Picor Corporation www.picorpower.com
QPO-1-EVAL5 Data Sheet Rev. 1.1 Page 1 of 4
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QPO-1-EVAL5
QPO-1 Evaluation Board, Mini Foot Print DC-DC Converters
Description
The QPO-1-EVAL5 is designed to allow full testing of
the QPO-1 and its various performance settings to
optimize final system design. The board offers switch
settings for the user to select preset values for the
Rhr, Rsc, and Rsa resistors. Solder pads are available
to mount user-selected values of these components
if required. Please refer to the QPO-1 product data
sheet and the following pages for the proper
application of this board. The EVAL5 accommodates
Vicor's Mini DC-DC converters with an input up to
72 Vdc.
The QPO-1 output ripple attenuator SiP uses active
filtering to reduce output ripple and noise (PARD)
over 20 dB from 50 Hz to 500 kHz. The QPO-1
operates over a voltage range from 3 to 30Vdc and
supports load currents as high as 10A. Output
regulation is maintained with remote sense or trim
adjustment of the power supply. The closed loop
architecture improves transient response and ensures
precise point-of-load regulation.
Other eval boards (see www.picorpower.com) allow
easy evaluation with other DC-DC converters or
power supplies with standard terminations.
Note 1: For off-line supplies 20dB attenuation can be achieved
down to 50Hz with additional capacitance added from the
VREF pin to the REFGND pin.
Features of the QPO-1
>30 dB PARD attenuation, 1 kHz to 500 kHz
>20 dB PARD attenuation, 50 Hz to 500 Hz
1
10A rating over a 3-30 Vdc operating range
Supports precise point-of load regulation
Up to 99% efficiency with power limit protection
User selectable optimization of attenuation,
power dissipation & transient load response
Peak detector function optimizes for ripple
amplitude variation automatically
1.0 x 1.0 x 0.2" SiP with BGA or LGA mounting
Improves transient response of most DC-DC
converters and power supplies
Reduces required number of output capacitors
to support dynamic loads.
Patents Pending
Typical Application
QPO-1 Performance
Rhr
SC SET
CESR
QPO OUT
VREF
GND
SC
QPO IN
REFGND
QPO-1
Cout
Rsc
VOUT+
VOUT-
SENSE+
SENSE-
SC
LOAD+
LOAD-
Figure 1 SC/Trim supports applications without the use of
remote sense.
Figure 2 Typical performance with a 3.3 Volt converter.
QPO IN (AC)
QPO OUT (AC)
LOAD CURRENT (DC) 1A/DIV
QuietPower
TM
Picor Corporation www.picorpower.com
QPO-1-EVAL5 Data Sheet Rev. 1.1 Page 2 of 4
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Board rev.2
Slope Adjust
SC CAP
10A Maximum
Mini Application
3V to 30V Input
-
+
PICOR QPO-1
EARTH/Baseplate
Remote
Sense
SC
12V
5V
3.3V
SC ON
Enable
User Defined = All Off
Optional Transient
Capacitors
SC
QPO OUT
QPO IN
GND
SW4
C11
C10
C9
C8
R10
VREF
QPO-1
R9
R8
R7
R6
Input Supply
C5
C7
R5
R4
R2
R1
COUT
C6
D1
Load-
Load+
Q1
R11
R12
SW1
SW2
SW3
QPO-1
XXXXA
US AND FOREIGN PATENTS, PATENTS PENDING
PHIL
ENGINEERING SAMPLE
QPO-1
Supply+
Supply-
Earth
LOAD+
LOAD-
LOAD+
LOAD-
1
2
3
4
56
78
9
+
+
1
2
N
O
1
1
2
3
O
N
Figure 3 EVAL5 layout and measurement locations
SC
1
2
3
Input Supply
C1
4.7nF
C3
4.7nF
C4
4.7nF
C2
4.7nF
BasePlate
BasePlate
5
6
7
8
9
12
34
MINI FOOTPRINT
C5
100uF
QPO IN
QPO OUT
VREF
R5
User Defined
R2
User Defined
COUT
15uF
QPO OUT
9
SLOPE ADJ
2
QPO OUT
7
SC SET
6
CESR
5
QPO OUT
8
QPO OUT
10
QPO OUT
17
VREF
3
GND
1
SC
16
PEAK IN
15
QPO IN
14
QPO IN
18
QPO IN
13
QPO IN
12
QPO IN
11
REFGND
4
GND
19
GND
20
QPO-1
R4
TBD
QPO IN
QPO OUT
VREF
R6
86.6K
R8
35.7K
1
2
Load-
R11
2.67K
R7
9.76K
R9
4.02K
SC SET
CESR
C8
270uF
C9
270uF
R1
TBD
C7
TBD
1
12
2
11
SW3A
204-213ST
3
10
4
9
SW3B
204-213ST
5
8
6
7
SW3C
204-213ST
SC SET
VREF
QPO OUT
R10
23.7K
1
4
SW2A
204-2ST
2
3
SW2B
204-2ST
1
8
7
2
3
6
5
4
SW1
204-221ST
QPO OUT
C6
22uF
R12
5.1
SENSE+
Remote Sense GND
Q1
IRLML6401
SENSE+
QPO OUT
QPO IN
Low Voltage Start-up Circuit
QPO IN
D1
12V
SC
1
2
Load+
Shorted when SW1 in SC mode
Resistor's based on 350mV headroom at all voltages.
