Datasheet

LM25037
UVLO
PGND
AGND
COMP
OUTB
OUTA
VCC
SS
RT1
REF
RES
CS
VIN
VIN
VOUT
RT2
FB
RAMP
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Powering and Loading Considerations www.ti.com
Figure 1. Typical Push-Pull Circuit
3 Powering and Loading Considerations
When applying power to the LM25037 evaluation board certain precautions should be followed. A
misconnection can damage the assembly.
3.1 Proper Connections
When operated at low input voltages the evaluation board can draw up to 5A of current at full load. Ensure
that the input supply has sufficient current capability. The maximum rated output current is 10A. Be sure to
choose the correct connector and wire size when attaching the source supply and the load. Monitor the
current into and out of the evaluation board. Monitor the voltage directly at the output terminals of the
evaluation board. The voltage drop across the load connecting wires will give inaccurate measurements.
This is especially true for accurate efficiency measurements.
3.2 Source Power
The evaluation board can be viewed as a constant power load. At low input line voltage (16V) the input
current can reach 3.75A typically in steady state, while at high input line voltage (32V) the input current
will be approximately 1.9A. Therefore, to fully test the LM25037 evaluation board a DC power supply
capable of at least 50V and 5A is required. The power supply must have adjustments for both voltage and
current. The power supply and cabling must present low impedance to the evaluation board. Insufficient
cabling or a high impedance power supply will droop during power supply application with the evaluation
board inrush current. If large enough, this droop will cause a chattering condition upon power up. This
chattering condition is an interaction with the evaluation board under-voltage lockout, the cabling
impedance and the inrush current.
3.3 Loading
When using electronic load, it is strongly recommended to power up the evaluation board at light load and
then slowly increase the load. This is necessary as most of the electronic loads do not draw any current till
the power supply output voltage reaches an internally set point; this can result in soft-start function to not
work as desired and can trip the current sense comparator. Electronic loads, in general, are best suited for
monitoring steady state waveforms.
2
AN-1861 LM25037 Evaluation Board SNVA352C–July 2008–Revised May 2013
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