ADD5211 LED Driver SPEC. Issue

Dear Sir:

I study ADD5211 LED Driver now. check ADD5211 PrA Datasheet have may question. pls see below. thanks

Q1:The Figure 2. "dimming control". This function how to control it? not have any description in this document. can you tell me control it? It can be divided into the number of maximum stages. ex max is 4 stages PWM*30% , PWM*60% , PWM*80% , PWM*100%....etc

Q2:Have any testing report for this chip about electrical characteristics of the test conditions and data have any detailed information?ex:VIN = 12 V, EN = high, TA = −25°C to +85°C, ..etc test report

Q3:ADD5211 FB1 To FB4, I can FB1 and FB2 connection to use it? Iout current maximum 400mA it's right?

Q4: In this document not have any H/W schematic design / layout guideline and external component selection guild. can you tell me how to selection it and design ?

Q5:I check ADD5211 Web page description contrast with ADD5211 PrA. Datasheet found many unreasonable ex: ADI website show Vout maximum +80V but ADD5211 Datasheet Table 1. rating Show FB1~FB4 maximum +55V. another ADI ADD5211 website show Max Current Per String (mA) 200mA/CH but ADD5211 datasheet Figure 4. Show 100mA/CH….etc, a lot of data has a problem. which one is right.


Q6:what time have official ADD5211 Ver:A Datasheet can release? Have any dependable H/W document can provide to me design?

Best Regards,

  • 0
    •  Analog Employees 
    on May 14, 2013 10:14 PM

    Hi Jacky,

    The ADD5211 will be released in June 2013 and the final datasheet will be on the web then.  But if you need it sooner, please send me an email from your company domain to and I will send you an updated datasheet and some design files. 

    But here are the answers to your questions:

    Q1:  The ADD5211 has a PWM input pin.  When this pin is high, the current sinks (FB1-4) are on, when it is low they are off.  So if PWM has a frequency greater than about 120 Hz, then the eye will average the intensity and dimming is performed by changing the duty cycle of the PWM input. 

    Q2:  The final datasheet will have all the tests and guarnateed limits.  The operating junction temperature range is -40C to +125C.

    Q3:  Yes, you can connect FB pins together to get higher current through the LED strings.

    Q4:  The new datasheet has this information in it. 

    Q5:  There is a difference between the maximum boost voltage (Vout) and the voltage that the ADD5211 current sinks are at (the voltage on the FBx pins).  It is because even when the curren sinks are off there is still a small current (like 1uA) through the LEDs.  This gives them some forward drop (usually about 1 to 1.5V).  So the maximum Vout of the ADD5211 is the max FB voltage (55V) plus the "off state" LED forward voltage drop times the number of LEDs per string.  For a 22 LED string, and the LEDs used on the demo board, that means that Vout can be as high as 88V. 

    Q5:  The Figure 4 shows one operating condition of the ADD5211 (LED current = 100mA/channel).  But the LED current can be as high as 200mA or as low as 40mA.

    I hope that helps, let me  know if you have any other questions.

    Best Regards,

      - Jon