MAX639, MAX640, MAX653 5V/3.3V/3V Adjustable, High-Efficiency, Low-IQ, Step-Down DC-DC Converters

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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.

Key Features

Applications/Uses

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

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

Key Specifications: Step-Down Switching Regulators

Part Number

V_IN (min) (V)

V_IN (max) (V)

Min. V_OUT (V)

Max. V_OUT (V)

Preset V_OUT (V)

I_OUT (A)

Output Adj. Method

Operating Current, I_CC (max) (mA)

Number of DC-DC Outputs

Features

EV-Kit

Package

RoHS Available

Operating Temp. Range (°C)

Price^**

MAX639

11.5

1.3

11.5

0.225

Preset
Resistor

0.02

•	Current Limit

•	Internal Power Switches

•	Low Battery/ Power OK Output

•

Shutdown

Yes

Ceramic DIP/8
PDIP/8
SOIC/8

Yes

-40 to +85
0 to +70

$2.96 @ 1k

MAX640

3.3

$2.15 @ 1k

MAX653

$2.15 @ 1k

See All Step-Down Switching Regulators (223)

Key Specifications: Switch-Mode DC-DC Power Supplies

Part Number

Topology

V_IN (min) (V)

V_IN (max) (V)

Number of DC-DC Outputs

Preset V_OUT (V)

Digital/VID Programmed Output

Min. Adjustable V_OUT (V)

Max. Adjustable V_OUT (V)

I_OUT (A)

Operating Current, I_CC (max) (mA)

Internal Power Switch(es)

Package

Price^**

MAX639

Step-Down

11.5

1.3

11.5

0.225

0.02

Yes

Ceramic DIP/8
PDIP/8
SOIC/8

$2.96 @ 1k

MAX640

3.3

$2.15 @ 1k

MAX653

$2.15 @ 1k

See All Switch-Mode DC-DC Power Supplies (429)

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 prices and delivery, please see the price and availability page or contact an authorized distributor.