AUIR2085S

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© 2008 International Rectifier

11

Pin Descriptions

Cs:

The input pin to the overcurrent comparator. Exceeding the overcurrent threshold value specified in

“Static Electrical Parameters” Section will terminate output pulses and start a new soft start cycle as soon as

the voltage on the pin reduce below the threshold value.

OSC:

The oscillator-programming pin. Only two components are required to program the internal oscillator

OSC to COM. The approximate oscillator frequency is determined by the following simple formula:

Where frequency is in Hertz (Hz), RT resistance in Ohms (Ω) and CT capacitance in Farads (F). The

recommended range of timing resistors is between 10kΩ and 100kΩ and range of time capacitances is

between 47pF and 470pF. The timing resistors less than 10kΩ should be avoided. The value of the timing

capacitor determines the amount of dead time between the two output drivers: lower the CT, shorter the

dead time and vice versa. It is not recommended to use a timing capacitor below 47pF, for best performance

traces to the timing components are encouraged.

COM:

Signal ground and power ground for all functions. Due to high current and high frequency operation, a

low impedance circuit board ground plane is highly recommended.

HO, LO:

High side and low side gate drive pins. The high and low side drivers can directly drive the gate of a

power MOSFET. The drivers are capable of 1A peak source and sink currents. It is recommended that the

high and low drive pins be very close to the gates of the high side and low side MOSFETs to prevent any

delay and distortion of the drive signals.

low-leakage Schottky diode and a ceramic capacitor. To prevent noise, the Schottky diode and bypass

capacitor should be very close to the AUIR2085S.

side MOSFET with a trace as short as possible.

current will be higher, depending on the gate charge of the MOSFETs connected to the HO and LO pins, and

voltage, the average current can be calculated from:

close as possible to the AUIR2085S.

between 7.5V and 8.5V).