TPS82130: LOGIC INTERFACE (EN) on Datasheet Electrical Characteristics

Yes, you must drive EN with at least (minimum) 0.9V to guarantee a high signal will be seen. And you must drive it low with at most (maximum) 0.3V to guarantee that a low is seen.

Hi Chris,

Customer has raised a concern on heat dissipation.

For the heat dissipation, the datasheet shows that on the evaluation board, temperature rise on the module is about 50 degree C, with very large copper area for heat dissipation. It seems heat dissipation is an issue. Could you advise?

Cheers.

Yes, and we have section 11.3 in the D/S explaining about this. Thermal concerns are very PCB design dependent.

What is the application? What is the Vin, Vout, Iout, ambient temp, etc?

Hi Chris,

Vin = 12V, Vout = 5V, Iout = 2A, ambient temperature = 55 degree C

Any recommendations for heat dissipation?

Cheers.

Per the D/S graphs, this should be ok since the temp and current are lower. Make sure to use vias directly under the IC to obtain best thermal performance.

Hi Chris,

Some concern on page 16 of the datasheet which shows the thermal measurement. The temperature rise is very severe. Any advice?

Cheers.

Please restate your exact concern about page 16.

This figure shows a 50 C temp rise. Even with your 55 ambient, this is still below the maximum of the device.

But more importantly, you only have 2A output current. This is much less power loss in the device than the 3A in the figure. Thus, the temp rise is lower.

Hi Chris,

1. Take note the thermal measurement shows temperature on surface, not junction. TJ for TPS82130 is 110 degree C.
  
2. Another question, Datasheet Page 4 lists "Absolute Maximum Ratings". For VOUT, it's 0 to 7V, does this mean that even when VIN = 0V, VOUT can stand an external voltage (up to 7V)?

Thanks.

It seems that you have many detailed questions about this device. Please visit ti.com/microsip to learn more about these types of products.

As well, thermal seems to be important in your application. I would like to understand more about this in order to help you make the best design decisions. If you would prefer not to post here, can you contact me via a 'conversation'? This are private.

1. It is impossible to show the junction because of how these devices are constructed. See the microSiP URL above for more details on that. But the inductor surface and die (the whole module in fact) are closely thermally coupled. You can see this is the tiny psi JT value on page 4. The junction will be very slightly above the top surface temperature.

1b. 125 C is the abs max limit. The 110 C limit is there if you want the standard TI-rated product life time of 100k hours. This is over 11 years. And this assumes 100% operation at that temperature--the device would always be at full power. Neither 100k hours operation or operation at 100% power are typically required in most applications.

2. If a voltage is applied to the output without an input voltage, the output voltage will appear on the input due to the body diode of the high side FET. This is true of almost any buck converter. If there are other circuits on the input, they will be powered. If the input is shorted, this will consume current. The Tj of the device is the limit to remain within in these cases. But again, this is fairly atypical in most applications to have this condition. So, I would really like to understand more about what you are trying to do.

Hello Chris,

Your comment;
"Yes, you must drive EN with at least (minimum) 0.9V to guarantee a high signal will be seen. And you must drive it low with at most (maximum) 0.3V to guarantee that a low is seen."

In other words, does this device has tolerance from 0.3-V to 0.9V for threshold of enable?

Regards,
ACGUY

Yes, as do most DC/DC converters. It is a normal digital input pin.

See the TPS62135 D/S for an example of a device with a precise EN pin input.

What is required in your application?

Thank you for reply.

Our customer think, does like to control the start voltage to more than 3V.
They can't add the other external circuit at around.
They hope accurately threshold voltage.

Read out from datasheet, EN control range is;
VIH : 0.3V - 0.9V
VIL : 0V - 0.9V

Is my recognition correct?

There are overlapping voltage ranges from VIH to VIL.
Is not this a problem?

Regards,
ACGUY

Starting above 3Vin is already covered by the UVLO circuit.

Both rising and falling thresholds will be between 0.3V and 0.9V. The falling threshold will always be lower than rising. This is how any digital input circuit is designed.

Minimum Vin threshold is 2.8V for starting voltage. It is not 3V fixed.

In other DC/DC devices, EN threshold has hysteresis, and  width voltage Vlowth to Vhighth is small.

The method of describing the threshold I know is as follows.

It surely turns ON with input of 1.2 V or more.

It surely turns OFF with input less than 0.4V.

Would you like to apply the control threshold of TPS82130 in the same way?

Regards,

ACGUY

What is your Vin and Vout?

The second image of the thresholds from another D/S matches the TPS82130's method. These specifications are the same (though the exact values of the threshold are different). I didn't catch your point on this.