POWER RD5 Datasheet

RD5

TOPSwitch-II

Reference Design Board

85 to 265 VAC Input, 20W (30W Peak) Output

Product Highlights

Low Cost Production Worthy Reference Design

• Only 22 components!

• Single sided board

• Low cost thru-hole components

• Fully assembled and tested

• Easy to evaluate and modify

• Extensive performance data

• Up to 80% efficiency

• Light weight – no heat sink required for TOPSwitch-II

1.69 in.

(43 mm)

3.57 in. (91 mm)

Fully Protected by

• Primary safety current limit

• Output short circuit protection

• Thermal shutdown protects entire power supply

Designed for World Wide Operation

• Designed for IEC/UL safety requirements

• Meets VDE Class B EMI specifications

TOPSwitch-II

Description

The RD5 reference design board is an example of a very low cost production worthy power supply design using the TOPSwitch family of Three-terminal Off-line PWM Switchers from Power Integrations. It is intended to help TOPSwitch users to develop their products quickly by providing a basic design that can be easily modified to fit a particular application. In most cases, a minor change to the transformer for a different output voltage is all that is needed. Multiple output voltages are obtained just as easily. A constant current or constant power output may be implemented with the addition of a few low cost components.

Typical applications include AC-DC adapters for laptops, notebooks and PDAs, battery chargers for cellular telephones, power tools and camcorders, VTR/VCR, video game, appliance and satellite decoder power supplies.

Figure 1. RD5 Board Overall Physical Dimensions.

PARAMETER LIMITS

Input Voltage Range 85 to 265 VAC Input Frequency Range 47 to 440 Hz Temperature Range 0 to 50°C Output Voltage (I = 1.0A) 12 V ± 5% Output Power (continuous) Output Power (peak) 30W Line Regulation (85-265 VAC) ± 1% Load Regulation (10%-100%) ± 1%

Efficiency 78%

25˚C 20W

50˚C 15W

1.06 in. (27 mm)

PI-2058-041698

Output Ripple Voltage ± 60 mV MAX Safety IEC 950 / UL1950

EMI

Figure 2. Table of Key Electrical Parameters.

VDE B (VFG243 B)

CISPR22

July 1997

RD5

VR1

P6KE200

19 mH

0.1 µF

250 VAC

3.15 A

BR1

600 V

C1 47 µF 400 V

UF4005

TOPSwitch-II

CONTROL

TOP224P

Figure 3. Schematic Diagram of the 12V RD5 Power Supply.

47 µF

6.8 Ω

7, 8

5, 6

50SQ100

1N4148

1 nF

250 VAC

560 µF

35 V

0.1 µF

3.3 µH

+12V

220 µF

35 V

RTN

39 Ω

150 Ω

PC817A

VR2

1N5241B

11 V

PI-2053-041698

BR1

POWER INTEGRATIONS INC.

RD5 Rev. A

S/N

COMPONENT SIDE SHOWN

Figure 4. Component Legend of the RD5.

General Circuit Description

The RD5 is a low-cost, flyback switching power supply using the TOP224P integrated circuit. The circuit shown in Figure 3 produces a 12 V, 20 W power supply that operates from 85 to 265 VAC input voltage. The 12 V output is directly sensed by optocoupler U2 and Zener diode VR2. The output voltage is determined by the Zener diode (VR2) voltage and the voltage drops across the optocoupler (U2) LED and resistor R1. Other output voltages are also possible by adjusting the transformer

VR1

VR2

turns ratios and value of Zener diode VR2.

AC power is rectified and filtered by BR1 and C1 to create the high voltage DC bus applied to the primary winding of T1. The other side of the transformer primary is driven by the integrated high-voltage MOSFET within the TOP224. D1 and VR1 clamp the leading-edge voltage spike caused by transformer leakage inductance to a safe value and reduce ringing. The

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Component Listing

Reference Value Part Number Manufacturer

BR1 600 V, 2 A 2KBPC06M General Instrument C1 47 µF, 400 V 381LX470M400H012 Cornell-Dubilier C2 560 µF, 35 V ECA-1VFQ561 Panasonic C3 220 µF, 35 V ECE-A1VGE221 Panasonic C4 0.1 µF, 50 V RPE131R104M50 Murata C5 47 µF, 10 V ECE-A1AG470 Panasonic C6 0.1 µF, 250 VAC, X F1772-410-2000 Roederstein C7* 1.0 nF, 400 VAC, Y1* DE1110E102M ACT4K-KD Murata

D1 600 V, 1A, UFR UF4005 General Instrument D2 100 V, 5A, Schottky 50SQ100 International Rectifier D3 75 V, Switching 1N4148 National Semiconductor L1 3.3 µH, 6.5 A 622LY-3R3M Toko L2 19 mH, 400 mA ELF15N005A Panasonic R1 39 Ω, 1/4 W 5043CX39R00J Philips R2 150 Ω, 1/4 W 5043CX150R0J Philips R3 6.8 Ω, 1/4 W 5043CX6R800J Philips T1** TRD5 Custom U1 TOP224P Power Integrations U2 PC817A Sharp VR1 200 V Zener TVS P6KE200 General Instrument VR2 11 V Zener 1N5241B Motorola F1 3.15 A, 250 VAC 19372K, 3.15A Wickman

