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800mA, Low-Noise, Step-Up DC-DC Converter with 500mA Linear Regulator

Highly Efficient Boost Converter with Integrated LDO for Battery Powered Devices

Product Details

Key Features

Parametric specs for Step-Down/Up Switching Regulators
VIN (V) (min) 1
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 5
IOUT1 (A) (max) 0.8
Switch Type Internal
Preset VOUT (V) 1.25
2.85
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (max) 0.2
# DC-DC Outputs 1
Alternate Topology Step-Up
# LDO/ Op.Amp. Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TSSOP/16
Oper. Temp. (°C) -40 to +85
Budgetary
Price (See Notes)
3.2
Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 1
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 5
IOUT1 (A) (max) 0.8
Switch Type Internal
Preset VOUT (V) 1.25
2.85
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 0.1
Shutdown Mode Supply Current (µA) (typ) 1
Shutdown Mode Supply Current (µA) (max) 10
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TSSOP/16
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down/Up Switching Regulators
VIN (V) (min) 1
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 5
IOUT1 (A) (max) 0.8
Switch Type Internal
Preset VOUT (V) 1.25
2.85
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (max) 0.2
# DC-DC Outputs 1
Alternate Topology Step-Up
# LDO/ Op.Amp. Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TSSOP/16
Oper. Temp. (°C) -40 to +85
Budgetary
Price (See Notes)
3.2
Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 1
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 5
IOUT1 (A) (max) 0.8
Switch Type Internal
Preset VOUT (V) 1.25
2.85
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 0.1
Shutdown Mode Supply Current (µA) (typ) 1
Shutdown Mode Supply Current (µA) (max) 10
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TSSOP/16

Key Features

  • High-Efficiency Step-Up Converter
    • Up to 93% Efficiency
    • Adjustable Output from +2.5V to +5.5V
    • Up to 800mA Output
    • PWM Synchronous-Rectified Topology
    • 1MHz Operating Frequency (or Sync)
  • LDO Linear Regulator
    • 500mA LDO Linear Regulator
    • 2.85V Linear Regulator Output or Adjustable (1.25V to 5V)
    • Low 125mV Dropout at 500mA
  • +0.7V to +5.5V Input Range
  • 0.1µA Logic-Controlled Shutdown
  • Adjustable Inductor Current Limit and Soft-Start
  • Thermal Shutdown
  • 1.5W, 16-Pin TSSOP-EP Package Available

Applications/Uses

  • Handheld Instruments (PDAs, Palmtops)
  • Palmtop Computers
  • PCS Phones
  • Personal Communicators
  • Portable Audio Players
  • Wireless Handsets

Description

The MAX1765 is a high-efficiency, low-noise, step-up DC-DC converter intended for use in battery-powered wireless applications. This device operates at a high 1MHz fixed frequency while maintaining an exceptionally low quiescent supply current (200µA). Its small external components and tiny package make this device an excellent choice for small hand-held applications that require the longest possible battery life.

The MAX1765 uses a synchronous-rectified pulse-width-modulation (PWM) boost topology to generate 2.5V to 5.5V outputs from a wide range of input sources, such as one to three alkaline or NiCd/NiMH cells or a single lithium-ion (Li+) cell. Maxim's proprietary architecture significantly improves efficiency at low load currents while automatically transitioning to fixed-frequency PWM operation at medium to high load currents to maintain excellent full-load efficiency. Forced-PWM mode is available for applications that require constant-frequency operation at all load currents, and the MAX1765 may also be synchronized to an external clock to protect sensitive frequency bands in communications equipment.

The MAX1765's low-dropout (LDO) linear regulator and DC-DC converter have separate shutdown control. The linear regulator's 250mΩ pass device maintains excellent dropout voltage at currents up to 500mA. The MAX1765 also features analog soft-start and current-limit functions to permit optimization of efficiency, external component size, and output voltage ripple.

The MAX1765 comes in a 16-pin QSOP package and a thermally enhanced 16-pin TSSOP-EP.

Simplified Block Diagram

MAX1765: Typical Operating Circuit MAX1765: Typical Operating 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 .