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PRELIMINARY

Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

QPO-1 Data Sheet

Page 3 of 8

Application Notes

Figure 1—Typical Configuration using Remote Sensing

Figure 2—Typical Configuration using Trim Control

15uF

9

2

7

SC SET 6

CESR 5

8

10

17

3

1

SC

16

15

14

18

13

12

11

4

GND

19

20

QPO-1

Load

Cps*

Rps

+

–

{

10

Ω

IN*

20k** 4.7uF**

1W

Module

+ OUT

+ Sense

– Sense

Module

– OUT

Trim

C

*Optional Component

See Description

**Required only for

engineering samples

Qp*

R

SS

15uF

2

SC SET 6

CESR

5

3

1

SC

16

4

GND

19

20

QPO-1

Load

+

–

IN*

C

Module

+ OUT

Trim

Module

– OUT

9

7

8

10

17

15

14

18

13

12

11

{

*Optional Component

See Description

20k** 4.7uF**

**Required only for

engineering samples

Functional Description

The QPO-1 is an active power filter that provides attenuation

of power supply output PARD. The measured attenuation

performance over frequency is shown in Figure 3 at output

voltage conditions of 3.3 and 28 Vdc. The user can select

and optimize the attenuation versus power dissipation by

setting the headroom voltage of the active loop.

The conditions in Figure 3 were measured with a low current

headroom setting of 375mV with approximately 100mV

peak-to-peak ripple voltage on the input to the QPO-1. The

remote sense circuit configuration was used as shown in

Figure 1 with the peak detector function enabled. Some

power supplies need to sense the output ripple for proper

operation. Cps couples the unfiltered ripple back to the sense

input while Rps provides the DC feedback to the power

supply from the load.

Typical improvement in output noise and transient

performance with a 3.3V converter is shown in Figure 4.

This measured data demonstrates the reduction in noise and

ripple at the output of the QPO-1 versus the source output as

well as the transient capability stepping from 1 to 10A

load current - the maximum current rating. This particular

converter has sufficient output capacitance and response

is needed on the input of the QPO-1 to reach a 10A level and

still maintain the output within ±50mV.

Ch3: Load Current – 10A peak, pulse width = 400µS

Load Current Static = 1A

Load Current Transient = 9A

Headroom Voltage @ 100mA = 400mV

Attenuation VS Frequency

-70

-60

-50

-40

-30

-20

-10

0

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+06

Frequency (Hz)

28V 10A

3.3V 10A

Figure 3— Attenuation vs. Frequency

Figure 4 – Transient Response using a Vicor

3.3V Half Brick Converter