User Guide UG:008
vicorpower.com
800-735-6200
Rev. 1.1
11/10
Page 12 of 19
8.3 PRM – VTM Operation, Non-isolated Remote Sense
In this configuration, the PRM and VTM Customer Boards are connected together to form a
PRM/VTM pair and regulation is performed at the VTM output. U09B is configured as a differential
amplifier with a gain set for the appropriate output voltage. R24,and R29 set the gain and
limit the maximum VTM output voltage based on Equation 1 assuming the trim pot (R22) is
fully clockwise.
8.3.1 PRM – VTM Remote Sense Setup
This is NOT the nominal configuration of the customer board and requires rework to implement.
1. Determine the maximum desired VTM output trim voltage (R
22
fully clockwise).
2. Use Equation 1 to select the appropriate value for R
24
/R
29
. Obtain the closest 1% standard
value, size 1206 resistors for installation.
3. Remove R
40
.
4. Install R
24
and R
29
in the appropriate positions
5. Determine the type of VTM Customer Board to be used.
a. Type A:
i. Install single male-to-male header to X01 only.
ii. Connect PRM and VTM Customer Boards together as illustrated in Figure 11.
iii. Connect the VS+ test point to the VTM +OUT test point, and VS- test point to the VTM
–OUT test point through a twisted pair of wire
b. Type B:
i. Install dual male-to-male headers to X01 and X03
ii. Connect PRM and VTM Customer Boards together as illustrated in Figure 12.
iii. Verify connection from VS+ to VTM +OUT, and VS- to VTM -OUT
6. Connect a jumper between VTM –OUT and VTM –IN
7. Connect input source to the input lugs. Verify proper polarity. Set to 0 Volts or OFF before
connecting.
8. Connect VTM output to desired load using the output lugs. Set load to 0 Amps or OFF.
1.24k
R 30
1.24k
R 23
V s-
V s+
PRMO UT
V S+
V S-
TP10
TP11
R4 0
R 24
R 29
6
5
7
U09B
GND
OPEN
Figure 10: Remote Sense
Configuration
Equation 1
Where: V
OUT_SET(MAX)
is the maximum VTM output trim voltage