AD5522JSVD AD [Analog Devices], AD5522JSVD Datasheet - Page 20

• Manufacturer Part Number: AD5522JSVD
• Description: Quad Parametric Measurement Unit With Integrated 16-Bit Level Setting DACs
• Manufacturer: AD [Analog Devices]

AD5522
CURRENT RANGE SELECTION
Integrated thin film resistors minimize external components
and allow easy selection of current ranges from 5 µA (200kΩ),
20μA (50kΩ), 200μA (5kΩ) and 2mA (500Ω). Per channel, one
current range up to 64mA may be accommodated by
connecting an external sense resistor. For current ranges in
excess of 64mA, it is recommended an external amplifier be
used.
For the suggested current ranges, the maximum voltage drop
across the sense resistors is ±1V, however, to allow for
correction of errors, there is some over range available in the
current ranges. The full-scale voltage range that can be loaded
to the DAC is ±11.5V; the forced current may be calculated as
follows:
Where:
FI = Forced Current
VFIN = Voltage of the FIN DAC, See V
RSENSE = Selected Sense Resistor
Gain of Current Measure Instrumentation amplifier, it may be
set (via the serial interface) to 5 or 10.
Using the 5kΩ sense resistor and ISENSE gain of 10, the
maximum current range possible is ±225μA. Similarly for the
other current ranges, there is an over range of 12.5% to allow for
correction.
Also, the forced current range will only be the quoted full scale
range with an applied reference of 5V or 2.5V (with ISENSE
AMP gain = 5). The ISENSE amplifier is biased by the Offset
DAC output voltage, in such as way as to center the Measure
current output irrespective of the voltage span used.
When using the EXTFOHx outputs for current ranges up to
64mA, there is no switch in series with the EXTFOHx line,
ensuring minimum capacitance presented at the output of the
force amplifier. This is also an important feature if using a Pin
electronics driver to provide high current ranges.
HIGH CURRENT RANGES
With the use of an external high current amplifier, one high
current range in excess of 64mA is possible. The high current
amplifier simply buffers the force output and provides the drive
for the required current.
FI
=
RSENSE
VFIN
×
Gain
OUT
for DAC levels.
Rev. PrM | Page 20 of 48
DEVICE UNDER TEST GROUND (DUTGND)
By default, there is one DUTGND input available for all four
PMU channels. In some applications of a PMU, it is necessary
that each channel operate from its own DUTGND level.
Therefore the shared pin GUARDIN(0-3) /DUTGND(0-3) may
be configured as either the input to the GUARD amplifier
(GUARDIN), or as a DUTGND per channel function.
This may be configured through the serial interface on power
on as per required operation. The default connection is SW13b
(GUARDIN) and SW14b (DUTGND PER DEVICE).
When configured as DUTGND per channel, this multifunction
pin is no longer connected to the input of the guard amplifier,
instead it is connected to the low end of the instrumentation
amplifier (SW14a), and the input of the Guard amplifier is now
connected internally to MEASVH (SW13a).
MEASOUT
Figure 19. Addition of high current amplifier for wider current range(>64mA)
AGNDx
x1/x0.2
x1
+
-
MEASURE
VOLTAGE
IN AMP
Figure 20. Using the DUTGND per channel Feature
OFFSET DAC
BIAS TO
CENTER
IRANGE
DAC
AGND
+
FIN
-
+
Preliminary Technical Data
-
x5 or x10
x1
+
-
+
-
+
-
a
b
SW 14
SW 13
+
-
+
-
+
-
+
-
a
b
INTERNAL RANGE SELECT
(5uA, 20uA, 200uA, 2mA)
GUARD AMP
Rsense
EN
MEASVH (0-3)
GUARDIN (0-3)/
DUTGND (0-3)
GUARD (0-3)
a
10kΩ
SW 16
DUTGND
EXTMEASIH
MEASVH
DUTGND
EXTFOH
C FF
FOH
EXTMEASIL
HIGH CURRENT
BUFFER
DUT
DUT
Rsense