MAX17548
28Pages

42V, Dual-Output, Synchronous Step-Down Controller General Description The MAX17548 is a dual-output, synchronous step-down controller that drives nMOSFETs. The device features a peak-current-mode, constant-frequency architecture, allowing it to operate up to 2.2MHz. The device can be configured as two singlephase, independent 10A power supplies or as a dualphase, single-output 20A power supply. The device also provides the ability to run two controllers 180° out-ofphase to reduce the power loss and noise due to the input-capacitor ESR. The IC supports current sensing using either an external current-sense resistor for accuracy or an inductor DCR for improved system efficiency. Current foldback limits MOSFET power dissipation under short-circuit conditions. The IC provides independent adjustable soft-start for each output and can start up monotonically into a prebiased output. The IC can be configured in either PWM or DCM modes of operation, depending on whether constant-frequency operation or light-load efficiency is desired. The IC operates over the -40°C to +125°C temperature range and is available in a lead(Pb)-free, 32-pin TQFN, 5mm x 5mm package with an exposed pad. Applications • Industrial Power Supplies • Distributed DC Power Systems • Motion Control • Programmable Logic Controllers • Computerized Numerical Control Benefits and Features • Wide Range of Operation • Wide 4.5V to 42V Input Voltage Range • Wide 0.8V to 24V Output Voltage Range • Rsense or Inductor DCR Current Sensing • Selectable In-Phase or 180° Out-of-Phase Operation • Adjustable 100kHz to 2.2MHz Switching Frequency • Independent Enable and PGOOD • Available in a Lead(Pb)-Free 32-Pin, 5mm x 5mm TQFN-EP Package • Enhances Power Efficiency • Low-Impedance Gate Drives for High Efficiency • DCM Operation at Light Loads • Auxiliary Bootstrap LDO • Operates Reliably in Adverse Industrial Environments • Independent Adjustable Soft-Start or Tracking • Current Foldback Limits MOSFET Heat Dissipation During a Short-Circuit Condition • Operates Over the -40°C to +125°C Temperature Range • Output Overvoltage and Overtemperature Protections Ordering Information appears at end of data sheet. maxim integrated

42V, Dual-Output, Synchronous Step-Down Controller Block Diagram

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics (V|n = 24V, RT = open, CycciNT = 4.7gF, EN_ = open, DH_, DL_ = open, Tj = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C.) (Note 2)

42V, Dual-Output, Synchronous Step-Down Controller Electrical Characteristics (continued) (Vin = 24V, RT = open, Cvccint = 4.7pF, EN_ = open, DH_, DL_ = open, Tj = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C.) (Note 2)

42V, Dual-Output, Synchronous Step-Down Controller Electrical Characteristics (continued) (Vin = 24V, RT = open, Cvccint = 4.7pF, EN_ = open, DH_, DL_ = open, Tj = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C.) (Note 2)

42V, Dual-Output, Synchronous Step-Down Controller Electrical Characteristics (continued) (Vin = 24V, RT = open, Cvccint = 4.7pF, EN_ = open, DH_, DL_ = open, Tj = -40°C to +125°C, unless otherwise noted. Typical values are at Ta = +25°C.) (Note 2) Note 2: Limits are 100% tested at Ta = +25°C. Limits over the temperature range and relevant supply voltage range are guaranteed by design and characterization. Note 3: This supply current excludes the switching current due to the external MOSFETs' gate charge.

42V, Dual-Output, Synchronous Step-Down Controller Typical Operating Characteristics (VIN = 24V, unless otherwise noted. See Figure 8.) EFFICIENCY vs. OUTPUT CURRENT VOUT = 3.3V, PWM MODE EFFICIENCY vs. OUTPUT CURRENT VOUT = 5V, DCM MODE toc04 INDUCTOR CURRENT AT LIGHT LOAD VIN = 24V, VOUT = 3.3V, IOUT = 0.3A toc06 STARTUP INTO PREBIASED OUTPUT VIN = 24V, VOUT1 = 5V, IOUT1 = 0A, VOUT2 = 3.3V, IOUT2 = 0A toc09 INDUCTOR CURRENT AT LIGHT LOAD VIN = 24V, VOUT = 5V, IOUT = 0.1A toc07 EFFICIENCY vs. INPUT VOLTAGE EFFICIENCY vs. OUTPUT CURRENT VOUT = 5V, PWM MODE EFFICIENCY vs. OUTPUT CURRENT VOUT...

42V, Dual-Output, Synchronous Step-Down Controller Typical Operating Characteristics (continued) (VIN = 24V, unless otherwise noted. See Figure 8.) LOAD TRANSIENT RESPONSE VIN = 24V, VOUT2 = 3.3V, IOUT2 = 0A to 5A PWM MODE toc12 LOAD TRANSIENT RESPONSE VIN = 24V, VOUT2 = 3.3V, IOUT2 = 0.1A to 5A DCM MODE toc11 1V/div VOUT2 LOAD TRANSIENT RESPONSE VIN = 24V, VOUT1 = 5V, IOUT1 = 0A to 2.5A PWM MODE toc15 100mV/div AC-COUPLED OVER CURRENT PROTECTION VIN = 24V, VOUT1 = 5V, IOUT1 = SHORT PWM MODE toc18 OVERCURRENT PROTECTION VIN = 24V, VOUT2 = 3.3V, IOUT2 = SHORT PWM MODE toc17 LOAD TRANSIENT...

42V, Dual-Output, Synchronous Step-Down Controller Typical Operating Characteristics (continued) (VIN = 24V, unless otherwise noted. See Figure 8.) SHORT-CIRCUIT UNDER STEADY-STATE VIN = 24V, VOUT1 = 5V, IOUT2 = 5A TO SHORT PWM MODE toc20 CLOSED-LOOPBODE PLOT VIN = 24V, VOUT = 5V, IOUT = 5A CROSSOVER FREQUENCY = 39kHz PHASE MARGIN = 64.9◦ SHORT-CIRCUIT UNDER STEADY-STATE VIN = 24V, VOUT2 = 3.3V, IOUT2 = 10A TO SHORT PWM MODE toc19 CLOSED-LOOP BODE PLOT V IN = 24V, V OUT = 3.3V, IOUT = 10A toc22 CROSSOVER FREQUENCY = 39.8kHz PHASE MARGIN = 69° 180° OUT-OF-PHASE OPERATION V IN = 36V, V OUT1 =...

42V, Dual-Output, Synchronous Step-Down Controller Typical Operating Characteristics (continued) (VIN = 24V, unless otherwise noted. See Figure 8.) V CCINT VOLTAGE vs. INPUT VOLTAGE CS_- PIN INPUT BIAS CURRENT vs. VSENSE COMMON MODE VOLTAGE 5 10 15 20 VSENSE COMMON MODE VOLTAGE (V) SWITCHING FREQUENCY vs. TEMPERATURE V CCINT LOAD REGULATION CS_- PIN INPUT CURRENT vs. TEMPERATURE MAXIMUM CURRENT SENSE VOLTAGE (mV) CS- PIN INPUT BIAS CURRENT (µA) MAXIMUM CURRENT SENSE VOLTAGE vs. FEEDBACK VOLTAGE toc27 VCCINT LOAD CURRENT (mA)