QPO-2L - Vicor Corporation

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 1 of 11

Description

The QPO-2 output ripple attenuator SiP uses active

filtering to reduce supply output ripple and noise (PARD)

by over 30 dB from 1 kHz to 500 kHz. The QPO-2 is biased

through the VAUX input and filters an input voltage

range of 0.3 Vdc to 5.5 Vdc while supporting load currents

as high as 20 A. The VAUX input range is 7 V to 12 V with

a minimum required difference between VAUX and QPO

OUT of 7 V. Output regulation is maintained by using

either the remote sense or the trim adjustment of the

power supply. The product can be used in an open loop

configuration when ripple and noise reduction are the

main objective and load regulation is not as critical. The

QPO-2 architecture improves transient response and

ensures quiet point-of-load regulation when used with

most switching power supplies. The performance

waveform in figure 2 is an example of the ripple

reduction and transient load improvement the QPO-2 can

provide using a 3.3V brick style converter.

Applications

• Distributed Point of Load Power Systems

• Sensors Requiring Low Noise Power

• Medical Instrumentation Note 1: For off-line supplies 20 dB attenuation can be achieved

down to 50 Hz with additional capacitance added from the VREF

pin to REFGND.

Features of the QPO-2

• >30 dB PARD attenuation, 1 kHz to 500 kHz

• >20 dB PARD attenuation, 50 Hz to 500 Hz (1)

• 20 A rating over a 0.3-5.5 Vdc operating range

• Supports precise point-of load regulation

• 90-95% efficiency with load vs. headroom trim

• User selectable performance optimization of the

attenuation, power dissipation & transient load

response

• Peak detector function optimizes headroom for

ripple amplitude variation automatically

• 25 x 25 x 4.5 mm SiP (System-in-a-Package)

• Low profile LGA package

• Closed loop control improves transient response

of most DC-DC converters and power supplies

• Reduces required number of output capacitors to

support dynamic loads.

• Patents Pending

RHR

SC SET

QPO OUT

SLOPE ADJ

GND

ADJUST

QPO IN

REFGND

QPO-2L

CSC

CIN*

*Optional

PEAK IN

RCLAMP

VAUX

Rsc

VREF

RSA

VOUT+

VOUT-

SENSE+

SENSE-

+TRIM

LOAD+

LOAD-

RCP

VAUX

Figure 1 – ADJUST/Trim supports applications that don’t

require remote sense.

Figure 2 – Typical performance with a 3.3 Volt converter, showing

1 to 10 A load step.

QPO IN (AC)

QPO OUT (AC)

LOAD CURRENT

QPO-2

QUIETPOWER®

QPO-2 Low Voltage Output Ripple Attenuator

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 2 of 11

Absolute Maximum Ratings – Exceeding these parameters may result in permanent damage to the product.

Electrical Characteristics – Parameter limits apply over the operating temp. range unless otherwise noted.

