19-0102; Rev 3; 9/95 5A/2A Step-Down, PWM, Switch-Mode DC-DC Regulators ____________________________Features The MXL1074/MXL1076 are monolithic, bipolar, pulsewidth modulation (PWM), switch-mode DC-DC regulators optimized for step-down applications. The MXL1074 is rated at 5A, while the MXL1076 is rated at 2A. Few external components are needed for standard operation because the power switch, oscillator, and control circuitry are all on-chip. Employing a classic buck topology, these regulators perform high-current step-down functions, but can also be configured as an inverter, a negative boost converter, or a flyback converter. ♦ Input Range: The regulators have excellent dynamic and transientresponse characteristics, while featuring cycle-by-cycle current limiting to protect against overcurrent faults and short-circuit output faults. The MXL1074/MXL1076 also have a wide 8V to 40V input range in the step-down configuration. In inverting and step-up configurations, the input can be as low as 5V. ♦ TO-220 Package The MXL1074/MXL1076 are available in a 5-pin TO-220 package. The devices have a preset 100kHz oscillator frequency and a preset current limit of 6.5A for the MXL1074, and 2.6A for the MXL1076. The MXL1074/ MXL1076 are pin compatible with the LT1074/LT1076. ________________________Applications Up to 40V ♦ 5A On-Chip Power Switch (MXL1074) 2A On-Chip Power Switch (MXL1076) ♦ Adjustable Output: 2.5V to 35V ♦ 100kHz Switching Frequency ♦ Excellent Dynamic Characteristics ♦ Few External Components ♦ 8.5mA Quiescent Current ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MXL1074CT 0°C to +70°C 5 TO-220 MXL1074ET -40°C to +85°C 5 TO-220 MXL1076CT 0°C to +70°C 5 TO-220 MXL1076ET -40°C to +85°C 5 TO-220 ___________________Pin Configuration FRONT VIEW Distributed Power from High-Voltage Buses MXL1074 MXL1076 High-Current, High-Voltage Step-Down Applications High-Current Inverter Negative Step-Up Converter 5 4 3 2 1 VIN VSW GND VC FB 5-PIN TO-220 Multiple-Output Step-Down Converter CASE IS CONNECTED TO GROUND. STANDARD PACKAGE HAS STAGGERED LEADS. CONTACT FACTORY FOR STRAIGHT LEADS. Isolated DC-DC Conversion __________________________________________________Typical Operating Circuits INPUT 8V TO 40V 50µH MXL1074 VC 100µH MBR745 FB 220µF MXL1076 2.8k MBR745 FB VC 470µF OUTPUT 5V AT 2A VSW VIN 2.21k 2.7k INPUT 8V TO 40V VSW VIN 220µF OUTPUT 5V AT 5A 2.8k 470µF 2.21k 2.7k GND GND 0.01µF 0.01µF 5A STEP-DOWN CONVERTER 2A STEP-DOWN CONVERTER ________________________________________________________________ Maxim Integrated Products Call toll free 1-800-998-8800 for free samples or literature. 1 MXL1074/MXL1076 _______________General Description MXL1074/MXL1076 5A/2A Step-Down, PWM, Switch-Mode DC-DC Regulators ABSOLUTE MAXIMUM RATINGS Input Voltage ..........................................................................45V Switch Voltage with Respect to Input Voltage .......................50V Switch Voltage with Respect to Ground Pin (VSW negative) (Note 1) ..............................................................................35V Feedback Pin Voltage ...............................................-0.3V, +10V Operating Temperature Ranges MXL1074CT/MXL1076CT ...................................0°C to +70°C MXL1074ET/MXL1076ET .................................-40°C to +85°C Junction Temperature Ranges MXL1074CT/MXL1076CT .................................0°C to +125°C MXL1074ET/MXL1076ET ...............................