MAXREFDES1050: -15V/1.5A Buck-Boost DC-DC Converter Using the Step-Down Controller MAX17504


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The MAXREFDES1050 is a positive input, negative output power supply that delivers up to 1.5A at -15V from a 18V to 30V supply voltage. It is designed for industrial control equipment that uses analog components like amplifiers and multiplexers that operate on negative supply voltage. Typically operating at ±12V, ±18V or other variations, these voltages are generated from a 24V DC bus. The MAXREFDES1050 illustrates techniques using the synchronous buck regulators to generate negative voltages. This document explains how the MAX17504 synchronous step-down converter can be used to generate -15V from 18V to 30V input voltage. An overview of the design specification is shown in Table 1. The MAX17504/MAX17504S high-efficiency, highvoltage, synchronously rectified step-down converter with dual integrated MOSFETs operates over a 4.5V to 60V input. Maxim’s portfolio of high-voltage synchronous buck regulators offers 50% lower power loss, which allows equipment to operate 50% cooler. The device features a peak-current-mode control architecture with a MODE feature that can be used to operate the device in pulsewidth modulation (PWM), pulse-frequency modulation (PFM), or discontinuous mode (DCM) control schemes. Built-in compensation across the output voltage range eliminates the need for external components. The feedback (FB) regulation accuracy over -40°C to +125°C is ±1.1%. A programmable soft-start feature allows users to reduce input inrush current. The device also incorporates an output enable/undervoltage lockout pin (EN/UVLO) that allows the user to turn on the part at the desired input-voltage level. An open-drain active-low RESET pin provides a delayed power-good signal to the system upon achieving successful regulation of the output voltage. The device is available in a compact (5mm x 5mm) TQFN lead (Pb)-free package with an exposed pad. Simulation models are available.


Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.



PCB Layout

Test Results


Input Type Vin(Min) Vin(Max) Iout(Max) Single/Multiple Output Vout(V) Pout(W) Isolated/Non-Isolated Topology
DC 18 30 1.5 - -15.0 22.5 Non-Isolated Buck-Boost


Input Type DC
Vin(Min) 18
Vin(Max) 30
Iout(Max) 1.5
Single/Multiple Output -
Vout(V) -15.0
Pout(W) 22.5
Isolated/Non-Isolated Non-Isolated
Topology Buck-Boost

Maxim Devices (1)

Part Number Name Product Family Order Design kits and evaluation modules
MAX17504 4.5V–60V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter with Internal Compensation Switching Regulator - Switching Regulators Buy Now Design Kits

Maxim Devices (1)

Part Number Product Family
Switching Regulator - Switching Regulators
4.5V–60V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter with Internal Compensation

Design Files (4)

Title Type Size Date
maxrefdes1050-schematic PDF 12KB 2019-07-09
MAXREFDES1050 - Design Verification Testing PDF 116KB 2019-07-09
maxrefdes1050-bom PDF 84KB 2019-07-09
maxrefdes1050-pcb PDF 2MB 2019-07-09
Date Type


(PDF, 12KB)


MAXREFDES1050 - Design Verification Testing

(PDF, 116KB)



(PDF, 84KB)



(PDF, 2MB)

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