Pins Parameter Notes Min Max Units

VAUX to Gnd Input voltage Continuous -0.5 13.2 Vdc

All others to Gnd REFGND Input voltage Continuous -.05 6 Vdc

VAUX to Gnd Input bias current 50 mAdc

QPOin to QPOout Input to output current 10 seconds @ 25°C 25 Adc

Package Power dissipation Pd= ILoad x Vhr 4 W

Package Operating temperature PCB to QPO Interface -40 100 °C

Package Thermal resistance Free Air 50 °C/W

Package Thermal resistance PCB Layout Fig. 12 12 °C/W

Package Storage temperature -40 125 °C

Package Re-flow temperature 20 second exposure @ (4) 212 °C

Symbol Parameter Notes Min Max Units

ILoad Operating load current range No Internal Current Limit (2) 0.01 (3) 20 Adc

VQPOOUT Output voltage range Continuous 0.3 5.5 Vdc

VHR Headroom voltage range See Applications Detail For Setting 75 425 mVdc

IAUX VAUX input current 10 20 mA

Vtout Transient response-step load Vhr=375mV Cin=200uF

change of 10A@<1A/usec Iload=1A @ t=0 See Figure 2 example 50 mVdc

Vnout Output noise Input PARD=100mVpp 50-500kHz Cvref=25uF 10 mVpp

5 mVrms

Iscout SC output current accuracy See applications detail for setting -2 +2 %

Iscout SC output source current Input current from QPOIN to Gnd 10 mA

Note 2: User must protect the load path and limit the steady state load current to be less than the absolute maximum of 20 Amps.

Note 3: User must provide a minimum load current of greater than 10mA at the output of the QPO-2.

Note 4: RoHS compliant product maximum peak temperature is 245°C for 20 seconds.

GND

ADJUST

PEAK IN

QPO IN

QPO OUT

SC SET

REFGND

VREF

SLOPE ADJ

234

9101112

17 18

1920

VAUX

RCLAMP

Pad Descriptions LGA Pattern

Pad

Number Name Description

1, 19, 20 GND Input ground

2 SLOPE ADJ RSA resistor connection allows setting of

the slope of headroom voltage vs. load (mV/A)

3 VREF Input to the active filter, setting the

output voltage at the QPOOUT pins

4 REFGND Ground reference for the VREF pin

(critical low noise connection)

5 SC SET Rsc resistor connection allows setting of

the SC/trim current applied to the

converter trim input.

6, 7, 8, 17 QPOOUT Output pins

9 VAUX Input bias voltage

10 RCLAMP External resistor to program VREF

quick-charge level at start-up

11, 12, 13, QPOIN Input pins (critical thermal path to remove

14, 18 heat from the package, see PCB suggested

layout Fig.13)

15 PEAK IN Ripple Peak Detector Input

16 ADJUST A current source that mirrors the current

through RSC and drives a converter’s

SC/TRIM pin.

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 3 of 11

Product Highlights

Picor’s QPO-2, System-in-a-Package (SiP) output ripple

attenuator, is easy to apply and provides the user with

features that can be tailored to optimize the product’s

performance to meet their system needs. It uses active

filtering to achieve greater than 30 dB of attenuation of

Periodic And Random Deviation (PARD) over the frequency

range of 1 kHz to 500 kHz. For converters running off-line

with greater low frequency output ripple, the attenuation

can be extended to be greater than 20 dB down at 50 Hz

by connecting a 25 uF capacitor between the VREF and

REFGRD pins.

The QPO-2 operates over an output voltage range of 0.3 to

5.5 Vdc and requires an external input bias voltage of 7

volts above the QPO output for proper operation. It is

compatible with most switching power supplies and

converters and regulates the output load by using either a

converter’s remote sensing feature or the SC/trim function

of the QPO-2 with the converter. The SC/Trim feature will

correct the converter’s output voltage to compensate for

the headroom voltage drop of the filter if remote sensing

is not available or not preferred. The QPO-2 SC function

works with converters that feature a positive reference

trim adjustment by sourcing correction current into the

trim reference pins commonly found on many power

supplies. The QPO-2 can also be used when remote sense

or SC/trim is not possible. In this mode of operation the

QPO-2 will still provide greater than 30 dB of ripple and

noise attenuation but DC errors will not be corrected for

once the converter and headroom voltages are set,

resulting in reduced load and transient performance.

The QPO-2’s closed loop architecture greatly improves load

transient response of the converter while ensuring steady-

state precise point of load voltage regulation. The

headroom setting of the filter dramatically reduces the

capacitance needed at the converter output to provide the

equivalent transient performance and ripple reduction.

Figure 2 demonstrates how the product can be an ideal

solution for noise sensitive applications providing ripple

and noise reduction and improved output regulation with

high current transient load demands.

