AD5522JSVDZ datasheet(39/45 Pages) AD

39 / 45 page

Preliminary Technical Data

AD5522

Rev. PrL | Page 39 of 45

SETTING UP THE DEVICE ON POWER ON

On power on, default conditions are recalled from the power on

reset register ensuring each PMU and DAC channel is powered

up to a known condition. To operate the device, the user must:

Configure the device by writing to the System Control

Calibrate out errors and load required calibration values to

(Gain) m and (Offset) c registers, and load codes to each

DAC input register (x1). Once x1 values are loaded to the

individual DACs, the calibration engine calculates the

appropriate x2 value and stores it ready for the PMU

address to call it.

Load the required PMU channel with the required force

mode, current range etc. Loading the PMU channel

configures the switches around the Force Amplifier,

Measure function, clamps and comparators and also acts as

a load signal for the DACs, loading the DAC register with

the appropriate stored x2 value.

As the voltage and current ranges have individual DAC

registers associated with them, each PMU register mode of

operation calls a particular x2 register. Hence, only updates

(changes to x1 register) to DACs associated with the

selected mode of operation are reflected to the output of

the PMU. If there is a change to the x1 value associated

with a different PMU mode of operation, then this x1 value

and it’s m and c coefficients are used to calculate a

corresponding x2 value which is stored in the correct x2

CHANGING MODES

There are different ways of handling a mode change:

Load any DAC x1 values that are required to change.

Remember that x1 registers are available per voltage and

current range (for Force Amplifier and Comparator

DACs), so you can preload these and may not need to

make changes. The calibration engine will calculate the x2

values and store them.

Now change into the new PMU mode. This will load the

new switch conditions in the PMU circuitry and load the

DAC register with the stored x2 data.

Use the Hi-Z V or Hi-Z I mode in the PMU register, this

makes the amplifier high impedance.

Now load any DAC x1 values that need to be loaded.

Remember that x1 registers are available per voltage and

current range, so you can preload these and may not need

to make changes.

When the Hi-Z (V or I) modes are used, the relevant DAC

outputs are automatically updated (FIN, CLL, CLH DACs).

For example, when selecting Hi-Z V (Voltage), the FIN

Voltage x2 result is loaded, offset and gain corrected,

cached and loaded to the FIN DAC. When forcing a

voltage, current clamps are engaged, so the CLL I (Current)

to the DAC register. Similarly, for the CLH I register.

Now change into the new PMU mode (FI/FV). This will

load the new switch conditions in the PMU circuitry. As

the DAC outputs are already loaded, transients when

changing current or voltage mode will be minimized.

AD5522JSVDZ 数据表(PDF) 39 Page - Analog Devices

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