Creating compact models using standard spreadsheet software

Abstract

Methods are proposed for the determination of boundary conditions independent (BCI) compact thermal models. These flexible techniques can be utilized in combination with the input/output capabilities and standard functions of common spreadsheet programs, which are particularly useful in the process of error minimization. First, the steady-state is considered where resistor models are applicable. On a fast time scale, one-dimensional Cauer resistor-capacitor networks are sufficient to model transient behavior. This paper presents a way to obtain analytical solutions for RC ladders of arbitrary size. The method also eases network conversion. The steady-state and short-time behavior is used as basis information for derivation of BCI transient models. A numerical integration technique applicable to any network is outlined. The proposed techniques are used within the process of development of a transient BCI model for Infineon's BTS840S2 dual chip device, assembled in a P-DSO-20-10 package, which predicts the junction temperatures for any switching state.