| 摘要 |
<p>An integrated circuit current-output relaxation oscillator utilizes an internal or external capacitor (C) which is alternately charged from +VBE to a predetermined upper trip point and then discharged to +VBE. A control current (Icnt) proportional to the voltage across the capacitor is generated and compared with a reference current (Iref). When the control current (Icnt) achieves a predetermined value with respect to the reference current (Iref), a transistor (Q4) is turned on permitting the capacitor to discharge to +VBE. The control current (Icnt) is generated by the same current mirror circuit (2) which generates the oscillating output current and is either equal or proportional thereto. Therefore, the magnitude of the oscillating output current (Iout) is dominantly proportional to the magnitude of the reference current (Iref), and the frequency of oscillation is dominantly dependent on passive components; i.e. a resistor (R1) and a capacitor (C).</p> |
