The LM3909 is a monolithic oscillator specifically designed to flash Light Emitting Diodes By using the timing capacitor for voltage boost it delivers pulses of 2 or more volts to the LED while operating on a supply of 1 5V or less The circuit is inherently self-starting and requires addition of only a battery and capacitor to function as an LED flasher Packaged in an 8-lead plastic mini-DIP the LM3909 will operate over the extended consumer temperature range of b 25 C to a 70 C It has been optimized for low power drain and operation from weak batteries so that continuous operation life exceeds that expected from battery rating Application is made simple by inclusion of internal timing resistors and an internal LED current limit resistor As shown in the first two application circuits the timing resistors supplied are optimized for nominal flashing rates and minimum power drain at 1 5V and 3V Timing capacitors will generally be of the electrolytic type and a small 3V rated part will be suitable for any LED flasher using a supply up to 6V However when picking flash rates it should be remembered that some electrolytics have very broad capacitance tolerances for example b20% to a 100%