Functional Description

The QPO-2 is an active power filter that provides

conducted differential attenuation of power supply output

PARD. It is design to be inserted between the output of the

supply and the load, providing closed loop regulation

through remote sensing or by means of the SC/Trim

feature of supplies having a positive referenced based trim

capability and is set by RSC. The core of the design is a high

bandwidth closed loop function that forces the QPOOUT

pins to be equal to the VREF pin. The VREF pin is a filtered

ratio metric representation of the input voltage that is

determined by the RHR value selection. The voltage

difference between the input to the QPO-2 and VREF pin is

defined as the headroom voltage VHR. The filter time

constant of the VREF pin determines the low frequency

attenuation response of the QPO-2. The high frequency

attenuation response is determined by the roll-off

characteristics of the active loop. To speed up the charging

of the Vref pin the RCP resistor can be used to clamp the

pin just below the steady state regulation point avoiding

excessive delay and headroom during start-up.

The QPO-2 has a current sensing function that creates a

voltage at the Slope Adjust pin that is proportional with

the load current. This feature can be used to improve the

efficiency of the filter when supply ripple amplitude

reduces with increasing load as with Vicor products. By

selecting the appropriate RSA resistor value the slope of the

headroom reduction versus load can be set. The effect of

this function is to reduce the headroom voltage by the

amount determined by the RSA value resulting in reduced

power dissipation and increased efficiency as compared to

a fixed headroom setting.

There is also a Peak Detection function that adds the input

peak of the ripple voltage to the headroom voltage. The

QPO-2 will track the input ripple adjusting the headroom

within the dynamic range of the filter as the peak of the

ripple changes. The peak of the ripple will automatically be

summed with the DC setting of the headroom voltage.

This feature in combination with the slope adjust feature

allows the user to optimize the initial headroom voltage

and overall efficiency required for their specific

application.

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 4 of 11

Remote Sense Application Circuit Schematic

SC/Trim Application Circuit Schematic

Optional

Bold lines indicate high-current path.

Rhr

SLOPE ADJ

SC SET 5

VAUX

VREF

GND

ADJUST+

PEAK IN

RCLAMP

11 QPO IN

QPO IN

REFGND

GND

QPO-2L

Rsa

Csc

QPO OUT

Cin*

VOUT+

VOUT-

SENSE+

SENSE-

+TRIM

LOAD+

LOAD-

Rsl

Rsc

RCP

QPO OUT

VAUX

Figure 3 – Use this circuit for applications requiring remote sensing. Components marked * are optional, see text.

Figure 4 – Simplest application of QPO-2 when the SC/Trim pin is available, see text.

RHR

SLOPE ADJ

SC SET 5

VAUX

VREF

GND

ADJUST

PEAK IN

RCLAMP

QPO IN

REFGND

GND

QPO-2L

RSA

CRS

22μF

RRS

5.1

QPO OUT

CIN*

* Optional

Csc*

Bold lines indicate high-current path.

}{

RCP

VOUT+

VOUT-

SENSE+

SENSE-

SC/TRIM

LOAD+

LOAD-

VAUX

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 5 of 11

Application of the QPO-2

This product can be used over a 0.3 Vdc to 5.5 Vdc output

voltage range using either the remote sense or the

voltage trim feature of the selected converter. These

circuit configurations are shown in Figures 3 and 4.

In either configuration, the source output voltage will

increase to accommodate the headroom voltage of the

QPO-2 filter in order to maintain the load voltage at the

required level. In the case where remote sense or SC/Trim

use is not possible the QPO-2 can still be used to provide

PARD attenuation with the DC loss of the headroom

voltage at the load. If the supply output can be trimmed

up, the headroom voltage drop of the QPO-2 can be

compensated for at a given load. Further DC correction

for load variation at the QPO-2 output will occur only

within the supply’s control loop. The QPO-2’s output will

be controlled to the voltage present at the VREF pin in

this open loop filter configuration.