-40°C to +125°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 25V, Tj = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MIN Input Supply Voltage Range 8.0 ISW = 1A MXL1074 ISW = 5A Switch-On Voltage (Note 2) MXL1076 MXL1074 Switch-Off Leakage MXL1076 Supply Current (Note 3) Minimum Supply Voltage Switch-Current Limit (Note 5) 40.0 1.85 Tj < 0°C 2.10 Tj ≥ 0°C 2.30 Tj < 0°C 2.50 ISW = 0.5A Tj = +25°C 5 VIN = 40V, VSW = 0V Tj = +25°C 10 VIN ≤ 25V, VSW = 0V Tj = +25°C VIN = 40V, VSW = 0V V Tj = +25°C 300 500 150 8.5 11 Normal Mode 7.3 8.0 3.5 4.8 Tj ≥ 0°C 3.5 5.0 MXL1074 Tj < 0°C 5.5 6.5 8.5 MXL1076 2 2.6 3.2 85 90 Tj = +25°C 90 100 Tj ≤ +125°C 85 VFB = grounded through 2kΩ (Note 5) Tj = +25°C µA 250 VFB = 2.5V, VIN ≤ 40V 8V ≤ VIN ≤ 40V V 1.7 VIN ≤ 25V, VSW = 0V Start-Up Mode (Note 4) UNITS 1.2 ISW = 2A Switching Frequency 2 MAX Tj ≥ 0°C Maximum Duty Cycle Switching Frequency Line Regulation TYP mA V A % 110 120 kHz 0.1 %/V 20 0.03 _______________________________________________________________________________________ 5A/2A Step-Down, PWM, Switch-Mode DC-DC Regulators MXL1074/MXL1076 ELECTRICAL CHARACTERISTICS (continued) (VIN = 25V, Tj = TMIN to TMAX, unless otherwise noted.) CONDITIONS PARAMETER Error-Amplifier Voltage Gain 1V ≤ VC ≤ 4V Error-Amplifier Transconductance MIN TYP Tj = +25°C MAX UNITS 2000 V/V µmho Tj = +25°C 3000 5000 9000 Error-Amplifier Source Current VFB = 2V Tj = +25°C 100 140 225 µA Error-Amplifier Sink Current VFB = 2.5V Tj = +25°C 0.6 1.0 1.7 mA Feedback Pin Bias Current VFB = VREF 0.5 2 µA Reference Voltage VC = 2V 2.155 2.210 2.265 V ±0.5 ±1.5 ±1 ±2.5 0.005 0.02 VREF (nominal) = 2.21V Reference Voltage Tolerance Reference Voltage Line Regulation All conditions of input voltage, output voltage, temperature and load current 8V ≤ VIN ≤ 40V VC Voltage at 0% Duty Cycle Thermal Resistance Junction to Case (Note 6) Tj = +25°C % %/V Tj = +25°C 1.5 V Tj = TMIN to TMAX -4 mV/°C MXL1074 2.5 MXL1076 4.0 °C/W Note 1: Do not exceed switch-to-input voltage limitation. Note 2: For switch currents between 1A and 5A, maximum switch on voltage can be calculated via linear interpolation. Note 3: By setting the feedback pin (FB) to 2.5V, the VC pin is forced to its low clamp level and the switch duty cycle is forced to zero, approximating the zero load condition. Note 4: For proper regulation, total voltage from VIN to ground must be ≥8V after start-up. Note 5: To avoid extremely short switch-on times, the switch frequency is internally scaled down when VFB is less than 1.3V. Switch current limit is tested with VFB adjusted to give a 1µs minimum switch-on time. Note 6: Guaranteed, not production tested. _______________________________________________________________________________________ 3 MXL1074/MXL1076 5A/2A Step-Down, PWM, Switch-Mode DC-DC Regulators ________________________________________________________Package Information DIM A E F φP Q H1 D L2 J1 A B C1 D E e F H1 J1 J2 J3 L L1 L2 φP Q INCHES MAX MIN 0.190 0.140 0.040 0.015 0.022 0.014 0.650 0.560 0.420 0.380 0.067 BSC 0.055 0.045 0.270 0.230 0.115 0.080 0.185 0.170 0.335 0.327 0.200 0.170 0.340 0.260 0.720 0.700 0.161 0.139 0.120 0.100 MILLIMETERS MIN MAX 3.56 4.82 0.38 1.01 0.41 0.50 14.23 16.51 9.66 10.66 1.70 BSC 1.14 1.39 5.85 6.85 2.04 2.92 4.32 4.70 8.31 8.51 4.32 5.08 6.60 8.64 17.78 18.29 3.54 4.08 2.54 3.04 21-005- L L1 5-PIN TO-220 (STAGGERED LEAD) PACKAGE C1 B J2 e J3 DIM A E F φP Q H1 D J1 A B C1 D E e F H1 J1 L φP Q INCHES MAX MIN 0.190 0.140 0.040 0.015 0.022 0.014 0.650 0.560 0.420 0.380 0.067 BSC 0.055 0.045 0.270 0.230 0.115 0.080 0.580 0.500 0.161 0.139 0.120 0.100 MILLIMETERS MIN MAX 3.56 4.82 0.38 1.01 0.41 0.50 14.23 16.51 9.66 10.66 1.70 BSC 1.14 1.39 5.85 6.85 2.04 2.92 12.70 14.73 3.54 4.08 2.54 3.04 21-4737- L B C1 e 5-PIN TO-220 (STRAIGHT LEAD) PACKAGE CONTACT FACTORY FOR AVAILABILITY Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 4 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 © 1995 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products