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Data Sheet

AD5380

ON-CHIP SPECIAL FUNCTION REGISTERS (SFR)

The AD5380 contains a number of special function registers

(SFRs), as outlined in Table 13. SFRs are addressed with REG1

= REG0 = 0 and are decoded using Address Bits A5 to A0.

Table 13. SFR Register Functions (REG1 = 0, REG0 = 0)

R/W

Function

NOP (No Operation)

Write CLR Code

Soft CLR

Soft Power-Down

Soft Power-Up

Control Register Write

Control Register Read

Channel Monitor

Soft Reset

SFR COMMANDS

NOP (No Operation)

REG1 = REG0 = 0, A5 to A0 = 000000

Performs no operation, but is useful in serial readback mode to

clock out data on DOUT for diagnostic purposes. BUSY pulses

low during a NOP operation.

Write CLR Code

REG1 = REG0 = 0, A5–A0 = 000001

DB13 to DB0 = Contain the CLR data

Bringing the CLR line low or exercising the soft clear function

will load the contents of the DAC registers with the data con-

tained in the user configurable CLR register, and will set

VOUT0 to VOUT39 accordingly. This can be very useful for

setting up a specific output voltage in a clear condition. It is also

beneficial for calibration purposes; the user can load full scale

or zero scale to the clear code register and then issue a hard-

ware or software clear to load this code to all DACs, removing

the need for individual writes to each DAC. Default on power-

up is all zeros.

Soft CLR

REG1 = REG0 = 0, A5 to A0 = 000010

DB13 to DB0 = Don’t Care

Executing this instruction performs the CLR, which is func-

tionally the same as that provided by the external CLR pin.

The DAC outputs are loaded with the data in the CLR code

indicated by the BUSY low time.

Soft Power-Down

REG1 = REG0 = 0, A5 to A0 = 001000

DB13 to DB0 = Don’t Care

Executing this instruction performs a global power-down

feature that puts all channels into a low power mode that

reduces the analog supply current to 2 µA max and the digital

current to 20 µA max. In power-down mode, the output

amplifier can be configured as a high impedance output or can

provide a 100 kΩ load to ground. The contents of all internal

registers are retained in power-down mode. No register can be

written to while in power-down.

Soft Power-Up

REG1 = REG0 = 0, A5 to A0 = 001001

DB13 to DB0 = Don’t Care

This instruction is used to power up the output amplifiers and

the internal reference. The time to exit power-down is 8 µs. The

hardware power-down and software function are internally

combined in a digital OR function.

Soft RESET

REG1 = REG0 = 0, A5 to A0 = 001111

DB13 to DB0 = Don’t Care

This instruction is used to implement a software reset. All

internal registers are reset to their default values, which

correspond to m at full scale and c at zero scale. The contents of

the DAC registers are cleared, setting all analog outputs to 0 V.

The soft reset activation time is 135 µs. Only perform a soft

reset when the AD5380 is not in power-down mode.

Rev. D | Page 23 of 40

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