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# TPS62816-Q1: TPS62816-Q1

Part Number: TPS62816-Q1

Hello,

we are using TPS62816-Q1 in one of the applications. To calculate the power dissipation certain parameters are not available like gate drive details, dead time, switching time have not been mentioned. Could you please provide the mentioned details?

The output capacitor mentioned minimum in the datasheet is 22uF. Could you please provide the equation for the same? I am not able to get that value with the general formula for output capacitor.

Thanks,

Regards,

Roopa.

• Hi Roopa,

We normally collect efficiency data for many corners. (Vout, Iout, Vin). With the efficiency you'll be able to calculate the power dissipation of the device together with the inductor.

Do you have a specific set of conditions where you would like to know the power dissipation?
Have you tried our Webench software before?

Regarding the output capacitance. This value is dependent not only on the ripple allowed but also on the converter stability. A too low capacitance may cause stability issues. To calculate the minimum output cap you can refer to Table 9-1 on the datasheet.

Let me know if this information helps you with your design.

Best regards
Nelson

• Hello Nelson,

thanks for the quick response. I am doing worst calculation.I have calculated conduction loss due to switches, inductor loss,capacitor loss. I am trying to calculate switching loss , gate drive loss, dead time loss so that I can have overall estimation of the loss. I did webench simulation too.

• Hi Roopa,

Switching losses may depend on Vin. I could not provide a figure for that. What we can offer is the efficiency for a given condition.

For the Webench circuit I refer you to:

Vin = 5V
Vout = 0.9V
Iout = 3A
Eff = 86.5%

Eff = Pout / Pin = Vout * Iout / (Vin * Iin)

Iin = Vout * Iout / (Eff * Vin)

Iin = 0.624A

Pin = 3.12W
Pout = 2.7W

Pin - Pout = Total loss =0.42W = L_loss + Dev_loss

L_loss =L_DCloss + L_ACloss + L_Coreloss

L_DCloss= DCR*Iout^2 = 4.2mOhm * (3)^2 = 37.8mW

If we are far from saturation of the inductor, the AC loss might be negligible.

Dev_loss = 420mW - 37.8mW = 382.2mW

Let me know if this example helps you find out the losses in your application.
From my experience, I would recommend to measure the efficiency for the given condition in the lab because it is hard to have all parameters and the real measurement will be more accurate than any calculation.

Regards
Nelson

• Hello Nelson,

how to consider rise time and fall time for TPS62816 IC as these parameters have not been mentioned in the datasheet. Even dead time which is critical parameter has not been mentioned in the datasheet. These parameters are required to calculate the total power dissipation. Is there any method through which we can calculate these parameters?

• Hi Roopa,

I will check internally if we have these parameters. In the meantime, could you indicate me the typical rail you would like to implement and the amount of current that is drawn by the load. This might be helpful to shrink the scope of the data?

Regards
Nelson

• 1.05V, 5.15A.

Thanks,

Regards,

Roopa

• Hi Roopa,

Unfortunately we are not able to provide this data. We can assure that the dead time is optimized to minimize losses.

With this Webench link you'll be able to get the efficiency for the corner you indicated.
https://webench.ti.com/power-designer/switching-regulator/customize/18?VinMin=5&VinMax=5.1&O1V=1.05&O1I=5.15&base_pn=TPS62816-Q1&AppType=None&Flavor=None&op_TA=30&origin=pf_panel&lang_chosen=en-US&optfactor=3&Topology=Buck&flavor=None&VoltageOption=None

L=0.25nH (XFL4012-251MEB) for this Webench calculation.

We also have data for Vout=1V and L= 0.25nH (XGL4020-251MEC) in the datasheet.

At 5.15A output current, the effects that dominate the losses are mostly the RdsON of the switches and the DCR of the inductor. We recommend using ceramic capacitors, for which you can neglect the losses.

I hope this data offers you an alternative way to calculate the losses.

Regards
Nelson