MAX685 Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD

Description

The MAX685 DC-DC converter provides low-noise dual outputs for powering CCD imaging devices and LCDs. This device uses a single inductor to provide independently regulated positive and negative outputs. Integrated power switches are included in a small 24-Pin 4mm x 4mm Thin QFN package to save space and reduce cost. A 16-pin QSOP package is also available.

Each output delivers up to 10mA from a +2.7V to +5.5V input voltage range. Output voltages are set independently up to 24V and down to -9V. With a few additional low-cost components, the output voltages can be set at up to 45V and down to -16V. Output ripple magnitude is 30mVp-p. The MAX685 uses a fixed-frequency, pulse-width-modulated (PWM) control scheme at 220kHz or 400kHz to permit output noise filtering and to reduce the size of external components. The frequency can also be synchronized to an external clock signal between 200kHz and 480kHz.

The MAX685 has a power-OK indicator output (POK) that signals when both outputs are within regulation. A logic-controlled shutdown completely turns off both outputs and reduces supply current to 0.1µA. The user can also set which output turns on first.

The preassembled MAX685 evaluation kit is available to reduce design time.

An evaluation kit is available: MAX685EVKIT

Key Features

Applications/Uses

Dual Output Using a Single Inductor
Low-Noise Output, 30mVp-p Ripple
Output Voltages up to 24V and down to -9V (up to 45V and down to -16V with added components)
Internal Switches in a Small 24-Pin 4mm x 4mm Thin QFN Package
220kHz/400kHz Fixed-Frequency PWM Operation
Frequency Can Be Synchronized to External Clock
Power-OK Indicator
Selectable Power-On Sequencing
0.1µA Logic-Controlled Shutdown

	Camcorders
	CCD Imaging Devices
	Digital Cameras
	LCDs
	Notebook Computers

Key Specifications: Inverting Switching Regulators

Part Number

V_IN
(V)

V_OUT
(V)

Output Adjust. Method

DC-DC Outputs

Alternate Topology

Oper. Freq.
(kHz)

Package/Pins

Smallest Available Pckg.
(mm²)

Price

min

max

min

max

max w/pins

See Notes

MAX685

2.7

5.5

2.7

Resistor

Inverting

Step-Up

480

QSOP/16

TQFN/24

$3.44 @1k

See All Inverting Switching Regulators (25)

Key Specifications: Step-Up Switching Regulators

Part Number

V_IN
(V)

V_OUT
(V)

Output Adjust. Method

DC-DC Outputs

Oper. Freq.
(kHz)

Package/Pins

Smallest Available Pckg.
(mm²)

Price

min

max

min

max

max w/pins

See Notes

MAX685

2.7

5.5

2.7

Resistor

480

QSOP/16

TQFN/24

$3.44 @1k

See All Step-Up Switching Regulators (91)

Diagram

Typical Operating Circuit

Evaluation Kits

MAX685EVKIT

Reliability Reports

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Software/Models

none

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: 1-9 of 9

MAX685 Free
Sample Buy Status

Package: TYPE PINS FOOTPRINT

DRAWING CODE/VAR *

Temp RoHS/Lead-Free?
Materials Analysis

MAX685C/D

Active DICE SALES;NA pin;0 mm²

Land Pattern: Not Applicable
Use pkgcode/variation: DICE*
See data sheet

MAX685EEE

Active QSOP;16 pin;31 mm²
Outline Drawing: 21-0055 (PDF)
Land Pattern: 90-0167 (PDF)
Use pkgcode/variation: E16-1*
-40°C to +85°C RoHS/Lead-Free: No
Materials Analysis

MAX685EEE-T

Active QSOP;16 pin;31 mm²
Outline Drawing: 21-0055 (PDF)
Land Pattern: 90-0167 (PDF)
Use pkgcode/variation: E16-1*
-40°C to +85°C RoHS/Lead-Free: No
Materials Analysis

MAX685EEE+

Active QSOP;16 pin;31 mm²
Outline Drawing: 21-0055 (PDF)
Land Pattern: 90-0167 (PDF)
Use pkgcode/variation: E16+1*
-40°C to +85°C RoHS/Lead-Free: Lead Free
Materials Analysis

MAX685EEE+T

Active QSOP;16 pin;31 mm²
Outline Drawing: 21-0055 (PDF)
Land Pattern: 90-0167 (PDF)
Use pkgcode/variation: E16+1*
-40°C to +85°C RoHS/Lead-Free: Lead Free
Materials Analysis

MAX685ETG

Active TQFN;24 pin;17 mm²
Outline Drawing: 21-0139 (PDF)
Land Pattern: 90-0022 (PDF)
Use pkgcode/variation: T2444-4*
-40°C to +85°C RoHS/Lead-Free: No
Materials Analysis

MAX685ETG-T

Active

Land Pattern: Not Available

-40°C to +85°C See data sheet

MAX685ETG+

Active TQFN;24 pin;17 mm²
Outline Drawing: 21-0139 (PDF)
Land Pattern: 90-0022 (PDF)
Use pkgcode/variation: T2444+4*
-40°C to +85°C RoHS/Lead-Free: Lead Free
Materials Analysis

MAX685ETG+T

Active

Land Pattern: Not Available

-40°C to +85°C See data sheet

Notes and Comments

Internal Switches Save Space, 0.1 µA Logic Controlled Shutdown Extends Battery Life

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Document Ref.: 19-1353; Rev 1; 2003-06-25
This page last modified: 2007-06-01