MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter General Description The MAX17501 high-efficiency, high-voltage, synchronous step-down DC-DC converter with integrated MOSFETs operates over a 4.5V to 60V input voltage range. This device is offered in a fixed 3.3V, 5V, or adjustable output voltage (0.9V to 92%VIN) while delivering up to 500mA of current. The output voltage is accurate to within ±1.7% over -40°C to +125°C.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Absolute Maximum Ratings VIN to GND.............................................................-0.3V to +70V EN/UVLO to GND.......................................-0.3V to (VIN + 0.3V) LX to PGND................................................-0.3V to (VIN + 0.3V) FB, RESET, COMP, SS to GND..............................-0.3V to +6V VCC to GND..............................................................-0.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Electrical Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected. TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 0.55 0.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Electrical Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected. TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.) 80 60 0 20 40 60 80 100 120 CURRENT LIMIT (A) 60 80 1.18 1.17 1.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Operating Characteristics (continued) (VIN = 24V, VGND = VPGND = 0V, CVIN = CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected, RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Pin Configuration TOP VIEW MAX17501 10 LX 9 GND 3 8 RESET VCC 4 7 N.C./COMP FB/VO 5 6 SS PGND 1 VIN 2 EN/UVLO + EP* TDFN (3mm x 2mm) *EP = EXPOSED PAD. CONNECT TO GND Pin Description PIN NAME FUNCTION 1 PGND Power Ground. Connect PGND externally to the power ground plane. Connect GND and PGND pins together at the ground return path of the VCC bypass capacitor.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Block Diagram VCC PGND N DRIVER 5µA SS LX MAX17501 HICCUP SS P DRIVER VIN CURRENT SENSE VCC PWM COMPARATOR LDO CLK PWM, PFM LOGIC OSC COMP HICCUP SLOPE COMPENSATION START EN RESET LOGIC SS 900mV REFERENCE SWITCHOVER LOGIC RESET COMP N.C./COMP GM FB INTERNAL COMPENSATION (FOR A, B, E, F VERSIONS) GND www.maximintegrated.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Detailed Description GND. The device employs an undervoltage-lockout circuit that disables the internal linear regulator when VCC falls below 3.7V (typical). The internal VCC linear regulator can source up to 40mA (typical) to supply the device and to power the low-side gate driver. The device uses a peak-current-mode control scheme. An internal transconductance error amplifier generates an integrated error voltage.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter In hiccup mode, the converter is protected by suspending switching for a hiccup timeout period of 32,768 clock cycles. Once the hiccup timeout period expires, soft-start is attempted again. This operation results in minimal power dissipation under overload fault conditions. the input DC bus further.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Soft-Start Capacitor Selection The MAX17501 implements adjustable soft-start operation to reduce inrush current. A capacitor connected from the SS pin to GND programs the soft-start period. The soft-start time (tSS) is related to the capacitor connected at SS (CSS) by the following equation: C= SS 5.55 × t SS where tSS is in milliseconds and CSS is in nanofarads.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter External Loop Compensation for Adjustable Output Versions The MAX17501 uses peak current-mode control scheme and needs only a simple RC network to have a stable, high-bandwidth control loop for the adjustable output voltage versions. The basic regulator loop is modeled as a power modulator, an output feedback divider, and an error amplifier. The power modulator has DC gain GMOD(dc), with a pole and zero pair.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter PCB Layout Guidelines Careful PCB layout is critical to achieve low switching losses and stable operation. For a sample layout that ensures first-pass success, refer to the MAX17501 evaluation kit layouts available at www.maximintegrated.com. Follow these guidelines for good PCB layout: 1) All connections carrying pulsed currents must be very short and as wide as possible.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter PGND PLANE VOUT PLANE C4 L1 C1 LX PLANE EP VIN PLANE R1 R2 RESET R3 C2 R4 C3 R5 C9 C5 GND PLANE VIAS TO BOTTOM SIDE PGND PLANE VIAS TO BOTTOM SIDE VOUT TRACK VIAS TO BOTTOM SIDE GND PLANE Figure 5. Recommended Component Placement for MAX17501G/H www.maximintegrated.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Typical Applications Circuits VIN 24V C1 1µF 1206 LX VIN 1 JU1 2 3 L1 33µH C4 10µF, 1206 R1 3.32MΩ EN/UVLO R2 866kΩ C2 1µF C3 3300pF PGND VOUT 3.3V, 500mA MAX17501 GND VCC FB/VO SS RESET N.C. RESET Figure 6. MAX17501A/E Application Circuit (3.3V Output, 500mA Maximum Load Current, 600kHz Switching Frequency) VIN 24V C1 1µF 1206 LX VIN 1 JU1 2 3 L1 47µH C4 10µF, 1206 R1 3.
MAX17501 VIN 24V 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter C1 1µF 1206 LX VIN 1 JU1 2 3 PGND EN/UVLO R2 316kΩ C3 6800pF VOUT 12V, 500mA C4 4.7µF, 1206 R1 3.32MΩ C2 1µF R4 174kΩ MAX17501 GND VCC FB/VO SS R5 14kΩ COMP C9 10pF L1 100µH RESET RESET R3 27.4kΩ C5 1200pF Figure 8. MAX17501G Application Circuit (12V Output, 500mA Maximum Load Current, 600kHz Switching Frequency) VIN 24V C1 2.2µF 1210 LX VIN 1 JU1 2 3 C4 22µF, 1210 R1 3.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Ordering Information/Selector Guide PART PIN-PACKAGE OUTPUT VOLTAGE (V) SWITCHING FREQUENCY (kHz) MODE MAX17501AATB+ 10 TDFN-EP* 3.3 600 PFM MAX17501BATB+ 10 TDFN-EP* 5 600 PFM MAX17501EATB+ 10 TDFN-EP* 3.
MAX17501 60V, 500mA, Ultra-Small, High-Efficiency, Synchronous Step-Down DC-DC Converter Revision History REVISION NUMBER REVISION DATE PAGES CHANGED DESCRIPTION 0 5/12 Initial release 1 11/12 Added MAX17501A, MAX17501B, MAX17501G, MAX17501H to data sheet 1–22 2 1/13 Added explanation on detailed condition for RESET 11, 14 3 7/13 4 8/14 Added output voltage accuracy for the MAX17501A and MAX17501B Edited General Description, Benefits and Features, Pin Description, and Adjusting Output V