C10
15uF
VIN+
VIN-
12V
5V
3.3V
C11
TBD
2
1
3
SW4
CAS-120B1
SC
QPO IN
QPO OUT
GND
Figure 4 Schematic of EVAL5 board
Picor Corporation www.picorpower.com
QPO-1-EVAL5 Data Sheet Rev. 1.1 Page 3 of 4
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Switch Tables
The QPO-1-EVAL5 board has been designed to
accommodate a wide range of output voltages from
a Vicor Mini DC-DC converter. Please refer to the
QPO-1 datasheet for description of the product.
SW1 is used to select the method of regulating the
output voltage of the converter. When switched
to the left, the converter is operating in "Remote
Sense" mode where the sense pins of the converter
monitor the point of load to regulate the converter's
output voltage. When switched to the right,
the converter's sense pins are tied directly to their
respective output pins. The QPO trims the SC pin of
the converter to compensate for its voltage drop.
If the SC mode is selected SW2 should be set to
have the SC function connected to the converter
as described below.
SW2 has two switches. One engages the SC control
function. The second adds a capacitor to the SC pin
of the converter. In the "on" position (right), the
first switch of SW2 connects a 3.3uF capacitor (C11)
between the SC pin of the converter and ground.
C11 extends the soft start time of the converter.
This capacitor should only be needed with low
voltage converters (<12V) that startup before the
QPO can establish proper operation. The second
switch of SW2 in the "on" position (right) connects
the SC control circuit of the QPO to the SC pin of
the converter. When the switches are in the "off"
(left) position, the capacitor and SC connection
are opened and out of the circuit.
SW3 is located in the lower-right corner of the pc
board. It is used to set the appropriate headroom
voltage and SC current for converters 12V, 5V, or
3.3V outputs. A "user defined" position for
converter voltage and headroom settings is provided
to support other output voltages. The user can
also adjust other operating parameters with the
"user defined" position
With all switches in the "down" position (open
circuit), the board is set to a "user defined" setting
for use with any output voltage between 3 and 30V.
The QPO-1-EVAL5 board lets the user populate the
R2 and R5 locations to adjust headroom (Rhr) and SC
current, (Rsc) with appropriate resistors. The user
must calculate a value for the headroom voltage
setting resistor (R5 = Rhr in the product datasheet
and formula below) and the SC current setting
resistor (R2 = Rsc in the product datasheet and
formula below).
With the first switch position of SW3 in the "up"
position, and the rest in the "down" position, the
headroom voltage and SC current setting is adjusted
to work with a 12V converter. With the second
switch of SW3 in the "up" position, the rest "down",
the converter is set to work with a 5V converter.
With the third switch "up", the rest "down", the
board is set to work with a 3.3V converter. This
switching network will parallel the switched in
resistors with connections to the R5 and R2 positions.
If a predefined voltage is to be used, R5 and R2
should not be populated. At no time should more
than one switch be in the "up" position to get
accurate results. The user defined values for R2 and
R5 will have to be connected once their values have
been determined using the formulas that follow.
SW4 is used to engage the optional Slope Adjust
resistor (R4) when in the "up" position. Please refer
to the QPO-1 datasheet for further explanation of
this function.
Instructions for Use
The terminal block in the lower left-hand corner of
the pc board (labeled "Input Supply") is used to
provide the input voltage to the DC-DC converter.
The Earth connection serves as the converter shield
that is the common node for the Y capacitors that
are on the bottom of the board. The converter
should be mounted to the EVAL board with screws
and a heat sink to ensure a good electrical
connection to the bypass capacitors on the bottom
of the board. If this step is no taken, common mode
noise may be excessive. The output load should
be connected to the terminal block on the right,
labeled "External Load" and should not exceed
10 Amps.
The QPO application board has Johnson Jacks,
to reduce the effect of radiated noise on
measurements. The jacks allow three key
measurements; QPO IN is the input to the QPO
from the DC-DC converter; QPO OUT is the output
of the QPO where effects of the various settings
can be analyzed; VREF is the reference voltage that
the QPO uses to maintain a desired output voltage.
Picor Corporation www.picorpower.com QPO-1-EVAL5 Data Sheet
P/N 27092 Rev. 1.1 8/03/10M
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.
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
If SW3 is not used as described above, a resistor in
position R5 will determine the QPO's headroom
voltage. If the user decides to use a headroom
setting other than what is preset by SW3, select a
headroom resistor for R5 using the following
equation:
where;
Rhr is headroom resistor value,
QPOout is the voltage seen on the QPO's output,
Vhr is the target headroom voltage.
The Rsc resistor is tied between QPOOUT and SC SET
pin and sets the correction current used to trim up
the converter to maintain a constant output voltage
on the QPO's output. The value for the SC SET
resistor is calculated by the following equation:
where;
Rsc is SC SET resistor value,
Rin is the input resistance of the SC or TRIM input
of the converter,
Vout is the desired QPO output voltage,
Vrpt is the pre-trimmed reference of the SC
or TRIM.
On the application board there are two spots for
additional capacitors (C8 and C9) to be added to the
QPO's input. Extra output capacitors maybe required
in applications with converters with output voltages
over 10V that are subjected to high transient load
steps. Experiment with these components to obtain
the desired result.
The peak detector function is enabled on the
evaluation board. A low value for R1 (less than 10
ohms) is on the board and C7 is not populated.
To disable the peak detector function, use R1= 1K
and C7 = .1uF as shown in the datasheet. 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 as to cause the converter's output to
increase to the point where it is in an over-voltage
fault and shut down.
Rhr =
QPOout
* 2.5k
Vhr
Part Number
Description
QPO-1-EVAL5
Evaluation board for QPO-1
for Mini footprint DC-DC
Converters
Ordering Information
Rsc =
Rin * Vout
Vrpt
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