**Other Parts Discussed in Thread:**TPSI3050-Q1

Sometimes it can be challenging to simulate devices models in *PSpice For TI* given all the different buttons and knobs. The intent behind this post is to guide the reader on how to simulate the TPSI305x-Q1 models in *PSpice For TI* to aid the design-in process. The following assumes *PSpice For TI* is already installed. The *Explore PSpice for TI design and simulation tool* video series can be viewed here for additional guidance.

### Opening TPSI305x-Q1 Model in PSpice For TI

- Download TPSI305x-Q1 PSpice Model (SLVMDV1C.ZIP) and Calculation Tool (SLVRBI9) from product page.

##### Figure 1: TPSI305x-Q1 Product Page View

- Run PSpice For TI and open TPSI305x-Q1 testbench.

##### Figure 2: Opening TPSI305x-Q1 Testbench

##### Figure 3: Opening TPSI305x-Q1 Testbench

### Determining CVDRV, CDIV1, and CDIV2

Electrical concepts can often be compared to water. Using this analogy, the *TPSI305x-Q1* can be likened to a water delivery system for a pool. The power transfer setting corresponds to the volume of water being delivered to the pool. Each activation (drive) of a MOSFET can be thought of as scooping out some water, leading to a drop in the pool's water level. The bigger the pool, the smaller the drop for each scoop. In this example, the pool represents the *CDIV1* and *CDIV2* capacitors. With every MOSFET activation, a specific charge is injected into its gate. This charge is taken from *CDIV1* and *CDIV2*, resulting in a voltage drop (*VDDHdroop* and *VDDMdroop*). Therefore, *CDIV1* and *CDIV2* should be adequately sized. The amount of charge is determined by the total gate charge specification in the MOSFET datasheet and can be modelled as a capacitor, *CVDRV*.

##### Figure 4: TPSI305x-Q1 with MOSFET Diagram

- Select MOSFET and determine total gate charge from datasheet for sizing load capacitor (CVDRV) in testbench. In this example, we use a MOSFET from the EVM.

##### Figure 5: UJ4C075060K3S Vgs vs. Qg Graph

- Total gate charge = 38 nC

CVDRV=Q/V

CVDRV=38 nC/15 V (would use 10-V for TPSI3050-Q1)

CVDRV=__2.53 nF__ - Determine
*CDIV1*and*CDIV2*using Calculation Tool (SLVRBI9). The calculation tool can also be used to understand other key parameters and how they affect performance.- When selecting a value for
*VDDHdroop*, consider the MOSFET’s Miller plateau, an operating region where the MOSFET is conducting current but not fully enhanced and as a result dissipating the most power (read more about Miller plateau here). Limit the voltage drop to stay above the Miller plateau in addition to auxiliary circuitry receiving power from*VDDM*and*VDDH*and their absolute maximum specifications.

##### Figure 6: Taking CDIVx from Calculation Tool

- When selecting a value for
- Set
*CDIV1*,*CDIV2*, and*CVDRV*values in testbench. For the sake of realistic capacitances, CDIV1=100 nF, CDIV2=330 nF

##### Figure 7: Setting CDIVx and CVDRV in PSpice

- Open PSpice > Edit Simulation Profile
- Enable Auto Converge

##### Figure 8: Enable Auto Converge

- Go to Configuration Files > Library and
__remove__nom_pspti.lib*- Simulating with this library file generates subcircuit errors.

##### Figure 9

- Simulating with this library file generates subcircuit errors.

- Enable Auto Converge

### Simulating TPSI305x-Q1 in PSpice For TI

- Set desired switching characteristics.
- Limit switching frequency within the maximum possible switching frequency given by the calculation tool. In this case, the period should not be shorter than 10 µs.

##### Figure 10: Maximum Switching Frequency

##### Figure 11: Setting Switching Characteristics

- Limit switching frequency within the maximum possible switching frequency given by the calculation tool. In this case, the period should not be shorter than 10 µs.
- Run simulation

##### Figure 12

- View results and compare with calculation tool and datasheet. Start time, droops, and rising UVLO voltage levels seem close enough.

##### Figure 13: Calculation Tool Droop Values

##### Figure 14: Calculation Tool Power Transfer Table

##### Figure 15: PSpice Results Waveforms