AD5560JBCZ datasheet(31/68 Pages) AD

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Data Sheet

AD5560

Rev. D | Page 31 of 68

resistors to further optimize stability and settling time perform-

ance. The AD5560 has three compensation modes: safe mode,

autocompensation mode, and manual compensation mode, all

of which are described in more detail in the Force Amplifier

Stability section.

The range of suggested compensation capacitors allows

optimum performance for any capacitive load from 0 pF

to 160 μF using one of the modes previously listed.

Although there are four compensation input pins and five feed-

forward capacitor inputs pins, all capacitor inputs may be used

only if the user intends to drive large variations of DUT load

capacitances. If the DUT load capacitance is known and does

not change for all combinations of voltage ranges and test

conditions, then it is possible only one set of CCx and CFx

capacitors may be required.

Table 8. Suggested Compensation Capacitor Selection

Capacitor

Value

100 pF

330 pF

3.3 nF

4.7 nF

22 nF

100 nF

470 nF

2.2 μF

The voltage range for the CCx and CFx pins is the same as the

voltage range expected on FORCE; therefore, choice of capa-

citors should take this into account. CFx capacitors can have

10% tolerance; this extra variation directly affects settling

times, especially when measuring current in the low current

ranges. Selection of CCx should be at ≤5% tolerance.

CURRENT RANGE SELECTION

Integrated thin film resistors minimize external components

and allow easy selection of current ranges from ±5 µA to

±25 mA. Using external current sense resistors, two higher

current ranges are possible: EXTFORCE1 can drive currents

up to ±1.2 A, while EXTFORCE2 is designed to drive currents

up to ±500 mA. The voltage drop across the selected sense resistor

is ±500 mV when full-scale current is flowing through it.

The measure current amplifier has two gain settings, 10 and

20. The two gain settings allow users to achieve the quoted/

specified current ranges with large or small voltage swings.

The gain of 20 setting is intended for use with a 5 V reference,

and the gain of 10 setting is for use with a 2.5 V reference. Both

combinations ensure the specified current ranges. Other

VREF/gain setting combinations should only be used to

achieve smaller current ranges. Attempting to achieve greater

current ranges than the specified ranges is outside the intended

operation of the AD5560. The maximum guaranteed voltage

across RSENSE is ±0.64 V (gain of 20) or ±0.7 V (gain of 10).

HIGH CURRENT RANGES

For currents in excess of 1200 mA, a gang mode is available

whereby multiple devices are ganged together for higher currents.

There are two methods of ganging channels together; these are

discussed in the following two sections.

Master and Slaves in Force Voltage (FV) Mode

All devices are placed in force voltage (FV) mode. One device

acts as the master device and the other devices act as slaves. By

connecting in this manner, any device can be configured as the

master. Here, the MASTER_OUT pin of the master device is

connected to the output of the force amplifier, and it feeds the

inputs of each slave force amplifier (via the SLAVE_IN pin ).

All devices are connected externally to the DUT. For current

to be shared equally, there must be good matching between

each of the paths to the DUT. Settings for DPS Register 2 are

master = 0x0000, slave = 0x0400. Clamps should be disabled in

the slave devices.

EXTMEASIL

SENSE

MASTER DPS

EXTMEASIH1

SW5-a

FIN

DAC

×1

SW5-a

SW16

RSENSE

LOCAL

FEEDBACK

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

DUT

DUTGND

EXTMEASIL

SENSE

SLAVE DPS 1

EXTMEASIH1

SW5-a

FIN

DAC

×1

×20

×W

×20

×W

×20

×W

SW5-a

SW16

LOCAL

FEEDBACK

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

EXTMEASIL

SENSE

SLAVE DPS 2

EXTMEASIH1

SW5-a

FIN

DAC

ISENSE

AMP

VSENSE

AMP

ISENSE

AMP

VSENSE

AMP

ISENSE

AMP

VSENSE

AMP

×1

SW5-a

SW16

LOCAL

FEEDBACK

SW5-b

SW6

MASTER OUT

EXTFORCE1

EXTFORCE2

SLAVE IN

Figure 54. Simplified Block Diagram of High Current Ganging Mode

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