MIC4575 200kHz Simple 1A Buck Regulator General Description Features The MIC4575 is a series of easy to use fixed and adjustable BiCMOS step-down (buck) switch-mode voltage regulators. The 200kHz MIC4575 duplicates the pinout and function of the 52kHz LM2575. The higher switching frequency may allow up to a 2:1 reduction in output filter inductor size. The MIC4575 is available in 3.3V, and 5V fixed output versions or a 1.23V to 20V adjustable output version. Both versions are capable of driving a 1A load with excellent line and load regulation. The feedback voltage is guaranteed to ±2% tolerance for adjustable versions, and the output voltage is guaranteed to ±3% for fixed versions, within specified voltages and load conditions. The oscillator frequency is guaranteed to ±10%. In shutdown mode, the regulator draws less than 200µA standby current. The regulator performs cycle-by-cycle current limiting and thermal shutdown for protection under fault conditions. This series of simple switch-mode regulators requires a minimum number of external components and can operate using a standard series of inductors. Frequency compensation is provided internally. The MIC4575 is available in TO-220 (T) and TO-263 (U) packages for the industrial temperature range. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • • • • • • • • • • • • Fixed 200kHz operation 3.3V, 5V, 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 switch current Wide 4V to 24V input voltage range Wide 1.23V to 20V output voltage range Requires minimum external components < 200µA typical shutdown mode 75% efficiency (adjustable version > 75% typical) Standard inductors and capacitors are25% of typical LM2575 values • Thermal shutdown • Overcurrent 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) Battery charger Negative boost converter Step-down 6V to 3.3V for Intel Pentium® and similar microprocessors ___________________________________________________________________________________________________________ Typical Application Shutdown Enable 8V to 24V C1 150µF 35V 5 1 SHDN SW MIC4575-5.0_T VIN FB GND 2 L1 5.0V/1A 68µH 4 3 D1 1N5819 C2 330µF 16V Fixed Regulator Adjustable Regulator Pentium is a registered trademark of Intel Corporation Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2009 1 M9999-072909 Micrel, Inc. MIC4575 Ordering Information Part Number Standard RoHS Compliant* Voltage Temperature Range Package MIC4575-3.3BT MIC4575-3.3WT 3.3V –40° to +85°C 5-Pin TO-220 MIC4575-5.0BT MIC4575-5.0WT 5.0V –40° to +85°C 5-Pin TO-220 MIC4575BT MIC4575WT Adj. –40° to +85°C 5-Pin TO-220 MIC4575-3.3BU MIC4575-3.3WU 3.3V –40° to +85°C 5-Pin TO-263 MIC4575-5.0BU MIC4575-5.0WU 5.0V –40° to +85°C 5-Pin TO-263 MIC4575BU MIC4575WU Adj. –40° to +85°C 5-Pin TO-263 * RoHS compliant with ‘high-melting solder’ exemption. TAB Pin Configuration 5-Pin TO-220 (T) 5 4 3 2 1 SHDN FB GND SW VIN 5-Pin TO-263 (U) Pin Description Pin Number Pin Name 1 IN 2 SW 3, TAB GND 4 FB Feedback (Input): Output voltage feedback to regulator. Connect to output of supply for fixed versions. Connect to 1.23V tap of resistive divider for adjustable versions. 5 SHDN Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts down regulator. July 2009 Pin Function Supply Voltage (Input): Unregulated +4V to +40V supply voltage. Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. Ground. 2 M9999-072909 Micrel, Inc. MIC4575 Absolute Maximum Ratings (1) Supply Voltage (VIN) ..................................................+40V Shutdown Voltage (VSHDN)............................. –0.3V to +36V Output Switch (VSW) .......................................................–1V Storage Temperature (Ts) ........................... –65°C to 150°C ESD(2) Operating Ratings Supply Voltage (VIN).....................................................