The HV9910C is an open loop, current mode, control LED driver IC. The HV9910C can be programmed to operate in either a constant frequency or constant off-time mode. It includes a 15 – 450V linear regulator which allows it to work from a wide range of input voltages without the need for an external low voltage supply. HV9910C includes a TTL compatible PWM dimming input that can accept an external control signal with a duty ratio of 0 – 100% and a frequency of up to a few kilohertz. It also includes a 0 – 250mV linear dimming input which can be used for linear dimming of the LED current. As opposed to the HV9910B, the HV9910C is equipped with built-in thermal-shutdown protection.
The HV9910C is ideally suited for buck LED drivers. Since the HV9910C operates in open loop current mode control, the controller achieves good output current regulation without the need for any loop compensation. Also, being an open loop controller, PWM dimming response is limited only by the rate of rise of the inductor current, enabling a very fast rise and fall times of the LED current. The HV9910C requires only three external components (apart from the power stage) to produce a controlled LED current making it an ideal solution for low cost LED drivers.
Switch mode controller for single switch LED drivers