consumes

higher power, but allows higher operating speed. If the

bus line has higher capacitance due to long metal

traces or multiple device connections to the bus line, a

smaller pull-up resistor is needed to compensate the

long RC time constant. The pull-up resistor is typically

chosen between 1 k

Ω and 10 kΩ ranges for standard

and fast modes, and less than 1 k

Ω for high speed

mode.

8.1.1

DEVICE CONNECTION TEST

The user can test the presence of the device on the I2C

bus line using a simple I2C command. This test can be

achieved by checking an acknowledge response from

the device after sending a read or write command.

Figure 8-1 shows an example with a read command.

The steps are:

Set the R/W bit “High” in the device’s address

byte.

Check the ACK bit of the address byte.

If the device acknowledges (ACK = 0) the

command, then the device is connected,

otherwise it is not connected.

Send Stop bit.

FIGURE 8-1:

I2C Bus Connection Test.

SCL

SDA

1A2 A1 A0 1

Start

Bit

Address Byte

Address bits

Device Code

R/W

Stop

Bit

Device

Response

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