AD5242(RevB) Просмотр технического описания (PDF) - Analog Devices

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AD5242
(Rev.:RevB)

I2C® Compatible 256-Position Digital Potentiometers

Analog Devices 

AD5241/AD5242

Users can also activate O1 and O2 in three different ways with-

out affecting the wiper settings.

1. Start, Slave Address Byte, Acknowledge, Instruction Byte

with O1 and O2 specified, Acknowledge, Stop.

2. Complete the write cycle with Stop, then Start, Slave Address

Byte, Acknowledge, Instruction Byte with O1 and O2 speci-

fied, Acknowledge, Stop.

3. Do not complete the write cycle by not issuing the Stop, then

Start, Slave Address Byte, Acknowledge, Instruction Byte

with O1 and O2 specified, Acknowledge, Stop.

All digital inputs are protected with a series input resistor and

parallel Zener ESD structures shown in Figure 9. This applies

to digital input Pins SDA, SCL, and SHDN.

SELF-CONTAINED SHUTDOWN FUNCTION

Shutdown can be activated by strobing the SHDN Pin or pro-

gramming the SD Bit in the Write Mode Instruction Byte. In

addition, shutdown can even be implemented with the device

digital output as shown in Figure 8. In this configuration, the

device will be shut down during power-up, but users are allowed

to program the device. Thus when O1 is programmed high, the

device will exit from the shutdown mode and respond to the

new setting. This self-contained shutdown function allows abso-

lute shutdown during power-up, which is crucial in hazardous

environments without adding extra components.

O1

SHDN

RPD

SDA

SCL

Figure 8. Shutdown by Internal Logic Output

340⍀

LOGIC

VSS

Figure 9. ESD Protection of Digital Pins

A,B,W

VSS

Figure 10. ESD Protection of Resistor Terminals

–12–

REV. B

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