Supertex announced the LR8K4, the industry's first D-Pak, three-pin, high voltage linear regulator with adjustable output voltage (1.20V to 440V). The new LR8K4 gives designers the flexibility to incorporate higher current capabilities at higher input voltages in switch mode power supplies, meter reading supply applications, MEMS biasing supplies, LED and relay drivers and cost-sensitive applications such as small consumer appliances and lighting controls.

The device offers a 12V to 450V input voltage range, ideal for universal off-line power supplies. The built-in over-temperature and over-current protection features of the LR8K4 provide circuit protection during operation and tolerates faults without blowing fuses. This allows quick recovery to normal operation once the fault condition is over. Additionally, a 10 microA typical biasing current supply provides higher efficiency than discrete implementations.

'In the new 3-pin D-Pak, the LR8K4 lowers cost and decreases the overall part count in applications where space is a major concern,' said Brian Hedayati, Marketing Director at Supertex. 'This versatile linear regulator is perfect for industrial control and telecommunication applications that require generation of any regulated voltage. The success that we've had with earlier package versions of the LR8K4 make this device a valuable addition to our portfolio of high voltage off-line power management ICs.

Supertex, Inc., 1235 Bordeaux Drive, Sunnyvale, CA 94089. Tel: 408-744-0100. Website: www.supertex.com

This adjustable linear regulator will find a good home in the telecom market and in designs that use switched mode power supply start-up circuits. Except for its higher voltage rating, the LR8K4 operates like any other 3-terminal adjustable linear regulator. The wide input range of 12 V to 450 V, in concert with the 1.2 V to 440 V output range, makes this a safe bet for many companies to keep in stock for a variety of projects. The output voltage is adjusted simply by means of two external resistors (see figure).

The voltage range allows you to eliminate the voltage selector switch used for universal input power supplies. This chip has a low quiescent current and the over temperature protection provides added protection. Supertex even thought to offer the regulator in three package types, the TO-92, TO-243AA (SOT-89) and TO-252 (D-Pak) versions.

The LR8K4 may be configured to provide a constant current output. The current is independent of both supply voltage and load impedance. Constant current operation finds application in driving LEDs and trickle-charging NiCad batteries. The trickle charger is for applications that require battery backup such as emergency lights. It also has a built-in current limit of 10 mA minimum. So, if the current drawn by the pulse width modulator controller exceeds this limit, the LR8K4 may still be used because its output capacitor will supply a portion of the current until the power supply can bootstrap itself and the LR8 is no longer needed.

Unit price for the LR8K4 in 10K piece quantities is $0.55 each. Samples are available from stock. Lead-time for production quantities is 4 to 6 weeks ARO.

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