MAX1620, MAX1621 Digitally Adjustable LCD Bias Supplies

Description

The MAX1620/MAX1621 convert a 1.8V to 20V battery voltage to a positive or negative LCD backplane bias voltage. Backplane bias voltage can be automatically disabled when the display logic voltage is removed, protecting the display. These devices use very little PC board area, come in ultra-small QSOP packages, and require only small, low-profile external components.

Output voltage can be set to a desired positive or negative voltage range with external resistors, and adjusted over that range with the on-board digital-to-analog converter (DAC) or with a potentiometer. The MAX1620/ MAX1621 include a 5-bit DAC, allowing digital software control of the bias voltage. The MAX1620 uses up/down digital signaling to adjust the DAC, and the MAX1621 uses the System Management Bus (SMBus™) 2-wire serial interface.

These devices use a low-cost, external, N-channel MOSFET power switch or NPN transistor, and can be configured for positive or negative output voltages. Operating current is a low 150µA, typically provided from a display's logic supply of 3.0V to 5.5V. The MAX1620/MAX1621 are available in a 16-pin QSOP package.

Key Features

Applications/Uses

1.8V to 20V Battery Input Voltage
Automatic Disable when Display Logic is Shut Down
Extremely Small QSOP Package
32-Level Internal DAC
SMBus Serial Interface (MAX1621)
Positive or Negative Output Voltage

	Notebook Computers
	Palmtop Computers
	PDAs and Other Handheld Devices
	Portable Data-Collection Terminals

Key Specifications: Inverting Switching Regulators

Part Number

V_IN (min) (V)

V_IN (max) (V)

I_OUT (A)

Output Adj. Method

Operating Current, I_CC (max) (mA)

Number of DC-DC Outputs

Alternate Topology

Operating Freq. (kHz)

Package

Price^**

MAX1620

1.8

0.07

Digital
Resistor

0.25

Inverting
Step-Up

300

QSOP/16

$1.99 @ 1k

MAX1621

See All Inverting Switching Regulators (22)

Key Specifications: Step-Up Switching Regulators

Part Number

V_IN (min) (V)

V_IN (max) (V)

I_OUT (A)

Output Adj. Method

Operating Current, I_CC (max) (mA)

Number of DC-DC Outputs

Operating Freq. (kHz)

Package

Price^**

MAX1620

1.8

0.07

Digital
Resistor

0.25

300

QSOP/16

$1.99 @ 1k

MAX1621

See All Step-Up Switching Regulators (90)

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: 1-8 of 8

MAX1620

Free
Sample

Buy

Package:	TYPE PINS FOOTPRINT
	DRAWING CODE/VAR *

Temp

RoHS/Lead-Free?
Materials Analysis

MAX1620EEE

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16-1*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1620EEE-T

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16-1*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1620EEE+

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16+1*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

MAX1620EEE+T

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16+1*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

MAX1621

Free
Sample

Buy

Package:	TYPE PINS FOOTPRINT
	DRAWING CODE/VAR *

Temp

RoHS/Lead-Free?
Materials Analysis

MAX1621EEE

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16-1*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1621EEE-T

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16-1*

-40°C to +85°C

RoHS/Lead-Free: No
Materials Analysis

MAX1621EEE+T

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16+1*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

MAX1621EEE+

QSOP;16 pin;
Dwg: 21-0055 (PDF)
Use pkgcode/variation: E16+1*

-40°C to +85°C

RoHS/Lead-Free: Lead Free
Materials Analysis

Notes and Comments

Internal 5-bit DAC allows digital adjustment of bias voltage. MAX1620 uses Up/Down digital inputs. MAX1620 uses SMBus interface.

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