LM34923 Datasheet, PDF (5/12 Pages) National Semiconductor (TI) – EVAL evaluation board provides the design engineer with a fully

Under-Voltage Detector
The Under Voltage Detector can be used to monitor the input
voltage, or any other system voltage as long as the voltage at
the UV pin does not exceed its maximum rating. On this eval-
uation board the input voltage is monitored via resistors R2
and R3.
An appropriate pull-up voltage less than 10 volts must be
connected to test point TP2-UVO on this evaluation board. R4
is the pull-up resistor for the UVO output. The under-voltage
status can then be monitored at the TP3-Status test point.
On this evaluation board the UVO output switches low when
the input voltage exceeds 12V, and it switches high when the
input voltage is less than 11V. If it is desired to change the
thresholds, the equations for determining the resistor values
are:
Where V_UVH is the upper threshold at VIN, and V_UVL is the
lower threshold. The threshold at the UV pin is 2.5V.
The UVO output is high when the VCC voltage is below its
UVLO threshold, or when the LM34923 is shutdown by
grounding the TP1-SD test point, regardless of the voltage at
the UV pin.
FIGURE 6. Complete Evaluation Board Schematic (As Supplied)
30161525
Monitor The Inductor Current
The inductor’s current can be monitored or viewed on a scope
with a current probe. Remove R9, and install an appropriate
current loop across the two large pads where R9 was located.
In this way the inductor’s ripple current and peak current can
be accurately determined.
Scope Probe Adapters
Scope probe adapters are provided on this evaluation board
for monitoring the waveform at the SW pin, and at the circuit’s
output (V_OUT), without using the probe’s ground lead which
can pick up noise from the switching waveforms.
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