1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS April 7, 1998 LM2575 LM2576 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The LM2575/6 series switching regulators are monolithic integrated circuits designed for use in "buck" or "buck/boost" regulator applications requiring accurate output voltages over combined variations of line, load and temperature. This unique series greatly simplifies switching power supply design. The LM2575 has a maximum output current of 1A and the LM2576 is rated for 3A. The LM2575/6 series miniconverters include a switching regulator and compensation network all within the same package. Just add a choke, catch diode and two capacitors to obtain an efficient DC-toDC converter. Current limit and thermal shutdown features of the LM2575/6 series fully protect the device against overstress conditions. The LM2575/6 series offers an alternative to popular 3 terminal linear regulators by providing higher efficiency with reduced heatsink size. In many applications a heat sink will not be required. BLOCK DIAGRAM FEATURES * Pin for pin interchangeable with National's * * * * * * * LM2575/LM2576 series DC-to-DC buck or buck/boost converter requiring only 4 support components Fixed or adjustable voltages Preset output voltages of 3.3, 5 and 12V Wide output voltage range, 1.23 to 35V 82% typical efficiency @ 5V Wide input voltage range, 4V to 40V Inhibit/enable control pin ABSOLUTE MAXIMUM RATINGS Parameter Input Voltage Output Voltage to Common (Steady State) Thermal Resistance Junction to Case TO-220 TO-263 (1) DEVICE PACKAGE (2) LM2575T-XX TO-220 LM2575S-XX TO-263 LM2576T-XX LM2576S-XX 1A (3) (2) TO-220 3A (3) TO-263 Notes: (1) XX = Voltage Option 3.3, 5.0, 12, and ADJ (1.23V to 35V). (2) T-XX = Straight in-line; T-XX-V = Vertical Staggered; T-XX-H = Horizontal Staggered. (3) Add suffix `TR' for tape and reel (TO-263). PD Units 45 V -0.3VVIN V -1 V Internally Limited W JC 2.0 2.0 C/W JA 55 60 C/W Operating Junction Temperature Range TJ -40 to 125 C Storage Temperature Range TSTG -40 to 125 C Lead Temperature (Soldering) 10 Sec TLEAD 260 C Thermal Resistance Junction to Ambient TO-220 TO-263 CURRENT VIN On/Off Pin Input Voltage Power Dissipation ORDERING INFORMATION Symbol Maximum ESD Class 2 1 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 ELECTRICAL CHARACTERISTICS Unless otherwise specified, VIN = 12V for 3.3V, 5V and ADJ options; 25V for 12V; VOUT = 5V for ADJ, TJ = 25C. VIN rated = 40V; IO = 0.5 to 3A (LM2576), 0.2 to 1A (LM2575). Test Conditions Parameter Output Voltage Symbol VIN VO LM2576-3.3 IO Test Limits TJ (4) 0.5A 8V to O.T. VIN Rated LM2576-5 0.5A VO 8V to O.T. VIN Rated LM2576-12 0.5A VO 15V to O.T. VIN Rated Feedback Voltage VOUT = 5V 8V to O.T. VIN Rated LM2576-ADJ Feedback Bias Current 0.5A IFB IB 12V VO 0.2A 8V to O.T. VIN Rated 0.2A VO 8V to O.T. VIN Rated LM2575-12 0.2A VO 15V to O.T. VIN Rated Feedback Voltage 0.2A IFB VOUT = 5V 8V to O.T. VIN Rated LM2575-ADJ Feedback Bias Current LM2575-ADJ Max Units 3.23 3.30 3.37 V 3.14 3.30 3.47 3.20 3.30 3.40 4.90 5.00 5.10 4.76 5.00 5.25 4.85 5.00 5.15 11.76 12.00 12.24 11.40 12.00 12.60 11.52 12.00 12.48 1.217 1.230 1.243 1.180 1.230 1.280 1.193 1.230 1.267 50 100 O.T. LM2575-3.3 LM2575-5 Typ 0.5A LM2576-ADJ Output Voltage Min IB 12V 0.2A O.T. V V V nA 500 3.23 3.30 3.37 3.14 3.30 3.47 3.20 3.30 3.40 4.90 5.00 5.10 4.75 5.00 5.25 4.85 5.00 5.15 11.76 12.00 12.24 11.40 12.00 12.60 11.52 12.00 12.48 1.217 1.230 1.243 1.180 1.230 1.280 1.193 1.230 1.267 500 V V V