+24V Junction Temperature (TJ) ....................................... +150°C Package Thermal Resistance TO-220, TO-263 (θJA) ........................................65°C/W TO-220, TO-263 (θJC) ..........................................2°C/W Electrical Characteristics(4) VIN = 12V; ILOAD = 200mA; TJ = 25°C, bold values indicate –40°C< TJ < +85°C, unless noted. Parameter Condition Min Typ Max Units 1.217 1.230 1.230 1.243 V 1.267 1.280 V V % 100 500 nA nA 3.366 V 3.432 3.465 V V % 5.100 V 5.200 5.250 V V % 220 kHz 1.3 1.5 V V % 3.0 3.2 A A 0 7.5 5 50 1.4 2 35 10 200 mA mA mA µA 1.2 1.0 0.8 30 10 V V V V µA µA MIC4575 [Adjustable] Feedback Voltage Feedback Voltage Efficiency Feedback Bias Current 8V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 1.193 1.180 ILOAD = 1A, VOUT = 5V 77 50 MIC4575-3.3 Output Voltage Output Voltage Efficiency MIC4575-5.0 Output Voltage Output Voltage Efficiency MIC4575 / -3.3 / -5.0 3.234 6V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 3.168 3.135 ILOAD = 1A 72 4.900 8V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 4.800 4.750 ILOAD = 1A Oscillator Frequency Saturation Voltage IOUT = 1A Maximum Duty Cycle (On) Current Limit FB connected to 0V Peak Current, tON ≤ 3µs Output Leakage Current VIN = 24V, FB connected to 0V Output = 0V Output = –1V SHDN = 5V (regulator off) VOUT = 0V (regulator off) SHDN Input Current VOUT = 3.3 or 5V (regulator on) 5.0 5.0 77 180 Quiescent Current Standby Quiescent Current SHDN Input Logic Level 3.3 3.3 90 1.7 1.3 2.2 2.4 SHDN = 5V (regulator off) SHDN = 0V (regulator on) –10 200 1 95 2.2 4 0.01 Notes: 1. The MIC4575 is not guaranteed to survive a short circuit to ground for input voltage above 24V. 2. Devices are ESD sensitive. Handling precautions recommended. July 2009 3 M9999-072909 Micrel, Inc. MIC4575 Functional Diagram Block Diagram with External Components Fixed Step-Down Regulator ⎛ ⎜ ⎝ ⎛ ⎜ ⎝ ⎛ ⎜ ⎝ ⎛ ⎜ ⎝ Block Diagram with External Components Adjustable Step-Down Regulator July 2009 4 M9999-072909 Micrel, Inc. MIC4575 A higher feedback voltage increases the error amplifier output voltage. A higher error amplifier voltage (comparator inverting input) causes the comparator to detect only the peaks of the sawtooth, reducing the duty cycle of the comparator output. A lower feedback voltage increases the duty cycle. Functional Description The MIC4575 is a variable duty cycle switch-mode regulator with an internal power switch. Refer to the block diagrams. Supply Voltage The MIC4575 operates from a +4V to +24V unregulated input. Highest efficiency operation is from a supply voltage around +15V. Output Switching When the internal switch is on, an increasing current flows from the supply VIN, through external storage inductor L1, to output capacitor COUT and the load. Energy is stored in the inductor as the current increases with time. When the internal switch is turned off, the collapse of the magnetic field in L1 forces current to flow through fast recovery diode D1, charging COUT. Enable/Shutdown The shutdown (SHDN) input is TTL compatible. Ground the input if unused. A logic-low enables the regulator. A logic-high shuts down the internal regulator which reduces the current to typically 50µA. Feedback Fixed versions of the regulator have an internal resistive divider from the feedback (FB) pin. Connect FB directly to the output line. Adjustable versions require an external resistive voltage divider from the output voltage to ground, connected from the1.23V tap to FB. Output Capacitor External output capacitor COUT provides stabilization and reduces ripple. Return Paths During the on portion of the cycle, the output capacitor and load currents return to the supply ground. During the off portion of the cycle, current is being supplied to the output capacitor and load by storage inductor L1, which means that D1 is part of the high-current return path. Duty Cycle Control A fixed-gain error amplifier compares the feedback signal with a 1.23V bandgap voltage reference. The resulting error amplifier output voltage is compared to a 200kHz sawtooth waveform to produce a voltage controlled variable duty cycle output. July 2009 5 M9999-072909 Micrel, Inc. MIC4575 Application Information The applications circuits that follow have been constructed and tested. Refer to Application Note 15 for additional information, including efficiency graphs and manufacturer’s addresses and telephone numbers for most circuits. For a mathematical approach to component selection and circuit design, refer to Application Note 14. Figure 4. 