Circuits for bleeding supply voltage from a device in a power down state
View Patent ↗Embodiments of the present disclosure include an apparatus. The apparatus includes a flash memory with a device threshold voltage for an on/off state, a sense circuit, a decoupling capacitor, and a bleeder circuit. The sense circuit is configured to sense a voltage level of a voltage supply line. The bleeder circuit is configured to bleed a remaining charge available on the decoupling capacitor. The sense circuit is configured to determine a state of the flash memory based on the voltage level of the voltage supply line. The bleeder circuit is configured to bleed the decoupling capacitor in an off state and to preserve the remaining charge available in an on state.
1. An apparatus, comprising:
a flash memory including a device threshold voltage for an on/off state;
a decoupling capacitor;
a voltage supply line connected to the flash memory and the decoupling capacitor;
a sense circuit coupled to the voltage supply line, the sense circuit configured to sense a voltage level of the voltage supply line; and
a bleeder circuit configured to bleed a remaining charge available on the decoupling capacitor;
wherein:
the sense circuit is configured to determine a state of the flash memory based on the voltage level of the voltage supply line;
the bleeder circuit is configured to bleed the remaining charge available on the decoupling capacitor when the flash memory is in an off state; and
the bleeder circuit is configured to preserve the remaining charge available on the decoupling capacitor when the flash memory is in an on state.
2. The apparatus of claim 1 , wherein the bleeder circuit is configured to preserve a read/write state of the flash memory depending upon the on/off state of the flash memory as detected through the voltage supply line.
3. The apparatus of claim 1 , further comprising a control circuit coupled to the sense circuit and the bleeder circuit, the control circuit configured to:
detect that a value of the voltage supply line is less than or equal to the device threshold voltage; and
in response to detecting that the value of the voltage supply line is less than or equal to the device threshold voltage, output a control signal configured to allow current to flow between the voltage supply line and ground.
4. The apparatus of claim 1 , further comprising a control circuit coupled to the sense circuit and the bleeder circuit, the control circuit configured to:
detect that a voltage on the voltage supply line is greater than the device threshold voltage of transistors in the device; and
in response to detecting that the voltage on the voltage supply line is greater than the device threshold voltage of transistors in the device, output a control signal configured to inhibit current flow between the voltage supply line and ground.
5. A method, comprising:
providing a flash memory, the flash memory including a device threshold voltage for an on/off state;
providing a decoupling capacitor;
providing a voltage supply line connected to the flash memory and the decoupling capacitor;
sensing a voltage level of the voltage supply line; and
bleeding a remaining charge available on the decoupling capacitor;
determining a state of the flash memory based on the voltage level of the voltage supply line;
bleeding the remaining charge available on the decoupling capacitor when the flash memory is in an off state; and
preserving the remaining charge available on the decoupling capacitor when the flash memory is in an on state.
6. The method of claim 5 , further comprising preserving a read/write state of the flash memory depending upon the on/off state of the flash memory as detected through the voltage supply line.
7. The method of claim 5 , further comprising:
detecting that a value of the voltage supply line is less than or equal to the device threshold voltage; and
in response to detecting that the value of the voltage supply line is less than or equal to the device threshold voltage, outputting a control signal configured to allow current to flow between the voltage supply line and ground.
8. The method of claim 5 , further comprising:
detecting that a voltage on the voltage supply line is greater than the device threshold voltage of transistors in the device; and
in response to detecting that the voltage on the voltage supply line is greater than the device threshold voltage of transistors in the device, outputting a control signal configured to inhibit current flow between the voltage supply line and ground.