MCP4902-ESLASHP datasheet(21/48 Pages) MICROCHIP

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 2010 Microchip Technology Inc.

DS22250A-page 21

MCP4902/4912/4922

4.2.4

SHUTDOWN MODE

The user can shut down each DAC channel selectively

by using a software command or shut down all chan-

nels by using the SHDN pin. During Shutdown mode,

most of the internal circuits in the channel that was shut

down are turned off for power savings. The serial inter-

face remains active, thus allowing a write command to

bring the device out of the Shutdown mode. There will

be no analog output at the channel that was shut down

and the VOUT pin is internally switched to a known

resistive load (500 k

typical. Figure 4-4 shows the

analog output stage during the Shutdown mode.

The condition of the Power-on Reset circuit during the

shutdown is as follows:

Turned-off, if the shutdown occurred by the

SHDN pin;

On, if the shutdown occurred by the software.

The device will remain in Shutdown mode until the

SHDN pin is brought to high or a write command with

<SHDN> bit = 1 is latched into the device. When a DAC

is changed from Shutdown to Active mode, the output

settling time takes less than 10 µs, but more than the

standard active mode settling time (4.5 µs).

FIGURE 4-4:

Output Stage for Shutdown

Mode.

500 k



Power-Down

Control Circuit

Resistive

Load

VOUT

Amp

Resistive String DAC

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