Power supply slew rate detector
In some embodiments, a power supply slew rate detector may include a filter circuit having a capacitive element operably coupled to a power supply output provided to a flash memory circuit and a resistive element operably coupled to the capacitive element and to ground, and a Schmitt trigger including an input operably coupled to a node between the capacitive element and the resistive element, the Schmitt trigger further including an output configured to indicate a slew rate of the power supply output.
1. A power supply slew rate detector, comprising:
a filter circuit including a capacitive element operably coupled to a power supply output provided to a flash memory circuit, and a resistive element operably coupled to the capacitive element and to ground; and
a Schmitt trigger comprising an input operably coupled to a node between the capacitive element and the resistive element, the Schmitt trigger further comprising an output configured to indicate a slew rate of the power supply output, the Schmitt trigger further comprising:
rising trip circuitry configured to switch an output node from a first logic state to a second logic state in response to an input voltage being greater than a high threshold voltage, the rising trip circuitry including a first NMOS transistor configured to receive the high threshold voltage and a second NMOS transistor configured to receive the input voltage, the first NMOS transistor operably coupled to the second NMOS transistor through a PMOS current mirror; and
falling trip circuitry operably coupled to the rising trip circuitry and configured to switch the output node from the second logic state to a first logic state in response to the input voltage being smaller than a low threshold voltage, the falling trip circuitry including a first PMOS transistor configured to receive the low threshold voltage and a second PMOS transistor configured to receive the input voltage, the first PMOS transistor operably coupled to the second PMOS transistor through an NMOS current mirror.
2. The power supply slew rate detector of claim 1 , wherein the capacitive element includes a Metal-Oxide-Semiconductor (MOS) transistor.
3. The power supply slew rate detector of claim 1 , wherein the output is configured to identify a selected range of slew rate values.
4. The power supply slew rate detector of claim 1 , wherein the output is configured to indicate the slew rate based upon a comparison between a voltage at the node and a selected threshold voltage.
5. The power supply slew rate detector of claim 4 , wherein the threshold voltage is selected via a voltage divider as a percentage of the power supply output.
6. The power supply slew rate detector of claim 1 , wherein the PMOS current mirror is a 1:1 current mirror having two or more PMOS transistors.
7. The power supply slew rate detector of claim 1 , wherein a gate of the first NMOS transistor is configured to receive the high threshold voltage, and wherein a drain of the first NMOS transistor is operably coupled to the PMOS current mirror.
8. The power supply slew rate detector of claim 1 , wherein an output of the PMOS current mirror is operably coupled to a drain of the second NMOS transistor through a first switch, wherein a gate of the first switch is operably coupled to the output node, and wherein a gate of the second NMOS transistor is configured to receive the input voltage.
9. The power supply slew rate detector of claim 8 , wherein the first switch is another NMOS transistor having its gate operably coupled to the output node.
10. The power supply slew rate detector of claim 8 , further comprising a third NMOS transistor having a drain operably coupled to the output node, its source operably coupled to the drain of the second NMOS transistor, and its gate operably coupled to the input voltage.
11. The power supply slew rate detector of claim 8 , wherein the NMOS current mirror is a 1:1 current mirror having two or more NMOS transistors.
12. The power supply slew rate detector of claim 1 , wherein a gate of the first PMOS transistor is configured to receive the low threshold voltage, and wherein a source of the first PMOS transistor is operably coupled to the NMOS current mirror.
13. The power supply slew rate detector of claim 12 , wherein an output of the NMOS current mirror is operably coupled to a source of the second PMOS transistor through a second switch, wherein a gate of the second switch is operably coupled to the output node, and wherein a gate of the second PMOS transistor is configured to receive the input voltage.
14. The power supply slew rate detector of claim 13 , wherein the second switch is another PMOS transistor having its gate operably coupled to the output node.
15. The power supply slew rate detector of claim 14 , further comprising a third PMOS transistor having a source operably coupled to the output node, its drain operably coupled to the source of the second PMOS transistor, and its gate operably coupled to the input voltage.
16. A method, comprising:
monitoring an input voltage at a node within an RC filter operably coupled to a power supply output provided to a flash memory circuit; and
switching an output node of a Schmitt trigger from a first logic state to a second logic state in response to the input voltage meeting a threshold voltage, wherein the second logic state indicates that a slew rate of the power supply output is within a selected range of values, wherein the threshold voltage is applied to a first transistor of a first doping type and the input voltage is applied to a second transistor of the first doping type, the first and second transistors operably coupled to each other through a current mirror of a second doping type.
17. The method of claim 16 , further comprising selecting the threshold voltage via a voltage divider as a percentage of the power supply output.
18. An electronic circuit, comprising:
a power supply circuit configured to provide power to at least one of a plurality of power domains within a flash memory circuit; and
a power supply slew rate detector circuit operably coupled to the power supply circuit, the power supply slew rate detector circuit including a filter circuit having a capacitive element operably coupled to a power supply output and a resistive element operably coupled to the capacitive element and to ground, the power supply slew rate detector circuit further including a first Schmitt trigger having an input operably coupled to a node between the capacitive element and the resistive element and an output configured to indicate a first range slew rate values of the power supply output, the power supply slew rate detector circuit further including a second Schmitt trigger having an input operably coupled to the node between the capacitive element and the resistive element and an output configured to indicate a second range slew rate values of the power supply output.