LP2951 TINA Battery Charger Simulation

Timothy,

Could you provide the circuit your are using?

If you use the WEBENCH® interactive design tool, you can look at the proper schematic as it is generated for you.

Hi Britt,

The design I want to use is from this link www.ti.com/.../snva557.pdf.

It is the Single Cell 150 mA charger for Lithium-Ion batteries. I have already imported the LP2951 .lib model into TINA.

If possible I would like to use TINA so that I can mess around by adding components at the output, only problem is that is does not seem to preform as expected.

Thank you.

Covey

Hi Britt,

What I did was use the WEBENCH® Design Center to export the model of the LP2951 into TINA as the PSpice model I downloaded form the 'Tools and Software' is not suitable.

The problem still persists as the output is not around 5V in TINA. It was in WEBENCH® Design Center when I tried it but the solution/circuit design is not what I intend on using.

Covey

Covey,

That is strange. The simulation works fine for me. Please note that the design in the application note is for 4.2V and uses a potentiometer for trimming. I will not use a potentiometer in the simulation. You can adjust the output voltage by trimming the value of the lower resistor until it meets your specific needs (same thing the potentiometer was doing). Also, the load I have chosen is for the maximum output current of 160mA at 4.2V. As your battery charges, this "load" will increase and the current will decrease as described in the application note. This will NOT happen in the simulation unless you have a battery model that can show the impedance rise as the voltage stored increases.

Do not use a battery symbol as your load.

Please see the attached simulation.

LP2951_5V.tsc

The PSpice model you downloaded should work fine, but you would have to import it into TINA-TI and create the circuit you want to use. I simply exported a design and created the application from the application note.

Hi Britt,

This is rather odd, but I just downloaded the file that you provided, ran it in its default state and it still does not show the 4.2 V you were saying.

Instead it still remains a negative value of -1.36 nV before the diode when it should be 4.2 V.

Covey

Britt,

Unless this is is only applicable to be used for a circuit with an actual battery across the end?

Covey

Covey,

How are you measuring the voltage at the output? The waveforms I see are here:

Vout clearly goes to 4.2V and so does the voltage before the diode (I did not plot it here, but did previously).

Hi Britt,

I am rather new to this and would like to ask how do you get those graphs? I see that they are based on certain points on the wires and I would like to know how you add them as well?

I have only been using the DC/AC table of results hoping to get the points of interest. Thank you.

Covey

Thank you so much for your help