6V–24V to 3.3V/1A Buck Converter Low-Profile Surface Mount Figure 1. 6V–24V to 3.3V/1A Buck Converter Through Hole Figure 5. 8V–24V to 5V/1A Buck Converter Low-Profile Surface Mount Figure 2. 8V–24V to 5V/1A Buck Converter Through Hole 5 16V to 24V 1 C1 68µF 63V SHDN SW MIC4575BT FB VIN 2 4 GND 3 C1 C2 D1 L1 Nichicon Nichicon Motorola Sumida L1 150µH MBR160 Figure 6. 16V–24V to 12V/1A Buck Converter Low-Profile Surface Mount 12V/1A R2 13.0k 1% R1 1.50k 1% C2 330µF 16V MBR160 Figure 3. 16V–24V to 12V/1A Buck Converter Through Hole Figure 7. 6V–24V to 3.3V/1A Buck Converter Lower-Cost Surface Mount Note 2: Surface-mount component. July 2009 6 M9999-072909 Micrel, Inc. MIC4575 Figure 8. 8V–24V to 5V/1A Buck Converter Lower-Cost Surface Mount Figure 10. 8V–18V to –5V/0.2A Buck-Boost Converter Through Hole Figure 9. 16V–24V to 12V/1A Buck Converter Lower-Cost Surface Mount Figure 11. 5V to –5V/0.3A Buck-Boost Converter Through Hole 5 VIN 8V to 18V 1 C1 22µF 35V SHDN SW 2 4 FB 4 1 MIC4575BU VIN GND 3 C1 C2 C4 D1 T1 L1 T1 68µH 3 1µH R2 3.01k 1% C4 220µF 10V R1 1.00K 1% 2 D1 MBRS130LT3 VOUT 5V/1A L1 C3 3300pF 5mVP-P C2 220µF 10V AVX AVX AVX Motorola MBRS130LT3 Coiltronics Coilcraft DO1608C-102 Figure 12. Low Output-Noise Regulator (5mV Output Ripple ) July 2009 7 M9999-072909 Micrel, Inc. MIC4575 5 VIN 8V to 18V 1 C1 22µF 35V SHDN SW 2 FB 4 MIC4575BU VIN T1 68µH 2 +VOUT/+IOUT 5V/0.5A 1 R2 3.01k 1% R1 1.00K 1% GND 3 D1 MBRS130LT3 C3 3300pF C2 220µF 10V 4 C5 220µF 10V L1 3 +I C1 C2 C4 C5 D1 D2 T1 AVX AVX AVX AVX Motorola MBRS130LT3 Motorola MBRS130LT3 Coiltronics C4 220µF 10V D2 MBRS130LT3 + –I -VOUT/-IOUT -5V/0.5A at VIN 15V Load Regulation 5% A +V + 0.5V DC V – 0.5V 40% then – I 40% then – I × (1 – DC) Figure 13. Split ±5V Supply Figure 14. Adjustable (0V–12V) Output-Voltage Regulator U1 5 VIN 4V to 15V C1 150µF 35V 1 SHDN SW MIC4575BT FB VIN GND 2 L1 68µH VOUT 1V/1A 3 4 1 2 U2 LM358 3 D1 1N5819 R1 R2 249 1% 1.00k 1% C2 330µF 16V R3 1k C1 C2 D1 Motorola 1N5819 L1 U2 National LM358 Figure 15. Low Output-Voltage Regulator (1V) July 2009 8 M9999-072909 Micrel, Inc. MIC4575 Figure 16. 1A Battery Charger (6–8 cells) D3 1N4148 5 VIN 8V to 24V 1 SHDN MIC4575-BT FB VIN GND V Micrel National Micrel Nichicon Nichicon Motorola Motorola Motorola Coiltronics KRL Siliconix 1N5819 1N5819 1N4148 C2 330µF 16V R2 100 1% C4 1000pF VIN 3 R7 1k MIC4575BT LM358 LM4041CIZ-1.2 D2 1N5819 R1 0.1 D1 1N5819 R6 3k 4 3 C1 150µF 35V U1 U2 U3 C1 C2 D1 D2 D3 L1 R1 Q1 SW L1 68µH 2 1 2 U2A 1/2LM358 R3 10k VIN 8 C3 0.01µF U2B 1/2 LM358 5 7 DZ1 1N5244 14V Q1 VN2222LL SP-1-A1-0R100J VN2222LL IOUT 0.1A to 1A 2-8 Cells VBATT R5 10k VR1 10k U3 LM4041CIZ-1.2 6 4 R4 1.21k 1% / 0.9 + 2.5V Figure 17. 0.1A–1A Variable-Current Battery Charger July 2009 9 M9999-072909 Micrel, Inc. MIC4575 Figure 18. 1A Battery Charger (2–8 Cells) Figure 19. Remote-Sensing Regulator July 2009 10 M9999-072909 Micrel, Inc. MIC4575 Figure 20. 6V–18V to Split ±12V/100mA Supply Figure 21. 1A Battery Charger July 2009 11 M9999-072909 Micrel, Inc. MIC4575 ⎛ ⎝⎜ ⎛ ⎜⎝ Figure 22. Improved Adjustable Output-Voltage Regulator (0V–12V) Figure 23. Switchable Battery-Pack Charger July 2009 12 M9999-072909 Micrel, Inc. MIC4575 ⎛ ⎝⎜ ⎛ ⎜⎝ Figure 24. Lithium-Ion Battery Charger with End-of-Charge Flag ⎛ ⎝⎜ ⎛ ⎜⎝ Figure 25. Low Output-Noise Regulator (<1mV) July 2009 13 M9999-072909 Micrel, Inc. MIC4575 Package Information 5-Pin TO-220 (T) 5-Pin TO-263 (U) July 2009 14 M9999-072909 Micrel, Inc. MIC4575 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. © 1997 Micrel, Incorporated. July 2009 15 M9999-072909