V nA (CONTINUED NEXT PAGE) 2 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 ELECTRICAL CHARACTERISTICS (cont.) Test Conditions Parameter Test Limits (4) Symbol VIN IO 12V LM2575-1A 77 LM2576-3A 82 TJ Min Typ Max Units Efficiency/Option 3.3 5 12 15V 88 ADJ VO = 5V 12V 82 Switching Frequency FSX O.T. Saturation Voltage (1) Max Duty Cycle (On) VSAT (3) (1) Current Limit 52 58 43 52 62 O.T. 0.9 1.2 LM2576-3A O.T. 0.9 1.4 DC 93 98 ICL 4.2 5.8 O.T. ICL 3.5 1.7 O.T. Output Leakage Current 47 LM2575-1A Peak Current LM2576 Peak Current LM2575 % kHz V % 6.9 A 7.5 2.2 1.3 3.0 A 3.2 (2) Output = 0V IL VIN RATED 2 Output = -1V (2) Quiescent Current IQ 7.5 30 5 10 O.T. Standby Quiescent mA 12 ISTBY A 50 Current (On/Off Pin = 5V) mA O.T. 50 500 On/Off Pin Logic Input Level VIH VOUT = 0V VOUT = Option O.T. VIL O.T. 2.2 1.4 2.4 1.4 V 1.2 1.0 1.2 0.8 V On/Off Input Current On/Off = 5V (Off) IIH 0.5A 12 30 On/Off = 0V (On) IIL 0.5A 0 10 A NOTES: (1) Output sourcing current-resistive load, no inductor or capacitor. (2) Feedback = VO + 1.0V. (3) Feedback = 0V. (4) Over Temp. (O.T.) = over specified operating junction temperature range. 3 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2575 - OPERATIONAL DATA 4 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2575 - OPERATIONAL DATA 5 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2575 - OPERATIONAL DATA 6 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2576 - OPERATIONAL DATA 7 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2576 - OPERATIONAL DATA 8 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 LM2576 - OPERATIONAL DATA 9 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 TYPICAL APPLICATION - BUCK MODE LM2575 LM2576 L1 330H 100H D1 3A 7A CIN 68F 120F COUT 330F 1,000F LM2575 LM2576 The above component selections will be adequate for most applications for output currents from 250mA to 3.0A (LM2576) or 150mA to 1.0A (LM2575). Applications with VOUT below 5V or above 24V may require component adjustment for maximum performance; please contact factory for application assistance. 1. DEVICE SELECTION. Select an appropriate device from the "Ordering Information" guide based upon voltage option and package. 2. THERMAL CONDITIONS. Most applications will not require a heatsink for the TO-220 package. Approximate power dissipation is: P= VO VOIO VSAT + 0 .02 VIN VIN VIN L1 330H 100H D1 3A 7A CIN 68F 120F COUT 330F 1,000F 3. CATCH DIODE. If the output must be capable of a sustained short, the IF rating must be above 3A for the LM2575 and 7A for the LM2576. The use of an ultra fast diode with soft recovery characteristics or a Schottky will be adequate. The major impact on Schottky versus an ultra fast is efficiency. Schottkys will provide approximately 4% to 5% improvement for VOUTS below 12V, whereas above 12V the difference will become less significant. Breakdown rating must be in excess of VIN for margin. 4. INPUT CAPACITOR. The value shown will be adequate for most applications. Ripple voltage at the switching frequency is caused by the input capacitor supplying load current during the on time of the power switch. The use of a low ESR switching type capacitor will minimize ripple to an acceptable level. 10 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 5. LAYOUT. Use short connections with a central point ground to prevent improper operation caused by stray inductance and ground loops. 