
Picor Corporation www.picorpower.com QPO-1-EVAL1 Data Sheet
P/N 26801 Rev. 1.2 7/04/10M
The peak detector function is enabled on the
evaluation board. Connecting a 0.1uF capacitor to
the CP pads disables the peak detector if not desired
for the application. The QPO’s peak detector circuit
will increase the headroom of the QPO by roughly
half of the peak-to-peak ripple on the QPO’s input.
Excessive ripple with low voltage converters could
create enough additional headroom to cause the
converter’s output to increase to the point where an
over-voltage fault is created and the converter will
shut down. Check the converter’s OVP set point and
select component values to keep the QPO headroom
adjustment from reaching the OVP trip point.
The slope adjust feature can be set to zero providing
relatively constant headroom versus load using an
Rsa of 100k
. To improve efficiency of the filter the
slope adjust feature can provide a specific reduction
in headroom (slope adjust) over a desired current
range. The user can optimize performance based on
the expected variation in load current and the
desired power dissipation range. The formula below
should be used to calculate the Rsa value for the
desired headroom slope versus current. If the peak
detector is enabled, the peak of the ripple will be
added back to the headroom at a given load
condition.
where:
Iout = Maximum load current change
Vhr= Change in headroom desired over the
load range
Rsa= Slope adjust resistor value
Typical standard 1% values for the Rhr and Rsc
resistors and the listed voltages
Note1: These Rsc values are for a converter with a
1.23 Volt pre-trimmed reference and 1k Ohm input
resistance on the SC/Trim.
Typical Value For Rsa Resistor and Typical Voltages
Vicor Corporation
25 Frontage Road, Andover, MA, USA 01810
Tel: 800-735-6200 Fax: 978-475-6715
Email
Vicor Express: vicorexp@vicr.com
Technical Support: apps@vicr.com
Vicor’s comprehensive line of power solutions includes high-density AC-DC & DC-DC modules and accessory
components, fully configurable AC-DC & DC-DC power supplies, and complete custom power systems.
Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its
use. No license is granted by implication or otherwise under any patent or patent rights of Vicor. Vicor components are not
designed to be used in applications, such as life support systems, wherein a failure or malfunction could result in injury or
death. All sales are subject to Vicor’s Terms and Conditions of Sale, which are available upon request.
Specifications are subject to change without notice.
Part Number
Description
QPO-1 EVAL1
Evaluation board for QPO-1
Ordering Information
R
SA
= 0.05(V/A) *
Iout
*2.5k
Vhr
QPOout
Voltage
3.3V
5.0V
12.0V
15.0V
24.0V
28.0V
Headroom
Voltage
375mV
375mV
375mV
375mV
375mV
375mV
Rhr
Value
22k
33.2k
80.6k
100k
160k
187k
Rsc
Value
1
2.67k
4.02k
9.76k
12.1k
19.6k
22.6k
QPOout
Voltage
Headroom
Voltage
Change
(Slope=
V)
150mV
150mV
150mV
150mV
150mV
150mV
Rsa
Value
Load
Current
Change
3.3V
5.0V
12.0V
15.0V
24.0V
28.0V
8.25k
8.25k
8.25k
8.25k
8.25k
8.25k
10 A
10 A
10 A
10 A
10 A
10 A