LD8116Q

08/04/2020

8

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD8116Q-DS-00 August 2020

Application Information

Operation Overview

The LD8116Q is an excellent 3 in 1 dimming controller

for LED lighting applications. It integrates more

functions to reduce the external components counts and

the size. Its major features are described as below.

The LD8116Q convert input DC potential or PWM signal

into PWM output. The output of LD8116Q is an

open-drain configuration which can pull down any

source directly to control power supply dimming. The

DIM pin of LD8116Q provides an adjustable bias current

for potentiometer. So LD8116Q can satisfy with active

and passive dimmers both. It also can be used in

isolation application with opto-coupler.

Startup

and

Under

Voltage

Lockout

(UVLO)

An UVLO comparator is embedded to detect the voltage

on the VCC pin to ensure the supply voltage enough to

power on the LD8116Q. The turn on and turn off

threshold voltage is fixed at 7V and 6V. When the

voltage of VCC pin is above 6V, the LD8116Q output

PWM which is basing on input DC potential, PWM single

or potentiometer.

Bias Current of DIM Pin

ISET pin of LD8116Q is used to set bias current source

of DIM pin by a resistor (= RISET) on ISET pin which is

connected to GND. For the typical application, the

output bias current of DIM pin is 100μA when RISET is

100k ohm and 150μA when RISET is 66.5k ohm. The

relationship between resistor and output bias current is:

IDIM=

2.5V

R

× K

Where, KDIM is a coefficient of current ratio of IDIM per

ISET. The resistance range of RISET is recommend from

33k to 330k ohm and the range of bias current is

approach to 30μA ~ 300μA.

Dimming Performance

0~10V Potential Dimming

When the input signal of DIM pin is DC potential,

LD8116Q will transfer to PWM signal output at OUT pin.

The frequency of output PWM on OUT pin is 1.5kHz

around. The range of typical dimming curve is from 1.5V

to 8.6V, which has the corresponding duty cycle from

9.5% to 100%. When DC input on DIM pin is under 1.5V,

the output duty cycles on OUT pin is clamp at ~10%

around.

PWM Dimming (Leadtrend‘s patent)

During PWM signal input on the DIM pin, the output of

LD8116Q OUT pin is PWM, too. And the output

frequency is the same as 0-10V potential or

potentiometer dimming mode. The input amplitude of

PWM signal has to be higher than 3.2V and lower than

1.2V on DIM pin. Besides, recommend PWM frequency

range is from 500Hz to 10kHz and 1%~99% operation

range. ICs PWM rising slew rate of DIM pin is faster

than 3 V/μs through 1.2V to 3.2V and continuous 4

cycles, only in this way the PWM dimming mode can

operate. Then detection of high and low voltage level on

1.8V and through LPF pin filter from PWM to DC then

compare internal triangular wave. So, output duty cycle

approaches input PWM duty. Once it enters PWM

dimming mode, dimming mode will be kept until VCC is

reset by UVLO_off. The below is suggestion for filter

capacitor on LPF pin.

PWM signal frequency (Hz)

Suggestion CLPF (nF)

500~3k

220

3k~10k

100

Potentiometer Dimming

When DIM pin has connected a potentiometer to GND,

bias current source of DIM pin is pass thought this

potentiometer then cause a DC voltage potential on DIM

pin, LD8116Q will transfer to PWM signal output on