• Replaces a two-stage linear power supply and chopper circuit with a simple
single-stage design
• Eliminates the chopper circuits normally used to achieve variable-speed control
of DC motors
• Motor speed is controllable by a small potentiometer or a 3.6 V to 10 V variable
DC voltage
• Easily meets CISPR-22 / EN55022B limits with E-Shields and Frequency
jittering feature.
The products and applications illustrated herein (including circuits external to the products and transformer
construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign
patent applications assigned to Power Integrations. A complete list of Power Integrations’ pate nts may be found at
www.powerint.com
.
Power Integrations
5245 Hellyer Avenue, San Jose, CA 95138 USA.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
Important Note:
Although this board is designed to satisfy safety isolation requirements, the engineering
prototype has not been agency approved. Therefore, all testing should be performed
using an isolation transformer to provide the AC input to the prototype board.
Page 3 of 32
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
1 Introduction
This document is an engineering report describing a motor drive power supply capable of
delivering up to 36 W of continuous power and up to 72 W of peak power, utilizing a
PKS606YN device. This power supply is intended as a demonstration platform for the
PeakSwitch family of devices and their application in motor drives. The PeakSwitch
family of devices is ideally suited to this role due to their ability to provide very high peak
power for short periods of time, as is often encountered in motor drive applications.
This document contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit board layout and performance data.
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
4 Circuit Description
The motor drive power supply shown in Figure 1 is a switch mode power supply design
utilizing the flyback topology.
4.1 Input EMI Filtering
Differential mode EMI filtering is provided by X-capacitor C3. Y-capacitors C1, C2, C10
and C12, together with the common-mode choke L1, provide common-mode EMI
filtering. Additionally the transformer E-Shields™, together with the frequency jittering
features, provide adequate EMI margins.
4.2 PeakSwitch Primary
Fuse F1 protects the power supply from a catastrophic failure due to a short circuit fault.
A high voltage DC bus is created from the AC line voltage by the full-wave rectifier
formed by diodes D1-D4. Capacitor C4 smoothes and filters the rectified AC voltage.
The PKS606YN (U1) integrates a high voltage MOSFET, along with startup and all
necessary control circuitry.
During the MOSFET’s on-time, current flows through the primary of transformer T1,
storing energy in the transformer core.
During the turn off event, the voltage across the primary winding reverses. A voltage
equal to the sum of DC bus voltage and the reflected output voltage (VOR) appears
across the DRAIN and SOURCE of the PeakSwitch, with an additional spike generated
by the leakage inductance. A primary clamp circuit formed by D6, VR1, R3 and C5 limits
this voltage and resets the leakage energy prior to the next switching cycle.
Diode D7 rectifies the supply’s bias winding while capacitor C9 provides DC filtering.
This bias supply is connected to the PeakSwitch’s BP pin via R7, which powers the
device during normal operation.
4.3 Under-voltage Protection and Fast AC Reset circuit
Under-voltage shutdown is implemented by a separate line rectifying diode, D5, which
charges capacitor C7. Resistors R5 and R6 program the UV start-up voltage to
approximately 104 VDC, which is the DC voltage across C7, at which a current equal to
25 µA flows into the EN/UV pin.
This separate AC line sense network (formed by D5, C7) allows the PeakSwitch to
identify the cause of a fault condition. If the input voltage is above the under-voltage
threshold and the EN/UV pin has not been pulled low for 30 ms, a fault condition is
assumed, and the PeakSwitch latches off. Once the supply is latched off, the AC line
voltage must be removed to allow capacitor C7 to discharge and allow the current into
the EN/UV pin to fall below 25 µA.
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
If the EN/UV pin has not been pulled low for 30 ms and the input voltage is below the
under-voltage threshold, then the loss of regulation is assumed to be due to a low line
condition, and the PeakSwitch will stop switching until the under-voltage threshold is
exceeded again.