6. OUTPUT CAPACITOR. Ripple voltage on VOUT is directly related to the value of COUT and the internal resistance ESR of COUT. Output noise can be lowered by increasing COUT or by selecting a capacitor with a lower ESR. ESR must be approximately 0.03 for the LM2576 or 0.07 for the LM2575, or above to maintain stability, otherwise raise value of COUT. 7. SWITCHING SPIKES. Switching spikes will also occur due to distributive capacitance across turns of the inductor when combined with output capacitor series inductance (ESL). Reduction to a level at or below the switching ripple can be achieved by using a post filter as shown. SWITCHING SPIKE REDUCTION 11 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 TYPICAL BUCK SHUTDOWN TURN-ON DELAY 12 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 UNDER VOLTAGE LOCKOUT TURN-ON DELAY WITH SPIKE FILTER 13 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 TYPICAL APPLICATION - INVERTING BUCK/BOOST Inverting buck/boost operation is a different topology of operation than buck. This difference reduces the output current capability of the device, in that the inductor must supply all of the load current during the time the power switch is off. Maximum output current is approximately: IOUT IOUT 3 .5 2 V 1 + O VIN 1 .3 2 V 1 + O VIN (LM2576 ) LM2575 LM2576 CIN 47F 100F D1 3A 7A L1 100H 68H COUT 2,700F 6,800F IOUT 250mA 500mA LM2575 LM2576 CIN 47F 100F D1 3A 7A L1 100H 68H COUT 470F 2,700F IOUT 100mA 750mA Component stress requirement is very similar to the buck with a few exceptions: * * catch diode breakdown VBR must be greater than VIN + |VOUT| input capacitor is larger due to the increased peak current during switch turn on. Power dissipation is approximately: VO PD VO + VIN IO V 1 + O VIN V VSAT + 0 .02 VIN O VIN (LM2575 ) Please contact factory for additional assistance when using the buck/boost topology. 14 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 INVERTING BUCK/BOOST SHUTDOWN 15 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 SUPPORT COMPONENTS INFORMATION PRE-WOUND INDUCTORS: Hurricane Electronics Lab P.O. Box 1280 Hurricane Industrial Park Hurricane, UT 84737 (801) 635-2003 CORE SOURCE: Micro Metals, Inc. 1190 N. Hawk Circle Anaheim, CA 92807 (714) 630-7420 CAPACITORS: VPR Series Mallory Capacitor Co. 4760 Kentucky Avenue Indianapolis, IN 46241 (317) 856-3731 LXF Series United Chemi-con 9801 West Higgins Road Rosemont, IL 60018 (708) 696-2000 HEAT SINKS: AAVID Engineering Co. P.O.Box 400 One Kool Path Laconia, NH 03247 (603) 528-3400 Thermalloy, Inc. 2021 W. Valley View Lane Dallas, TX 76381 (214) 243-4321 511D & 673 Series Sprague Electric Co. North Adams, MA (413) 664-4411 DIODES - CATCH: Ultra Fast/Soft Recovery Semtech Corporation 652 Mitchell Road Newbury Park, CA 91320 (805) 498-2111 HFQ, HFZ Series Panasonic Industrial Co. 2 Panasonic Way Secaucus, NJ 07094 (201) 392-6142 DIODES - SCHOTTKY: Fuji/Collmer Semiconductor 14368 Proton Road Dallas, TX 76244 (800) 527-0521 PF, PL Series Nichicon Corp. 927 E. State Pkwy. Schaumburg, IL 60195 (708) 843-7600 Micro Quality 1000 N. Shiloh Garland, TX 76046 (214) 272-7811 16 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 OUTLINE - TO-220 (T-XX Option) OUTLINE - TO-220 (T-XX-H Option) OUTLINE - TO-220 (T-XX-V Option) 17 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 1.0 & 3.0 AMP MINICONVERTER SWITCHING REGULATORS LM2575 LM2576 April 7, 1998 OUTLINE - TO-263 PIN CONFIGURATIONS LM2575, LM2576 TO-263 PIN FUNCTION 1 VIN 2 OUTPUT 3 COMMON 4 FEEDBACK 5 ON/OFF TAB IS COMMON TO-220 18 (c) 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320