| 摘要 |
PURPOSE:To ensure stable operation of a battery even when the battery voltage is low by comparing a mirror current of a mirror circuit connected across both ends of the battery with an attraction current of other transistors. CONSTITUTION:When a battery voltage is applied between a terminal VCC and a terminal GND, current I0 flows to a load circuit made up of a transistor (TR)Q1, diodes D1 and D2 and a resistor R1 while a mirror current I1 equal to that I0 flows through a TRQ2 composing a mirror circuit with the transistor TRQ1. On the other hand, a voltage of the battery runs to a series circuit of resistors R3 and R2 and the transistor TRQ3 while a attraction current I3 flows through the transistor TRQ4. The transistors TRQ2 and Q4 are so set that the current I1 is less than the current I3 when the voltage of th battery exceeds a specified value. If so, when the battery voltage is above the specified value, the transistor TRQ5 is turned ON while the transistor TRQ5 is turned OFF when it is below the value, whereby the output can be drawn from a terminal OUT. Thus, a stable battery checking can be performed. |
