| 摘要 |
PURPOSE:To reduce a chip area and to cut down the price by being equipped with a holding means to hold an output signal of a comparison means, a low- pass filter and a timing means and by integrating them into the same chip. CONSTITUTION:A pulse width modulation stabilized power source is composed of a comparator 1, a timing generator 2, a multiplexer 3, a latch 4, a D/A converter 5, a RAM 6, a selector 7, a computing element 8, a MAIN PWM circuit 9, a control means 20 and a low-pass filter 30. Together with a microprocessor to control the operation of an image formation device, a memory, a timer, etc., they are integrated into the same chip for composition except the control means 20. This stabilized power source is equipped with two sorts of modes of the operation as an A/D converter and as a PWM control circuit. The operation as the PWM control circuit is compared with the output of the D/A converter 5 through the multiplexer 3 by the comparator 1 and is held to the latch 4. One of them is supplied to the above PWM circuit 9. |
