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TLC5941: Output current variation among channels and devices

Takashi Onawa
Genius 13200 points
Part Number: TLC5941

Hi team,

My customer wants to clarify max output current variation of TLC5941 including errors introduced by load and line regulations.

1. Do you have any data for the max output current variation?
I'm asking this questions because IO(LC) looks that it doesn't include errors introduced by load and line regulations.

2. As one quick confirmation. "Device to Device" and "channel to channel" variation are involved in IO(LC), right?

3. If you don't have the data, Can we estimate the max value by following equation?

Max error range(480ohm) = (ΔIO(LC)^2+ΔIO(LC3)^2+ΔIO(LC3)^2)^(1/2) = (13.12^2+6^2+8^2)^(1/2) = 16.5%


Here is my understanding of each parameter in the datasheet

IO(LC) : Estimated output current range under VO = 1 V, R(IREF) = 640 Ω(Vo and IREF dependency are not included)

ΔIO(LC0) : Channel to Channel output current error

ΔIO(LC1) : Device to Device output current error @ 20mA

ΔIO(LC2) : Device to Device output current error @ 80mA

ΔIO(LC3) : Output current error depending on VCC

ΔIO(LC3) : Output current error depending on VO

Regards,

Takashi Onawa

  • 0
    TI__Genius 11836 points

    Hi Takashi,

         Q1:Do you have any data for the max output current variation?I'm asking this questions because IO(LC) looks that it doesn't include errors introduced by load and line regulations.

          Normally, the errors introduced by load regulations are related to Vo values. Since the value of Vo are different in different applications, it's hard to test all the cases. Hence, max output current variation under fixed Vo is usually provided in datasheet.

          Q2: As one quick confirmation. "Device to Device" and "channel to channel" variation are involved in IO(LC), right?

         In my opinion, "device to device" and "channel to channel" variation are already contained in IO(LC). Since only Vo is fixed in datasheet of TLC 5941, the line regulation may be already contained. However, the real meaning depends on the test conditions at that time.

           Q3: If you don't have the data, Can we estimate the max value by following equation?Max error range(480ohm) = (ΔIO(LC)^2+ΔIO(LC3)^2+ΔIO(LC3)^2)^(1/2) = (13.12^2+6^2+8^2)^(1/2) = 16.5%

           As mentioned in reply to Q2, the errors introduced by load and line regulations are related to actual Vcc and Vo values. Please note that the units of ΔIO(LC3) and ΔIO(LC4) are %/V, you should calculate the error according to the specific Vcc and Vo value. The worst case should be IO(LC) max*(1+6%*ΔVomax) @R(IREF) = 640 Ω if line regulation is already contained in IO(LC)max.

         

  • 0 in reply to Charles-Chen
    TI__Genius 13200 points

    Hi Chen-san,

    Thanks for your quick response on this.

    OK, I understand that we need to look at Vo more to estimate its max variation.

    Then, One quick confirmation, Do you have any "ch to ch" and "device to device" variation data of this device? 
    My customer want to know that at start of error estimation.

    Regards,

    Takashi Onawa

  • 0 in reply to Takashi Onawa
    TI__Genius 11836 points

    Hi Takashi,

         Why do you think the data provided in datasheet page4 is not enough to estimate the max variation? What's the output current and Vcc voltage in your application? What kind of application did customer plan to use this part? And how about the accuracy requirement?

  • 0 in reply to Charles-Chen
    TI__Genius 11836 points

    Hi Takashi,

         Do you have any more questions? I'll close this thread due to inactivity and if you have more questions please reply to it directly and it will open again.