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TPS54226 / about ton min time

Tsukui Yusuke
Guru 21930 points
Other Parts Discussed in Thread: TPS54226

Hi,

Could you tell me about TPS54226 minimum on time and Fsw?
Customer is going to use TPS54226 following conditions.
◇Vin=18V、Vout=1.1V、Iout=2A
Data sheet shows the following.

However，In the case of Min Ton time = 145ns, can I keep the 700kHz?
Customers want to know the above.
Or, Could you tell me the Max and Min value of Min on time

Best Regards,
Yusuke/Japan Disty

  • 0
    TI__Guru**** 191445 points
    I have used TPS54226 at Vin = 18 V and Vout = 1.05 V with no issues. I did not check the on time or frequency though. Let me see if I have a circuit to measure.
  • 0 in reply to JohnTucker
    TI__Guru**** 191445 points
    I did a quick check...here are the results:

    Vin Vout Fsw Ton
    12 V 1.046 V 713 kHz 157 nsec
    14 1.046 702 136
    16 1.047 685 122
    18 1.048 662 112

    Frequency does fall below 700 kHz and on times can go below the typical minimum.
  • 0 in reply to JohnTucker
    Guru 21930 points

    John-san

    Thank you for your kind support.
    Let me ask you one more thing.
    Customer is considering the following condition.
    1.Vin=5V,Vout=1V
    2.Vin=12V,Vout=1V
     
    D-cap2 uses adaptive on-time.
    (Ts=Ton/D=Vin/Vo*Ton)
    For that reason,Customer is concerned about ripple by Vin condition.
    In pattern1 and pattern2, which can make small ripple level?

    Best Regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    TI__Guru**** 191445 points
    Ripple on the input or output? For TPS54226 output ripple is generally very low as the output capacitors are ceramic with very low ESR. Output ripple can rise if you are operating in eco-mode though. That is the trade off, higher efficiency for increased ripple. All other things being equal, output voltage ripple for the 5 V input may be slightly less than for 12 V input as the inductor ripple current is less. For input ripple voltage the relationship may be the opposite.