The LDX-3620B is a very low noise current source that runs on batteries and is fine tuned for use in narrow linewidth or stable wavelength laser diode applications. It is capable of accurate current output and delivers <100 nA rms noise and <10ppm stability. It features a dual output range of 200 mA/500 mA in constant current or constant power operation mode. In addition it has laser diode protection and error detection circuits that work in both modes. This design uses long life batteries that can operate for up to 16 hours without charging and has a battery charge mode with a level indicator located on the front panel.