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ADP7185-3.3-EVALZ

P1-P3P4-P6P7-P9
UG-795 ADP7183-EVALZ/ADP7185-EVALZ User Guide
Rev. A | Page 4 of 9
VOLTAGE, REGULATION, AND CURRENT MESUREMENTS
OUTPUT VOLTAGE MEASUREMENTS
Figure 4 shows how the evaluation boards can be connected to a
voltage source and a voltmeter for basic output voltage accuracy
measurements.
A resistor can be used as the load for the regulator. Ensure that
the resistor has a power rating that is adequate to handle the power
expected to dissipate across it. An electronic load can also be
used as an alternative. Ensure that the voltage source can supply
enough current for the expected load levels.
Follow these steps to connect the evaluation boards to a voltage
source and voltmeter:
1. Connect the positive terminal (+) of the voltage source to
one of the GND pads on the evaluation boards.
2. Connect the negative terminal (−) of the voltage source to
the VIN pad on the evaluation boards.
3. Connect a load between the VOUT pad and one of the
GND pads on the evaluation boards.
4. Connect the positive terminal (+) of the voltmeter to the
VOUT pad on the evaluation boards.
5. Connect the negative terminal (−) of the voltmeter to one
of the GND pads on the evaluation boards.
When these steps are completed, the voltage source can be turned
on. If J1 is inserted (connecting EN to VIN for automatic startup),
the regulator powers up.
If the load current is large, the user must connect the voltmeter as
close as possible to the output capacitor to reduce the effects of
IR drops.
DROPOUT VOLTAGE MEASUREMENTS
Use the configuration shown in Figure 4 to measure the dropout
voltage. The dropout voltage is defined as the input to output
voltage differential when the input voltage is set to the nominal
output voltage. The ADP7183 and ADP7185 enter dropout mode
only for output voltages of at least −2.5 V. For lower voltage
outputs, the ADP7183 and ADP7185 enter undervoltage lockout
(UVLO) and shuts down. The dropout voltage increases with
larger loads.
For accurate measurements, use a second voltmeter to monitor
the input voltage across the input capacitor. The input supply
voltage may need adjusting to account for IR drops, especially
when using large load currents. Figure 3 shows the typical curve
of the dropout voltage measurements with different load currents.
12921-211
–200
–180
–160
–140
–120
–100
–80
–60
–40
–20
0
–1000 –100
–10
DROPOUT VOLTAGE (mV)
LOAD CURRENT
(mA
)
Figure 3. Dropout Voltage vs. Load Current (I
LOAD
), V
OUT
= −3.3 V, T
A
= 25°C
–
+
VOLTAGE SOURCE
LOAD
–+
VOLTMETER
–3.29999 V
12921-003
Figure 4. Output Voltage Measurement Setup
ADP7183-EVALZ/ADP7185-EVALZ User Guide UG-795
Rev. A | Page 5 of 9
LINE REGULATION MEASUREMENTS
For line regulation measurements, the output of the regulator is
monitored while its input is varied. For optimal line regulation,
the output must change as little as possible with varying input
levels. To ensure that the device is not in dropout mode during
line regulation measurement, V
IN
must be varied between V
OUT
−
0.5 V (or −2 V, whichever is greater) and −5.5 V. For example,
for an ADP7183 or ADP7185 with a fixed −3.3 V output, V
IN
must vary between −3.8 V and −5.5 V. Note that this measurement
can be repeated under different load conditions. Figure 5 shows
the typical line regulation performance of an ADP7183 or
ADP7185 with a fixed −3.3 V output.
12921-220
–3.40
–3.38
–3.36
–3.34
–3.32
–3.30
–3.28
–3.26
–3.24
–3.22
–5.5 –5.3 –5.1 –4.9 –4.7 –4.5 –4.3 –4.1 –3.9
V
OUT
(V)
V
IN
(V)
NO LOAD
I
LOAD
= –10mA
I
LOAD
= –100mA
I
LOAD
= –300mA
I
LOAD
= –500mA
Figure 5. Output Voltage (V
OUT
) vs. Input Voltage (V
IN
) at V
OUT
= −3.3 V, T
A
= 25°C
LOAD REGULATION MEASUREMENTS
For load regulation measurements, while the load varies,
monitor the output of the regulator. For optimal load regula-
tion, the output must change as little as possible with varying
loads. Hold the input voltage constant during load regulation
measurement. The load current can be varied from 0 mA to
−300 mA for the ADP7183 and from 0 mA to −500 mA for the
ADP7185. Figure 6 shows the typical load regulation perfor-
mance of an ADP7183 or ADP7185 with a fixed −3.3 V output
for an input voltage of −3.8 V.
V
OUT
(V)
I
LOAD
(mA)
–1000 –10–100
–3.369
–3.349
–3.329
–3.309
–3.289
–3.269
3.249
12921-219
Figure 6. Output Voltage (V
OUT
) vs. Load Current (I
LOAD
) at
V
IN
= −3.8 V, V
OUT
= −3.3 V, T
A
= 25°C
UG-795 ADP7183-EVALZ/ADP7185-EVALZ User Guide
Rev. A | Page 6 of 9
–+
VOLTAGE SOURCE
LOAD
–+
AMMETER
–0.00355 A
12921-007
Figure 7. Ground Current Measurement Setup
GROUND CURRENT MEASUREMENTS
Figure 7 shows how to connect the ADP7183 and ADP7185
evaluation board to a voltage source and an ammeter for ground
current measurements.
Use a resistor as the load for the regulator. Ensure that the resistor
has a power rating that is adequate to handle the power expected
to dissipate across it. As an alternative, use an electronic load.
Ensure that the voltage source can supply enough current for
the expected load levels.
Follow these steps to connect the evaluation board to a voltage
source and ammeter:
1. Connect the negative terminal (−) of the voltage source to
the VIN pad on the evaluation board.
2. Connect the negative terminal (−) of the ammeter to one of
the GND pads of the evaluation board.
3. Connect the positive terminal (+) of the ammeter to the
positive terminal (+) of the voltage source.
4. Connect a load between the positive terminal (+) of the
voltage source and the VOUT pad of the evaluation board.
When these connection steps are completed, turn on the voltage
source. If J1 is inserted (connecting EN to VIN for automatic
startup), the regulator powers up.
Ground Current Consumption
Ground current measurements can determine how much current
the internal circuits of the regulators consume while the circuits
perform the regulation function. To be efficient, the regulators
must consume as little current as possible. Typically, the regulators
use the maximum current when supplying their largest load level
(−300 mA for the ADP7183 and −500 mA for the ADP7185).
Figure 8 shows the typical ground current consumption for the
various load levels at V
OUT
= −3.3 V and T
A
= 25°C.
When the device is disabled (EN = GND), the ground current
drops to less than 2 μA.
I
LOAD
(mA)
GROUND CURRENT (mA)
12921-208
–6
–5
–4
–3
–2
–1
0
–500 –450 –400 –350 –300 –250 –200 –150 –100 –50 0
Figure 8. Ground Current vs. Load Current (I
LOAD
), V
OUT
= −3.3 V, T
A
= 25°C
P1-P3P4-P6P7-P9

ADP7185-3.3-EVALZ

Mfr. #:
Buy ADP7185-3.3-EVALZ
Manufacturer:
Analog Devices Inc.
Description:
3.3V VOUT EVALUATION BOARD
Lifecycle:
New from this manufacturer.
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