| 摘要 |
PURPOSE:To facilitate a selection of a Zener diode and to ensure the overall stability of a power supply circuit by providing a common Zener diode to two constant voltage circuit. CONSTITUTION:When the power is supplied to an LSI1 containing a memory circuit, two constant voltage circuits are prepared. Then the power is supplied to a power supply terminal 4 for protection of memory via either one of two constant voltage circuits. While the power is supplied to a power supply terminal 3 via the other constant voltage circuit as well as a power supply switch S. The bases of transistors Q1 and Q2 of both constant voltage circuits are connected directly to each other and then connected to the minus side of a power supply B via a common Zener diode D1. |
