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36V, 3.5A, 2.2MHz Step-Down Converters with 28µA Quiescent Current

3.5A, 36V, 2MHz Automotive Buck Converter with Low IQ and EMI Management

Product Details

The MAX16935/MAX16939 are 3.5A current-mode step-down converters with integrated high-side and low-side MOSFETs designed to operate with an external Schottky diode for better efficiency. The low-side MOSFET enables fixed-frequency forced-PWM (FPWM) operation under light-load applications. The devices operate with input voltages from 3.5V to 36V, while using only 28µA quiescent current at no load. The switching frequency is resistor programmable from 220kHz to 2.2MHz and can be synchronized to an external clock. The devices’ output voltage is available as 3.3V/5V fixed or adjustable from 1V to 10V. The wide input voltage range along with its ability to operate at 98% duty cycle during undervoltage transients make the devices ideal for automotive and industrial applications.

Under light-load applications, the FSYNC logic input allows the devices to either operate in skip mode for reduced current consumption or fixed-frequency FPWM mode to eliminate frequency variation to minimize EMI. Fixed-frequency FPWM mode is extremely useful for power supplies designed for RF transceivers where tight emission control is necessary. Protection features include cycle-by-cycle current limit and thermal shutdown with automatic recovery. Additional features include a power-good monitor to ease power-supply sequencing and a 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT to create cascaded power supplies with multiple devices.

The MAX16935/MAX16939 operate over the -40°C to +125°C automotive temperature range and are available in 16-pin (5mm × 5mm) TQFN-EP and 16-pin TSSOP-EP packages.

Key Features

  • Integration and High-Switching Frequency Saves Space
    • Integrated 3.5A High-Side Switch
    • Low-BOM-Count Current-Mode Control Architecture
    • Fixed Output Voltage with ±2% Accuracy or Externally Resistor Adjustable (1V to 10V)
    • 220kHz to 2.2MHz Switching Frequency with Three Operation Modes (Skip Mode, Forced Fixed-Frequency Operation, and External Frequency Synchronization)
    • Automatic LX Slew-Rate Adjustment for Optimum Efficiency Across Operating Frequency Range
  • 180° Out-of-Phase Clock Output at SYNCOUT Enables Cascaded Power Supplies for Increased Power Output
  • Spread-Spectrum Frequency Modulation Reduces EMI Emissions
  • Wide Input Voltage Range Supports Automotive Applications
    • 3.5V to 36V Input Voltage Range
    • Enable Input Compatible from 3.3V Logic Level to 42V
  • Robust Performance Supports Wide Range of Automotive Applications
    • -40°C to +125°C Automotive Temperature Range
    • Thermal-Shutdown Protection
    • AEC-Q100 Qualified
  • Power-Good Output Allows Power-Supply Sequencing
  • Tight Overvoltage Protection Provides Smaller Overshoot Voltages (MAX16939)

Applications/Uses

  • Distributed DC Power Systems
  • Navigation and Radio Head Units
  • Point-of-Load Applications
Parametric specs for Step-Down (Buck) Switching Regulators
VIN (V) (min) 3.5
VIN (V) (max) 42
VOUT1 (V) (min) 1
VOUT1 (V) (max) 10
IOUT1 (A) (max) 3.5
Switch Type Internal
Preset VOUT (V) 5
Output Adjust. Method Preset
Resistor
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 200
2200
Design Tools EE-Sim
Package/Pins TQFN/16
TSSOP/16
Budgetary
Price (See Notes)
$1.67 @1k
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Simplified Block Diagram

MAX16935: Typical Application Circuit MAX16935: Typical Application Circuit Zoom icon

Technical Docs

Design & Development

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Description

The MAX16935 evaluation kit (EV kit) demonstrates the MAX16935 high-voltage, current-mode step-down converter with low operating current. The EV kit operates over a wide 3.5V to 36V input range and the output is set for 5V at 3.5A.
The EV kit comes with the MAX16935RAUE/V+ installed.

View Details

Features

  • Wide 3.5V to 36V Input Supply Range
  • Forced-PWM or Skip-Mode Operation
  • Programmable Switching Frequency
  • Power-Good Output
  • Proven PCB Layout
  • Fully Assembled and Tested

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Tools & Models

EE-Sim: Design & Simulate MAX16935

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Parameters

Parametric specs for Step-Down (Buck) Switching Regulators
VIN (V) (min) 3.5
VIN (V) (max) 42
VOUT1 (V) (min) 1
VOUT1 (V) (max) 10
IOUT1 (A) (max) 3.5
Switch Type Internal
Preset VOUT (V) 5
Output Adjust. Method Preset
Resistor
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 200
2200
Design Tools EE-Sim
Package/Pins TQFN/16
TSSOP/16
Budgetary
Price (See Notes)
$1.67 @1k

Key Features

  • Integration and High-Switching Frequency Saves Space
    • Integrated 3.5A High-Side Switch
    • Low-BOM-Count Current-Mode Control Architecture
    • Fixed Output Voltage with ±2% Accuracy or Externally Resistor Adjustable (1V to 10V)
    • 220kHz to 2.2MHz Switching Frequency with Three Operation Modes (Skip Mode, Forced Fixed-Frequency Operation, and External Frequency Synchronization)
    • Automatic LX Slew-Rate Adjustment for Optimum Efficiency Across Operating Frequency Range
  • 180° Out-of-Phase Clock Output at SYNCOUT Enables Cascaded Power Supplies for Increased Power Output
  • Spread-Spectrum Frequency Modulation Reduces EMI Emissions
  • Wide Input Voltage Range Supports Automotive Applications
    • 3.5V to 36V Input Voltage Range
    • Enable Input Compatible from 3.3V Logic Level to 42V
  • Robust Performance Supports Wide Range of Automotive Applications
    • -40°C to +125°C Automotive Temperature Range
    • Thermal-Shutdown Protection
    • AEC-Q100 Qualified
  • Power-Good Output Allows Power-Supply Sequencing
  • Tight Overvoltage Protection Provides Smaller Overshoot Voltages (MAX16939)

Applications/Uses

  • Distributed DC Power Systems
  • Navigation and Radio Head Units
  • Point-of-Load Applications

Description

The MAX16935/MAX16939 are 3.5A current-mode step-down converters with integrated high-side and low-side MOSFETs designed to operate with an external Schottky diode for better efficiency. The low-side MOSFET enables fixed-frequency forced-PWM (FPWM) operation under light-load applications. The devices operate with input voltages from 3.5V to 36V, while using only 28µA quiescent current at no load. The switching frequency is resistor programmable from 220kHz to 2.2MHz and can be synchronized to an external clock. The devices’ output voltage is available as 3.3V/5V fixed or adjustable from 1V to 10V. The wide input voltage range along with its ability to operate at 98% duty cycle during undervoltage transients make the devices ideal for automotive and industrial applications.

Under light-load applications, the FSYNC logic input allows the devices to either operate in skip mode for reduced current consumption or fixed-frequency FPWM mode to eliminate frequency variation to minimize EMI. Fixed-frequency FPWM mode is extremely useful for power supplies designed for RF transceivers where tight emission control is necessary. Protection features include cycle-by-cycle current limit and thermal shutdown with automatic recovery. Additional features include a power-good monitor to ease power-supply sequencing and a 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT to create cascaded power supplies with multiple devices.

The MAX16935/MAX16939 operate over the -40°C to +125°C automotive temperature range and are available in 16-pin (5mm × 5mm) TQFN-EP and 16-pin TSSOP-EP packages.

Simplified Block Diagram

MAX16935: Typical Application Circuit MAX16935: Typical Application Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal.