LM2575_09

LM2575 52kHz Simple 1A Buck Regulator General Description The LM2575 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. Fixed versions are available with a 3.3V, 5V, 12V, fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 1A load with excellent line and load regulation. These regulators are simple to use because they require a minimum number of external components and include internal frequency compensation and a fixed-frequency oscillator. The LM2575 series offers a high efficiency replacement for popular three-terminal adjustable linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. A standard series of inductors available from several different manufacturers are ideal for use with the LM2575 series. This feature greatly simplifies the design of switchmode power supplies. The feedback voltage is guaranteed to ±2% tolerance for adjustable versions, and the output voltage is guaranteed to ±3% for fixed versions, within specified input voltages and output load conditions. The oscillator frequency is guaranteed to ±10%. External shutdown is included, featuring less than 200µA standby current. The output switch includes cycle-by-cycle current limiting and thermal shutdown for full protection under fault conditions. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. Features • 3.3V, 5V, 12V, and adjustable output versions • Voltage over specified line and load conditions: – Fixed version: ±3% max. output voltage – Adjustable version: ±2% max. feedback voltage • Guaranteed 1A output current • Wide input voltage range – 4V to 40V • Wide output voltage range – 1.23V to 37V • Requires only 4 external components • 52kHz fixed frequency internal oscillator • Low power standby mode IQ typically 80%) • Uses readily available standard inductors • Thermal shutdown and current limit protection • 100% electrical thermal limit burn-in Applications • • • • • Simple high-efficiency step-down (buck) regulator Efficient pre-regulator for linear regulators On-card switching regulators Positive to negative converter (inverting Buck-Boost) Isolated flyback converter using minimum number of external components • Negative boost converter ___________________________________________________________________________________________________________ Typical Applications 7V–40V Unregulated DC Input 1 4 Feedback +5V, 1A Regulated Output + COUT 330µF 7V–40V Unregulated DC Input 1 4 LM2575 Feedback +5V, 1A Regulated Output + COUT 330µF R2 3.09k R1 1k +VIN + CIN 100µF LM2575-5.0 Output L1 2 330µH 3 5 Gnd On/Off D1 1N5822 +VIN + CIN 100µF Output L1 2 330µH D1 1N5822 3 5 Gnd On/Off Note: Pin numbers are for TO-220 Package Note: Pin numbers are for TO-220 Package VOUT = 1.23 1 + R2 R1 ( ) Fixed Regulation in Typical Application Adjustable Regulation in Fixed Output Application Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com May 2009 1 M9999-051209-B Micrel, Inc. LM2575 Ordering Information Part Number Standard LM2575BN* LM2575-3.3BN LM2575-5.0BN LM2575-12BN LM2575BWM* LM2575-3.3BWM LM2575-5.0BWM LM2575-12BWM LM2575BT*† LM2575-3.3BT LM2575-5.0BT LM2575BU* LM2575-3.3BU LM2575-5.0BU LM2575-12BU Notes: * ** † Pb-Free / RoHS Compliant Contact Factory Contact Factory LM2575-5.0YN LM2575-12YN LM2575YWM* LM2575-3.3YWM LM2575-5.0YWM LM2575-12YWM LM2575WT*/** † † Temperature Range –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C –40° to +85°C Package 16-Pin Plastic DIP 16-Pin Plastic DIP 16-Pin Plastic DIP 16-Pin Plastic DIP 24-Pin Wide SOIC 24-Pin Wide SOIC 24-Pin Wide SOIC 24-Pin Wide SOIC 5-Pin TO-220 5-Pin TO-220 5-Pin TO-220 5-Pin TO-220 5-Pin TO-263 5-Pin TO-263 