The user must decide on the control mode to be used and

to select the appropriate circuit configuration for that

mode. They must take into consideration the effects of

the headroom setting and power dissipation versus PARD

attenuation. The majority of the power dissipation of the

QPO-2 is the product of the headroom voltage times the

load current and must always be less than 4 watts. The

dynamic headroom range of the QPO-2 is 75 mv to 425 mv

as long as the maximum power is not exceeded. It is

important that the user understands the range of

expected ripple and transient performance of their power

source to properly bias and utilize the QPO features. The

objective is to maximize attenuation and minimize

dissipation while staying within the QPO-2 dynamic

operating range. Knowing the worse case maximum

steady state ripple, output impedance and transient

response time of the power source will determine the

minimum required headroom of the QPO-2, which is set

by the value of RHR. See figure 5 below for the safe

operating power curve.

If the peak detector option is enabled the headroom will

automatically increase by the peak of the ripple amplitude

from the setting determined by RHR. This makes the initial

headroom setting less critical because the headroom

and dynamic range will track the peak of the ripple,

maintaining the required QPO-2 biasing to actively

attenuate. Caution must be taken such that the added

peak detection headroom does not cause power

dissipation in excess of 4 watts. The time constant of this

feature is roughly 30 ms in response to ripple amplitude

changes. This feature can be enabled by connecting the

PEAKIN pin to the QPOIN pins and disabled by putting a

resistor between QPOIN and the PEAKIN pin as shown in

Figure 6.

Conversely the optional slope adjust feature will reduce

the headroom proportional to load current depending on

the RSA value selected. This will reduce the maximum

ripple range so this feature is most useful when the

converter ripple amplitude decreases with increased load

current. The feature can be enabled by selecting the

proper RSA value as described in the headroom slope

adjust section of the datasheet and effectively disabled by

using RSA = 100 Kohms.

Figure 7 shows the relationship of the headroom voltage

versus attenuation of the QPO-2 for a 3.3 volt output with

a 15 amp load. This relationship is relatively constant over

the full output voltage rating of the product so this graph

can be used for the 0.3 V to 5.5 V range when selecting

the headroom voltage. The value of headroom resistor

will be dependent on desired output and headroom

voltages. The selection of the final headroom voltage

should be based on the maximum expected ripple, desired

attenuation, based on the curves in Figure 7, and the

transient response time of the converter. Formulas for SC

current setting resistor, RSC and the RCP clamp setting

resistor, are provided in their respective sections. The

headroom range indicated in Figure 7 shows that

increasing the headroom voltage will increase the

attenuation, up to a point of diminishing returns, over the

range of 10 kHz to over 1 Mhz. With an external 25 uF

VOUT QPO-1 IN

PEAK IN

0.1 uF

Figure 6 – Peak detect disable circuit.

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16 18 20

Output Current (Amps)

Maximum Headroom

Voltage (mVolts)

Figure 5 – Safe operating power curve.

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 6 of 11

capacitor connected between the VREF and REFGND pins

the low frequency attenuation from 10 Hz to 10 kHz will

reduce by roughly 10 dB. Review the following transient

considerations below before selecting the operating

headroom. The RHR resistor value is determined by using

the following formula.

where; RHR is headroom setting resistor value,

QPOOUT is the expected voltage on the

QPO’s output,

VHR is the target headroom voltage for the

desired range of attenuation.

To ensure sufficient headroom during transient load

changes, a greater headroom voltage than what would

normally be set based on maximum ripple should be

considered. To provide margin to cover the instantaneous

drop in the converter output and the line drops,

additional headroom will be needed. In the example

shown in Figure 2 an additional 75 mV was included with

the headroom voltage value selected from the graph in

Figure 7 to cover the instantaneous drop in the supply

output during the 10 Amp step as explained below.

