LM2567 LAN DC/DC Converter General Description Features The LM2567 DC/DC converter is intended for use in LAN applications as a power supply for the DP8392 Coaxial Transceiver. The converter may be operated from an input voltage of 5V ( g 10%) to 15V. It provides an isolated output of b9V for loads of up to 180 mA, with an efficiency of 78% (typical). The few external components required for the converter are completely specified within this datasheet. Protection features for the LM2567-based DC/DC converter include thermal and current limit. Undervoltage lockout and soft-start are incorporated to minimize the inrush current during start-up. Y Y Y Y Y Y Y Wide input voltage range, 5V to 15V Tight line regulation, 0.5% (typ) Output voltage tolerance g 5% Few external components required Surface-mount packaging Fixed switching frequency of 52 kHz Current-mode operation for improved transient response Typical Applications Y Power supply for DP8392 (LAN) coaxial transceiver: Isolated b9V output for up to 180 mA load Typical Application DC-to-DC Converter for DP8392 Coaxial Transceiver TL/H/11731 – 1 Connection Diagram and Ordering Information 24-Lead Surface Mount (M) Order Number LM2567M See NS Package Number M24B TL/H/11731 – 2 *No internal connection Top View C1995 National Semiconductor Corporation TL/H/11731 RRD-B30M115/Printed in U. S. A. LM2567 LAN DC/DC Converter November 1992 Absolute Maximum Ratings (Note 1) Operating Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Output Switch Voltage Supply Voltage Output Switch Voltage Output Switch Current Power Dissipation Storage Temperature Range Supply Voltage 3.5V s VIN s 35V 0V s VSW s 45V Output Switch Current Junction Temperature Range Ambient Temperature Range 40V 50V 6.0A Internally Limited ISW s 3.0A 0§ C s TJ s a 125§ C 0§ C s TA s a 70§ C b 65§ C to a 150§ C Lead Temperature (Soldering, 10 sec.) 260§ C Maximum Junction Temperature 150§ C 2 kV Minimum ESD Rating (C e 100 pF, R e 1.5 kX) Electrical Characteristics Specifications with standard type face are for TJ e 25§ C, and those in bold typeface apply over full Operating Temperature Range. Unless otherwise specified, VIN e 5V, VFB e VREF, and ISWITCH e 0. (Note 2) Symbol Parameter Conditions Typ Min Max Units GENERAL DEVICE PARAMETERS IS Input Supply Current VFB e 1.5V (Switch Off) 7.5 10.0 14.0 mA mA ISW e 2.0A VCOMP e 2.0V (Max. Duty Cycle) 20 50 85 mA mA VUV Input Supply Undervoltage Lockout ISW e 100 mA VCOMP e 1.2V 2.90 2.60 2.55 3.10 3.15 V V fO Oscillator Frequency Measured at Switch Pin ISW e 100 mA 52 48 42 56 62 kHz kHz VREF Reference Voltage Measured at Feedback Pin VIN e 3.5V to 35V VCOMP e 1.0V 1.230 1.214 1.206 1.246 1.254 V V DVREF/ DVIN Reference Voltage Line Regulation VIN e 3.5V to 35V 0.5 mV iJA Thermal Resistance Junction-to-Ambient (Note 3) 100 § C/W ERROR AMPLIFIER PARAMETERS IB Error Amp Input Bias Current VCOMP e 1.0V 100 GM Error Amp Transconductance ICOMP e b30 mA to a 30 mA VCOMP e 1.0V 3700 2400 1600 AV Error Amp Voltage Gain VCOMP e 1.1V to 1.6V RCOMP e 1.0 MX (Note 4) 800 500 250 V/V V/V Error Amp Output Swing Upper Limit VFB e 1.0V 2.4 2.2 2.0 V V Lower Limit VFB e 1.5V 0.3 g 200 nA nA 4800 5800 mmho mmho 0.40 0.55 V V g 130 g 300 g 90 g 400 mA mA 7.5 9.5 mA mA Error Amp Output Current VFB e 1.0V to 1.5V VCOMP e 1.0V ISS Soft Start Current VFB e 1 0V VCOMP e 0V 5.0 2.5 1.5 D Maximum Duty Cycle VCOMP e 1.2V ISW e 100 mA 95 93 88 2 300 800 % % Electrical Characteristics (Continued) Specifications with standard type face are for TJ e 25§ C, and those in bold typeface apply over full Operating Temperature Range. Unless otherwise specified, VIN e 5V, VFB e VREF, and ISWITCH e 0. (Note 2) Symbol Parameter Conditions Typ Min Max Units SWITCH PARAMETERS DISWITCH/ DVCOMP Switch Transconductance IL Switch Leakage Current Switch Off (VFB e 1.5V) VSW e 50V 10 300 600 mA mA VSAT Switch Saturation Voltage ISW e 2.0A VCOMP e 1.2V 0.5 0.75 1.0 V V ICL NPN Switch Current Limit VCOMP e 2.0V 4.3 5.3 6.0 A A 12.5 A/V 3.7 3.0 Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions the device is intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. Note 3: Junction-to-Ambient thermal resistanoe with approximately 1 square inch of p.c. board copper surrounding the leads. Additional copper area will lower thermal resistance further. Note 4: A 1.0 MX resistor is connected to the compensation pin (which is the error amplifier’s output) to ensure accuracy in measuring AVOL. In actual applications, this pin’s load resistance should be t 10 MX, resulting in AVOL that is typically twice the guaranteed minimum limit. 3 Typical Performance Characteristics Supply Current vs Temperature Reference Voltage vs Temperature D Reference Voltage vs Supply Voltage Supply Current vs Switch Current Current Limit vs Temperature Current Limit Response Time vs Overdrive Switch Saturation Voltage vs Switch Current Switch Transconductance vs Temperature Oscillator Frequency vs Temperature Feedback Pin Bias Current vs Temperature Error Amp Transconductance vs Temperature Error Amp Voltage Gain vs Temperature TL/H/11731 – 4 4 LM2567 Block Diagram TL/H/11731 – 5 LM2567 DC-to-DC Converter* in DP8392C Typical Application (*See Typical Application on Front Page of this Datasheet.) TL/H/11731 – 6 Note: T1 is a 1:1 pulse transformer, L e 100 mH Pulse Engineering (San Diego) Part No. 64103 Valor Electronics (San Diego) Part No. LT6003 or equivalent 5 Auxiliary Circuits Regulator Shutdown Control from Totem-Pole Logic ² TL/H/11731 – 9 *BZX84C2V7 (in SOT-23) available from Zetex and Phillips ² Partial regulator circuit shown. Regulator Shutdown Control from Open-Collector Logic ² TL/H/11731 – 10 *BZX84C2V7 (in SOT-23) available from Zetex and Phillips ² Partial regulator circuit shown. Typical Performance Characteristics of LM2567 DC-to-DC Converter Line Regulation Load Regulation TL/H/11731–7 TL/H/11731 – 8 6 7 LM2567 LAN DC/DC Converter Physical Dimensions inches (millimeters) 0.300 Wide SO Package (M) Order Number LM2567M NS Package Number M24B LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. 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