AL1698 datasheet(7/15 Pages) DIODES

7 / 15 page

AL1698

Document number: DS42216 Rev. 1 - 2

7 of 15

www.diodes.com

September 2019

AL1698

Functional Description and Application Information

Operation

The AL1698 is a single stage, single winding, high efficiency, and high power factor dimmable LED driver for triac dimmable LED lamp

applications. The AL1698 integrates a high voltage JFET and a 600V/2A high voltage MOSFET, and it can cover 230VAC triac dimmable

applications with eliminating external high voltage MOSFET and VCC startup resistors.

The AL1698 adopts source-driver technique to decrease the system operating current. It uses a novel method to detect the tOFF time which results

in the removal for the need of an auxiliary winding. The AL1698 operates at Boundary Conduction Mode (BCM) which can ease EMI design and

achieve high efficiency. High Power Factor (HPF) is achieved by using constant on-time mode. Coupled with a closed loop of constant current

control, the AL1698 achieves good line and load regulation.

GND

Input

FR1

DB1

COMP

VCC

ROVP

LEDS

AL1698 Buck-Boost Application Circuit

Startup and Supply Voltage

Before startup, the VCC capacitor C4 is charged by internal HV JFET. When the start-up voltage is reached, the AL1698 starts switching.

The AL1698 has an internal VCC clamp voltage (typical 9.5V), which is limited by one internal active Zener diode.

When VCC voltage drops to below the VOPR(MIN), switching will be stopped. So the device can operate normally when the voltage on VCC pin is

between VOPR(MIN) and VCC clamp voltage.

Protections

Under Voltage Lockout (UVLO)

When the voltage on the VCC pin drops below VCC_CHARGE, the IC stops switch. The IC can restart when the voltage on VCC exceeds the startup

voltage (VTH(ST)).

Leading-Edge Blanking (LEB)

To prevent false detection of the peak current of the inductor, a blanking time following switch-on is designed. When the internal switch turns on, a

short current spike can occur because of the capacitive discharge of the voltages over the drain and source. It is disregarded during the LEB time

(tON_MIN).

AL1698 Datasheet(PDF) 7 Page - Diodes Incorporated