Document
MAX17544
EVALUATION KIT AVAILABLE
4.5V–42V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter
With Internal Compensation
General Description
The MAX17544 high-efficiency, high-voltage, synchronous step-down DC-DC converter with integrated MOSFETs operates over 4.5V to 42V input. The converter can deliver up to 3.5A and generates output voltages from 0.9V up to 0.9 x VIN. The feedback (FB) voltage is accurate to within ±1.1% over -40°C to +125°C.
The MAX17544 uses peak-current-mode control. The device can be operated in pulse-width modulation (PWM), pulse-frequency modulation (PFM), or discontinuous conduction mode (DCM) control schemes.
The device is available in a 20-pin (5mm x 5mm) TQFN package. Simulation models are available.
Applications
●● Industrial Power Supplies
●● Distributed Supply Regulation
●● High-Voltage Single-Board Systems
●● Base Station Power Supply
●● General-Purpose Point-of-Load
For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX17544.related.
Benefits and Features
●● Reduces External Components and Total Cost • No Schottky—Synchronous Operation • Internal Compensation for Any Output Voltage • Built-In Soft-Start • All-Ceramic Capacitors, Compact Layout
●● Reduces Number of DC-DC Regulators to Stock • Wide 4.5V to 42V Input • Adjustable 0.9V to 0.9 x VIN Output • 100kHz to 2.2MHz Adjustable Switching Frequency with External Synchronization
●● Reduces Power Dissipation • Peak Efficiency > 90% • PFM/DCM Enables Enhanced Light-Load Efficiency • 2.8µA Shutdown Current
●● Operates Reliably in Adverse Industrial Environments • Peak Current-Limit Protection • Built-In Output Voltage Monitoring with RESET • Programmable EN/UVLO Threshold • Monotonic Startup into Prebiased Load • Overtemperature Protection • -40°C to +125°C Operation
Ordering Information appears at end of data sheet.
Typical Application Circuit—5V, 500kHz Switching Frequency
VIN (7.5V TO 42V)
C2 2.2µF
EN/UVLO VIN VIN
RT SYNC MODE VCC SGND
MAX17544
VIN BST LX LX LX FB
RESET
CF SS
PGND PGND PGND
C3 12000pF
C1 2.2µF
C8 2.2µF
C5 0.1µF
L1 10µH
VOUT 5V, 3.5A
C4 22µF
C9 22µF
R3 100kΩ
fSW = 500kHz
R4 22.1kΩ
19-7055; Rev 0; 9/14
MAX17544
4.5V–42V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter
With Internal Compensation
Absolute Maximum Ratings
VIN to PGND..........................................................-0.3V to +48V EN/UVLO to SGND................................................-0.3V to +48V LX to PGND................................................-0.3V to (VIN + 0.3V) BST to PGND.........................................................-0.3V to +53V BST to LX..............................................................-0.3V to +6.5V BST to VCC............................................................-0.3V to +48V CF, RESET, SS, MODE, SYNC,
RT to SGND......................................................-0.3V to +6.5V FB to SGND..........................................................-0.3V to +1.5V VCC to SGND........................................................-0.3V to +6.5V
SGND to PGND.....................................................-0.3V to +0.3V LX Total RMS Current.........................................................±5.6A Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70ºC) (multilayer board) TQFN (derate 30.3mW/ºC above TA = +70ºC).......2424.2mW Operating Temperature Range.......................... -40°C to +125°C Junction Temperature.......................................................+150°C Storage Temperature Range............................. -65°C to +160°C Lead Temperature (soldering, 10s).................................. +300°C Soldering Temperature (reflow)........................................+260°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.
Package Thermal Characteristics (Note 1)
TQFN Junction-to-Ambient Thermal Resistance (θJA)...........30°C/W Junction-to-Case Thermal Resistance (θJC)..................2°C/W
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
(VIN = VEN/UVLO = 24V, RRT = 40.2kΩ (500kHz), CVCC = 2.2μF, VPGND = VSGND = VMODE = VSYNC = 0V, LX = SS = RESET = open, VBST to VLX = 5V, VFB = 1V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to SGND, unless other.