MAX17245 Datasheet, PDF (1/17 Pages) Maxim Integrated Products – Eliminates External Components and Reduces

MAX17245
EVALUATION KIT AVAILABLE
3.5V–36V, 3.5A, Synchronous Buck Converter
With 28μA Quiescent Current and Reduced EMI
General Description
The MAX17245 high-efficiency, synchronous step-down
DC-DC converter with integrated MOSFETs operates
over a 3.5V to 36V input voltage range with 42V input
transient protection. The MAX17245 can operate in drop-
out condition by running at 98% duty cycle. This converter
delivers up to 3.5A and generates fixed output voltages of
3.3V/5V, along with the ability to program the output voltage
between 1V to 10V.
The MAX17245 uses a current-mode control architecture
and can operate in the pulse-width modulation (PWM)
or pulse-frequency modulation (PFM) control schemes.
PWM operation provides constant frequency operation at
all loads and is useful in applications sensitive to switching
frequency. PFM operation disables negative inductor
current and additionally skips pulses at light loads for
high efficiency. Under light-load applications, the external
sync pin FSYNC logic input allows the device to operate
in either PFM mode for reduced current consumption or
fixed-frequency PWM (forced-PWM) mode to eliminate
frequency variation to minimize EMI. Fixed-frequency
PWM mode is extremely useful for power supplies
designed for RF transceivers where tight emission control
is necessary.
This device is available in a compact 16-pin (5mm x 5mm)
TQFN package with exposed pad and 16-pin TSSOP.
-40°C to +85°C operation.
Typical Application Circuit
VBAT
CCOMP1
1000pF
RCOMP
20kI
CIN1
R___
0I
CIN3
4.7µF
CIN2
4.7µF
CBST
SUP
SUPSW _0.1µF
OSC SYNC PULSE
CCOMP2
12pF
RFOSC
12kI
EN
FSYNC
COMP
MAX17245
FOSC
BST
LX
VOUT
VBIAS
OUT
FB
L1
2.2µH
D1
RSNUB*
CSNUB*
VOUT
VBIAS
RSYNCOUT
100I
RPGOOD
10kI
VOUT
5V AT 3.5A
COUT
22µF
CBIAS
1µF
BIAS
PGOOD
SYNCOUT
PGND AGND
POWER-GOOD OUTPUT
180° OUT-OF-PHASE OUTPUT
*RSNUB = 1I and CSNUB = 220pF required for
the following operating conditions:
VBAT R 25V, VOUT P 5V, fSW R 1.8MHz,
FPWM mode enabled
Benefits and Features
●● Eliminates External Components and Reduces
Total Cost
• Integrated High-Side and Low-Side Switch Enables
Synchronous Operation for High Efficiency and
Reduced Cost
• All-Ceramic Capacitor Solution Allows
Ultra-Compact Solution Size
• 220kHz to 2.2MHz Adjustable Frequency with
External Synchronization
• Power Good Output and High-Voltage EN Input
Simplify Power Sequencing
●● Increases Design Flexibility
• 180° Out-of-Phase Clock Output at SYNCOUT
Enables Cascaded Power Supplies for Increased
Power Output
• Fixed Output Voltage with ±2% Accuracy (5V/3.3V)
or Externally Resistor Adjustable (1V to 10V)
●● Reduces Power Dissipation
• >90% Peak Efficiency
• PWM and PFM Operation Optimizes Conversion
Efficiency From Heavy to Light Loads
• Automatic LX Slew-Rate Adjustment for Optimum
Efficiency Across Operating Frequency Range
• Low 5μA (typ.) Shutdown Current
• Low 28μA (typ.) Quiescent Current
●● Operates Reliably
• 42V Input Voltage Transient Protection
• Fixed 8ms Internal Software Start Reduces Input
Inrush Current
• Cycle-by-Cycle Current limit, Thermal Shutdown
with Automatic Recovery
• Reduced EMI Emission with Spread-Spectrum
Control
Applications
●● Distributed Supply Regulation
●● Wall Transformer Regulation
●● General-Purpose Point-of-Load
Ordering Information/Selector Guide appears at end of data
sheet.
19-8527; Rev 0; 4/16