5-Pin TO-263 5-Pin TO-263 LM2575-3.3WT** LM2575-5.0WT** LM2575-12WT** LM2575WU*/** LM2575-3.3WU** LM2575-5.0WU** LM2575-12WU** LM2575-12BT† Adjustable output regulators. RoHS compliant with "high-melting solder" exemption. Contact factory for bent or staggered leads option. May 2009 2 M9999-051209-B Micrel, Inc. LM2575 Pin Configuration 5 ON/OFF 4 FB 3 GND 2 OUT 1 VIN 5-Pin TO-220 (T) 5 4 3 2 1 5-Pin TO-263 (U) ON/OFF FB GND OUT VIN TAB TAB PWR GND NC NC NC 1 2 3 4 5 6 7 8 9 24 NC 23 NC 22 NC 21 NC 20 NC 19 NC 18 OUT 17 OUT 16 NC 15 VIN 14 VIN 13 NC 24-Pin Wide SOIC (WM) NC 1 NC 2 OUT 3 NC 4 GND 5 NC 6 FB 7 NC 8 16 VIN 15 NC 14 GND 13 GND 12 GND 11 GND 10 NC 9 ON/OFF NC NC FB SIG GND NC ON/OFF 10 NC 11 PWR GND 12 16-Pin Plastic DIP (N) May 2009 3 M9999-051209-B Micrel, Inc. LM2575 Absolute Maximum Ratings(1) Maximum Supply Voltage (VIN) ......................................45V ON/OFF Pin Input Voltage. ......................–0.3V ≤ V ≤ +40V Output Voltage to Ground (Steady State) ......................–1V Power Dissipation .....................................Internally Limited Maximum Junction Temperature................................ 150°C Lead Temperature (soldering, 10 sec.)...................... 260°C Storage Temperature (Ts) .........................–65°C to +150°C Minimum ESD Rating C = 100pF, R = 1.5kΩ.............................................. 2kV FB Pin ...................................................................... 1kV Operating Ratings Supply Voltage (VIN).......................................................40V Junction Temperature Range (TJ).......–40°C ≤ TJ ≤ +125°C Electrical Characteristics Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V, and ILOAD = 200mA. LM2575 Limit (Note 2) Units (Limits) Symbol Parameter Condition SYSTEM PARAMETERS, ADJUSTABLE REGULATORS (Note 3) Test Circuit Figure 1 Typ Feedback Voltage VOUT VIN = 12V , ILOAD = 0.2A VOUT = 5V 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V VOUT = 5V 1.230 1.217 1.243 1.230 1.193/1.180 1.267/1.280 82 3.3 3.234 3.366 3.3 3.168/3.135 3.432/3.465 75 5.0 4.900 5.100 5.0 4.800/4.750 5.200/5.250 82 12 11.760 12.240 12 11.520/11.400 12.480/12.600 88 Feedback Voltage LM2575 η Efficiency VIN = 12V, ILOAD = 1A, VOUT = 5V SYSTEM PARAMETERS, 3.3V REGULATORS (Note 3) Test Circuit Figure 1 Output Voltage VOUT VIN = 12V , ILOAD = 0.2A VOUT = 3.3V 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V VOUT = 3.3V V V(min) V(max) V V(min) V(max) % V V(min) V(max) V V(min) V(max) % V V(min) V(max) V V(min) V(max) % V V(min) V(max) V V(min) V(max) % Output Voltage LM2575-3.3 η Efficiency VIN = 12V, ILOAD = 1A SYSTEM PARAMETERS, 5V REGULATORS (Note 3) Test Circuit Figure 1 Output Voltage VOUT VIN = 12V , ILOAD = 0.2A VOUT = 5V 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V VOUT = 5V Output Voltage LM2575-5.0 η Efficiency VIN = 12V, ILOAD = 1A SYSTEM PARAMETERS, 12V REGULATORS (Note 3) Test Circuit Figure 1 Output Voltage VOUT VIN = 25V , ILOAD = 0.2A VOUT = 12V 0.2A ≤ ILOAD ≤ 1A, 15V ≤ VIN ≤ 40V VOUT = 12V VIN = 25V, ILOAD = 1A Output Voltage LM2575-12 η Efficiency May 2009 4 M9999-051209-B Micrel, Inc. LM2575 Limit (Note 2) LM2575 Symbol Parameter Condition DEVICE PARAMETERS, ADJUSTABLE REGULATOR Typ Units (Limits) IB Feedback Bias Current VOUT = 5V DEVICE PARAMETERS, FIXED and ADJUSTABLE REGULATORS fO Oscillator Frequency 50 52 100/500 nA kHz kHz(min) kHz(max) V V(max) % %(max) A A(min) A(max) mA(max) mA mA(max) mA mA(max) µA µA(max) °C/W 47/42 58/63 Saturation Voltage Max Duty Cycle (ON) Current Limit IOUT = 1A (Note 4) (Note 5) Peak Current, tON ≤ 3µs (Note 4) 0.9 1.2/1.4 