L8565L-S08-R datasheet(6/13 Pages) UTC

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L8565

Preliminary

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

6 of 13

www.unisonic.com.tw

QW-R114-004.d

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FUNCTIONAL DESCRIPTION

1. General

The UTC L8565 is an active power factor correction controller for boost PFC application. The IC comes in DIP

package and is suitable for wide input range applications from 85 to 265 VAC. The IC is usually realized with boost

converters and it operates in continuous conduction mode with average current control.

The UTC L8565 operates with a cascaded control; the inner current loop and the outer voltage loop. The inner

current loop of the IC controls the sinusoidal profile for the average input current. It uses the dependency of the

PWM duty cycle on the line input voltage to determine the corresponding input current. This means the average

input current follows the input voltage as long as the device operates in CCM. Under light load condition, depending

on the choke inductance, the system may enter into discontinuous conduction mode (DCM). In DCM, the average

current waveform will be distorted but the resultant harmonics are still low enough to meet the Class D requirement

of IEC 1000-3-2. The outer loop controls the output voltage. Depending on the load condition, OTA1 establishes an

appropriate voltage at VCOMP pin which controls the amplitude of the average input current.

The UTC L8565 provides several protection features to ensure safe operating condition for both the system and

device. Important protection features are namely Brown-out protection, Current Limitation and Output Under-voltage

Protection.

2. Power Supply

The operating voltage range of the VCC is from 10V to 21V. An internal under voltage lockout (UVLO) block

monitors the VCC power supply. As soon as it exceeds 11.2V and the voltage at pin 1 (VSENSE) is >0.8V, the IC

begins operating its gate drive and performs its Soft-Start as shown in Fig. 3.

If VCC drops below 10.2V, the IC is off. The IC will then be consuming typically 200µA, whereas consuming 18mA

during normal operation.

The IC can be turned off and forced into standby mode by pulling down the voltage at pin 1 (VSENSE) to lower than

0.8V. The current consumption is reduced to 3mA in this mode.

L8565L-S08-R датащи(PDF) 6 Page - Unisonic Technologies