Rev 1.5

vicorpower.com

Page 8 of 15

08/2015

800 927.9474

QPI-21

Figure 13 — Base-plate EMI test setup using the QPI-21-CB1 carrier board with 48 V converter

Ambient Temperature (°C)

QPI-21 Current

QPI-21 Power Dissipation

0

2

4

6

8

10

12

14

16

-40

-15

10

35

60

85

110

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Figure 14 — Current de-rating and power dissipation over ambient temperature range

Attenuation Test Setups

BUS+

QPI+

BUS-

QPI-

QPI

VIN+

VOUT+

VIN-

VOUT-

CONVERTER

CY1

CY2

CY3

C2

C1

47uF

LISN

LISN

PCB Plane Under Converter

100uF

~1.25m

Shielded Box

Shield Plane (Earth Ground)

QPI CB1 Board

BUS

SUPPLY

In Figures 11, 12 and 13, C1 is the required 47 uF capacitor (United

Chemi-Con EMVE101ARA470MKE0S or equivalent), C2 is a

converter input cap (value dependent on converter), and the CY

capacitors are high-voltage, 4.7 nF ceramics (Murata’s

GRM31BR73A472KW01L or equivalent).

The de-rating curve in Figure 14 is based on the maximum allowable

internal component temperature and the 14 A maximum rating of

the QPI-21. The power dissipation curve is based on the current

squared multiplied by the internal resistance between the inputs and

outputs of the filter. The internal resistance temperature coefficient is

compensated for in the power dissipation curve. The left Y axis is in

amps for the solid trace, the right Y axis is in watts for the

dashed trace.