MAX8901B 查看數據表（PDF） - Maxim Integrated

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MAX8901B

Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package

Maxim Integrated 

EVALUATION KIT AVAILABLE

MAX8901A/MAX8901B

Highest Efficiency Supply

for 2 to 6 Series WLEDs in a

2mm x 2mm TDFN Package

General Description

The MAX8901A/MAX8901B step-up converters drive

from two to six series-connected white LEDs (WLEDs)

with constant current to provide uniform WLED intensity

for LCD backlighting in cell phones, PDAs, and other

handheld devices. The MAX8901_ operate at a fixed

750kHz (typ) switching frequency, allowing for tiny exter-

nal components, and are optimized for the highest possi-

ble efficiency over the full 1-cell Li+/Li-Poly battery range.

These converters use a single input (ON) to enable the

IC and to control WLED intensity. The MAX8901A

requires a direct PWM input to regulate WLED intensity

with the WLED current proportional to the PWM duty

cycle. The MAX8901B uses single-wire, serial-pulse

dimming that reduces the WLED intensity in 32 linear

steps. Full-scale WLED current for serial-pulse

dimming is 24.75mA (MAX8901B, 0.75mA/step).

The MAX8901_ feature an internal soft-start to eliminate

inrush currents during startup, input overvoltage

protection, WLED overvoltage protection, and a shut-

down mode with 0.01µA (typ) shutdown current. No

WLED current is present in shutdown provided the

WLED forward voltage is greater than the input supply

voltage. Additional features include undervoltage lock-

out (UVLO) and thermal shutdown.

The MAX8901_ are available in tiny 8-pin, 2mm x 2mm

TDFN-EP packages (0.8mm max height).

Applications

Display Backlight (from 2 to 6 WLEDs)

Cellular Phones

PDAs and Smartphones

MP3 and Portable Media Players

Portable Navigation Devices

Digital Cameras

Typical Operating Circuits

INPUT

2.6V TO 5.5V

PWM DIMMING

CONTROL

3

IN

MAX8901A

7 COMP

LX 4

1

OVP

6

GND

5

PGND

2 ON

EP

CS 8

OUTPUT

UP TO 25V

Benefits and Features

• Cost-Effective and Flexible Solution for Wide Range of

Backlighting Applications

• Supplies from 2 to 6 WLEDs with 1.3% LED Current

Accuracy

• 2.6V to 5.5V Input Voltage Range

• Fixed-Frequency Operation

• Flexible Dimming Control

• Direct PWM Dimming (MAX8901A)

• 32-Step, Single-Wire Serial Dimming (MAX8901B)

• Protection Features Improve System Reliability

• WLED Overvoltage Protection (25V typ)

• Internal Soft-Start and Thermal Shutdown

• Input Undervoltage Lockout

• Input Overvoltage Lockout

• High Efficiency Extends Battery Life

• Up to 91% Efficiency

• 0.01µA (typ) Shutdown Current

• No WLED Current in Shutdown

• 8-Pin, 2mm x 2mm TDFN Package Saves Space

Ordering Information

PART

MAX8901AETA+T

PIN-PACKAGE

8 TDFN-EP*

2mm x 2mm

TOP MARK

+ABA

MAX8901BETA+T

8 TDFN-EP*

2mm x 2mm

+ABB

Note: All devices are specified over the -40°C to +85°C operating

temperature range.

+Denotes a lead(Pb)-free/RoHS-compliant package.

*EP = Exposed pad.

T = Tape and reel.

Pin Configuration appears at end of data sheet.

INPUT

2.6V TO 5.5V

SERIAL-PULSE

DIMMING

CONTROL

3

IN

MAX8901B

7

COMP

LX 4

1

OVP

6

GND

5

PGND

2 ON

EP

CS 8

OUTPUT

UP TO 25V

19-0865; Rev 4; 5/15

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