M7085

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

5 of 7

www.unisonic.com.tw

QW-R502-092, Ba

APPLICATION INFORMATION

Setting the output voltage

and GND (see the Typical Operating Circuit). Choose R2 for a reasonable bias current in the resistive divider. A wide

range of resistor values is acceptable.

R1, R2 is given by:

across an additional sense resistor. When current limit is activated, the UTC M7085 turns off the external P-Channel

resistor. This voltage is compared to the voltage across the P-Channel or sense resistor. The ADJ voltage can be

calculated as follows:

COMP

5.5µA

ADJ

5

1

comparator triggers the 9μs one shot pulse generator forcing the driver to turn the P-Channel off. The driver turns

the P-Channel back on after 9μs. If the current has not reduced below the set threshold, the cycle will repeat

continuously.

comparator will not be accidentally triggered. A value of 100pF to 1nF is recommended in most applications. Higher

values can be used to create a soft-start function. The current limit comparator has approximately 100ns of blanking

time. This ensures that the P-Channel is fully on when the current is sensed. However, under extreme conditions

such as cold temperature, some P-Channels may not fully turn on within the blanking time. In this case, the current

limit threshold must be increased. If the current limit function is used, the on time must be greater than 100ns. Under

low duty cycle operation, the maximum operating frequency will be limited by this minimum on time.