Datasheet
J1
1
9
8
PVIN
PVIN
AVIN
Ren
GND
DAP
GND
EN
4
5
EN
Cin
Cboost
D1
SW
2
FB
SW
SW
R_S
L1
LMR12020XSD
10
GND
Rfbt2
Rfbt1
Rdload
Rfbb
Co1 Co2
Cff
VOUT
VIN
SYNC
6
Evaluation Module Schematic
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3 Evaluation Module Schematic
Figure 1. LMR12020 Evaluation Module Schematic
4 Powering and Loading Considerations
Read this entire section prior to attempting to power the evaluation board.
4.1 Quick Start Procedure
Step 1: Set the bench power supply current limit to 2A. Set the power supply voltage to 12V. Turn off the
power supply output. Connect the power supply to the LMR12020 demo board. Positive connection to V
IN
and negative connection to GND.
Step 2: Connect a load, as high as 2A, to the V
OUT
terminal. Positive connection to V
OUT
and negative
connection to GND.
Step 3: Turn on the bench power supply with no load applied to the LMR12020 and the shunt for the
jumper J1 in place. The V
OUT
would be in regulation at a nominal 3.3V output. With the shunt out, a
minimum load of 10mA would be required to have the V
OUT
in regulation at 5V.
Step 4: Gradually increase the load and V
OUT
should remain in regulation as the load is increased up to 2
Amps. The V
OUT
should also be regulated when the input is swept from the minimum input to 20V.
4.2 Starting Up
The EN pin is tied to V
IN
to simplify start-up. The pull-up resistor allows the power supply design engineer
to toggle EN independently, if desired, and observe the start-up behavior of the LMR12020. Use the EN
post to disable the device by pulling this node to GND. A logic signal may be applied to the post to test
startup and shutdown of the device.
2
AN-2279 LMR12020 Evaluation Module SNVU191A–October 2012–Revised April 2013
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