Picor Corporation • www.picorpower.com

QPI-4L Data Sheet Rev. 3.0 Page 4 of 8

If the manufacturer does not specify a value for the Y-capacitors use 4.7nF. Ry=10Ω, 1/4 W.

BUS+

QPI+

BUS-

QPI-

BUS

SUPPLY

QPI

SHIELD

CONVERTER

Optional Connection

C1

C2

C3

C4

RY

PCB plane under converter

CB

47µF

QPIs will filter multiple DC-DC converters up to the

maximum current rating. The schematic in Figure 7

shows the required circuit for multiple DC-DC

converters. The Shield Plane should be added under

each converter as a common EMI Shield. Note that only

a single RY is required in a multiple converter

configuration.

If higher attenuation is required, QPIs can be

connected in series. Figure 8 shows the proper

schematic for QPIs in series. Note that only one RY is

required in this configuration.

The QPI can also be used to filter embedded or “down”

converters made up of discrete components. Where

ever possible a Shield Plane and Y-capacitor decoupling

should be included in the embedded converter design.

Follow the circuit and layout recommendations for a

brick converter shown in Figures 7, 9 & 10.

Thermal Considerations

The current derating curve shown in Figure 5 should be

used when the PCB temperature in close proximity of

the QPI-4 exceeds 60°C. For example, the QPI-4 will

support up to 6.5 A of current or 312 W from a 48 Vdc

bus at an 80°C interface temperature. Temperature

should be measured at the PCB interface to the QPI-4

on the Bus +/- pads or the QPI+/- pads. Refer to Figures

9, 10 & 12 for PCB layout recommendation.

010

20

30

4050

6070

80

90

100

PCB to QPI Interface Temperature (Deg. C)

8

6

4

2

0

Figure 5 – QPI-4 current derating curve.