Voltage scaling system with sleep mode
A voltage scaling system can scale a supply voltage while preventing processor access of system components that are rendered unstable from the scaling. A processor receives an instruction to scale a system supply voltage to a target supply voltage. The processor executes the instruction and enters into a sleep mode. The processor can send, to a controller that saves power, an indication that the processor is in the sleep mode. When the processor is in the sleep mode, the processor becomes inactive and cannot access any components, e.g., Flash memory data, of the voltage scaling system. The controller can configure a voltage regulator to scale the system supply voltage to the target supply voltage. Once the target supply voltage is reached, the voltage regulator sends an interrupt to the processor, thereby waking up the processor from the sleep mode.
1. A method performed by a circuit for scaling voltage, the method comprising:
receiving an instruction to scale a system supply voltage to a target supply voltage;
placing a processor into a sleep mode, where the sleep mode halts a clock of the processor;
receiving, at a first input of a logic gate, an indication that the processor is in the sleep mode;
receiving, at a second input of the logic gate, an output of a register that is configured to be in a first state upon receipt of the instruction to scale the system supply voltage to the target supply voltage;
setting an output of the logic gate to a first value in response to receiving the indication that the processor is in the sleep mode and receiving the output of the register in the first state;
based on setting the output of the logic gate to the first value, providing a signal to a voltage regulator to scale the system supply voltage to the target supply voltage;
scaling the system supply voltage to the target supply voltage using the voltage regulator upon providing the signal to the voltage regulator; and
in response to the scaling, waking up the processor from the sleep mode with an interrupt signal, where the interrupt signal is sent by the voltage regulator when the system supply voltage has reached the target supply voltage.
2. The method of claim 1 , where the voltage regulator is operating when the processor is in the sleep mode.
3. The method of claim 1 , where the instruction is sent by a user through a user interface.
4. The method of claim 1 , where the waking comprises:
receiving an updated indication that the processor is no longer in the sleep mode.
5. The method of claim 4 , where the updated indication is detected by an edge detector.
6. The method of claim 1 , where prior to the waking, masking any interrupt other than the interrupt signal from the voltage regulator.
7. A system for scaling voltage, comprising:
a processor that provides an indication of whether the processor is in a sleep mode, where the sleep mode halts a clock of the processor;
a logic gate that is configured to:
receive, at a first input of the logic gate, the indication that the processor is in the sleep mode;
receive, at a second input of the logic gate, an output of a register that is configured to be in a first state upon receipt of an instruction to scale a system supply voltage to a target supply voltage; and
set an output of the logic gate to a first value in response to receiving the indication that the processor is in the sleep mode and receiving the output of the register in the first state;
a multiplexor that is configured to provide a signal to a voltage regulator to scale the system supply voltage to the target supply voltage in response to setting the logic gate to the first value; and
the voltage regulator that is configured to scale the system supply voltage to the target supply voltage when the processor is in the sleep mode, where the voltage regulator sends an interrupt signal to the processor when the target supply voltage is reached, where the interrupt signal causes the processor to wake up from the sleep mode.
8. The system of claim 7 , further comprising:
a controller configured to provide the target supply voltage to the voltage regulator.
9. The system of claim 8 , where the controller is configured to run the voltage regulator when the processor is in the sleep mode.
10. The system of claim 8 , where before sending the interrupt signal, the controller is configured to mask any interrupt signal other than the interrupt signal from the voltage regulator.
11. A circuit for scaling voltage, comprising:
a processor, where the processor provides a flag that indicates whether the processor is in a sleep mode, and where the processor enters into the sleep mode based on a received instruction to scale a system supply voltage to a target supply voltage;
a register that enables voltage scaling for the system, where the register is configured to be high upon receipt of the received instruction and low otherwise;
one or more logic gates having the flag of the processor as a first input and an output of the register as a second input;
a voltage regulator having a run operating mode and a sleep operating mode, where the run operating mode transitions the system supply voltage to the target supply voltage, where the sleep operating mode renders the voltage regulator inactive or running with low power, and where in the run operating mode, the voltage regulator sends an interrupt signal to the processor upon reaching the target supply voltage, where the interrupt signal wakes up the processor from the sleep mode;
a power scaling system that provides signals of both operating modes for the voltage regulator; and
a multiplexor that forwards one of the signals provided by the power scaling system based on the output of the one or more logic gates, where the voltage regulator operates on a mode indicated by the forwarded signal.
12. The circuit of claim 11 , further comprising:
an edge detector that clears the register, where the edge detector detects a falling edge of the flag of the processor.
13. The circuit of claim 11 , where the one or more logic gates comprises:
an AND gate having the flag of the processor as the first input of the AND gate and the output of the register as the second input of the AND gate;
a NOT gate having the flag of the processor as an input of the NOT gate; and
an OR gate having output of the AND gate as a first input of the OR gate and output of the NOT gate as a second input of the OR gate, where output of the OR gate is the output of the one or more logic gates.
14. The circuit of claim 13 , where if the output of the OR gate is high, the run operating mode is passed to the voltage regulator through the multiplexor, and where if the output of the OR gate is low, the sleep operating mode is passed to the voltage regulator through the multiplexor.
15. The circuit of claim 11 , where the power scaling system provides the target supply voltage to the voltage regulator.
16. The method of claim 1 , wherein providing the signal to the voltage regulator to scale the system supply voltage to the target supply voltage comprises:
receiving, at a multiplexor, signals provided by a power scaling system for controlling an operating mode of the voltage regulator, wherein the operating mode of the voltage regulator is one of a run operating mode and a sleep operating mode, where the run operating mode transitions the system supply voltage to the target supply voltage and the sleep operating mode renders the voltage regulator inactive or running with low power, and where, in the run operating mode, the voltage regulator sends the interrupt signal to the processor;
receiving, at the multiplexor, the output of the logic gate; and
providing, by the multiplexor and to the voltage regulator, a signal corresponding to the run operating mode upon receiving the output of the logic gate at the first value.
17. The method of claim 1 , wherein setting the output of the logic gate to the first value comprises setting the output of the logic gate to a high value.
18. The system of claim 7 , wherein setting the output of the logic gate to the first value comprises setting the output of the logic gate to a high value.