Quick DC and Transient Evaluation of Switching Mode DC-DC Converter

This 3-page application brief introduces the example to make DC and Transient Evaluation of Switching Mode DC-DC Converter effectively using the Keysight B2900A Series of Precision Source/Measure Units.

current, source, voltage, DC-DC, B2961A, B2962A, power, supply, B2900A

Quick DC and Transient Evaluation of Switching Mode DC-DC ...

Load regulation: This converts an inputted DC voltage into a stable DC output voltage even if the output current is varying. • Load transient response: This ...

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5991-3119
Quick DC and Transient Evaluation of Switching Mode DC-DC Converter
B2900A Series of Precision Source/Measure Units

DC Evaluation of DC-DC Converters

Multimeter

DC VoltageBs2o9ur1c2eA (front view)

This

two-pager

outlines

an

example

of

load

regulation

and load
Multimeter

transient

responseDC Voltage

source

characterization for an off-the-shelf switching mode DC-DC converter.

· Load regulation: This converts an inputted DC voltage into a stable DC output voltage even if the output current is varying.
· Load transient response: This is the variation or glitching that occurs in the output when the output load undergoes transient changes.
A dual-channel SMU (Source/Measure Unit) such as tIhNe B2902A DoUr TB2912A is aOnUT ideal choice for these types of measurements.

B2912A (rear view)
RL
The B2900A Series is BenchVue Software enabled.

Bench-top setup example for 4-terminal DUT

Multimeter Multimeter

DC Voltage source DC Voltage source

Channel 2 on the back side

Channel 1

RL

IN

DUT

OUT

IN

DUT

OUT

SMU setup example for 4-terminal DUT

Bench-top setup example for 4-terminal DUT

B2900A Series of SMU reduces the number of instruments and eliminates messy wiring

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Channel 2 on the back side

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Measurement Examples
It is easy to estimate load regulation by measuring the output voltage drift while sweeping the output load current. The load transient response can be monitored by measuring the output voltage transient when a pulsed current load is applied. In the example shown below, Ch 1 applies a constant voltage (12 V) to the input while Ch 2 either sweeps current to test load regulation or applies pulsed current to test the load transient response.
Note: Channel 1's high capacitance mode is ON in this example.

B2912A
A
Ch1

LTM8047

IN Vin

C1

RUN

C2 R1

BIAS ADJ

SS

GND

Vout Vout

725VDC Isolation

5V
C3
R2

B2912A
V
Ch2

DUT (LTM8047 on DC1693 Demo circuit Module) Note: LTM8047 and DC1693 Demo circuit are products of LINEAR TECHNOLOGY

Example 1: Load Regulation with 4-wire Measurement Technique
Sweeping the load current from 25 mA to 175 mA using a 4-wire Kelvin probe set shows stable measurement results1. Since the demo circuit board has an offset load of 25 mA, this is equivalent to testing the load regulation from 50 mA to 200 mA (the device's desired test condition). Moreover, since both the X and Y axes have two cursors available, you can easily readout the data and the variation from the display.

Note: 4-wire Kelvin probes with both sense and force outputs as shown in the measurement setup on the previous page are required for this type of measurement.
1. The displayed current increases in negative value as you go from right to left.

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Output voltage

Load regulation can be read as be read as 30 mV under 150 mA output current change

Output load current

Load regulation measurement result

Sense

Force

Kelvin measurement setup

How Broad is the B2900A SMU Series' Capability?

Sufficient to meet almost all bench-top evaluation needs!

Product number B2901A
B2902A
B2911A
B2912A

Number Max output

of channel DC

Pulse

1

210 V

200 V

3.03 A

10.5 A

2

210 V

200 V

3.03 A

10.5 A

1

210 V

200 V

3.03 A

10.5 A

2

210 V

200 V

3.03 A

10.5 A

Min source resolution
1 pA 1 µV 1 pA 1 µV 10 fA 100 nV 10 fA 100 nV

Min measure resolution
100 fA 100 nV 100 fA 100 nV 10 fA 100 nV 10 fA 100 nV

Min timing interval 20 µs
20 µs
10 µs
10 µs

Viewing mode Single, Graph Single, Dual, Graph Single, Graph, Roll Single, Dual, Graph, Roll

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Example 2: Load Transient Response with 10 s Sampling
This shows the load transient response as measured using the minimum 10 s 2 sampling interval of the B2912A. In this example the load current is changed from 100 mA to 200 mA for 5 msec and then returned to its original 100 mA value. The cursors' delta data shows that the transient undershoot is about 175 mV and its duration is about 1 ms.
Note: The B2900A SMU series have the ability to observe a 100 s level transient
2. The minimum sampling interval of the B2901A/02A is 20 s.

Output voltage

100 mV

Load current 100 mA

1 ms
Load transient response
200 mA

Load transient undershoot voltage can be read as 175 mV in 1 ms duration

Time (s)

Load transient response measurement result

Multiple Free Software Control Options
The B2900A series also offers Multiple free software control options, allowing you to choose the solution that best fits your particular application

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Related Applications
· LDO-Low Dropout regulator (measurement of output source/sink current capabilities)
· Linear regulator (measurement of output source/sink current capabilities) · Op amp (measurement of output source/sink current capabilities) · Other linear ICs requiring current source/sink capabilities
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This information is subject to change without notice. © Keysight Technologies, 2013 - 2019, Published in USA, August 30, 2019, 5991-3119EN

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