4.4 Output Rectification and Filtering
Diode D9 rectifies the output voltage while capacitors C13 and C14 provide output
filtering. The output capacitor current ripple rating is chosen t6 79S327.74 Bicsin
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
7.4 Transformer Build Diagram
1
3
1/2 Primary:
19T X 2 - #31AWG
(filled)
7,8
9,10
1
4
5
3
2
Shield:
Secondary:
Bias:
1/2 Primary:
7T X 4 - #29AWG
(filled)
4T X4 - #23AWG_TIW
(in 1.5 layers)
5T X 2 - #29AWG
(Spread)
(scatterd)
19T X 2 - #31AWG
(filled)
Bobbin: EE25 Vertical
Lp = 148 uH
Figure 5 – Transformer Build Diagram.
Page 13 of 32
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
7.5 Transformer Construction
Bobbin Preparation
1st Half Primary
Winding
Insulation
Bias Winding
Insulation
Secondary Winding
Insulation
Shield Winding
2nd Half Primary
Winding
Insulation
Core Assembly
Varnish
Pin side of the bobbin is oriented to the left hand side. Winding direction is
clockwise when viewed from the non-pin side.
Start on pin 2, wind 19 bi-filar turns of item [3], Magnet Wire: #31 AWG, from left to
right with tight tension and bring the wire back across the bobbin and terminate the
winding on pin 3.
Apply 1 layer of item [6], 3M 1298 Polyester Film tape, for insulation.
Start on pin 5, wind 5 bi-filar turns of item [4], Magnet Wire: #29 AWG, from left to
right, spreading the windings evenly across the bobbin. Bring the wire back across
the bobbin and terminate the winding on pin 4.
Apply 2 layers of item [6], 3M 1298 Polyester Film tape, for insulation.
Start on pin 9 and 10 using 2 wires for each pin. Wind 4 quad-filar turns of item [5],
#23 AWG Triple Insulated Wire, from right to left. Continue winding the second
layer from right to left, spreading the turns evenly across the bobbin. Terminate the
winding on pins 7 and 8 using two wires for each pin.
Apply 2 layers of item [6], 3M 1298 Polyester Film tape, for insulation.
Start on pin 1 and wind 7 quad-filar turns of item [4], Magnet Wire: #29 AWG from
left to right with tight tension across the bobbin. Cut and finish the end.
Start on pin 3, wind 19 bi-filar turns of item [3], Magnet Wire: #31 AWG, from left to
right with tight tension and bring the wire back across the bobbin and terminate the
winding on pin 1.
Apply 3 layers of item [6], 3M 1298 Polyester Film tape, for insulation
Assemble and secure core halves.
Dip varnish assembled transformer with item [7], varnish.
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
8 Transformer Spreadsheet
ACDC_PeakSwitch_020107;
Rev.1.13; Copyright Power
Integrations 2007
ENTER APPLICATION VARIABLES Customer
VACMIN 90 Volts Minimum AC Input Voltage
VACMAX 265 Volts Maximum AC Input Voltage
fL 50 Hertz AC Mains Frequency
Nominal Output Voltage (VO) 12.00
Maximum Output Current (IO) 6.00 Amps Power Supply Output Current (corresponding to peak
Minimum Output Voltage at Peak Load 12.00 Volts Minimum Output Voltage at Peak Power (Assuming
Continuous Power 35.00
Peak Power
n 0.68 Efficiency Estimate at output terminals and at peak
Z 0.60 Loss Allocation Factor (Z = Secondary side losses /
tC Estimate 3.00 mSec
CIN 180.00 180 uFar
ENTER PeakSwitch VARIABLES
PeakSwitch PKS606Y PKS606Y
Chosen Device
ILIMITMIN 2.600 Amps Minimum Current Limit
ILIMITMAX 3.000 Amps Maximum Current Limit
fSmin 250000 Hertz Minimum Device Switching Frequency
I^2fmin 1955 A^2k
VOR 120.00 120 Volts Reflected Output Voltage (VOR <= 135 V
VDS 10 Volts PeakSwitch on-state Drain to Source Voltage
VD 0.7 Volts Output Winding Diode Forward Voltage Drop
VDB 0.7 Volts Bias Winding Diode Forward Voltage Drop
VCLO
KP (STEADY STATE) 0.47 Ripple to Peak Current Ratio (KP < 6)
KP (TRANSIENT) 0.29 Ripple to Peak Current Ratio under worst case at
