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MAXREFDES1004: Boost, Single-Output, -73V to -35V Input, 5V/100mA Output DC-DC Converter Using the MAX668

MAXREFDES1004

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Description

The MAX668/MAX669 constant-frequency, pulse-width modulating (PWM), current-mode DC-DC controllers are designed for a wide range of DC-DC conversion applications, including step-up, SEPIC, flyback, and isolated-output configurations. Power levels of 20W or more can be controlled with conversion efficiencies of over 90%. The input voltage range of 1.8V to 28V supports a wide range of battery and AC-powered inputs. An advanced BiCMOS design features low operating current (220μA), adjustable operating frequency (100kHz to 500kHz), soft-start, and a SYNC input, allowing the MAX668/MAX669 oscillator to be locked to an external clock.

The MAX669 is optimized for low input voltages with a guaranteed start-up voltage of 1.8V. It requires bootstrapped operation (IC-powered from boosted output) and supports output voltages of up to 28V. The MAX668 operates with inputs as low as 3V and can be connected in either a bootstrapped or non-bootstrapped (IC-powered from input supply or other source) configuration. When not bootstrapped, it has no restriction on output voltage. Both ICs are available in an extremely compact 10-pin μMAX® package.

Features

  • 1.8V Minimum Start-Up Voltage (MAX669)
  • Wide Input Voltage Range (1.8V to 28V)
  • Tiny 10-Pin μMAX Package
  • Current-Mode PWM and Idle Mode Operation
  • Adjustable 100kHz to 500kHz Oscillator or SYNC Input
  • 220μA Quiescent Current
  • Logic-Level Shutdown
  • Soft-Start

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Designed, Built, Tested

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

 

Schematic

PCB Layout

Bill of Materials

Test Results

Parametrics

Input Type Vin(Min) Vin(Max) Iout(Max) Single/Multiple Output Vout(V) Pout(W) Isolated/Non-Isolated Topology
DC -73.0 -35.0 0.1 - 5.1 0.5 Isolated Flyback

Parametrics

Input Type DC
Vin(Min) -73.0
Vin(Max) -35.0
Iout(Max) 0.1
Single/Multiple Output -
Vout(V) 5.1
Pout(W) 0.5
Isolated/Non-Isolated Isolated
Topology Flyback

Maxim Devices (2)

Part Number Name Product Family Order Design kits and evaluation modules
MAX668 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Switching Regulator - Switching Regulators Buy Now Design Kits
MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Switching Regulator - Switching Regulators Buy Now Design Kits

Maxim Devices (2)

Part Number Product Family
Switching Regulator - Switching Regulators
1.8V to 28V Input, PWM Step-Up Controllers in µMAX
Switching Regulator - Switching Regulators
1.8V to 28V Input, PWM Step-Up Controllers in µMAX

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