DPA422-426 PI-2770-032002 DPA4227 DPA423 DPA424 DPA425 DPA4265 DPA422

DPA-Switch Family ® Highly Integrated DC-DC Converter ICs for Power over Ethernet & Telecom Applications Product

DPA422-426 DPA422-426 DPA-Switch Family ® Highly Integrated DC-DC Converter ICs for Power over Ethernet & Telecom Applications Product Highlights Highly Integrated Solution · Eliminates up to 50 external componentssaves space, cost · Integrates 220 V high frequency MOSFET, PWM control · Lower cost plastic DIP surface mount (G package) and through-hole (P package) options for designs 35 W · Thermally efficient TO-263-7C (R package) option for high power applications Superior Performance and Flexibility · Eliminates all external current sensing circuitry · Built-in auto-restart for output overload/open loop protection · Pin selectable 300/400 kHz fixed frequency · Wide input (line) voltage range: 16-75 VDC · Externally programmable current limit · Source connected tab reduces EMI · Line under-voltage (UV) detection: meets ETSI standards · Line overvoltage (OV) shutdown protection · UV/OV limits gate drive voltage for synchronous rectification · Fully integrated soft-start for minimum stress/overshoot · Supports forward or flyback topology · Cycle skipping: regulation to zero load without pre-load · Hysteretic thermal shutdown for automatic fault recovery · RoHS compliant P and G package options ® EcoSmart Energy Efficient · Extremely low consumption at no load · Cycle skipping at light load for high standby efficiency Applications · PoE applications, VoIP phones, WLAN, security cameras · Telco central office equipment: xDSL, ISDN, PABX · Distributed power architectures (24 V/48 V bus) · Industrial controls VO SENSE CIRCUIT DPA-Switch VIN D L CONTROL RESET/ CLAMP CIRCUIT S X C F PI-2770-032002 PI-2770-032002 Figure 1. Typical Forward Converter Application. Output Power Table 36-75 VDC Input Range (Forward)2 Total Device Dissipation3 0.5 W 1W 2.5 W 4W 6W Max Power Output1 DPA4227 DPA4227 7.5 W 10 W - - - 10 W DPA423 DPA423 12 W 16 W - - - 18 W DPA424 DPA424 16 W 23 W 35 W - - 35 W DPA425 DPA425 23 W 32 W 50 W 62 W - 70 W DPA4265 DPA4265 25 W 35 W 55 W 70 W 83 W 100 W Product4 36-75 VDC Input Range (Flyback)2 Total Device Dissipation3 0.5 W 0.75 W 1W 1.5 W Max Power Output1 6.5 W 9.0 W - - 9.0 W Product4 DPA422 DPA422 Description DPA423 DPA423 9W 13 W - - 13 W The DPA-Switch IC family is a highly integrated solution for DC-DC conversion applications with 16-75 VDC input. DPA424 DPA424 10 W 14.5 W 18 W 24 W 26 W DPA425 DPA425 -6 -6 -6 25.5 W 52 W DPA-Switch uses the same proven topology as TOPSwitch®, cost effectively integrating a power MOSFET, PWM control, fault protection and other control circuitry onto a single CMOS chip. High performance features are enabled with three user configurable pins. Hysteretic thermal shutdown is also provided. In addition, all critical parameters (i.e. current limit, frequency, PWM gain) have tight temperature and absolute tolerance, to simplify design and reduce system cost. www.powerint.com Table 1. Output Power Table. Notes: 1. Maximum output power is limited by device internal current limit. 2. See Applications Considerations section for complete description of assumptions and for output powers with other input voltage ranges. 3. For device dissipation of 1.5 W or below, use P or G packages. Device dissipation above 1.5 W is possible with R package. 4. Packages: P: DIP-8, G: SMD-8, R: TO-263-7C. For lead-free package options, see Part Ordering Information. 5. Available in R package only. 6. Due to higher switching losses, the DPA425 DPA425 may not deliver additional power compared to a smaller device. 7. Available in P and G package only. December 2007 DPA422-426 DPA422-426 Section List Functional Block Diagram . 3 Pin Functional Description . 3 DPA-Switch Family Functional Description . 4 CONTROL (C) Pin Operation . 4 Oscillator and Switching Frequency. 5 Pulse Width Modulator & Maximum Duty Cycle . 5 Minimum Duty Cycle and Cycle Skipping . 6 Error Amplifier . 6 On-chip Current Limit with External Programmability . 6 Line Under-Voltage Detection (UV). 6 Line Overvoltage Shutdown (OV) . 6 Line Feed-Forward with DCMAX Reduction . 6 Remote ON/OFF . 7 Synchronization. 7 Soft-Start . 8 Shutdown/Auto-Restart . 8 Hysteretic Over-Temperature Protection . 8 Bandgap Reference . 8 High-Voltage Bias Current Source . 8 Using Feature Pins . 8 FREQUENCY (F) Pin Operation . 8 LINE-SENSE (L) Pin Operation . 9 EXTERNAL CURRENT LIMIT (X) Pin Operation . 9 Typical Uses of FREQUENCY (F) Pin . 11 Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins . 11 Application Examples . 14 Key Application Considerations . 16 DPA-Switch Design Considerations . 16 DPA-Switch Layout Considerations . 18 Quick Design Checklist . 19 Design Tools . 20 Product Specifications and Test Conditions . 21 Typical Performance Characteristics . 27 Part Ordering Information . 30 Package Outlines . 31 2 Rev. S 12/07 www.powerint.com DPA422-426 DPA422-426 VC 0 DRAIN (D) CONTROL (C) ZC INTERNAL SUPPLY 1 SHUNT REGULATOR/ ERROR AMPLIFIER + SOFT START 5.8 V 4.8 V - - 5.8 V + INTERNAL UV COMPARATOR IFB VI (LIMIT) CURRENT LIMIT ADJUST SOFT START + VBG + VT SHUTDOWN/ AUTO-RESTART EXTERNAL CURRENT LIMIT (X) 1V VBG OV/UV LINE SENSE DCMAX CONTROLLED TURN-ON GATE DRIVER STOP SOFTSTART DMAX DCMAX CLOCK 300/400 kHz FREQUENCY (F) CURRENT LIMIT COMPARATOR HYSTERETIC THERMAL SHUTDOWN STOP LOGIC LINE-SENSE (L) - ÷8 ON/OFF SAW + OSCILLATOR S Q LEADING EDGE BLANKING R PWM COMPARATOR RE CYCLE SKIPPING SOURCE (S) PI-2760-070501 PI-2760-070501 Figure 2. Functional Block Diagram. Pin Functional Description DRAIN (D) Pin: High voltage power MOSFET drain output. The internal startup bias current is drawn from this pin through a switched highvoltage current source. Internal current limit sense point for drain current. SOURCE (S) Pin: Output MOSFET source connection for the power return. Primary side control circuit common and reference point. Tab internally connected to SOURCE pin (See layout considerations) CONTROL (C) Pin: Error amplifier and feedback current input pin for duty cycle control. Internal shunt regulator connection to provide internal bias current during normal operation. It is also used as the connection point for the supply bypass and auto-restart/ compensation capacitor. R Package (TO-263-7C) LINE-SENSE (L) Pin: Input pin for overvoltage (OV), under-voltage (UV) lock out, line feed-forward with the maximum duty cycle (DCMAX) reduction, remote ON/OFF and synchronization. A connection to SOURCE pin disables all functions on this pin. P Package (DIP-8) G Package (SMD-8) C 2 7 S 3 6 D F FREQUENCY (F) Pin: Input pin for selecting switching frequency: 400 kHz if connected to SOURCE pin and 300 kHz if connected to CONTROL pin. S X 123 4 5 CLX S F 8 L EXTERNAL CURRENT LIMIT (X) Pin: Input pin for external current limit adjustment and remote ON/OFF. A connection to SOURCE pin disables all functions on this pin. 1 4 5 S 7 D PI-4030-110507 PI-4030-110507 Figure 2. Pin Configuration (Top View). 3 www.powerint.com Rev. S 12/07 DPA422-426 DPA422-426 DPA-Switch Family Functional Description In addition to the standard TOPSwitch features, such as the high-voltage start-up, the cycle-by-cycle current limiting, loop compensation circuitry, auto-restart and thermal shutdown, DPA-Switch also offers many advanced features that reduce system cost and increase power supply performance and design flexibility. Following is a summary of the advanced features: 1. A fully integrated 5 ms soft-start limits peak currents and voltages during start-up and reduces or eliminates output overshoot in most applications. 2. A 75% maximum duty cycle (DCMAX) together with the line feed-forward with DCMAX reduction feature makes DPA-Switch well suited for both flyback and forward topologies. 3. High switching frequency (400 kHz/300 kHz, pin selectable) allows the use of smaller size transformers and offers high bandwidth for power supply control loop. 4. Cycle skipping operation at light load minimizes standby power consumption (typically