AD5206 datasheet(12/20 Pages) AD

12 / 20 page

AD5204/AD5206

Rev. C | Page 12 of 20

OPERATION

The AD5204 provides a 4-channel, 256-position digitally

controlled VR device, and the AD5206 provides a 6-channel,

256-position digitally controlled VR device. Changing the pro-

grammed VR settings is accomplished by clocking an 11-bit

serial data-word into the SDI pin. The format of this data-word

is three address bits, MSB first, followed by eight data bits, MSB

first. Table 6 provides the serial register data-word format.

Table 6. Serial Data-Word Format

Address

Data

B10

MSB

LSB

MSB

LSB

210

See Table 10 for the AD5204/AD5206 address assignments to

decode the location of the VR latch receiving the serial register

data in Bit B7 through Bit B0. The VR outputs can be changed

one at a time in random sequence. The AD5204 presets to

midscale by asserting the PR pin, simplifying fault condition

recovery at power up. Both parts have an internal power-on

preset that places the wiper in a preset midscale condition at

power on. In addition, the AD5204 contains a power shutdown pin

(SHDN) that places the RDAC in a zero power consumption

state, where terminals Ax are open circuited and wipers Wx are

connected to terminals Bx, resulting in only leakage currents

being consumed in the VR structure. In shutdown mode, the

VR latch settings are maintained so that the VR settings return

to their previous resistance values when the device is returned

to operational mode from power shutdown.

RDAC

LATCH

AND

DECODER

SHDN

Figure 21. AD5204/AD5206 Equivalent RDAC Circuit

AD5206 Datasheet(PDF) 12 Page - Analog Devices