Inquiry regarding simulation tool of TPS55010

Hello, thank you for your prompt reply.

I have one additional inquiry regarding output current limit setting on this device.

Please refer to the item below, and feedback us with your comment.

When referring page5 of this datasheet, High side sourcing current limit and Low Side Sinking Current Limit are defined.

I assume that this limit is aimed for short protection. 

Since we would like to separately set 500mA current limit on primary side, please let us know whether you have any suggestion for this case.

We thank you once again for your information.

Best regards,

Hello, thank you for your continuous support.

I have additional inquiry regarding output accuracy on this device.

Please refer to the item below, and feedback us with your comment.

When referring datasheet page 3, the accuracy of voltage reference seems to be +/1 3% on whole temperature range.

However, we could not find out the accuracy of error amplifier.

We would like to find out total accuracy on VSENSE pin in case using 0.5% resistor for Rhs and Rls on whole temperature range.

Please let us clarify how should we find this.

We thank you once again for your information.

Best regards,

Probably the simplest way is to model that using the pspice transient model.

The accuracy of the error amplifier is included in the accuracy of the reference. You would then need to only add in the resistor tolerance into this for the primary side voltage.

For the secondary side voltage it depends heavily on external components as the load is varied. Two key things to reduce to have smaller variation of load is the leakage inductance of the transformer and the forward voltage of the schottky diode. The Rdson of the low-side FET and DCR of the transformer will also impact the load regulation as these will add additional voltage drops with current.

Hello, thank you for your prompt reply.

With regard to secondary side, I got some feedback from them.

The load variation on secondary side is less than 80mA. The forward voltage if schottky diode is estimated to vary 0.2 to 0.5V, however the leakage inductance of the transformer is ignorable for this impact.

Meanwhile, I have one additional inquiry whether the accuracy could be influenced by input voltage transient since this could be varied from 3.6 to 4.2V.

We would appreciate if we could find out some equation to estimate the feedback accuracy including both primary and secondary side.

We thank you once again for your information.

Best regards,

In theory there is little impact on the load regulation with different input voltage. This is because the primary side voltage stays regulated to the same value regardless of the input voltage.

In reality there is some change in regulation of the secondary side because of the change in duty cycle. At higher duty cycles or lower input voltages there will be higher peak current on the secondary side side due to a shorter time period of power being transferred to the secondary side. This can increase DC voltage drops. The leakage inductance will also have a bigger impact on the regulation at higher duty cycles. This causes the secondary side volage to be lower at lower input voltages.

Sorry I do not have an equation to estimate the secondary side regulation right now.