LT1076-5

LT1076-5 5V Step-Down Switching Regulator FEATURES n n n n n n n n DESCRIPTION The LT®1076-5 is a 2A fixed 5V output monolithic bipolar switching regulator which requires only a few external parts for normal operation. The power switch, all oscillator and control circuitry, all current limit components, and an output monitor are included on the chip. The topology is a classic positive “buck” configuration but several design innovations allow this device to be used as a positive-to-negative converter, a negative boost converter, and as a flyback converter. The switch output is specified to swing 40V below ground, allowing the LT1076-5 to drive a tapped inductor in the buck mode with output currents up to 4A. The LT1076-5 uses a true analog multiplier in the feedback loop. This makes the device respond nearly instantaneously to input voltage fluctuations and makes loop gain independent of input voltage. As a result, dynamic behavior of the regulator is significantly improved over previous designs. On-chip pulse by pulse current limiting makes the LT10765 nearly bust-proof for output overloads or shorts. The input voltage range as a buck converter is 8V to 60V, but a self-boot feature allows input voltages as low as 5V in the inverting and boost configurations. The LT1076-5 is available in a low cost 5- and 7-lead TO220 packages with frequency pre-set at 100kHz and current limit at 2.6A. See Application Note 44 for design details. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Fixed 5V Output 2A On-Board Switch 100kHz Switching Frequency 2% Output Voltage Tolerance Over Temperature Greatly Improved Dynamic Behavior Available in Low Cost 5- and 7-Lead Packages Only 9.5mA Quiescent Current Operates Up to 60V Input APPLICATIONS n n n 5V Output Buck Converter Tapped Inductor Buck Converter with 4A Output at 5V Positive-to-Negative Converter TYPICAL APPLICATION Basic Positive Buck Converter 100μH** † 8V TO 40V VIN LT1076-5 SENSE GND VC R3 1.5k C2 0.033μF VSW MBR340* 5V ≤1.8A * MBR330P MAY BE USED FOR VIN ≤ 25V ** COILTRONICS #100-1-52 HURRICANE #HL-AG210LL † + C3 200μF + C1 500μF 25V LT1076-5 TA01 VALUE MAY BE REDUCED TO 50μH FOR OUTPUT LOADS BELOW 1.5A 10765fc 1 LT1076-5 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage LT1076-5 .............................................................45V LT1076HV-5 .........................................................64V Switch Voltage with Respect to Input Voltage LT1076-5 ..............................................................64V LT1076HV-5 .........................................................75V Switch Voltage with Respect to Ground Pin (VSW Negative) LT1076-5 (Note 6) ................................................35V LT1076HV-5 (Note 6) ...........................................45V Sense Pin Voltage ............................................ –2V, 10V Maximum Operating Ambient Temperature Range LT1076C-5, LT1076HVC-5 ....................... 0°C to 70°C LT1076I-5, LT1076HVI-5 ..................... –40°C to 85°C Maximum Operating Junction Temperature Range LT1076C-5, LT1076HVC-5 ..................... 0°C to 125°C LT1076I-5, LT1076HVI-5 ................... –40°C to 125°C Maximum Storage Temperature ............ –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C PACKAGE/ORDER INFORMATION FRONT VIEW 5 4 3 2 1 Q PACKAGE 5-LEAD PLASTIC DD VIN VSW GND VC FB/SENSE TAB IS GND FRONT VIEW 7 6 5 4 3 2 1 R PACKAGE 7-LEAD PLASTIC DD SHDN VC SENSE GND ILIM VSW VIN ORDER PART NUMBER LT1076CQ-5 ORDER PART NUMBER LT1076CR-5 θJC = 4°C/W, θJA = 30°C/W FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD PLASTIC TO-220 VIN VSW GND VC SENSE TAB IS GND θJC = 4°C/W, θJA = 30°C/W FRONT VIEW 7 6 5 4 3 2 1 T7 PACKAGE 7-LEAD PLASTIC TO-220 SHDN VC SENSE GND ILIM VSW VIN TAB IS GND ORDER PART NUMBER LT1076CT-5 LT1076HVCT-5 LT1076IT-5 LT1076HVIT-5 ORDER PART NUMBER LT1076CT7-5 LEADS ARE FORMED STANDARD FOR STRAIGHT LEADS, ORDER FLOW 06 θJC = 4°C/W, θJA = 50°C/W θJC = 4°C/W, θJA = 50°C/W Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. ELECTRICAL CHARACTERISTICS SYMBOL Switch “On” Voltage (Note 2) Switch “Off” Leakage CONDITIONS ISW = 0.5A ISW = 2A VIN = 25V, VSW = 0 VIN = 25V, VSW = 0 The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. VIN = 25V, unless otherwise noted. MIN l l TYP MAX 1.2 1.7 150 250 UNITS V V μA μA 10765fc 2 LT1076-5 ELECTRICAL CHARACTERISTICS SYMBOL Supply Current (Note 3) CONDITIONS VOUT = 5.5V, VIN ≤ 40V 40V < VIN < 60V VSHDN = 0.1V (Device Shutdown) (Note 9) Normal Mode Start-Up Mode (Note 4) ILIM = Open RLIM = 10k (Note 10) RLIM = 7k (Note 10) l l l l l The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. VIN = 25V, unless otherwise noted. MIN TYP 8.5 9.0 140 7.3 3.5 2 2.6 1.8 1.2 90 100 20 l MAX 11 12 300 8.0 4.8 3.2 UNITS mA mA μA V V A A A % kHz kHz kHz %/V V/V μmho μA mA kΩ V % % %/V V mV/°C V Minimum Supply Voltage Switch Current Limit (Note 5) Maximum Duty Cycle Switching Frequency TJ ≤ 125°C VOUT = VSENSE = 0V (Note 5) Switching Frequency Line Regulation 8V ≤ VIN ≤ VMAX (Note 8) Error Amplifier Voltage Gain (Note 8) 1V ≤ VC ≤ 4V Error Amplifier Transconductance (Note 8) Error Amplifier Source and Sink Current Sense Pin Divider Resistance Sense Voltage Output Voltage Tolerance VC = 2V VOUT (Nominal) = 5V All Conditions of Input Voltage, Output Voltage, Temperature and Load Current 8V ≤ VIN ≤ VMAX (Note 7) Over Temperature Multiplier Reference Voltage Shutdown Pin Current Shutdown Thresholds Thermal Resistance Junction to Case Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: To calculate maximum switch “on” voltage at currents between low and high conditions, a linear interpolation may be used. Note 3: A sense pin voltage (VSENSE) of 5.5V forces the VC pin to its low clamp level and the switch duty cycle to zero. This approximates the zero load condition where duty cycle approaches zero. Note 4: Total voltage from VIN pin to ground pin must be ≥ 8V after startup for proper regulation. For TA < 25°C, limit = 5V. Note 5: Switch frequency is internally scaled down when the sense pin voltage is less than 2.6V to avoid extremely short switch on times. During VSHDN = 5V VSHDN ≤ VTHRESHOLD (≅ 2.5V) Switch Duty Cycle = 0 Fully Shut Down Source (VSENSE = 4.5V) Sink (VSENSE = 5.5V) l l 85 90 85 110 120 0.1 8000 225 1.6 8 5.15 ±2 ±3 0.02 0.03 2000 3700 100 0.7 3 5000 140 1.0 5 5 ±0.5 ±1.0 0.005 1.5 –4.0 24 5 2.2 0.1 10 2.45 0.30 l l l l 4.85 Output Voltage Line Regulation VC Voltage at 0% Duty Cycle 20 50 2.7 0.5 4 μA μA V V °C/W current limit testing, VSENSE is adjusted to give a minimum switch on time of 1ms. Note 6: Switch to input voltage limitation must also be observed. Note 7: VMAX = 40V for the LT1076-5 and 60V for the LT1076HV-5. Note 8: Error amplifier voltage gain and transconductance are specified relative to the internal feedback node. To calculate gain and transconductance from the Sense pin (Output) to the VC pin, multiply by 0.44. Note 9: Does not include switch leakage. Note 10: ILIM ≈ RLIM − 1k 5k 10765fc 3 LT1076-5 PACKAGE DESCRIPTION Q Package 5-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1461) .060 (1.524) TYP .256 (6.502) .060 (1.524) .390 – .415 (9.906 – 10.541) 15° TYP .