QPO-2EVAL1 Datasheet, PDF (1/2 Pages) Vicor Corporation – Evaluation Board for QPO-2 Active Output Filter

PRELIMINARY
®
QP0-2 EVAL1
QuietPower^™
Evaluation Board for QPO-2 Active Output Filter
The QPO-2-EVAL1 board provides an easy to use
evaluation platform for testing the QPO-2L in a low-
voltage system. A filtered voltage range of 0.3 Vdc to 5.5
Vdc at output load currents up to 20A can be
accomplished. A low current bias supply is required at the
VAUX input in the range of 7 to 12 volts respectively to
the output voltage range. The board comes with a QPO-2L
and some essential external components pre-mounted.
Please refer to the QPO- 2L datasheet for product details.
Terminals for horizontal or vertical mounting are also
provided. The user must select component values
dependant upon their system needs.
RCP will preset the QPO-2’s reference voltage to a value
close to the desired steady-state value. This reduces the
time required for the QPO-2’s output to reach the
steadystate output voltage. There is a provision for a start-
up circuit (Q1 RDLY D1 CDLY) if the initial headroom
voltage needs to start from zero and increase gradually to
the set headroom voltage. Remote sense components (CRS
RRS), Figure 3 of the product datasheet, are mounted on
the evaluation board.
When remote sensing is not used RSC1 is the current
programming resistor that determines the current sourced
by the QPO-2’s Adjust+ pin to drive the TRIM pin of a
converter. The RSL resistor shown in Figure 4 of the
product datasheet (not on the evaluation board) can be
used to limit the correction current sourced from the
Adjust+ circuit if needed during start-up preventing the
converter from tripping OVP.
RHR is the headroom voltage setting resistor that will
determine the voltage dropped across the QPO-2. The
RSA1 resistor is for the slope-adjust option, which can be
used to reduce the amount of voltage across the QPO-2
depending on load current. This reduced drop in voltage
will result in a lower power loss across the QPO-2
providing greater efficiency but lower attenuation. An
optional capacitor, CHR, can be added to extend the low-
frequency attenuation range of the QPO-2.
The RP resistor connects the QPO-2’s peak detection circuit
to the input voltage rail. The peak detector will adapt the
headroom voltage by adding half the peak-to-peak ripple
voltage to the headroom. RP is required. The peak
detection can be disabled adding a filter capacitor CP to
the board. The full product datasheet with equations to
calculate these component values plus more detailed
explanations of their functions, can be found at
www.picorpower.com.
QPO_IN
J6
QPO_IN
RCP
J2
VAUX
QPO_OUT
Low Voltage Start-up Circuit
QPO_IN
CRS
15 μF
J7
SENSE+
RRS
10
RDLY
20 K
D1
MA111
CDLY
0.1 μF
Q1
IRLML6401
QPO_OUT
VREF
J5
ADJUST/SC
J5
GND
J9
GND
J10
GND
Figure 1 - Evaluation board schematic
RP
10 9
11
12
13
14
18
QPO IN
QPO IN
QPO IN
QPO IN
QPO IN
PEAKIN 15 _{PEAK IN}
ADJUST 16 _ADJUST+/-
CP
19
20
GND
GND
QPO OUT
QPO OUT
QPO OUT
QPO OUT
17
8
7
6
SC SET ⁵
QPO-2
RSC1
1234
J1
QPO_OUT
RSA 1
RHR
VREF
CHR
J3
VREF
Picor Corporation • www.picorpower.com
QPO-2 EVAL1 Data Sheet Rev. 1 Page 1 of 2