98 93 2.2 1.7/1.3 3.0/3.2 2 75 30 5 10 Standby Quiescent Current ON/OFF Pin = 5V (OFF) 50 200 65 45 2 85 100 1.4 1.2 4 30 ON /OFF Pin = 0V (ON) 0.01 10 2.2/2.4 1.0/0.8 VSAT DC ICL IL Output Leakage Current VIN = 40V, (Note 6), (Note 6) (Note 6) Output = 0V Output = –1V Output = –1V IQ ISTBY Quiescent Current T Package, Junction to Ambient (Note 7) θJA Thermal Resistance T Package, Junction to Ambient (Note 8) θJA θJC T Package, Junction to Case N Package, Junction to Ambient (Note 9) θJA WM Package, Junction to Ambient (Note 9) θJA ON/OFF CONTROL, FIXED and ADJUSTABLE REGULATORS Test Circuit Figure 1 VIH VIL IIH IIL Notes: ON/OFF Pin Logic Input Level ON/OFF Pin Logic Current VOUT = 0V VOUT = 5V ON /OFF Pin = 5V (OFF) V(min) V(max) µA µA(max) µA µA(max) 1. Absolute Maximum Rating indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. 2. All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are100% production tested. All limits at temperature extreme are guaranteed via testing. 3. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2575/LM1575 is used as shown in Figure 1 test circuit, system performance will be shown in system parameters section of Electrical Characteristics. 4. Output (pin 2) sourcing current. No diode, inductor or capacitor connected to output. 5. Feedback (pin 4) removed from output and connected to 0V. 6. Feedback (pin 4) removed from output and connected to 12V to force the output transistor OFF. 7. Junction to ambient thermal resistance (no external heat sink) for the 5-pin TO-220 package mounted vertically, with 1/2" leads in a socket, or on PC board with minimum copper area. 8. Junction to ambient thermal resistance (no external heat sink) for the 5-pin TO-220 package mounted vertically, with 1/4" leads soldered to PC board containing approximately 4 square inches of copper area surrounding the leads. 9. Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper will lower thermal resistance further. May 2009 5 M9999-051209-B Micrel, Inc. LM2575 Test Circuits and Layout Guidelines FEEDBACK +VIN 1 7V - 40V U N R E G U L A TE D + DC INPUT 100µF C IN G ND 4 OU TPU T 5 2 L1 330µH D1 MBR360 + VOUT 5.00V C OUT 470µF R2 R1 L O A D C IN — 100µF, 75V Aluminum Electrolytic C OUT — 470µF, 15V Aluminum Electrolytic D1 — Schottky, MBR360 L1 — 330µH, 415-0926 (AIE) R1 — 1k, 0.01% R2 — 3.065k, 0.01% 5-pin TO-220 socket—2936 (Loranger Mfg. Co.) 4-pin TO-3 socket—8112-AG7 (Augat Inc.) LM2575 3 ON/OFF FEEDBACK +VIN 1 7V - 40V U N R E G U L A TE D + DC INPUT 100µF C IN LM2575-5.0 3 ON/OFF 5 4 OU TPU T 2 L1 330µH D1 MBR360 + VOUT 5.00V C OUT 220µF L O A D C IN — 100µF, 75V Aluminum Electrolytic C OUT — 330µF, 15V Aluminum Electrolytic D1 — Schottky, MBR360 L1 — 330µH, 415-0926 (AIE) 5-pin TO-220 socket — 2936 (Loranger Mfg. Co.) 4-pin TO-3 socket — 8112-AG7 (Augat Inc.) G ND Not e: Pin numbers are for TO-220 Package Figure 1. As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transient switch can cause problems. For minimal stray inductance and ground loops, the length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as indicated) or ground plane construction should be used for best results. May 2009 6 M9999-051209-B Micrel, Inc. LM2575 Typical Characteristics (circuit of Figure 1) Supply Current SUP PLY CURRE NT (mA ) S TA N D B Y Q U I E S C E N T C U R R E N T ( µ A ) Supply Current vs. Duty Cycle 20.0 S U P P LY C U R R E N T ( m A ) Standby Quiescent Current 200 VIN = 40V 20 18 16 14 12 10 8 6 4 0 10 20 30 Measured at Ground Pin TJ VOUT = 5 V 17.5 15.0 12.5 10.0 7.5 5.0 2.0 VIN f rom 7V to 40V 0 20 40 60 80 100 I L O AD= 2 00 mA 150 VON/OFF= 5 