This current regulator circuits that can be used to drive light emitting diodes. As always, take time to do some testing before attempting to use these circuits in actual applications.
The LM134/LM234/LM334 are 3-terminal adjustable current sources featuring 10,000:1 range in operating current, excellent current regulation and a wide dynamic voltage range of 1V to 40V. Current is established with one external resistor and no other parts are required. Initial current accuracy is ¡À3%. The LM134/LM234/LM334 are true floating current sources with no separate power supply connections. In addition, reverse applied voltages of up to 20V will draw only a few dozen microamperes of current, allowing the devices to act as both a rectifier and current source in AC applications.
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The sense voltage used to establish operating current in the LM134 is 64mV at 25¡ãC and is directly proportional to absolute temperature (¡ãK). The simplest one external resistor connection, then, generates a current with ¡Ö+0.33%/¡ãC temperature dependence. Zero drift operation can be obtained by adding one extra resistor and a diode. Applications for the current sources include bias networks, surge protection, low power reference, ramp generation,
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