Vicor Half-chip PRM-RS Customer Board - Manual (Page 4)

UG:008 vicorpower.com Applications Engineering: 800 927.9474 Page 4
12. Output Voltage Trim Pot (R
22
): 11 turn trim pot adjusts the output voltage by increasing or
decreasing the error amplifier reference voltage (V REF ). Turn clockwise to increase the output
voltage, and counterclockwise to decrease the output voltage. Adjustment slot is
1.5 mm (L) x 0.6 mm (W).
13. High Side Current Sense Circuit (R 08 , Q 02 ): Current sense shunt and IC monitor the output
current and provide feedback to the IF pin for current limit protection. Gain is typically 400
mV/A, and is set for appropriate current limit set point. IF signal can be monitored at the
Signal Test Point Header (#6) to provide approximate output current measurement, but should
not be used if accurate output current measurements are required (<10% error). Efficiency
measurements should always be performed using an external calibrated shunt.
14. Output Inductor (L01): 0.4 uH inductor provides high AC impedance between PRM ® and VTM ®
(when used) to prevent high- frequency switching currents from circulating between devices.
15. Voltage Sense and Error Amplifier (U09A, U09B): Dual op amp provides voltage sensing and
error amplifier function. The customer board is nominally configured for local voltage sensing
at the PRM output. U09B can be re-configured as a differential amplifier to allow for
non-isolated remote sensing at the VTM output or load. This requires rework as described in
Section 8.3.
16. Push Pin Heat Sink and Grounding Clip Mounting Holes: Use these holes for installing the
optional push pin heat sink and grounding clips included with the board.
Use of a heat sink is highly recommended for appropriate cooling of the PRM.
3.2 Test Points
In addition to the Signal Test Point Headers (#6, #7), there are a number of surface mount test
points on the board with the following functions.
1. V IN+ , V IN- (TP01, TP03): Input voltage test points provide Kelvin connections to the input
leads. Use these test points for measuring the input voltage to avoid error due to interconnect
losses.
2. V OUT+ , V OUT- (TP04, TP05): Output voltage test points provide Kelvin connections to the
output leads. Use these test points for measuring the output voltage to avoid error due to
interconnect losses.
3. Signal Ground (TP01): Signal Ground (SG) test point is the ground reference for all control
circuitry.
4. VS+, VS- (TP10, TP11): +/- sense inputs to the differential amplifier when remote sense is
implemented. When used with a VTM Customer Board, the sense leads may be wired to the
VTM output voltage through X03 depending on which VTM board is used. If not, a twisted
pair of wires can be used to connect sense leads to the VTM board output from these test
points.