Toshiba white LED driver IC powers up to 8 LEDs in series

Date Announced: 27 Oct 2005

New Device Ideal for Cell Phones and Other Small Portable Devices, Boasts High Output Power For Up to 800mW and Provides Surge Protection

SAN JOSE, Calif. -- Toshiba America Electronic Components, Inc. (TAEC) today announced the expansion of its constant-current white LED driver product line with a new driver IC that powers the multi- segment white light-emitting diodes (LEDs) used to backlight the new, larger color liquid-crystal display (LCD) panels in small portable devices such as cell phones and PDAs.

Designated TB62752AFUG, the high-precision, high-performance switching white LED driver IC can drive 2 to 8 LEDs serially, has high output power for up to 800 milliwatts (mW) LED loading and features a built-in surge-protection function.

"With the trend toward larger and larger LCD panels in each generation of portable devices, there is a commensurate need for excellent illumination of these displays in a compact, efficient solution. To meet this demand, Toshiba Corporation engineered the TB62752AFUG white LED driver, which easily drives a string of up to 8 white LEDs in series and has high output power for 800mW LED loading," said Andrew Burt, director of the Wireless Business Unit at TAEC. "As well, the new device features built-in surge protection."

Mr. Burt explained that if an LED should break, the circuit will detect this potential overload situation and clamp the output while continuing to illuminate the other working LEDs; this ensures safe operation of the device.

Main Features

* Can drive a string of up to 8 white LEDs in series using a Li-ion battery
* Employs high withstand voltage process with switching withstand voltage of 40 volts (V), standard 37V output voltage.
* Features a surge-detection pin that reduces the external part count while protecting the driver circuit
* Achieves high power-efficiency of 80 percent or more during 7-segment white LED operation
* Reaches a current precision guaranteed value of plus or minus 5 percent; can suppress white LED brightness fluctuation; achieves a capability value of plus or minus 3 percent.
* Uses Bi-CD process that includes a Double Diffused MOS (DMOS) with a high-withstand voltage and large-current capacity as well as a bipolar transistor with a high-current drive and CMOS FET for low-power consumption and high integration
* Designed with highly compatible pin placement
* Housed in a lead-free SOT23-6 package with package dimensions of 2.9mm deep (D) x 2.8mm wide (W), including lead length, a tiny package suitable for very compact portable applications

Development Background

Cell phones and other compact portable products incorporate color LCD panels that are growing in number and size from product generation to generation. As the display size increases, more white LEDs are required for backlighting. To meet this need, Toshiba developed the TB62752AFUG, which can drive up to 8 LEDs in series.

The Toshiba constant-current white LED driver product line consists of both switching and charge pump drivers for white LEDs. The switching drivers are targeted for applications such as cell phones and PDAs that require high efficiency, accuracy and drive capability with minimal external components. The charge pump drivers include high-current drive with reduced noise.

Pricing and Availability

Samples are currently available and mass production is scheduled to begin in December 2005 at a production volume of approximately 5 million units per month. Current pricing is $0.99 each in 1,000-piece quantities.



Process BiCD 0.6 micron - 40V
Function White LED driver, DC/DC converter type
Circuit Format Switching format
Recommended Coil10-22uH
Power Supply Voltage2.8V-5.5V
Output Rating7-segment: 25mA or greater, 800mW
(reference)
Surge Detection Voltage 34.5V-39.5V
Package Dimensions 2.9mm D x 2.8mm W x 1.3mm H, including lead length

Contact
Toshiba America Electronic Components, Inc. (TAEC)

E-mail:Tech.Questions@taec.toshiba.com

Web Site:http://chips.toshiba.com

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