Electronic device for monitoring a supply voltage

• US 8,400,849 B1
• Filed: 10/18/2011
• Issued: 03/19/2013
• Est. Priority Date: 10/18/2011
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Dornseifer, Frank, Kuhn, Ruediger, Gerber, Johannes
• Primary Examiner(s): Lam, David
• Application Number:
  US13/276,160
• Time in Patent Office: 518 Days
• Field of Search: 365/189.09, 365/189.07, 365/145, 365/226
• US Class Current: 365/189.09
• CPC Class Codes: G11C 5/144 Detection of predetermined disconnection or reduction of power supply, e.g. power down or power standby

Abstract

An electronic device comprising a first supply voltage domain, a second supply voltage domain and a low drop output voltage regulator (LDO) coupled to receive a supply voltage of the first supply voltage domain and to provide a supply voltage of the second supply voltage domain and the LDO being configured to be switched into a first state for providing and maintaining the supply voltage of the second supply voltage domain and into a second state for providing a high impedance output to the second supply voltage domain. The electronic device includes a comparator coupled to monitor the first supply voltage level at a first supply voltage node and to switch the LDO from the first state to the second state.

Claims

1. An electronic device comprising:

a first supply voltage domain;

a second supply voltage domain;

a low drop output voltage regulator (LDO) coupled to receive a supply voltage of the first supply voltage domain and to provide a supply voltage of the second supply voltage domain;

the LDO being configured to be switched into a first state for providing and maintaining the supply voltage of the second supply voltage domain and into a second state for providing a high impedance output to the second supply voltage domain;

a comparator coupled to monitor the first supply voltage level at a first supply voltage node and to switch the LDO from the first state to the second state, the comparator comprising a differential input transistor stage having one input coupled to the first supply voltage node and another input coupled to receive a first reference voltage level, a first current source configured to supply a current of a first magnitude, a second current source configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first current source is coupled with one side to the differential input stage for supplying the differential input stage and with the other side to a first node, the second current source is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node, and wherein the differential stage comprises a third input being coupled to receive a second reference voltage that is derived from the supply voltage level at the first supply voltage node.

2. The electronic device according to claim 1, wherein the differential stage comprises a first input transistor, a second input transistor and a third input transistor, the first input transistor being coupled with a control gate to the first supply voltage node, the second input transistor being coupled with a control gate to the first reference voltage and the third input transistor being coupled with a control gate to the second reference voltage.

3. The electronic device according to claim 2, further comprising a first voltage divider coupled to the first supply voltage node and configured to supply a divided supply voltage of the first voltage domain to the control gate of the first input transistor.

4. The electronic device according to claim 3, further comprising a second voltage divider coupled to the first supply voltage node and configured to supply a divided supply voltage of the first voltage domain to the control gate of the third input transistor.

5. The electronic device according to claim 4, wherein the third transistor is coupled in parallel to the second transistor.

6. The electronic device according to claim 4, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

7. The electronic device according to claim 4, further comprising a short detection inverter being coupled with an input to the first supply voltage level and being coupled with an output so as to switch the LDO from the first state to the second state.

8. The electronic device according to claim 3, wherein the third transistor is coupled in parallel to the second transistor.

9. The electronic device according to claim 8, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

10. The electronic device according to claim 8, further comprising a short detection inverter being coupled with an input to the first supply voltage level and being coupled with an output so as to switch the LDO from the first state to the second state.

11. The electronic device according to claim 3, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

12. The electronic device according to claim 3, further comprising a short detection inverter being coupled with an input to the first supply voltage level and being coupled with an output so as to switch the LDO from the first state to the second state.

13. The electronic device according to claim 2, wherein the third transistor is coupled in parallel to the second transistor.

14. The electronic device according to claim 13, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

15. The electronic device according to claim 2, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

16. The electronic device according to claim 2, further comprising a short detection inverter being coupled with an input to the first supply voltage level and being coupled with an output so as to switch the LDO from the first state to the second state.

17. The electronic device according to claim 1, further comprising slope detection stage that is coupled in parallel to a resistor of the first voltage divider, the slope detection stage comprising two transistors coupled in series, a first transistor configured to supply a current of a first magnitude, a second transistor configured to supply a current of a second magnitude, and a capacitor, wherein the first magnitude is greater than the second magnitude and the first transistor is coupled with one side to the resistor of the first voltage divider and with the other side to a second node, the second transistor is coupled with one side to the first node and with the other side to a second supply voltage node having a second supply voltage level and the capacitor is coupled with one side to the first node and with the other side to the first supply voltage node.

18. The electronic device according to claim 1, further comprising a short detection inverter being coupled with an input to the first supply voltage level and being coupled with an output so as to switch the LDO from the first state to the second state.

19. The electronic device according to claim 18, further comprising a logic gate for gating an output of the comparator and the output of the short detection inverter, wherein the output of the logic gate is coupled to switch the LDO from the first state to the second state.

20. The electronic device according to claim 19, wherein the output of the comparator is coupled to a second input of the short detection inverter.

21. The electronic device according to claim 1, further comprising a ferroelectric random access memory (FRAM) wherein the second supply voltage domain is confined to supply the FRAM.