MAX17761
17Pages

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter General Description The MAX17761, high-efficiency, high-voltage, synchronous step-down DC-DC converter with integrated MOSFETs operates over a 4.5V to 76V input. The converter can deliver up to 1A current. Output voltage is programmable from 0.8V up to 90% of Vin. The feedback voltage regulation accuracy over -40°C to +125°C is ±1.5%. The device features a peak-current-mode control architecture and can be operated in either the pulse-width modulation (PWM) or pulse-frequency modulation (PFM) control schemes. The MAX17761 is available in a 12-pin (3mm x 3mm) TDFN package. Simulation models are available. Applications • Industrial Control Power Supplies • General-Purpose Point-of-Load • Distributed Supply Regulation • Basestation Power Supplies • Wall Transformer Regulation • High-Voltage, Single-Board Systems Ordering Information appears at end of data sheet. Benefits and Features • Reduces External Components and Total Cost • No Schottky—Synchronous Operation • Internal Compensation Components • All-Ceramic Capacitors, Compact Layout • Reduces Number of DC-DC Regulators to Stock • Wide 4.5V to 76V Input • Output Adjustable from 0.8V up to 90% of Vin • Delivers up to 1A Over Temperature • 200kHz to 600kHz Adjustable Frequency with External Clock Synchronization • Programmable Current Limit • Reduces Power Dissipation • Peak Efficiency > 90% • PFM Mode Enables Enhanced Light-Load Efficiency • Auxiliary Bootstrap LDO for Improved Efficiency • 5pA Shutdown Current • Operates Reliably in Adverse Industrial Environments • Adjustable Soft-Start and Prebiased Power-Up • Built-in Output-Voltage Monitoring with RESET • Programmable EN/UVLO Threshold • Monotonic Startup into Prebiased Load • Overtemperature Protection • High Industrial -40°C to +125°C Ambient Operating Temperature Range/-40°C to +150°C Junction Temperature Range

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Continuous Power Dissipation (Ta = +70°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. Note 1: Junction temperature greater than +125°C degrades operating lifetimes. Maxim...

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC ConverterElectrical Characteristics (continued) (V|n = 24V, Ven/uvlo = unconnected, Rrt = 105kn (fSw = 400kHz), LX = unconnected, Ta = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C. All voltages are referenced to SGND, unless otherwise noted.) (Note 2)

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC ConverterElectrical Characteristics (continued) (V|n = 24V, Ven/uvlo = unconnected, Rrt = 105kD (fsw = 400kHz), LX = unconnected, Ta = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C. All voltages are referenced to SGND, unless otherwise noted.) (Note 2) Note 2: Electrical specifications are production tested at Ta = +25°C. Specifications over the entire operating temperature range are guaranteed by design and characterization.

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (VIN = 24V, VSGND = VPGND = 0V, CVIN = 2.2μF, CVCC = 1μF, VEN/UVLO = Open, CSS = 33nF, MODE/ILIM = unconnected, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to SGND, unless otherwise noted.) EFFICIENCY VS. LOAD CURRENT (3.3V OUTPUT, FIGURE 5 CIRCUIT) EFFICIENCY VS. LOAD CURRENT (5V OUTPUT, FIGURE 4 CIRCUIT) LOAD AND LINE REGULATION (5V OUTPUT, FIGURE 4 CIRCUIT) SOFT-START/SHUTDOWN FROM EN/UVLO, (5V OUTPUT, PWM MODE, 1A LOAD...

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VSGND = VPGND = 0V, CVIN = 2.2μF, CVCC = 1μF, VEN/UVLO = Open, CSS = 33nF, MODE/ILIM = unconnected, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to SGND, unless otherwise noted.) SOFT-START/SHUTDOWN FROM EN/UVLO, (3.3V OUTPUT, PWM MODE, 1A LOAD CURRENT, FIGURE 5 CIRCUIT) SOFT-START/SHUTDOWN FROM EN/UVLO, (5V OUTPUT, PFM MODE, 5mA LOAD CURRENT, FIGURE 4 CIRCUIT) toc11 SOFT-START WITH 2.5V PRE-BIAS, (5V...

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VSGND = VPGND = 0V, CVIN = 2.2μF, CVCC = 1μF, VEN/UVLO = Open, CSS = 33nF, MODE/ILIM = unconnected, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to SGND, unless otherwise noted.) LOAD CURRENT STEPPED FROM 0.5A TO 0.75A (3.3V OUTPUT, PWM MODE, FIGURE 5 CIRCUIT) toc19 IOUT IOUT LOAD CURRENT STEPPED FROM 0A TO 0.25A (3.3V OUTPUT, FIGURE 5 CIRCUIT) LOAD CURRENT STEPPED FROM 0A TO 0.25A (5V OUTPUT, FIGURE...

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Pin Configuration TOP VIEW VIN PGND VCC EN/UVLO RESET RT/SYNC TDFN (3mm x 3mm) *EP = EXPOSED PAD , CONNECTED TO SGND

4.5V to 76V, 1A, High-Efficiency, Synchronous Step-Down DC-DC Converter Functional (or Block) Diagram EXTVCC CURRENTSENSE LOGIC CURRENTSENSE AMPLIFIER HIGH-SIDE DRIVER PFM/PWM CONTROL LOGIC CLK LOW-SIDE DRIVER MODE SELECT SINK LIMIT EXTERNAL SOFT-START CONTROL ZX/ILIMN COMP ERROR AMPLIFIER RESET LOGIC Detailed Description The MAX17761 step-down regulator operates from 4.5V to 76V and delivers up to 1A load current on output. Feedback voltage regulation accuracy meets ±1.5% over load, line, and temperature. The device uses a peak-current-mode control scheme. An internal transconductance...