ENTER UVLO VARIABLES
V_UV_TARGET 96 Volts Target DC under-voltage threshold, above which the
V_UV_ACTUAL 100 Volts Typical DC start-up voltage based on standard value
RUV_IDEAL 3.75 Moh
RUV_ACTUAL 3.90 Moh
BIAS WINDING VARIABLES
VB 15.00 Volts Bias winding Voltage
NB 5 Number of Bias Winding Turns
PIVB 65 Volts Bias rectifier Maximum Peak Inverse Voltage
ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES
Core Type EE25 EE25 User Selected Core Size(Verify acceptable thermal
Core
Bobbin
INPUT INFO OUTPUT UNIT ACDC_PeakSwitch_020107_Rev1-13.xls;
PKS6
06Y
EE25
EE25_BOBBIN P/N:
Volts Nominal Output Voltage (at continuous power)
load. Enter 0.7 if no better data available
Total losses)
Bridge Rectifier Conduction Time Estimate
Input Capacitance
ads
PeakSwitch device
I^2f (product of current limit squared and frequency is
Hz
trimmed for tighter tolerance)
Recommended)
peak load (0.25 < KP < 6)
power supply with start
of RUV_ACTUAL
Calculated value for UV Lockout resistor
ms
Closest standard value of resistor to RUV_IDEAL
ms
rise under continuous load conditions)
P/N:
PC40EE25-Z
EE25_BOBBIN
Page 15 of 32
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
AE 0.404 cm^2 Core Effective Cross Sectional Area
LE 7.34 cm Core Effective Path Length
AL 1420 nH/T^2 Ungapped Core Effective Inductance
BW 10.20 mm Bobbin Physical Winding Width
M 0.00 mm Safety Margin Width (Half the Primary to
L 2.00
NS 4 4 Number of Secondary Turns
DC INPUT VOLTAGE PARAMETERS
VMIN
VMAX 375 Volts Maximum DC Input Voltage
CURRENT WAVEFORM SHAPE PARAMETERS
DMAX 0.61 Duty Ratio at full load, minimum primary
IAVG 1.37 Amps Average Primary Current
IP 2.60 Amps Minimum Peak Primary Current
IR 1.21 Amps Primary Ripple Current
IRMS 1.82 Amps Primary RMS Current
TRANSFORMER PRIMARY DESIGN PARAMETERS
LP 148 uHenries Typical Primary Inductance. +/- 12% to ensure a
LP_TOLERANCE 12 % Primary inductance tolerance
NP 38 Primary Winding Number of Turns
ALG 104 nH/T^2 Gapped Core Effective Inductance
Target BM
BM 2910 Gauss Calculated Maximum Operating Flux Density, BM <
BAC 677 Gauss AC Flux Density for Core Loss Curves (0.5 X Peak
ur 2053 Relative Permeability of Ungapped Core
LG
BWE 20.4 mm Effective Bobbin Width
OD 0.54 mm Maximum Primary Wire Diameter including
INS 0.07 mm Estimated Total Insulation Thickness (= 2 * film
DIA 0.47 mm Bare conductor diameter
AWG 25 AWG Primary Wire Gauge (Rounded to next smaller
CM 323 Cmils Bare conductor effective area in circular mils
CMA
TRANSFORMER SECONDARY DESIGN PARAMETERS
Lumped parameters
ISP 24.57 Amps Peak Secondary Current
ISRMS 13.82 Amps Secondary RMS Current
IRIPPLE 12.45 Amps Output Capacitor RMS Ripple Current
CMS 2763 Cmils Secondary Bare Conductor minimum circular mils
AWGS 15 AWG Secondary Wire Gauge (Rounded up to next larger
VOLTAGE STRESS PARAMETERS
VDRAIN 665 Volts Maximum Drain Voltage Estimate (Assumes 20%
PIVS 52 Volts Output Rectifier Maximum Peak Inverse Voltage
2 Number of Primary Layers
87 Volts Minimum DC Input Voltage
3000 Gauss Target Peak Flux Density at Maximum Current
0.45 mm Gap Length (Lg > 0.1 mm)
177 Cmils/A
mp
Secondary Creepage Distance)
inductance and minimum input voltage
minimum primary inductance of 132 uH
Limit
3000 is recommended
to Peak)
insulation
thickness)
standard AWG value)
Primary Winding Current Capacity (100 < CMA <
500)
standard AWG value)
zener clamp tolerance and an additional 10%
temperature tolerance)
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
9.4.2 External Voltage Control
Control Voltage vs. Output Voltage
14.00
12.00
10.00
8.00
6.00
Output Voltage (V)
4.00
2.00
3.003.504.004.505.005.506.006.507.007.50
Control Voltage (V)
Figure 12 – Output Voltage vs. External Control Voltage.