RD5

(or WKP102MCPE.OK Roederstein) (or PME294RB4100M Rifa)

Figure 5. Parts List for the RD5 (* Two Series Connected, 2.2 nF, Y2-Capacitors Such as Murata DE7100F222MVA1-KC can replace C7). ** T1 is available from Premier Magnetics (714) 362-4211 as P/N POL-12017, and from Coiltronics (561) 241-7876 as P/N CTX00-13742.

power secondary winding is rectified and filtered by D2, C2, L1, and C3 to create the 12 V output voltage. R2 and VR2 provide a slight pre-load on the 12 V output to improve load regulation at light loads. R2 also provides bias current for Zener VR2 to improve regulation. The bias winding is rectified and filtered by D3 and C4 to create a bias voltage to the TOP224P. L2 and Y1-capacitor C7 attenuate common-mode emission currents caused by high-voltage switching waveforms on the DRAIN side of the primary winding and the primary to secondary capacitance. L2 and C6 attenuate differential-mode emission currents caused by the fundamental and harmonics of the primary current waveform. C5 filters internal MOSFET gate drive charge current spikes on the CONTROL pin, determines the auto-restart frequency, and together with R1 and R3, compensates the control loop.

The circuit performance data shown in Figures 6-18 were measured with AC voltage applied to the RD5.

Load Regulation (Figure 6) – The amount of change in the DC output voltage for a given change in output current is referred to as load regulation. The 12 V output stays within ±1% from

10% to 100% of rated load current. The TOPSwitch on–chip overtemperature protection circuit will safely shut down the power supply under persisting overload conditions. Below minimum load, the 12 V output rises slightly due to the TOPSwitch minimum duty cycle.

Line Regulation (Figure 7) - The amount of change in the DC output voltage for a given change in the AC input voltage is called line regulation. The maximum change in output voltage is within ± 1%.

Efficiency (Line Dependent) – Efficiency is the ratio of the output power to the input power. The curves in Figures 8 and 9 show how the efficiency changes with input voltage.

Efficiency (Load Dependent) – The curves in Figures 10 and 11 show how the efficiency changes with output power for 115 VAC and 230 VAC inputs.

Power Supply Turn On Sequence – The internal switched, highvoltage current source provides the initial bias current for TOPSwitch when power is first applied. The waveforms shown

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RD5

General Circuit Description (cont.)

in Figure 12 illustrate the relationship between the high-voltage DC bus and the 12 V output voltage. Capacitor C1 charges to the peak of the AC input voltage before TOPSwitch turns on. The delay of 160 ms (typical) is caused by the time required to charge the auto-restart capacitor C5 to 5.8 V. At this point the power supply turns on as shown.

Figure 13 shows the output voltage turn on transient as well as a family of curves associated with an additional soft-start capacitor. The soft-start capacitor is placed across VR2 and can range in value from 4.7 uF to 47 uF as shown.

Line frequency ripple voltage is shown in Figure 14 for 115 VAC input and 20 W output. Switching frequency ripple voltage is shown in Figure 15 for the same test condition.

The power supply transient response to a step load change from

1.25 to 1.67 A (75% to 100%) is shown in Figure 16. Note that the response is quick and well damped.

The RD5 is designed to meet worldwide safety and EMI (VDE B) specifications. Measured conduction emissions are shown in Figure 17 for 115 VAC and Figure 18 for 230 VAC.

Thermal Considerations

The RD5 utilizes the printed circuit copper for TOPSwitch heatsinking. For 20 W output, the heatsink area is approximately

1.25 in2 (8 cm2). The copper area required for heatsinking at

15 W output is outlined on the non-component side of the board, and is approximately 0.56 in2 (3.6 cm2). The RD5 printed circuit board utilizes 2 oz. copper cladding. Printed circuit boards with lighter cladding will require apertures in the solder mask to build-up effective trace thickness.

Transformer Specification

The electrical specifications and construction details for transformer TRD5 are shown in Figures 19 and 20. Transformer TRD5 is supplied with the RD5 reference design board. This design utilizes an EI25 core and a triple insulated wire secondary winding. The use of triple insulated wire allows the transformer to be constructed using a smaller core and bobbin than a conventional magnet wire design due to the elimination of the margins required for safety spacing in a conventional design.

If a conventional margin wound transformer is desired, the design of Figures 21-22 can be used. This design (TRD5-1) uses a EEL22 core and bobbin to accommodate the 3 mm margins required to meet international safety standards when using magnet wire rather than triple insulated wire, and has the same pinout and printed circuit foot print as TRD5. The transformer is approximately 50% taller than the triple insulated wire design due to the inclusion of creepage margins required to meet international safety standards.

110

100

VIN = 115 VAC

PI-2062-070297

0.5

1 1.5

110

100

50 100 150 200 250 300

Load Current (A)

110

100

Output Voltage (% of Nominal)

0 0.5 1 1.5

VIN = 230 VAC

110

100

Output Voltage (% of Nominal)

50 100 150 200 250 300

Load Current (A)

Figure 6. Load Regulation Figure 7. Line Regulation

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PI-2063-070297

IL = 1.67 A

Input Voltage (VAC)

IL = 0.33 A

Input Voltage (VAC)

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