V VIN= 1 2V 50 100 I LO AD t o 1A 40 50 60 0 0 -75 -50 -25 0 25 50 75 100 125150 INPUT VOLTAGE ( V) D U TY C YC L E ( % ) Current Limit O U TPU T C U R R EN T ( A) Switch Saturation Voltage SATU R ATI O N VO LTAG E ( V) Efficiency 100 95 VOUT = 1 2V EFFI CI ENCY ( % ) 3 VIN = 2 5V 1.2 1.0 -55 C -40 C 0.8 25 C 90 85 80 75 70 65 1A VOUT = 3 V 200 mA 1A 2 200 mA 1 0.6 125 C 150 C 0.4 0 -75 -50 -25 0 25 50 75 100125 150 0 0.2 0.4 0.6 0.8 1.0 60 0 5 10 15 20 25 30 35 40 INPUT VOLTAGE ( V) SW I TC H C U R R EN T ( A) N O R M ALI ZED FEED BAC K VO LTAG E ( m V) 5.0 4.5 INPUT VOLTAGE ( V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -75 -50 -25 0 VO U T = 1.23V IL OAD= 200 mA 25 50 75 100125150 14 V 12 Normalized to IN = 1 0V VOUT = 5 V 10 I = 5 00mA 8 LO AD TJ = 25 6 4 2 0 -2 -4 -6 0 5 10 15 20 25 30 S TA N D B Y Q U I E S C E N T C U R R E N T ( µ A ) Minimum Operating Voltage Line Regulation Feedback Pin Current 100 75 50 25 0 -25 -50 -75 -100 -75 -50 -25 0 25 50 75 100 125150 INPUT VOL TAGE ( V) INPUT- OUTPUT DIFFERENTIAL ( V) O UTPUT VO LTAG E CHANG E ( m V ) Normalized Output Voltage NO RM ALI ZED FREQ UENCY ( % ) Oscillator Frequency +8 +6 +4 +2 0 -2 -4 --6 VIN = 4 0V Normalized at 25 C 2.0 Dropout Voltage I LO AD= 1 A VOUT = 5 % RIND = 02 . 100 75 50 25 0 -25 -50 -75 VIN = 1 2V I LO AD = 2 00mA Normalized to J = 2 5 C T 1.5 1.0 I LO AD = 2 00 mA 0.5 -100 -75 -50 -25 0 25 50 75 100125150 VIN = 1 2V -8 -75 -50 -25 0 25 50 75 100125150 0 -75 -50 -25 0 25 50 75 100125150 May 2009 7 M9999-051209-B Micrel, Inc. LM2575 Typical Characteristics (continued) N O R M ALI ZED FEED BAC K VO LTAG E ( m V) FE E D B A C K V O LTA G E C H A N G E ( m V ) Normalize d Feedback Voltage* 25 20 15 10 5 0 -5 -10 -15 -20 -25 -75 -50 -25 0 VIN = 12V IL O AD= 200mA Normalized to J = 25 C T 20 15 10 5 0 -5 -10 -15 -20 0 Feedback Voltage vs Duty Cycle* I LO AD = 2 00 mA VIN = 4 0V VIN = 7 V 25 50 75 100125150 20 40 60 80 100 D U TY C YC LE ( % ) * Adjustable version only May 2009 8 M9999-051209-B Micrel, Inc. LM2575 Functional Characteristics (circuit of Figure 1) L oad Transient Response Switching Waveforms Output Voltage Change +100mV 0 –100mV A 10V 0 B 1A 0 C 1A .5A 1.0A Output Current 0.5A 0 V OUT = 5V 100µs/div. D 0 V OUT = 5V VIN = 20V A: Output pin voltage 10V/div B: Output pin current 1A/div C: Inductor current 0.5A/div D: Output ripple voltage 20 mV/div. AC coupled Horizontal Time Base: 5µs/div Functional Diagrams V IN 1 4 3.1k FIXED GAIN ERROR AMP INTERNAL REGULATOR ON/OFF 5 ON/OFF FB + 1.0k COMPARATOR 1 AMP SWITCH DRIVER - + - 2 THERMAL SHUTDOWN CURRENT LIMIT OUT 1.23V BAND-GAP REFERENCE 52 kHz OSCILLATOR RESET 3 GND Note: Pin numbers are for the TO-220 package Fixed Regulator VIN 1 FIXED GAIN ERROR AMP INTERNAL REGULATOR ON/OFF 5 ON/OFF FB 4 + + - COMPARATOR 1 AMP SWITCH DRIVER 2 THERMAL SHUTDOWN CURRENT LIMIT OUT 1.23V BAND-GAP REFERENCE 52 kHz OSCILLATOR RESET 3 GND Adjustable Regulator May 2009 9 M9999-051209-B Micrel, Inc. LM2575 Package Information 0.780 MAX (19.812) PIN 1 .250±0.005 (6.350±0.127) 0.030-0.110 RAD (0.762-2.794) 0.025±0.015 (0.635±0.381) 0.130±0.005 (3.302±0.127) 0.040 TYP (1.016) 0.020 (0.508) 0.290-0.320 (7.336-8.128) 0-10 0.020 MIN (0.508) 0.100±0.010 (2.540±0.254) 0.125 MIN (3.175) 0.009-0.015 (0.229-0.381) 0.018±0.003 (0.457±0.076) +0.025 –0.015 +0.635 8.255 –0.381 0.325 ( ) 16-Pin Plastic DIP (N) 24-Pin Wide SOIC (WM) May 2009 10 M9999-051209-B Micrel, Inc. LM2575 5-Pin TO-220 (T) 5-Pin TO-263 (T) May 2009 11 M9999-051209-B Micrel, Inc. LM2575 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2000 Micrel, Incorporated. May 2009 12 M9999-051209-B