9.5 Thermal Performance
Thermal testing of the unit was conducted in a thermal chamber under convectional
cooling. The unit was placed horizontally. The volume of convectional cooling was
limited by a cardboard box with dimensions 12” x 10” x 9” (Height x Width x Depth). This
box was used to prevent forced air-cooling of the unit by the thermal chamber’s fan. The
temperature of the PeakSwitch was measured by attaching a thermocouple to the
device’s tab. The output diode’s temperature was monitored in an identical manner. The
unit’s output voltage was approximately 12.5 V during testing with a load of 3 A.
Item
Ambient
PeakSwitch, (U1)
Output Diode, (D9)
Transformer (T1)
Clamp (VR1)
Input Bridge (D1 – D4)
Temperature (°C)
90 VAC 230 VAC
40 40
106 100
91 100
93 94
115 113
86 81
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
90 VAC, 36 W load, 21ºC Ambient
Figure 13 – Infrared Thermograph of Open Frame Operation at Room Temperature.
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
10.4 Transient Response
Figure 22 – 90 VAC Input
Upper: V
Lower: I
, 500 mV / div. (AC coupled)
out
, 2 A / div.
DRAIN
(10 ms / div)
Figure 23 – 265 VAC Input and Maximum Load.
Upper: V
Lower: I
, 500 mV / div. (AC coupled)
out
, 2 A / div.
DRAIN
(10 ms / div)
10.5 Output Voltage and DC Bus Voltage Ripple
For this measurement the supply’s full peak power was pulsed for approximately 50 ms
and the DC bus voltage was measured in addition to the output voltage’s ripple.
Figure 24 – 90 VAC Input, V
Upper Trace: DC Bus Voltage 100 V /
div.
Middle Trace: V
Lower Trace: I
out
50 ms / div.
Page 25 of 32
=11 V
out
Ripple, 1 V / div.
out
=7 A
Figure 25 – 230 VAC Input, V
Upper Trace: DC Bus Voltage 100 V /
div.
Middle Trace: V
Lower Trace: I
50 ms / div.
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=11 V
out
Ripple, 1 V / div.
out
=12 A
out
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RDR-128 36 W, 72 W Peak Variable Output Power Supply 16-Aug-07
10.6 Latching Shutdown Operation
The waveform shown below illustrates the power supply’s latching shutdown feature. This
feature is invaluable in a motor application due to the short circuit condition that can
occur if the motor were to become jammed.
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
10.7 Output Ripple Measurements
10.7.1 Ripple Measurement Technique
For DC output ripple measurements, a modified oscilloscope test probe must be utilized
in order to reduce spurious signals due to pickup. Details of the probe modification are
provided in the figures below.
The 4987BA probe adapter is affixed with two capacitors tied in parallel across the probe
tip. The capacitors include one (1) 0.1 µF/50 V ceramic type and one (1) 1.0 µF/50 V
aluminum electrolytic. The aluminum electrolytic type capacitor is polarized, so proper
polarity across DC outputs must be maintained (see below).
Probe Ground
Probe Tip
Figure 27 – Oscilloscope Probe Prepared for Ripple Measurement. (End Cap and Ground Lead Removed)
16-Aug-07 RDR-128 36 W, 72 W Peak Variable Output Power Supply
Notes
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For the latest updates, visit our website:www.powerint.com
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power
Integrations does not assume any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS
MAKES NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT
LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
NON-INFRINGEMENT OF THIRD PARTY RIGHTS.
PATENT INFORMATION
The products and applications illustrated herein (incl uding transformer construction and circuits external to the products)
may be covered by one or more U.S. and foreign patents, or potentially by pen ding U.S. and foreign patent app lications
assigned to Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com
.
Power Integrations grants its customers a license under certain patent rights as set forth at
http://www.powerint.com/ip.htm.