Battery backed memory with battery disconnect for improved battery life

• US 6,822,346 B2
• Filed: 01/29/2002
• Issued: 11/23/2004
• Est. Priority Date: 01/29/2002
• Status: Expired due to Term

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Floro, William Edward, Priore, Frank Joseph
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Application Number:
  US10/059,061
• Publication Number:
  US 20030142574A1
• Time in Patent Office: 1,029 Days
• Field of Search: 307/66, 307/130
• US Class Current: 307/66
• CPC Class Codes: G11C 5/141 Battery and back-up supplies

Abstract

Battery backed memory for use in an industrial controller allows software disconnect of the battery and memory so that unplanned power outages may receive the benefit of battery backup, but battery power is not unduly wasted during planned power outages when data loss may be accommodated or other provisions may be made for saving data in nonvolatile memory.

Claims

1. A high reliability industrial controller for providing uninterrupted control operation comprising:

a volatile solid state memory holding a control program;

a processor executing the control program;

means for providing continuous battery backup to the volatile solid state memory during unplanned loss of line voltage; and

means for receiving an electrical signal from the user disabling the battery backup in the event of a planned loss of line voltage;

further including a non-volatile, solid-state memory communicating with the microprocessor wherein the microprocessor executes a program to transfer predetermined data from the volatile solid-state memory to the non-volatile, solid-state memory response to the electrical signal from the user indicating a planned cessation of line voltage prior to disabling the battery backup;

whereby the battery backup power is not unnecessarily depleted.

2. The high reliability industrial controller of claim 1 further including a latchable electronically controlled switch between the means or providing continuous battery backup and the volatile solid state memory whereby the electronically controlled switch is latched open upon receiving the disabling electrical signal even after loss of power to the circuit.

3. The high reliability industrial controller of claim 2 wherein the latch receives voltage from the means for providing continuous battery backup.

4. The high reliability industrial controller of claim 2 including circuitry for resetting the latch upon restoration of line voltage.

5. The high reliability industrial controller of claim 1 wherein the volatile memory includes memory selected from the group consisting of static and dynamic random access memory.

6. The high reliability industrial controller of claim 5 further including a DC/DC converter and wherein the dynamic random access memory receives voltage from the means for providing continuous battery backup via the DC/DC converter.

7. The high reliability industrial controller of claim 5 further including a voltage regulator circuit and wherein the static random access memory receives voltage from the means for providing continuous battery backup via the voltage regulator circuit.

8. A method of controlling a battery backed memory system in a high reliability industrial controller, the battery backed memory receiving a source of line power from a first line and receiving battery power from a second line to provide backup voltage when line power is lost;

the battery backed memory further having;

an electronically controlled switch;

a volatile solid state memory receiving power from the first line and further receiving power from the second line via the electronically controlled switch; and

a circuit communicating with the volatile solid state memory and the electronically controlled switch; and

a non-volatile solid-state memory communicating with a microprocessor, the method comprising the steps of;

(a) during a period when line power is present, providing power to the volatile solid state memory via the first line;

(b) during a period of unplanned loss of line power, causing the circuit to hold the electronically controlled switch closed to provide power to the volatile solid state memory via the second line;

(c) during a period of planned loss of line power, causing the circuit to open the electronically controlled switch; and

(d) transferring predetermined data from the volatile solid-state memory to the non-volatile solid-state memory in response to the signal indicating a planned cessation of line power prior to opening the electronically controlled switch.

9. The method of claim 8 wherein the battery backed memory system further includes a latch connected between the circuit and the electronically controlled switch and including the step of latching the electronically controlled switch open even after loss of power to the circuit.

10. The method of claim 9 wherein the latch receives battery power from the second line.

11. The battery backed memory system of claim 10 further including the step of resetting the latch upon restoration of line power on the first line.

12. The method of claim 8 wherein the volatile memory is dynamic random access memory receiving power from the second line via a DC/DC converter.

13. The method of claim 8 wherein the volatile memory is static random access memory receiving power from the second line via a power regulator circuit.

14. The battery backed memory system of claim 8 further including a user operated control providing the signal indicating the planned cessation of line power.

15. The battery backed memory system of claim 8 wherein the circuit includes a microprocessor executing a stored program.

16. The method of claim 8 including the step of receiving the signal indicating the planned cessation of line power from a user operated control.