Linear technology LT1074 free download

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LT1074/LT1076 Step-Down Switching Regulator FEATURES s s s s s s s s 5A On-Board Switch (LT1074) 100kHz Switching Frequency Greatly Improved Dynamic Behavior Available in Low Cost 5 and 7-Lead Packages Only 8.5mA Quiescent Current Programmable Current Limit Operates Up to 60V Input Micropower Shutdown Mode tions 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 LT1074 to drive a tappedinductor in the buck mode with output currents up to 10A. The LT1074 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 LT1074 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 LT1074 is available in low cost TO-220 or TO-3 packages with frequency pre-set at 100kHz and current limit at 6.5A (LT1076 = 2.6A). A 7-pin TO-220 package is also available which allows current limit to be adjusted down to zero. In addition, full micropower shutdown can be programmed. See Application Note 44 for design details. A fixed 5V output, 2A version is also available. See LT1076-5. APPLICATI s s s s s Buck Converter with Output Voltage Range of 2.5V to 50V Tapped-Inductor Buck Converter with 10A Output at 5V Positive-to-Negative Converter Negative Boost Converter Multiple Output Buck Converter DESCRIPTIO The LT1074 is a 5A (LT1076 is rated at 2A) monolithic bipolar switching regulator which requires only a few external parts for normal operation. The power switch, all oscillator and control circuitry, and all current limit components, are included on the chip. The topology is a classic positive "buck" configuration but several design innova- TYPICAL APPLICATI Basic Positive Buck Converter L1** 50 µH (LT1074) 100 µH (LT1076) 10V TO 40V LT1074 GND VC FB R3 2.7k C3 200 µF MBR745* R1 2.8k 1% R2 2.21k 1% + + C2 0.01µ F C1 500 µF 25V *USE MBR340 FOR LT1076 **COILTRONICS #50-2-52 (LT1074) #100-1-52 (LT1076) PULSE ENGINEERING, INC. #PE-92114 (LT1074) #PE-92102 (LT1076) HURRICANE #HL-AK147QQ (LT1074) #HL-AG210LL (LT1076) RIPPLE CURRENT RATING I OUT / 2 EFFICIENCY (%) VIN VSW UO U UO S Buck Converter Efficiency LT1074 100 5V 5A 90 80 VOUT = 12V, VIN = 20V VOUT = 5V, VIN = 15V 70 60 50 0 1 2 3 4 5 6 OUTPUT LOAD CURRENT (A) LT1074 · TPC27 L = 50 µ H TYPE 52 CORE DIODE = MBR735 LT1074 · TA01 1 LT1074/LT1076 ABSOLUTE AXI U RATI GS ILIM Pin Voltage (Forced) ... 5.5V Maximum Operating Ambient Temperature Range LT1074C/76C, LT1074HVC/76HVC ...