In Figure 2, a maximum load of 10 Amps allowed for the

RHR value to be calculated to provide 375 mV of headroom

to avoid exceeding 4 Watts. In this example, based on the

attenuation graph in Figure 7, 300 mV of headroom is the

point of diminishing returns so the maximum attenuation

would be achieved at the fundamental ripple frequency.

To stay within the dynamic range required by the active

loop during a transient, a total of 375 mV was used in the

formula to determine the RHR resistor value. The peak

detector will dynamically add 30 mV (derived from the 60

mV peak to peak input ripple) to the static headroom

setting providing the total dynamic headroom of typically

405 mV with the detector enabled.

The input capacitance to the QPO-2 will provide the

transient load current keeping the QPOOUT at the VREF

voltage until the converter loop responds to regulate the

load. During this time the transient load current capability

can be approximated by the formula below. The

capacitance CIN may be within the power supply that is

used or supplemented by external capacitance.

Consideration of the power supply’s sensitivity to

additional output capacitance and stability must be

understood before additional capacitance is added for

transient performance enhancement.

where; CIN = Input capacitance (assuming low

ESR/ceramic type) at the QPO-2 input,

I = Step load current change,

Tr = Converter response time,

VHR = headroom voltage.

The output voltage drop for a given supply during a

transient load step will be reduced at the output of the

QPO-2, effectively multiplying the CIN capacitance by the

ratio of VIN/VOUT which is typically greater than a

factor of 10.

ΔI = VHR * CIN

2Tr

RHR =QPOOUT * 2.5 kΩ

VHR +15 mV

-100

-80

-60

-40

-20

10 100 1K 10K 100K 1M 3M

Frequency [Hz]

27.4k

(269mV)

31.6k

(229mV)

33.2k

(216mV)

37.4k

(189mV)

Rhr=43.2k

(Vheadroom=159mV)

Vout=3.3V

Iload=15A

Rslope=100K

Figure 7 – Attenuation curves without slope adjust.

-20

-40

-60

-80

-100

10 100 1K 10K 100K 1M 3M

22.1k

(198mV)

23.7k

(173mV)

26.1k

(146mV)

27.4k

(126mV)

Rhr=29.4k

(Vheadroom=103mV)

Vout=3.3V

Iload=10A

Rslope=8.2K

Figure 8 – Attenuation Curves Using Slope Adjust Feature

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 7 of 11

The line inductance from the output of the QPO-2 to the

load should be minimized. This inductance will cause

voltage spikes and ringing proportional to the inductance

and the rate of change in the transient load current. This

effect is outside the control of the QPO-2 and may require

low ESR capacitance placed at the switching load when

long lines exists between the QPO-2 output and reference

ground and load. The rate of load change should be less

than 1 Amp per microsecond to minimize excessive

voltage ringing during the di/dt. The line inductance

between the power supply output and QPO input should

also follow low inductance layout practices.

The user must be aware of the converter’s over-voltage set

point and not create a headroom voltage that will cause a

shutdown condition. For this reason it is recommended

that the QPO-2 be used with power supplies running at

the factory pre-set voltages or in a trimmed down

configuration.

SC/Trim Adjustment

The RSC resistor is tied between QPOOUT and SC SET pin

and controls the correction current used to trim the

converter to compensate for the headroom voltage.

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 (4)

VOUT is the desired QPO output voltage,

VRPT is the pre-trimmed reference of the

SC or TRIM.

This feature can be used in conjunction with an initially

trimmed down supply.

Note 4: When applicable consider the equivalent impedance of

the SC/Trim pin after a trimmed down adjustment has been made

to the supply. Use the power supply manufacturer’s trim down

procedure by connecting a resistor from the SC/Trim pin to

ground.

The active loop performance of the QPO-2 has been

optimized to provide adequate phase margin over a worse

case load impedance range. Loading the QPO-2 directly

with low ESR ceramic capacitance however will

significantly reduce the phase margin and is not

recommended. The effects of the typical distributed

inductance of the load path will mitigate the reduction in

phase margin when low ESR ceramic capacitors are

dispersed about the load path. Tantalum and Electrolytic

capacitors are higher ESR components and are not a

concern for phase margin.

