MAX1644 2A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switches

Description

The MAX1644 constant-off-time, PWM step-down DC-DC converter is ideal for use in applications such as PC cards, CPU daughter cards, and desktop computer bus-termination boards. The device features internal synchronous rectification for high efficiency and reduced component count. It requires no external Schottky diode. The internal 0.10Ω PMOS power switch and 0.10Ω NMOS synchronous-rectifier switch easily deliver continuous load currents up to 2A. The MAX1644 produces a preset +3.3V or +2.5V output voltage or an adjustable output from +1.1V to V_IN. It achieves efficiencies as high as 95%.

The MAX1644 uses a unique current-mode, constant-off-time, PWM control scheme, which includes an Idle Mode™ to maintain high efficiency during light-load operation. The programmable constant-off-time architecture sets switching frequencies up to 350kHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The device also features an adjustable soft-start to limit surge currents during start-up, a 100% duty cycle mode for low-dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1µA. The MAX1644 is available in a 16-pin SSOP package.

Key Features

Applications/Uses

±1% Output Accuracy
95% Efficiency
Internal PMOS and NMOS Switches
- 70mΩ On-Resistance at V_IN = +4.5V
- 100mΩ On-Resistance at V_IN = +3V
Output Voltage
- +3.3V or +2.5V Pin-Selectable
- +1.1V to V_IN Adjustable
+3V to +5.5V Input Voltage Range
360µA (max) Operating Supply Current
< 1µA Shutdown Supply Current
Programmable Constant-Off-Time Operation
350kHz (max) Switching Frequency
Idle Mode Operation at Light Loads
Thermal Shutdown
Adjustable Soft-Start Inrush Current Limiting
100% Duty Cycle During Low-Dropout Operation
Output Short-Circuit Protection
16-Pin SSOP Package

	+3.3V PC Card and CardBus Applications
	+5V to +3.3V/+2.5V Conversion
	CPU Daughter Card Supply
	CPU I/O Supplies
	Desktop Bus-Termination Boards
	Notebook and Subnotebook Computers

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

Operating Freq. (kHz)

Features

EV-Kit

Package

RoHS Available

Operating Temp. Range (°C)

Price^**

MAX1644

5.5

1.1

5.5

2.5
3.3

Preset
Resistor

0.36

350

•	Adjustable Frequency

•	Current Limit

•	Fixed Frequency/ PWM Operation

•	Internal Power Switches

•

Shutdown

•	Soft Start

•	Synchronous Rectifier

Yes

SSOP/16

Yes

-40 to +85

$4.08 @ 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)

Operating Freq. (kHz)

Internal Power Switch(es)

Package

Price^**

MAX1644

Step-Down

5.5

2.5
3.3

1.1

5.5

0.36

350

Yes

SSOP/16

$4.08 @ 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.

Ordering Information

Notes:

Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.

Devices: 1-4 of 4

MAX1644

Free
Sample

Buy

Package:	TYPE PINS FOOTPRINT
	DRAWING CODE/VAR *

Temp

RoHS/Lead-Free?
Materials Analysis

MAX1644EAE

SSOP;16 pin;
Dwg: 21-0056C (PDF)
Use pkgcode/variation: A16-2*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1644EAE-T

SSOP;16 pin;
Dwg: 21-0056C (PDF)
Use pkgcode/variation: A16-2*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1644EAE+

SSOP;16 pin;
Dwg: 21-0056C (PDF)
Use pkgcode/variation: A16+2*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

MAX1644EAE+T

SSOP;16 pin;
Dwg: 21-0056C (PDF)
Use pkgcode/variation: A16+2*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

Notes and Comments

No external Schottky required. Integrated, lossless current-sense eliminates external current sense resistor. Space saving SSOP package.

Related Products

MAX1623 3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switches