Enpirion
®
Power Evaluation Board User Guide
EN5312QI PowerSoC
Using The External Voltage Divider
The EN5312Q-E evaluation board is designed to provide a great deal of flexibility in
evaluating the performance of the Altera Enpirion DCDC module.
Pre-tinned pads are provided to place 0402 sized 1% resistors on the board to implement
an external resistor divider to choose an output voltage other than one of the seven pre-set
voltages available on the VID.
V
IN
V
Sense
V
in
V
S1
V
S2
V
S0
EN5312
10
µ
F
4.7uF
V
OUT
V
out
GND
ENABLE
R1
R2
V
FB
Figure 2. External divider schematic.
Figure 3 demonstrates the placement of the R1 and R2 resistors.
The output voltage is selected by the following formula:
( )
2
1
16.0
R
R
OUT
VV +=
R
1
must be chosen as 200KΩ to maintain loop gain. Then R
2
is given as:
Ω
−
=
6.0
102.1
5
2
OUT
V
x
R
The external voltage divider option is chosen by setting the jumpers VS0, VS1, and VS2
to a logic “high”.
Page 4 of 8
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