Power supply monitoring with variable thresholds for variable voltage rails
Provided are embodiments for power supply monitoring with variable thresholds for variable voltage vails. An example method includes determining a proportionality factor based on a reference voltage value of a reference voltage and a rail voltage value of a rail voltage. The method further includes monitoring the rail voltage by a power supply monitoring circuit comprising a first resistor, a second resistor, and a third resistor, wherein the power supply monitoring circuit monitors the rail voltage based on the reference voltage to determine, by the power supply monitoring circuit, whether one of an under voltage condition or an over voltage condition occurs. The method further includes, responsive to a processor commanding a change in the rail voltage value of the rail voltage, causing, by the processor, a new reference voltage value to be generated based on the proportionality factor to adjust an under voltage threshold and an over voltage threshold.
1. A method comprising:
determining a proportionality factor based on a reference voltage value of a reference voltage and a rail voltage value of a rail voltage;
monitoring the rail voltage by a power supply monitoring circuit comprising a first resistor, a second resistor, and a third resistor, wherein the power supply monitoring circuit monitors the rail voltage based on the reference voltage to determine, by the power supply monitoring circuit, whether one of an under voltage condition or an over voltage condition occurs;
and responsive to a processor commanding a change in the rail voltage value of the rail voltage, causing, by the processor, a new reference voltage value to be generated based on the proportionality factor to adjust an under voltage threshold and an over voltage threshold
wherein the reference voltage is generated by a digital-to-analog converter controlled by the processor;
wherein the reference voltage is generated by a digital-to-analog converter controlled by the processor;
wherein the rail voltage is generated by a dynamic voltage scaling regulator controlled by the processor.
2. The method of claim 1 , wherein determining whether the under voltage condition occurs is based on the following equation:
V_Rail<V_Rail_UV_Th
where V_Rail is the rail voltage value and V_Rail_UV_Th is the under voltage threshold.
3. The method of claim 2 , wherein it is determined that the under voltage condition has occurred when the rail voltage is less than the under voltage threshold.
4. The method of claim 3 , wherein the under voltage threshold is defined by the following equation:
V
-
Rail
-
U
V
-
Th
=
V
-
Ref
×
(
R
1
+
R
2
+
R
3
R
3
)
where V_Rail_UV_Th is the under voltage threshold, V_Ref is the reference voltage value, R 1 is a value of the first resistor, R 2 is a value of the second resistor, and R 3 is a value of the third resistor.
5. The method of claim 1 , wherein determining whether the over voltage condition occurs is based on the following equation:
V Rail >V_Rail_OV_Th
where V_Rail is the rail voltage value and V_Rail_UV_Th is the under voltage threshold.
6. The method of claim 5 , wherein it is determined that the over voltage condition has occurred when the rail voltage is greater than the over voltage threshold.
7. The method of claim 6 , wherein the over voltage threshold is defined by the following equation:
V
-
Rail
-
OV
-
Th
=
V
-
Ref
×
(
R
1
+
R
2
+
R
3
R
2
+
R
3
)
where V_Rail_OV_Th is the over voltage threshold, V_Ref is the reference voltage value, R 1 is a value of the first resistor, R 2 is a value of the second resistor, and R 3 is a value of the third resistor.
8. The method of claim 1 , wherein a value of the third resistor is a selected value.
9. The method of claim 8 , wherein a value of the second resistor is calculated based on the reference voltage value, a current leak value through the third resistor, the rail voltage value, an under voltage threshold, and the value of the third resistor.
10. The method of claim 9 , wherein a value of the first resistor is calculated based on the rail voltage value, the current leak value through the third resistor, the value of the second resistor, and the value of the third resistor.
11. The method of claim 1 , wherein the power supply monitoring circuit further comprises a first comparator and a second comparator.
12. A system comprising:
a processor;
a dynamic voltage scaling regulator controlled by the processor and generating a rail voltage at a rail voltage value;
a digital-to-analog converter controlled by the processor and generating a reference voltage at a reference voltage value;
and a power supply monitoring circuit comprising a first resistor, a second resistor, and a third resistor, wherein the power supply monitoring circuit monitors the rail voltage based on the reference voltage to determine, by the power supply monitoring circuit, whether one of an under voltage condition or an over voltage condition occurs,
wherein the processor determines a proportionality factor based on the reference voltage value of the reference voltage and the rail voltage value of the rail voltage, and wherein the processor causes the digital-to-analog converter to vary the reference voltage value by the proportionality factor to adjust an under voltage threshold and an over voltage threshold responsive to the processor causing the dynamic voltage scaling regulator to change the rail voltage value of the rail voltage.
13. The system of claim 12 , wherein determining whether the under voltage condition occurs is based on the following equation:
V_Rail<V_Rail_UV_Th
where VV_Rail is the rail voltage value and V_Rail_UV_Th is the under voltage threshold.
14. The system of claim 13 , wherein it is determined that the under voltage condition has occurred when the rail voltage is less than the under voltage threshold.
15. The system of claim 14 , wherein the under voltage threshold is defined by the following equation:
V
-
Rail
-
U
V
-
Th
=
V
-
Ref
×
(
R
1
+
R
2
+
R
3
R
3
)
where V_Rail_UV_Th is the under voltage threshold, V_Ref is the reference voltage value, R 1 is a value of the first resistor, R 2 is a value of the second resistor, and R 3 is a value of the third resistor.
16. The system of claim 12 , wherein determining whether the over voltage condition occurs is based on the following equation:
V Rail >V_Rail_OV_Th
where V_Rail is the rail voltage value and V_Rail_UV_Th is the under voltage threshold.
17. The system of claim 16 , wherein it is determined that the over voltage condition has occurred when the rail voltage is greater than the over voltage threshold.
18. The system of claim 17 , wherein the over voltage threshold is defined by the following equation:
V
-
Rail
-
OV
-
Th
=
V
-
Ref
×
(
R
1
+
R
2
+
R
3
R
2
+
R
3
)
where V_Rail_OV_Th is the over voltage threshold, V_Ref is the reference voltage value, R 1 is a value of the first resistor, R 2 is a value of the second resistor, and R 3 is a value of the third resistor.