TPS62140: TPS62140 simulation

Also can anyone suggest if using TPS62140 in inverting mode for this application something like the attached is fine for a loading of 1Amp on the negative channel?

I think this is possible, but you need to redraw your circuit in a way that the negative output voltage is the simulator GND signal (node 0).

The net you call Vtest must be connected to the netlist node 0 (GND). In your schematic GND is connected to VOUT. So VOUT will be always zero.

no but i am trying to configure this in inverting mode where VOUT is grounded and output is taken from Vtest (PGND) as per datasheet page 26

Also for the inverting configuration will the schottky diode have to be connected externally between the SW pin & PGND?

I don't think you should change the circuit. It is just about changing the reference point for the simulator.

i found the below post, does this apply to this part also?

e2e.ti.com/.../3367.ground-nodes-in-ti-models

also how do you suggest to change the reference point, i think in the attached schematic i have done the same, is there any change that you suggest , could you please send the image ?

Correct. Most models have their GND node shorted internally and cannot simulate an inverting configuration. See this thread also: e2e.ti.com/.../2262000

What are you trying to simulate?

The TPS62140 can do 1A at 5Vin to -4.5Vout. II recommend reducing the inductor value and increasing the output capacitance. f needed, there is always the higher current TPS62130 which is pin to pin.

thanks i am trying to simulate and see if i get -4.5v from 5v input , is that possible to simulate this feature in TINA for this part?

thanks i am trying to simulate & see if i can get -4.5v from 5v input and voltage waveforms across different components & iterate a bit with different component values. what do i need to do to make the inverting configuration work out in TINA?

thanks can you please let me know which shorts are you indicating at? i think i have done the same thing to disconnect the GND symbol and give this net a different name , i have given the name Vtest,

Hi can anyone please confirm if the issue is with the TINA model as i do not see issue in the schematic i had attached made as per the datasheet section 9.3.3, and if yes can i request for updating the TINA model to support this or if there is a work around that i can follow to be able to simulate from 5v input to -4.5v output

Hi Chris also what is the preferred inductance & capacitance value ?

So, let me try it differently. I would suggest at least those 4 modifications:

The output voltage will be -V(VOUT).

thanks but its a bit confusing , can you please try on the attached schematic? in the previous post?

but this is not inverting configuration, will this give -4.5v on Vout ?

My earlier reply should have explained that the inverting configuration cannot be simulated with this IC. There are GND nodes inside the model which are tied to GND (not the GND pin).

The TPS62140 device can work for your application (to make -4.5V from 5Vin). What exactly were you trying to simulate with the model?

As well, we recently released this reference design with a power module from this family: www.ti.com/.../tida-01457

i am trying to check waveforms across different components & iterate a bit with different component values. checking for stress on the components as well. i need to use TPS62140 as of now, what is the preferred inductance & capacitance value ? Also the application note for inverting configuration states ILMAX on page 4-5, is that the rated current of the inductor being used in the design ?

www.ti.com/.../slva469c.pdf

I don't think you had time to look at the reference design that I just sent. When you do, I recommend reading its design guide. The recommended output filter is that one--1uH and 4x 22uF Cout.

The TPS62140's app note shows another output filter which is also possible: 2.2uH + 22uF Cout + cap from Vin to Vout + diode on the output. The output filter in the reference design is simpler.

The Ilmax is described earlier as 1.4A. This is the minimum value of current limit for the TPS62150 described in the app note. For TPS62140, this value is 2.45A.

The voltage stresses won't change with changes in the output filter. Mainly, the ripple current changes with the inductor value. This change can be calculated instead of simulated.

thanks i went through the link you had shared but since that is having a different part no. i did not use that, so are you suggesting to use 88u at the output & 78u capacitance on the input side ? But how does that avoid the need of diode? also i think the inductor is integrated for the reference design you sent because i am unable to see it on the schematic.

Ah, let me share some background. The TPS62130 is a 3A version of the 2A TPS62140. (On page 1 of the TPS62140 D/S, it notes that they are pin to pin.)

The TPS82130 (the 6 changes to an 8 in the part number) is a module version of the TPS62130. There is also a TPS82140 (and 1A TPS82150).

This is a whole family of mid-Vin step-down converters which operate basically the same way and can thus be used with the same basic application circuits.

In the TPS82130 D/S, it is noted that the inductor is 1 uH. These devices only require a 10uF cap at the device's input + whatever bulk Cin is needed to decouple the input impedance from the IC. This depends on your final application.

Both the app note link you sent and the design guide for the reference design I sent include a section on the diode and why it would be needed.