MAX8901BETA+T Maxim Integrated Products, MAX8901BETA+T Datasheet

IC LED DRIVR WHITE BCKLGT 8-TDFN

MAX8901BETA+T

Manufacturer Part Number
MAX8901BETA+T
Description
IC LED DRIVR WHITE BCKLGT 8-TDFN
Manufacturer
Maxim Integrated Products
Type
Backlight, White LEDr
Datasheet

Specifications of MAX8901BETA+T

Constant Current
Yes
Topology
PWM, Step-Up (Boost)
Number Of Outputs
1
Internal Driver
Yes
Type - Primary
Backlight
Type - Secondary
White LED
Frequency
700kHz ~ 800kHz
Voltage - Supply
2.6 V ~ 5.5 V
Voltage - Output
24V
Mounting Type
Surface Mount
Package / Case
8-TDFN Exposed Pad
Operating Temperature
-40°C ~ 85°C
Current - Output / Channel
25mA
Internal Switch(s)
Yes
Efficiency
91%
Operating Supply Voltage
2.6 V to 5.5 V
Maximum Supply Current
185 uA
Maximum Power Dissipation
953 mW
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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 hand-
held devices. The MAX8901_ operate at a fixed 750kHz
(typ) switching frequency, allowing for tiny external com-
ponents, and are optimized for the highest possible effi-
ciency 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).
19-0865; Rev 3; 8/10
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
Series WLEDs in a 2mm x 2mm TDFN Package
PWM DIMMING
2.6V TO 5.5V
CONTROL
INPUT
Display Backlight (from 2 to 6 WLEDs)
Cellular Phones
PDAs and Smartphones
MP3 and Portable Media Players
Portable Navigation Devices
Digital Cameras
7
6
3
2
IN
COMP
GND
ON
________________________________________________________________ Maxim Integrated Products
MAX8901A
EP
General Description
PGND
OVP
CS
LX
Highest Efficiency Supply for 2 to 6
1
4
5
8
Applications
UP TO 25V
OUTPUT
o High Efficiency, Up to 91%
o 2.6V to 5.5V Input Voltage Range
o Fixed-Frequency Operation
o Supplies from 2 to 6 WLEDs with 1.3% LED Current
o Flexible Dimming Control
o Input Undervoltage Lockout
o Input Overvoltage Lockout
o WLED Overvoltage Protection (25V typ)
o 0.01µA (typ) Shutdown Current
o No WLED Current in Shutdown
o Internal Soft-Start and Thermal Shutdown
Note: All devices are specified over the -40°C to +85°C operating
temperature range.
+
*
T = Tape and reel.
Pin Configuration appears at end of data sheet.
MAX8901AETA+T
MAX8901BETA+T
EP = Exposed pad.
Denotes a lead(Pb)-free/RoHS-compliant package.
Accuracy
Direct PWM Dimming (MAX8901A)
32-Step, Single-Wire Serial Dimming
2.6V TO 5.5V
SERIAL-PULSE
INPUT
DIMMING
CONTROL
PART
(MAX8901B)
Typical Operating Circuits
7
3
6
2
IN
COMP
GND
ON
Ordering Information
MAX8901B
PIN-PACKAGE
8 TDFN-EP*
2mm x 2mm
8 TDFN-EP*
2mm x 2mm
EP
PGND
OVP
CS
LX
1
5
4
8
Features
TOP MARK
+ABA
+ABB
UP TO 25V
OUTPUT
1

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MAX8901BETA+T Summary of contents

Page 1

... Input Overvoltage Lockout o WLED Overvoltage Protection (25V typ) o 0.01µA (typ) Shutdown Current o No WLED Current in Shutdown o Internal Soft-Start and Thermal Shutdown PART MAX8901AETA+T MAX8901BETA+T Applications Note: All devices are specified over the -40°C to +85°C operating temperature range. + Denotes a lead(Pb)-free/RoHS-compliant package Exposed pad ...

Page 2

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +7V CS, COMP GND ...............................-0. OVP GND .....................................................-0.3V to +28V ...

Page 3

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package ELECTRICAL CHARACTERISTICS (continued 3.6V OVP PGND GND Typical values are ...

Page 4

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package (Circuit of Figure 24.75mA, V LED IN LED EFFICIENCY vs. INPUT VOLTAGE WLEDs 80 6 WLEDs 75 INDUCTOR: ...

Page 5

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package (Circuit of Figure 24.75mA, V LED IN LED AND BOOST EFFICIENCY vs. INPUT VOLTAGE 6WLEDs, INDUCTOR: ...

Page 6

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package (Circuit of Figure 24.75mA, V LED IN PWM DIMMING RESPONSE (MAX8901A 90 10 ...

Page 7

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package PIN NAME WLED Overvoltage Protection Input. OVP monitors voltage at the WLEDs. Connect OVP to the 1 OVP positive terminal of the output capacitor. ...

Page 8

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package Figure 2. MAX8901A Block Diagram Detailed Description The high efficiency and tiny size of the MAX8901A/ MAX8901B WLED step-up converters make them ideally suited ...

Page 9

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package Figure 3. MAX8901B Block Diagram The MAX8901_ feature: • Internal soft-start that gradually illuminates the WLEDs to eliminate inrush current during startup. • Input ...

Page 10

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package Startup and Soft-Start The MAX8901_ use a single input (ON) to enable the IC and to control WLED intensity. After ON is driven high, ...

Page 11

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package Schottky Diode Selection The high switching frequency of the MAX8901_ demands a high-speed rectification diode for optimum efficiency. A Schottky diode is recommended due ...

Page 12

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package INPUT 2.6V TO 5.5V C1 1μF C3 0.022μF PWM DIMMING CONTROL Figure 4. MAX8901A Application Circuit INPUT 2.6V TO 5.5V C1 1μF R1 0Ω ...

Page 13

Highest Efficiency Supply for Series WLEDs in a 2mm x 2mm TDFN Package Pin Configuration TOP VIEW CS COMP GND PGND MAX8901 * OVP TDFN-EP ...

Page 14

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2010 Maxim Integrated Products ...

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