AD5560JBCZ datasheet(32/68 Pages) AD

32 / 68 page

AD5560

Data Sheet

Rev. D | Page 32 of 68

Master in FV Mode, Slaves in Force Current (FI) Mode

The master device is placed into FV mode, and all slave devices

into force current (FI) mode. The measured current of the

master device (MASTER_OUT) is applied to the input of all

slave devices (SLAVE_IN), and the slaves act as followers. All

channels work to share the current equally among all devices

in the gang. Because the slaves force current, matching the

DUT paths is not so critical. Settings for DPS Register 2 are

master = 0x0200, slave = 0x0600. Clamps should be disabled in

the slave devices.

EXTMEASIL

MASTER DPS

EXTMEASIH1

SW5-a

FIN

DAC

MEASOUT

BUFFER

AND GAIN

ISENSE

AMP

SENSE

SW5-a

SW16

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

EXTMEASIL

SLAVE DPS 1

EXTMEASIH1

SW5-a

FIN

DAC

MEASOUT

BUFFER

AND GAIN

ISENSE

AMP

SENSE

SW5-a

SW16

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

EXTMEASIL

SLAVE DPS 2

EXTMEASIH1

SW5-a

FIN

DAC

MEASOUT

BUFFER

AND GAIN

ISENSE

AMP

SENSE

SW5-a

SW16

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

DUT

DUTGND

×20

RSENSE

Figure 55. Simplified Block Diagram of Gang Mode,

Using an FV/FI Combination

The EXTFORCE1, EXTFORCE2, or ±25 mA ranges can be

used for the gang mode. Therefore, it is possible to gang devices

to get a high voltage/high current combination, or a low

voltage/high current combination.

For example, ganging five 25 V/25 mA devices using the 25 mA

range achieves a 25 V/625 mA range, whereas five 15 V/200 mA

devices using the EXTFORCE2 path can achieve a 15 V/1 A

range. Similarly, ganging four 3.5 V/1.2 A devices using the

EXTFORCE1 path results in a 3.5 V/4.8 A DPS.

IDEAL SEQUENCE FOR GANG MODE

Use the following steps to bring devices into and out of gang mode:

1. Choose the master device and force 0 V output, corres-

ponding to zero current.

2. Select slave DPS 1 and place it in slave mode (keep slaves in

high-Z mode via SW-INH or HW_INH until ready to gang).

3. Select to gang in either current or voltage mode.

4. Repeat Step 2 and Step 3 one at a time through the chain of

slaves.

5. Load the required voltage to the master device. The other

devices copy either voltage or current as programmed.

To remove devices from the gang, the master device should

be programmed to force 0 V out again. The procedure for

removing devices should be the reverse of Step 1 through Step 5.

Note that this may not always be possible in practice; therefore,

it is also possible to gang and ungang while driving a load. Just

ensure that the slave devices are in high-Z mode while confi-

guring them into the required range and gang setting.

Gang mode extends only to the ±25 mA range and the two high

current ranges, EXTFORCE1 and EXTFORCE2. Therefore, where

an accurate measurement is required at a low current, the user

should remove slaves from the gang to move to the appropriate

lower current range to make the measurement. Similarly, slaves

can be brought back into the gang if needed.

COMPENSATION FOR GANG MODE

When ganging, the slave devices should be set to the fastest

response.

When slaves are in FI mode, the AD5560 force amplifier over-

rides other compensation settings to enforce CFx = 0, RZ = 0,

and gmx ≤ 1. This is done internally to the force amplifier;

therefore, readback will not show that the signals inside the

force amplifier actually change.

SYSTEM FORCE/SENSE SWITCHES

System force/sense switches allow easy connection of a central

or system parametric measurement unit (PMU) for calibration

or additional measurement purposes.

The system device under test ground (SYS_DUTGND) switch

is shared with the GUARD/SYS_DUTGND pin (Pin 43). See

the DPS Register 2 in Table 19 for addressing details.

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