Datasheet

UG-336 Evaluation Board User Guide
Rev. 0 | Page 4 of 8
V
IN
TO V
OUT
RESISTANCE (RDS
ON
) MEASUREMENTS
5. Connect the positive terminal (+) of the voltage meter
to the VIN pad on the evaluation board.
RDS
ON
is defined as the input-to-output voltage differential
divided by load current. The voltage meter reading divided
by the load current value gives the equivalent RDS
ON
value.
The voltage source can now be turned on. If J2 is inserted
(connecting EN to VIN for automatic startup), the switch
powers up.
RDS
ON
can be measured using the configuration shown in
Figure 4. For more accurate measurements, a second voltage
meter can be used to monitor the input voltage across the input
capacitor. The input supply voltage may need to be adjusted to
account for IR drops, especially if large load currents are used.
Figure 3 shows a typical curve of RDS
ON
measurements with
different load currents.
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6
5mA
10mA
50mA
100mA
200mA
500mA
10294-003
RDS
ON
(Ω)
V
IN
(V)
Follow these steps to connect the evaluation board to a voltage
source and voltage meter:
1. Connect the negative terminal (−) of the voltage source
to the GND pad on the evaluation board.
2. Connect the positive terminal (+) of the voltage source
to the VIN pad on the evaluation board.
3. Connect a load between the VOUT pad and the GND pad
on the evaluation board.
4. Connect the negative terminal (−) of the voltage meter to
the VOUT pad on the evaluation board.
Figure 3. RDS
ON
vs. Input Voltage (V
IN
)
+
–
VOLTMETER
1.99711
+
–
VOLTAGE
SOURCE
LOAD
10294-004
Figure 4. RDS
ON
Measurement