High Temperature Schottky TTL Latchup

Selected devices of the low power and standard Schottky T2L family were radiation tested at elevated case temperatures to determine if there is a latchup susceptibility. No latchup was observed. Analysis of device circuit topology confirmed that the PNPN paths previously observed to latch in older devices had been redesigned and removed. Comparison was made to devices which did latchup in radiation tests. Case temperature is an important variable. Two devices were found which did not latch at room temperature but did latch at 100°C; two other devices showed a significantly lower latchup threshold at 110°C than at room temperature. This work emphasizes the necessity of performing latchup screens at worst case temperature and bias conditions.