Enpirion
®
Power Evaluation Board User Guide
EN5336 PowerSoC
V
Rb
V
Vout
Ra
75
.
0
1
*
)
75
.
0
(
1
−
=
If over-voltage protection is desired, use the following equation to set the resistor
Ra2 for the desired OVP trip-point. Note that the evaluation board leaves these
resistors un-populated.
V
Rb
V
OVPtrip
Ra
90
.
0
2
*
)
90
.
0
(
2
−
=
By design, if both resistor dividers are the same, the OV trip-point will be 20%
above the nominal output voltage.
XFB
C
SS
VOUT
POK
PGND
AGND
SS
PVIN
AVIN
XOV
V
OUT
V
IN
22
µ
F
~50uF
R
a1
R
a2
R
b1
R
b2
Figure 2.
V
OUT
and OVP resistor divider networks.
NOTE:
if no OVP divider is present, there will be no over-voltage protection and POK will remain
“high” as long as V
OUT
remains above 90% of the nominal V
OUT
setting.
Test Recommendations
Recommendations
To guarantee measurement accuracy, the following precautions should be
observed:
1. Make all input and output voltage measurements at the board using the
test points provided. This will eliminate voltage drop across the line and
load cables that can produce false readings.
2. Measure input and output current with series ammeters or accurate
shunt resistors. This is especially important when measuring efficiency.
3. Use a balanced impedance probe tip to measure switching signals to
avoid noise coupling into the probe ground lead.
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