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) +.008 .004 –.004 +0.203 0.102 –0.102 .060 (1.524) .183 (4.648) .330 – .370 (8.382 – 9.398) .059 (1.499) TYP ( ) .075 (1.905) .300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK +.012 .143 –.020 +0.305 3.632 –0.508 .067 (1.702) .028 – .038 BSC (0.711 – 0.965) TYP .013 – .023 (0.330 – 0.584) .095 – .115 (2.413 – 2.921) .050 ± .012 (1.270 ± 0.305) Q(DD5) 0502 ( ) .420 .080 .420 .276 .350 .205 .565 .325 .565 .320 .090 .067 .042 .067 .090 .042 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS 10765fc 4 LT1076-5 R Package 7-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1462) .060 (1.524) TYP .256 (6.502) .060 (1.524) .390 – .415 (9.906 – 10.541) 15° TYP .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) +.008 .004 –.004 +0.203 0.102 –0.102 .060 (1.524) .183 (4.648) .330 – .370 (8.382 – 9.398) .059 (1.499) TYP ( ) .075 (1.905) .300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK .050 (1.27) BSC .013 – .023 (0.330 – 0.584) .095 – .115 (2.413 – 2.921) .050 ± .012 (1.270 ± 0.305) R (DD7) 0502 ( +.012 .143 –.020 +0.305 3.632 –0.508 ) .026 – .035 (0.660 – 0.889) TYP .420 .420 .080 .276 .350 .205 .565 .325 .565 .320 .090 .050 .035 .050 .090 .035 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS 10765fc 5 LT1076-5 PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) .147 – .155 (3.734 – 3.937) DIA .230 – .270 (5.842 – 6.858) .460 – .500 (11.684 – 12.700) .570 – .620 (14.478 – 15.748) .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) .620 (15.75) TYP .165 – .180 (4.191 – 4.572) .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .095 – .115 (2.413 – 2.921) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) BSC .067 (1.70) .028 – .038 (0.711 – 0.965) .135 – .165 (3.429 – 4.191) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0801 10765fc 6 LT1076-5 PACKAGE DESCRIPTION T7 Package 7-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1422) .147 – .155 (3.734 – 3.937) DIA .230 – .270 (5.842 – 6.858) .460 – .500 (11.684 – 12.700) .570 – .620 (14.478 – 15.748) .330 – .370 (8.382 – 9.398) .620 (15.75) TYP .700 – .728 (17.780 – 18.491) .165 – .180 (4.191 – 4.572) .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) SEATING PLANE .152 – .202 .260 – .320 (3.860 – 5.130) (6.604 – 8.128) .050 (1.27) .026 – .036 (0.660 – 0.914) .095 – .115 (2.413 – 2.921) .155 – .195* (3.937 – 4.953) BSC .135 – .165 (3.429 – 4.191) .013 – .023 (0.330 – 0.584) *MEASURED AT THE SEATING PLANE T7 (TO-220) 0801 10765fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 LT1076-5 RELATED PARTS PART NUMBER LT1074/HV LT3430 LT1956 DESCRIPTION 4.4A (IOUT), 100kHz High Efficiency Step-Down DC/DC Converter 60V, 2.75A (IOUT), 200kHz High Efficiency Step-Down DC/DC Converter 60V, 1.2A (IOUT), 500kHz High Efficiency Step-Down DC/DC Converter COMMENTS VIN: 7.3V to 45V/64V, VOUT(MIN): 2.21V, IQ: 8.5mA, ISHDN: 10μA, DD5/7, TO-2205/7 VIN: 5.5V to 60V, VOUT(MIN): 1.20V, IQ: 2.5mA, ISHDN: 25μA, TSSOP16E VIN: 5.5V to 60V, VOUT(MIN): 1.20V, IQ: 2.5mA, ISHDN: 25μA, TSSOP16E 10765fc 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● LT 0407 REV C • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 1994