Batteryless data logger with backup status indication and method therefor

A data backup system comprising:

• (a) a computing device comprising:
• (i) a processor;
• (ii) a device memory coupled to the processor;
• and
• (iii) a device power supply, wherein the processor operates using power from the device power supply;
• and
• (b) a data storage device comprising:
• (i) at least one super-capacitor;
• (ii) a data backup unit comprising:
• a data control unit coupled to the at least one super-capacitor, wherein the data control unit is adjustable between a plurality of operational states, and the plurality of operational states include a backup state and an inactive state;
• and
• a non-volatile memory coupled to the data control unit;
• (iii) an interface bus coupled to the data backup unit and to the computing device;
• and
• (iv) a state control unit coupled to the at least one super-capacitor, to the data control unit, and to the interface bus, wherein the state control unit is operable to monitor a stored voltage level of the at least one super-capacitor, the state control unit is operable to monitor a device power level of the computing device by monitoring a received power level from the interface bus, and the state control unit is operable to control the operational state of the data control unit based on the stored voltage level and the device power level;
• wherein
• in the backup state, the data control unit is operable to store backup data in the non-volatile memory using power from the at least one super-capacitor, wherein the backup data is received from the computing device via the interface bus when the interface bus is connected to the computing device;
• the state control unit is configured to set the operational state of the data control unit as the backup state in response to determining that the device power level is less than a power off threshold and that the stored voltage level is greater than a backup voltage threshold;
• the state control unit is configured to adjust the operational state of the data control unit from the backup state to the inactive state in response to determining that the stored voltage level is less than a low voltage threshold, wherein the low voltage threshold is less than the backup voltage threshold by a predefined voltage difference, and the predefined voltage difference is defined to be greater than the voltage gain of the at least one super-capacitor due to dielectric absorption when the stored voltage level is equal to the low voltage threshold and the at least one super-capacitor is decoupled from a load;
• in the inactive state, the data control unit does not receive power from the at least one super-capacitor.

A method of backing up data for a computing device that operates using power from a device power supply, the method performed by a data storage device, wherein the data storage device includes at least one super-capacitor, a data control unit coupled to the at least one super-capacitor and a non-volatile memory coupled to the data control unit, and wherein the data storage device is connected to the computing device, the method comprising:

• (a) monitoring a device power level of the computing device;
• (b) monitoring a stored voltage level of the at least one super-capacitor;
• (c) if:
• (i) the device power level is less than a power off threshold, and (ii) the stored voltage level is greater than a backup voltage threshold, then operating the data control unit using power from the at least one super-capacitor to store backup data in the non-volatile memory, wherein the backup data is received from the computing device;
• (d) if:
• (i) the stored voltage level is less than a low voltage threshold, wherein the low voltage threshold is less than the backup voltage threshold by a predefined voltage difference, and (ii) the predefined voltage difference is greater than the voltage gain of the at least one super-capacitor due to dielectric absorption when the stored voltage level is equal to the low voltage threshold and the at least one super-capacitor is decoupled from a load, then disabling power supply from the at least one super-capacitor to the data control unit.