AD5241BRUZ1M-R7 datasheet(15/20 Pages) AD

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AD5241/AD5242

Rev. C | Page 15 of 20

ADDITIONAL PROGRAMMABLE LOGIC OUTPUT

The AD5241/AD5242 feature additional programmable logic

outputs, O1 and O2, that can be used to drive digital load, analog

switches, and logic gates. They can also be used as a self-contained

shutdown preset to Logic 0 that is further explained in the

Shutdown Function section. O1 and O2 default to Logic 0 during

power-up. The logic states of O1 and O2 can be programmed in

Frame 2 under the write mode (see Figure 4). Figure 34 shows

the output stage of O1, which employs large P-channel and N-

channel MOSFETs in push-pull configuration. As shown in

Figure 34, the output is equal to VDD or VSS, and these logic

outputs have adequate current driving capability to drive

milliamperes of load.

VDD

VSS

O1 DATA IN FRAME 2

OF WRITE MODE

Figure 34. Output Stage of Logic Output, O1

Users can also activate O1 and O2 in the following three different

ways without affecting the wiper settings:

Start, slave address byte, acknowledge, instruction byte

with O1 and O2 specified, acknowledge, stop.

Complete the write cycle with stop, then start, slave address

byte, acknowledge, instruction byte with O1 and O2 specified,

acknowledge, stop.

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

the parallel Zener ESD structures shown in Figure 36. This

applies to the digital input pins, SDA, SCL, and SHDN.

SHUTDOWN FUNCTION

Shutdown can be activated by strobing the SHDN pin or

programming the SD bit in the write mode instruction byte (see

). If the RDAC Register 1 or RDAC Register 2 (AD5242

only) is placed in shutdown mode by the software, SD bit, the

part returns the wiper to its prior position when a new command

is received.

Table 2

In addition, shutdown can be implemented with the device digital

output, as shown in Figure 35. In this configuration, the device

is shutdown during power-up but users are allowed to program

the device. Thus, when O1 is programmed high, the device exits

shutdown mode and responds to the new setting. This self-contained

shutdown function allows absolute shutdown during power-up,

which is crucial in hazardous environments, and it does not add

extra components.

SDA

SHDN

SCL

RPD

Figure 35. Shutdown by Internal Logic Output, O1

340

Ω

LOGIC

VSS

Figure 36. ESD Protection of Digital Pins

A,B,W

VSS

Figure 37. ESD Protection of Resistor Terminals

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