SOT23-3 Voltage Regulator Evaluation Board User’s Guide
DS51785A-page 8
©
2008 Microchip Technology Inc.
2.3.2
Ground Current and Quiescent Current
When measuring ground current, jumper JP3 should be removed, otherwise leave
jumper JP3 on. To measure ground current, perform the following steps:
1. Add the desired load resistor to R5.
2. Remove jumpers JP3 and JP4.
3. Connect an ammeter across testpoints TP6(+) and TP7(-). Select the
appropriate meter scale for the device that is being evaluated.
4. Connect a voltmeter across testpoints TP9(+) and TP10(-).
5. Add jumper JP1.
6. Apply source voltage to testpoints TP1(+) and TP2(-).
7. Verify that the voltage across testpoints TP9 and TP10 is within the expected
range of the tested device.
8. Read the Ground Current directly from the ammeter connected to testpoints TP6
and TP7.
9. Vary the input voltage to obtain data for ground current versus input voltage.
With no load attached to the output of the voltage regulator, the measured
“ground current” is also called the “quiescent current” of the regulator.
10. Add the load selection jumper, JP4.
11. Read the Ground Current directly from the ammeter connected to testpoints TP6
and TP7.
12. The data collected will be the “ground current” versus load current.
2.3.3
Load Resistance
R5 is used to set the desired load value. One choice is to set R5 to the minimum current
wanted for testing.
2.3.4
Line Step
Dynamic Line Step response may be evaluated by connecting an electronically
switched input voltage to testpoints TP1(+) and TP2(-), or to connector J1. An
oscilloscope is connected to TP3(Ch1 Trigger), TP9(Ch2) and TP10(Gnd). An
appropriate load is selected using R5 and JP4. The input voltage is then electronically
switched from a low voltage to a high voltage. The corresponding voltage waveform
data of the voltage regulator response is captured by the oscilloscope. Microchip will
be offering a Line Step module, part #102-00196, that connects directly to
connector J1. The Line Step module will be capable of switching between two voltage
levels that the user supplies.
2.3.5
Load Step
Dynamic Load Step response may be evaluated by connecting an electronically
switched load to testpoints TP9(+) and TP10(-) or to connector P1. An oscilloscope is
connected to the electronic load switch signal (Ch1 Trigger) and to TP9 (Ch2) and
TP10 (Gnd). The load is then electronically switched from a high resistance to a lower
one. The corresponding voltage waveform data of the voltage regulator response is
captured by the oscilloscope. Microchip will be offering a Load Step module, part
#102-00197, that connects directly to connector P1. The Load Step module will have
several selectable load values populated on board to cover a wide range of loads. The
load will have the ability to be electronically or manually switched.
