AL1771/1772

Document number: DS41314 Rev. 1 - 2

13 of 24

www.diodes.com

August 2018

© Diodes Incorporated

AL1771/1772

Over Current Protection (OCP)

Over Temperature Protection (OTP)

The PFC controller has built-in OTP function. When the junction temperature goes up to shut down temperature, the OTP will be triggered, the

switch will be shutdown. Until the junction temperature falls to the recovery temperature, the PFC controller will be restarted.

Single/Dual Dimmable Linear LED driver

The Single/Dual Channel Linear LED driver supports E-flicker free High Frequency PWM dimming with Deep Dimming Capability: Support 40kHz

down to 4%, 10kHz down to 1.0%, 4kHz down to 0.4%, or 1kHz down to 0.1% with good dimming linearity. When no PWM signal is detected by

the Linear LED driver, it will automatically enter the low-power mode for power saving purpose to be in compliance with Energy Star standby

power requirement for SCL bulbs. It also integrates Adaptive Thermal Management (ATM) scheme to minimize non-productive power dissipation.

The Linear LED driver has abundant of protection features, including Under-Voltage-Lockout (UVLO), LED string Open/Short protection and Over-

temperature protection (OTP); when detecting these fault conditions, it will report the fault status on FAULTB pin.

1.

Enable and Soft-Start LED Drivers

The Linear LED driver is enabled when the voltage at any PWMx pin is greater than approximately 2.5V, and disabled when all PWMx are lower

than 0.4V. Upon any PWMx pin is asserted and DVCC pin is ramped up beyond minimum operation voltage, a soft start will be performed with a

slew-rate-controlled current ramp over 2

00μS at LEDx output pins to minimize current overshoot through LED strings for optimal system reliability.

When all PWMx are inactive for 4ms, The LED Driver will enter Low-Power mode with ultra-low standby power.

2.

LED Current Setting and Capability

(1)

LED Current Setting

current level is expressed as below:

For AL1771:

For AL1772:

AL1772 provides same current amount of 500mA.

(2)

LED Current Capability

The maximum current of each channel can drive up to 750mA with a total driving current up to 1500mA (refer to Table 1 below). The minimum

channel current is recommended as in Table 2 in order to meet channel current accuracy and short protection specifications. Each channel can

still be individually controlled by digital PWM dimming. The integrated low-side current sinks allow LED common-anode connections for cost

effectiveness or different anode voltages for efficiency optimization.

—

Channel 1

Channel 2

Total IC Current

AL1771

1500mA

Not Applicable

1500mA

AL1772

750mA

750mA

1500mA

Table 1. Recommended Maximum Channel Current and Total IC Current for AL1771/1772