LT1076-5 5V Step-Down Switching Regulator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 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 The LT1076-5 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 LT1076-5 nearly bust-proof for output overloads or shorts. The input voltage range as a buck converter is 8V to 60V, but a selfboot 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 TO-220 packages with frequency pre-set at 100kHz and current limit at 2.6A. See Application Note 44 for design details. U APPLICATIO S ■ ■ ■ 5V Output Buck Converter Tapped Inductor Buck Converter with 4A Output at 5V Positive-to-Negative Converter , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATIO Basic Positive Buck Converter 100µH** † VIN 8V TO 40V 5V ≤1.8A VSW LT1076-5 MBR340* * MBR330P MAY BE USED FOR VIN ≤ 25V SENSE GND + C3 200µF ** COILTRONICS #100-1-52 HURRICANE #HL-AG210LL VC R3 1.5k C2 0.033µF † + C1 500µF 25V VALUE MAY BE REDUCED TO 50µH FOR OUTPUT LOADS BELOW 1.5A LT1076-5 TA01 10765fb 1 LT1076-5 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (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 FRONT VIEW 7 6 5 4 3 2 1 TAB IS GND ORDER PART NUMBER SHDN VC SENSE GND ILIM VSW VIN LT1076CR-5 R PACKAGE 7-LEAD PLASTIC DD θJC = 4°C, θJA = 30°C/W FRONT VIEW 5 4 3 2 1 TAB IS GND VIN VSW GND VC SENSE LT1076CT-5 LT1076HVCT-5 LT1076IT-5 LT1076HVIT-5 T PACKAGE 5-LEAD PLASTIC TO-220 LEADS ARE FORMED STANDARD FOR STRAIGHT LEADS, ORDER FLOW 06 θJC = 4°C, θJA = 50°C/W FRONT VIEW SHDN VC SENSE GND ILIM VSW VIN 7 6 5 4 3 2 1 TAB IS GND LT1076CT7-5 Y PACKAGE 7-LEAD PLASTIC TO-220 θJC = 4°C, θJA = 50°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. VIN = 25V, unless otherwise noted. PARAMETER Switch “On” Voltage (Note 2) Switch “Off” Leakage Supply Current (Note 3) Minimum Supply Voltage Switch Current Limit (Note 5) Maximum Duty Cycle Switching Frequency Switching Frequency Line Regulation Error Amplifier Voltage Gain (Note 8) Error Amplifier Transconductance (Note 8) CONDITIONS ISW = 0.5A ISW = 2A VIN = 25V, VSW = 0 VIN = VMAX, VSW = 0 (Note 7) 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) TJ ≤ 125°C VOUT = VSENSE = 0V (Note 5) 8V ≤ VIN ≤ VMAX (Note 8) 1V ≤ VC ≤ 4V MIN TYP ● ● ● ● ● ● ● 2 ● 85 90 85 ● ● 3700 8.5 9.0 140 7.3 3.5 2.6 1.8 1.2 90 100 20 0.03 2000 5000 MAX 1.2 1.7 150 250 11 12 300 8.0 4.8 3.2- 110 120 0.1 8000 UNITS V V µA µA mA mA µA V V A A A % kHz kHz kHz %/ V V/ V µmho 10765fb 2 LT1076-5 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. VIN = 25V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Error Amplifier Source and Sink Current Source (VSENSE = 4.5V) Sink (VSENSE = 5.5V) 100 0.7 3 4.85 140 1.0 5 5 ±0.5 ±1.0 225 1.6 8 5.15 ±2 ±3 µA mA kΩ V % % 0.02 5 0.005 1.5 –4.0 24 10 2.2 0.1 2.45 0.30 %/ V V mV/°C V µA µA V V °C/ W Sense Pin Divider Resistance Sense Voltage Output Voltage Tolerance Output Voltage Line Regulation VC Voltage at 0% Duty Cycle Multiplier Reference Voltage Shutdown Pin Current VC = 2V VOUT (Nominal) = 5V All Conditions of Input Voltage, Output Voltage, Temperature and Load Current 8V ≤ VIN ≤ VMAX (Note 7) ● Over Temperature ● ● ● VSHDN = 5V VSHDN ≤ VTHRESHOLD (≅ 2.5V) Switch Duty Cycle = 0 Fully Shut Down Shutdown Thresholds 20 50 2.7 0.5 4 Thermal Resistance Junction to Case Note 1: Absolute Maximum Ratings are those values beyond which the life of a device ay be impaired. 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 current limit testing, VSENSE is adjusted to give a minimum switch on time of 1µs. 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 U PACKAGE DESCRIPTIO R Package 7-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1462) .256 (6.502) .420 .080 .420 .060 (1.524) TYP .060 (1.524) .165 – .180 (4.191 – 4.572) .390 – .415 (9.906 – 10.541) .276 .060 (1.524) .350 .183 (4.648) .330 – .370 (8.382 – 9.398) .325 15° TYP .045 – .055 (1.143 – 1.397) .059 (1.499) TYP +.008 .004 –.004 +0.203 0.102 –0.102 .205 .565 .565 .090 .090 .050 .035 RECOMMENDED SOLDER PAD LAYOUT .050 .035 RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK ) .095 – .115 (2.413 – 2.921) .075 (1.905) .300 (7.620) .320 ( +.012 .143 –.020 +0.305 3.632 –0.508 ( ) .050 (1.27) BSC .013 – .023 (0.330 – 0.584) .026 – .035 (0.660 – 0.889) TYP .050 ± .012 (1.270 ± 0.305) R (DD7) 0502 NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE 10765fb 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. 3 LT1076-5 U PACKAGE DESCRIPTIO T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .570 – .620 (14.478 – 15.748) .460 – .500 (11.684 – 12.700) .620 (15.75) TYP .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) .095 – .115 (2.413 – 2.921) SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) BSC .067 (1.70) .135 – .165 (3.429 – 4.191) .028 – .038 (0.711 – 0.965) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0801 T7 Package 7-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1422) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .570 – .620 (14.478 – 15.748) .460 – .500 (11.684 – 12.700) .330 – .370 (8.382 – 9.398) .620 (15.75) TYP .700 – .728 (17.780 – 18.491) SEATING PLANE .260 – .320 (6.604 – 8.128) BSC .026 – .036 (0.660 – 0.914) .050 (1.27) .152 – .202 (3.860 – 5.130) .135 – .165 (3.429 – 4.191) .095 – .115 (2.413 – 2.921) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) *MEASURED AT THE SEATING PLANE T7 (TO-220) 0801 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1074/HV 4.4A (IOUT), 100kHz High Efficiency Step-Down DC/DC Converter VIN: 7.3V to 45V/64V, VOUT(MIN): 2.21V, IQ: 8.5mA, ISHDN: 10µA, DD5/7, TO-2205/7 LT3430 60V, 2.75A (IOUT), 200kHz High Efficiency Step-Down DC/DC Converter VIN: 5.5V to 60V, VOUT(MIN): 1.20V, IQ: 2.5mA, ISHDN: 25µA, TSSOP16E LT1956 60V, 1.2A (IOUT), 500kHz High Efficiency Step-Down DC/DC Converter VIN: 5.5V to 60V, VOUT(MIN): 1.20V, IQ: 2.5mA, ISHDN: 25µA, TSSOP16E 10765fb 4 Linear Technology Corporation LT/TP 1102 1K REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 1994