HV9980

The HV9980 is a fully integrated 3-channel peak-current PWM controller for driving buck converters in constant output current mode. It is optimized for use with a large array of 20~80mA LED strings, where multiple ICs are used sharing a common clock and a common reference voltage.

Both the clock and the voltage reference are external to the HV9980 for improved output current accuracy and uniformillumination. The output currents are programmed by controlling peak source current in each of the three internal 200V, 25 switching MOSFETs.

The peak current is detected by monitoring voltage at external sense resistors connected to RSENSE1-3. The HV9980 switching MOSFET is turned off when the corresponding current sense signal exceeds the reference voltage applied at REF1-3 (in the case of normal output signal polarity). Beginning of the next switching cycle is determined by the external clock signal received at the CLK input. All three channels operate at a switching frequency of 1/6 of the external clock frequency and positioned 120º out-of-phase for the purpose of input and output ripple current reduction. Each channel is protected from an output short circuit condition. When an over-current condition is detected in the output switch (RSENSE1-3), the corresponding channel shuts down for 200us. HV9980 recovers automatically, when the short circuit condition is removed. Each current sense input (CS1-CS3) is equipped with a leading edge blanking delay to prevent false triggering of the current sense comparators due to circuit parasitics.

Over-temperature protection is included in HV9980 to prevent destructive failures due to over-heating. Programmable slope compensation is available at each CS input. AGND and PGND1-3 must be tied together on the printed circuit board. VDD1-3 must be also connected together on the PCB.