Semiconductor integrated circuit device

1. A semiconductor integrated circuit device comprising a plurality of error voltage detecting circuits, an analog-to-digital (AD) converter, and a digital controller,

wherein each of the error voltage detecting circuits comprises:

a target voltage generating circuit configured to generate a target voltage; and

a differential output circuit configured to output an error voltage based on the difference between an output voltage and the target voltage;

the AD converter being configured to convert the error voltage to a digital value and output the digital value as an error signal,

wherein the digital controller generates a prediction value of the error signal in accordance with a first error signal generated by converting the error voltage to a digital value at a first timing and a second error signal generated by converting the error voltage to a digital value at a second timing that is before the first timing, the digital controller further generating a control signal so that the prediction value lies between a first control threshold and a second control threshold smaller than the first control threshold, and

wherein the prediction value is obtained at a third timing that is later than the first timing.

2. The semiconductor integrated circuit device according to claim 1 ,

wherein the AD converter outputs the error signals corresponding to the plurality of power supply detecting circuits to the digital controller in a time sharing manner;

wherein the digital controller has setting circuits of the number at least equal to that of the plurality of error voltage detecting circuits, the setting circuits each having a first register storing the first control threshold, a second register storing the second control threshold, and a third register storing a length of a prediction period between the first error signal and the prediction value, and

wherein the digital controller generates the control signals corresponding to the plurality of error voltage detecting circuits by using values of the registers of the setting circuits corresponding to the plurality of power error voltage detecting circuits, respectively.

3. The semiconductor integrated circuit device according to claim 2 ,

wherein the digital controller comprises a processor;

wherein the digital controller further comprises a sequencer capable of setting a cycle of generating the control signal corresponding to each of the plurality of error voltage detecting circuits and capable of setting priority of generation of the plurality of control signals, and

wherein the control signals are generated by the digital controller by outputting an interrupt request signal to the processor based on data set in the sequencer.

4. The semiconductor integrated circuit device according to claim 1 , wherein the digital controller determines erroneous operation when the first error signal is larger than the first control threshold and the prediction value is smaller than the second control threshold or when the first error signal is smaller than the second control threshold and the prediction value is larger than the first control threshold, and outputs the determination result.

5. The semiconductor integrated circuit device according to claim 4 ,

wherein the digital controller determines a first erroneous operation mode as the erroneous operation when the first error signal is larger than the first control threshold and the prediction value is smaller than the second control threshold, and determines a second erroneous operation mode as the erroneous operation when the first error signal is smaller than the second control threshold and the prediction value is larger than the first control threshold;

wherein the digital controller controls to decrease the output voltage by the control signal in the first erroneous operation mode, and

wherein the digital controller controls to increase the output voltage by the control signal in the second erroneous operation mode.

6. The semiconductor integrated circuit device according to claim 1 , wherein frequency of sampling the error voltage of the AC converter is higher than switching frequency of the switching element.

7. The semiconductor integrated circuit device according to claim 4 , wherein the digital controller further comprises a first register configured to set the first control threshold, a second register configured to set the second control threshold, and a third register configured to set length of a prediction period between the first error signal and the prediction value.

8. The semiconductor integrated circuit device according to claim 7 , wherein when the erroneous operation is detected, a value in at least any of the first, second, and third registers is rewritten from the outside.