TPS7B82-Q1: About the EN pin of the TPS7B8250

Hello,

We can get a typical value of some of the requested data from the plot in Figure 8-2 in the datasheet, but much of the data requires a lot more effort. With the available resources we have right now, we likely could not complete this request for 4 weeks or more. Is that acceptable?

narumir said:

③ What is the typ/min/max value of the current that flows into the EN terminal?

This isn't trivial to answer in the general case because it will depend on the voltage conditions. I believe there is also a diode between EN and IN with series resistance, so the VIN condition will also be important. 

narumir said:

④ Please tell me the details of the circuit block inside the EN terminal.

What kind of details are you hoping to have? We will only be able to share limited information about it.

narumir said:

⑤ Are there any resistors or diodes between the EN terminal and the GND terminal? If so, please tell me the resistance value.

I took a look at the design and there is a diode between EN and GND with approximately 1.3Mohm resistance between. 

Regards,

Nick

Hello.

Thank you for your reply.

About①,②：

I can wait your condition.

Could you check t1 and t2 time for typ/min/max?

If the times t1 and t2 depend on the rise/fall time of the EN pin voltage, please take that time into consideration.

We would like to know the t1/t2 times when the rise/fall times are 100us to 1ms and 1ms to 10ms　and 10ms≦t1,t2

Our situation is like this.

・IN and EN Voltage ：8V～16V

・Temperature：-10℃～90℃

・There is a switch circuit between IN and EN, and the Vout output is controlled by turning this switch ON/OFF.

About③；

We use this parts for Question①、② condition.

Please tell me the current.

About④：

When the switch circuit between IN and EN is turned OFF, the EN terminal voltage drops,

but I want to calculate the time until the EN terminal voltage becomes Lo,

so I would like to know circuit block information that shows that there are resistance and capacitance components inside EN.

About⑤：

I can understand it. thank you.

Hello,

Thank you for your understanding. I will get started on this and will get back to you if I have questions or when I finish collecting the information. Just for your understanding, I will be simulating the data with a Monte Carlo using the transistor model for the device, instead of collecting on the bench. 

Regards,

Nick

Hello,

I'm getting a simulation set up for this and I have some questions. 

I ran a preliminary simulation to get an idea of the times t1 and t2 as defined by you, and they are both nominally on the order of hundreds of microseconds. This was using a relatively fast EN rise time (2us). In the simulation I ran, I used a 2-V ramp, and measured the time differential from when VEN crosses 1V to the point where VOUT rises to 5% of the final voltage. So, if I slow down the EN ramp to 100us ~ 1ms or 1ms ~ 10ms, I need to know how you would like me to measure the enable voltage reference point from which I measure the time to turn-on or turn-off. In this case the error from the time point of EN rising (or falling) is at most less than 2us, but if the ramp speed is much slower the error can be much worse. What I expect is that the EN ramp speed is not actually important; I think that the time from the EN threshold being crossed rising/falling and the output coming up or turning off will be the same regardless of the EN ramp speed, but in a real application the exact EN threshold is not known so using the EN threshold as a reference in the simulator isn't very useful. So, how would you like me to measure the time differential? 

You mentioned that the voltage range for IN and EN are both 8V ~ 16V. Is it true that VEN = VIN when the switch is on and VEN = GND when the switch is off? Or is it something different?

Regards,

Nick