| 摘要 |
A minimum fan RPM control circuit constantly turns a computer exhaust fan at a minimum RPM while the computer is on. The RPM control circuit includes a blanking and reset circuit responsive to a ramp signal, for generating a reset pulse at a reset output. The RPM control circuit also includes a latch circuit conductively coupled to the reset output, the latch circuit responsive to the reset pulse, and responsive to a tachometer pulse, for generating a latch pulse at a latch circuit output. The RPM control circuit further includes an integration node conductively coupled to the latch circuit output, and responsive to the latch pulse, for generating an integral signal of the latch pulse. Finally, the RPM control circuit includes a power switch driver conductively coupled to the integration node, and responsive to the ramp signal and the integral signal, for generating an RPM control pulse.
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