When using the QPO as shown in Figure 4 the CSC

capacitor creates a soft starting of the headroom

correction current being sourced into the SC/Trim input of

the converter, preventing the output from tripping the

over voltage function while the QPO-2 output reaches

regulation. The QPO-2 ramp up time is typically 5 to 10

milliseconds. The CSC value will be supply dependent but

is typically around 1 to 10 µF.

The RSL resistor provides a means to isolate the SC/Trim pin

of the converter from CSC as well as limit the correction

current to a level below what will cause an OVP trip

condition during start up. The compliance of the SC

output current source is QPOIN plus 10 volts so the RSL

formula below can be used to limit the worst-case

correction current below the maximum trim up

specification of the converter being used. Note the

correction current set by RSC must always be lower than

the ISCMAX current after the start-up settling time interval

for proper headroom correction.

Headroom Slope Adjustment

This feature can be used to allow more headroom at

lighter loads inceasing the delta voltage available to

improve transient load capability, while approximating

constant power dissipation of the QPO-2 over the full load

range. The slope of this curve is set by the slope adjust

resistor RSA. Figure 9 shows the relationship of headroom

resistance versus power dissipation for a load current of 10

Amps. The same data is plotted in Figure 10 with the slope

adjust feature reducing the headroom by 150 mV over the

load range of 1 to 10 A, for a typical range of RHR values

with a 3.3 volt output. The headroom setting RHR value

was selected at the minimum load condition while

enabling the slope function using an RSA value of 8.2 k.

This feature is useful in improving the QPO-2 efficiency

RSC = RIN * VOUT

ΔVRPT

RSL = QPOIN + 10 V

ISCMAX

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 8 of 11

when using switching power supplies that have decreasing

ripple with increasing load current, like Vicor converters.

Figure 8 shows the headroom voltage vs. load with

different headroom resistors with RSA =8.2 k.

The slope adjust feature can be effectively disabled,

providing relatively constant headroom versus load, by

using an RSA of 100k. 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 versus current slope. 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,

Example: For a 5 A maximum load and a 150mV reduction

in headroom.

Figures 9 and 10 demonstrate the attenuation versus

power dissipation relationship with different headroom

resistor values with corresponding increasing power

dissipation at a fixed 10 A load. The low frequency

attenuation is flat with changing headroom as indicated

by the 50 Hz line. The active attenuation is dependent on

the headroom voltage and correlates to the attenuation

curves presented previously.

Figure 10 shows the increase in attenuation that can be

gained by using the slope adjust feature setting higher

headroom at lower loads while limiting the power

dissipation with reduced headroom at higher loads staying

within the 4 Watt limitation of the package. As stated

previously this will also increase the transient capability

with a load step providing more delta voltage across the

filter at lower loads.

Iload=10A (Vref Cap=25uF) 1% Rhr std. values for VOUT=3.3V

Rsa=100k (delta Vhr=0mV from 0.1 to 10A)

21 k

24.9 k

30.1 k

39.2 k

47.5 k

-60

-50

-40

-30

-20

-10

12 34

Watts

500 khz

50 hz

3.3 V QPO-2 output voltage

69.8 k Headroom resistor

Figure 9 – Power dissipation vs. RHR (Headroom voltage)

113 k

Load Current (A)

1A 2A 3A 4A 5A 6A 7A 8A 9A 10A

200mV

400mV

600mV

V Headroom

Rhr=64.9 k

75 k

82.5 k

124 k

102 k

93.1 k

Figure 8 – Effect of slope adjust on headroom value with

increasing current and RSA = 8.2 k.

