HV9921N8-G

PMIC - LED Drivers

The HV9921N8-G is an integrated high-brightness LED driver which combines a two switching charge pump, an analog multiplier and an adjustable current sink in a single low profile package, providing a cost-effective, low component count solution for driving up to 8 LEDs from a single cell Li-Ion battery.

Application Field

The HV9921N8-G has the capability to drive up to 8 strings of LEDs, with parallel-connected LEDs in each string. Its wide input voltage range makes it suitable for battery operated applications, providing a minimum LED current of 40mA for up to 200mA. It is a good choice for LED driver designs such as LED indicators, LED displays, LED backlighting and LED lighting applications.

Working Principle

The HV9921N8-G operates in a current mode, taking advantage of the constant frequency peak current mode control. To achieve the high efficiency charge pump, the oscillator frequency is varied according to an internal voltage reference, automatically picking up the adequate frequency for each input and output voltage condition. Such current mode control enables smooth transition through light diversification providing small ripple current for longer expected LED life and low EMI.

The HV9921N8-G uses a switching charge pump and the oscillator frequency selection is based on the output voltage, thus providing a feedback in the current regulation loop. The output current is digitally adjustable with a 2-bit enable input. The output voltage of the device is internally regulated to provide an accurate output voltage, as well as a wide input voltage range and low output voltage variation.

The HV9921N8-G integrates a high-side driver, allowing higher efficiency when driving very large number of LEDs in multiple strings. An analog multiplier and current limit circuitry are included to regulate the LED current in each LED string. The LED on/off control is done with 2-bit enable inputs and an RGB control algorithm is provided to ensure steadier LED electrical current through the life time of the product.

Conclusion

The HV9921N8-G is an integrated high-brightness LED driver that is ideal for designs such as LED indicators, LED displays, LED backlighting and LED lighting applications. It combines a two switching charge pump, an analog multiplier and an adjustable current sink in a single low profile package, providing a cost-effective, low component count solution for driving up to 8 LEDs from a single cell Li-Ion battery. The integrated circuitry provides high efficiency, fast response and low EMI switching, making it a great choice for controlling high brightness LEDs.