Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 47 subscribers
  • Views 215 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ALM2403-Q1: power dissipation calculation

Tosh+
Expert 7890 points
Part Number: ALM2403-Q1

Hello PRAMP team,

I got a question about power dissipation in the datasheet P18.
We assume the definition of V+ & VO(X) as below.

V+ ： VS+ voltage
VO(X) ： OUT(1)-OUT(2) = Vp-p
Threfore, For example at below figure;

We set that V+=20[V] & VO(X)=19[V]
Is my understanding correct?

  • +1
    TI__Guru 56821 points

    Hi Tosh-san,

    Enclosed is the power derivation of DC and AC signals for your references. 

    When we are talking about power dissipation in an IC that driving AC output, we need to refer to the power dissipation as the average AC power, not peak or rms power.

    I think that you were looking at the previous revision of ALM2403-Q1's datasheet. The new datasheet revision coincides with the above derivation. However, it is still not clear how the average power dissipation should be calculated. 

    Enclosed is an example of the Tina simulation where the average power dissipation may be estimated via simulation. You would need to specify the actual resolver load (L, R and C) and ran the simulation. The simulation assumed SPWM as the input signals from GPIOs of MCU. The average power dissipation is integrated based on the op amp's power dissipation marked in green box above. 

    We developed an icon to calculate the power dissipation, but you may also calculate add different parts of power dissipation manually to derive the figure. 

    The total average power dissipation (function of time) in a single supply rail is:

        (Vcc - Vout)*Iout+ (positive portion of sinusoidal Pwaveform) + abs[(Vcc - Vout)*Iout-] (negative portion of sinusoidal Pwaveform) + Vcc*Iq (quiescent current)

    ALM2403-Q1 Avg Pwr 09242023.TSC

    If you have other questions, please let me know. 

    Best,

    Raymond 

  • 0 in reply to Raymond Zhang1
    TI__Expert 7890 points

    Hi Raymond,

    Thanks for the reply.
    You commented that new datasheet revision coincides update calculation, right?
    As I download the datasheet on the web-site, these formula is not included.
    But I assume that the "worst case" power dissipation would be correct described in the datasheet.

    ti

  • 0 in reply to Tosh+
    TI__Guru 56821 points

    Hi Tosh-san,

    Yes, we made some changes to clarify the defined parameters in the maximum power in the datasheet. However, the IC's power dissipation is determined by the average power, not determined by the maximum peak power or rms power.

    Here is the definition of the average power, where p(t) = v(t) * i(t).  

     

    If you are interested in the max. peak power, then the previous derivation is shown by the equation in the captured image (DC or AC).

    If you have other questions, please let me know.

    Best,

    Raymond