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MAX639

5V/3.3V/3V Adjustable, High-Efficiency, Low-I_Q, Step-Down DC-DC Converters

Low Supply Current, High-Efficiency Over Wide Load Range

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Overview

Description

The MAX639/MAX640/MAX653 step-down switching regulators provide high efficiency over a wide range of load currents, delivering up to 225mA. A current-limiting pulse-frequency-modulated (PFM) control scheme gives the devices the benefits of pulse-width-modulated (PWM) converters (high efficiency at heavy loads), while using only 10µA of supply current (vs. 2mA to 10mA for PWM converters). The result is high efficiency over a wide range of loads.

The MAX639/MAX640/MAX653 input range is 4V to 11.5V, and the devices provide lower preset output voltages of 5V, 3.3V, and 3V, respectively. Or, the output can be user-adjusted to any voltage from 1.3V to the input voltage.

The MAX639/MAX640/MAX653 have an internal 1A power MOSFET switch, making them ideal for minimum-component, low- and medium-power applications. For increased output drive capability, use the MAX649/MAX651/MAX652 step-down controllers, which drive an external P-channel FET to deliver up to 5W.

MAX639, MAX640, MAX653: Typical Operating Circuit

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Key Features

High Efficiency for a Wide Range of Load Currents
10µA Quiescent Current
Output Currents Up to 225mA
Preset or Adjustable Output Voltage:
- 5.0V (MAX639)
- 3.3V (MAX640)
- 3.0V (MAX653)
Low-Battery Detection Comparator
Current-Limiting PFM Control Scheme

Applications/Uses

5V to 3.3V Conversion
9V Battery to 5V, 3.3V, or 3V Conversion
High-Efficiency Linear Regulator Replacement
Portable Instruments and Handy-Terminals

Parametric Specs

See parametric specs for Step-Down Switching Regulators (408)

Part Number

V_IN
(V)

V_OUT1
(V)

Preset V_OUT
(V)

Output Adjust. Method

I_OUT1
(A)

Switch Type

Power Good Signal

DC-DC Outputs

Package/Pins

Budgetary
Price

min

max

min

max

See Notes

MAX639

11.5

1.3

11.5

3.3

Preset

Resistor

0.225

Internal

Yes

DICE SALES/N

PDIP/8

SOIC (N)/8

$3.55 @1k

MAX640

3.3

DICE SALES/N

PDIP/8

SOIC (N)/8

$3.55 @1k

MAX653

CDIP/8

PDIP/8

SOIC (N)/8

$1.63 @1k

Pricing Notes:

This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Design Resources

Technical Documents

App Note 414 Solar Cells and Switching Regular Charge Batteries at Optimum Rates

Quality And Environmental

Request Reliability Report for: MAX639

Device	Fab Process	Technology	Sample size	Rejects	FIT at 25°C	FIT at 55°C	Material Composition

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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