RSA = 0.05(V/A) * ΔIOUT *2.5 kΩ

ΔVHR

RSA = 0.05(V/I) * 5 A *2.5 kΩ= 4.167 k Ω

0.15 V

Figure 10 – Power dissipation vs. RHR (Headroom voltage) with

150 mV of slope adjust.

Iload=10A (VREF Cap=25μF) 1% Rhr std. values for VOUT=3.3V

Rsa=8.4K (delta Vhr=150mV from 0.1 to 10A)

14.3 k

16.5 k

18.2 k

21 k

22.6k

24.9 k

-60

-50

-40

-30

-20

-10

1 2 3 4

Watts

500 kHz

50 Hz

3.3 V QPO-2 output voltage

27.4 k Headroom resistor

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 9 of 11

Headroom Start-up Clamp Feature

This feature allows for pre-charging the Vref capacitance

to the level just below the steady state headroom voltage.

It reduces the time for the QPOout to reach the desired

regulation voltage and converter output overshoot that

results in the delay through the QPO filter during start-up.

The following formula can be used to calculate the RCP

resistor value to set the clamp at 90% of the final output

value. To set the clamp voltage to different percentages of

the output substitute the 0.90 with the desired factor.

The following is a summary of typical configurations that a

user can select for the QPO-2.

• No slope adjust, no peak detect, fixed headroom,

attenuation vs headroom graph in Figure 7 apply

• No slope adjust, peak detector enabled, headroom will

increase by the peak of the ripple amplitude

• Slope adjust enabled, no peak detect, headroom will

decrease with the increase in load current

• Slope adjust enabled, peak detector enabled,

headroom will vary with ripple amplitude and load

variations

The attributes of these features have been explained in

this datasheet. The optimum use of them requires an

understanding of the characteristics of the power supply

to be filtered.

RCP = 100k* (VQPOIN - 0.90 * VQPOOUT) Ω

0.90 * VQPOOUT

0.1310

0.0880

0.0655

0.0880

15 places

0.0000

0.1000

0.3000

0.1000

0.3000

0.3970

0.4410

0.4850

0.2000

0.0000

0.1000

0.3000

0.4410

0.3970

0.4850

0.0000

0.1000

0.3000

0.3970

0.4850

0.1500

QPO Package Outline

QPO PCB Pad Pattern

(Top View)

4 places

0.492

0.2560

0.2060

Figure 11 - Recommended PCB receptor patterns. (dimensions in

inches)

QPO IN QPO OUT

0.4410 0.4410

Vias to

round plane

Figure 12 - Recommended PCB copper lands for low thermal resistance.

Picor Corporation • www.picorpower.com QPO-2 Data Sheet Rev. 1.5 Page 10 of 11

45.000°

0.0820

0.0625

0.0820

15 places

0.000

0.100

0.300

0.100

0.300

0.400

0.441

0.492

0.100

0.300

0.441

0.400

0.492

0.000

0.100

0.300

0.400

0.492

QPO SIP Package

4 places

0.1773

0.2000

0.441

(Bottom View)

0.250

0.050

0.000

0.050

0.250

0.325

0.075

0.000

0.325

0.2500

0.1250 0.0200

Figure 13 - Package dimensions (dimensions in inches)

Ordering Information

Part

Number Description

QPO-2L QPO-2 Land Grid Array Package

QPO-2LZ QPO-2 Land Grid Array Package,

RoHS Compliant

Picor’s Z version QP SIPs are not hermetically sealed and

must not be exposed to liquid, including but not limited

to cleaning solvents, aqueous washing solutions or

pressurized sprays.

When soldering, it is recommended that no-clean flux

solder be used, as this will insure that potentially

corrosive mobile ions will not remain on, around, or

under the module following the soldering process.

Post Solder Cleaning

Picor Corporation • www.picorpower.com • QPO-2 Data Sheet P/N 29738 Rev. 1.5 10/07

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

Vicor Express: vicorexp@vicr.com

Technical Support: apps@vicr.com