FIELD OF INVENTION :
The invention relates to a PC built- in a device for total power solution in general and to monitoring and regulating input AC mains variations and activating power back-up during power failure & abrupt fluctuations in particular.
BACK GROUND OF INVENTION :
Presently the PC (Personal Computers or Microcomputers ) are provided with power back-up during AC mains failure from external UPS (uninterrupted power supply ) systems. This needs an extra attachment and space apart from extra cost. The cost of the UPS will go abruptly high if the same has to be On-line and interactive. In case of failure of the UPS, manual changeover needs to be done for direct AC mains operation.
US patent no. 5,777,398 discloses a power back-up system for microcomputer through external attachment. The system is modular in shape and fits into a disc drive slot in the computer housing. Fitting has to be done by an skilled engineer, as the output connections needed to be made in the mother-board of the microcomputer. It has other drawbacks like, the output of the power unit needs to be connected in parallel to the microcomputer''s main power, no monitoring of input AC
mains fluctuations, the microcomputer needs to be rebooted after each power break.
The present invention overcomes the above mentioned drawbacks in a cost-effective method.
OBJECTS OF THE INVENTION :
An object of the present invention is to provide a power back-up for the PC during AC mains failure.
Another object of the present invention is to monitor AC mains input variations.
Another object of the present invention is to act as line interactive, allowing the SMPS of the PC to work with wide AC mains variations.
Yet another object of the present invention is to operate the power back-up whenever AC mains fluctuations go beyond the limit.
An another object of the present invention is to operate the SMPS of the PC in AC as well as DC.
Yet another object of the present invention is to connect AC mains directly to the PC SMPS in case DC-DC converter becomes faulty.
Yet another object of the present invention is to charge the internal 12v battery.
A further object of the present invention is to protect the internal battery from overcharge or deep discharge.
SUMMARY OF INVENTION :
The present invention is a PC with built-in device for total power solution. The built-in total power solution comprises of Microcontroller and charger, DC-DC converter, 12v battery, Auto by pass relay, back-up switch and special SMPS for PC having capability to work on wide range of 230v AC mains as well as 240v DC.
The Microcontroller controls all the monitoring and executing operations necessary to keep the PC and monitor working uninterruptedly. The Microcontroller monitors the input voltage on line for fluctuations and regulation done interactively within the limit of 140-280v AC. In case input voltage goes beyond the limit mentioned, the 12v internal battery supplies the power to the DC-DC converter for feeding power (240v DC) to the SMPS. Similar operation comes into play in absence of AC mains. It also monitors the status of the 12v internal battery during charging and disconnect the charging source to avoid over charging. Similarly it disconnects battery feed to the DC-DC Converter to avoid deep discharging. However before stopping the battery back-up, the PC running programmes are given shut down command to avoid corruption of software. If the DC-DC converter malfunctions, Microcontroller disconnects 12v DC feed to the DC-DC converter and connects AC mains directly to the SMPS (105). During these change-over, the computer will function normal without rebooting and manual intervention.
The device has capability to provide power back-up for 20±5 mins, in absence of AC mains.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS :
Figure 1: Block diagram of PC with built-in device for total power solution
The invention will now be described in an exemplary embodiment as depicted in the accompanying drawing. There can however be other embodiments of the same invention, all of which are deemed covered by the following description.
The present invention, PC with built-in device for total power solution, allows uninterrupted operation of the PC even during power failure for 20min+/-5mins.
The Microcontroller and charger (101) at the input, continuously monitors and regulates AC mains input to the charger. It gives regulated input to the charger for the input ranges from 140v through 280v. When AC mains fluctuates beyond these limits, it cuts off the input to the charger and starts the internal battery back-up. The charger feeds 12v DC to the DC-DC converter (102) and to the internal battery (103) for charging. The Microcontroller monitors the charging status of the battery during charging. It cuts off charging when the battery is fully charged, thus avoids over charging. During back-up period, when the battery charge falls below specified limit, the battery supply to the DC-DC converter is cut-off to avoid deep discharge.
The DC-DC converter (102) converts the 12v DC to 240v DC which is fed to the PC SMPS(105) for powering the PC (106) and monitor (107). The DC-DC converter (102) thus isolates input AC mains from PC SMPS (105) input. Hence any surge from the AC mains will not affect directly the SMPS (105). The DC-DC converter (102) gets 12v DC from the internal battery (103) during battery back-up.
The Microcontroller (101) also monitors the output of the DC-DC converter(102) to the SMPS. In absence of the 240v DC output from the converter (102) due to malfunctioning (even when 12v DC input from the battery is available ), the Microcontroller activates the auto by pass relay (104), having two number NO (normally open) contacts (109,110). The contact (109,110) connects AC mains directly to the SMPS (105). Back-up switch (108) disconnects 12v input to the DC-DC converter (102). The SMPS (105) supplies necessary power to the PC (106) and TFT monitor (107) by operating directly on AC mains.
In case of prolonged power failure when the internal battery (103) gets drained-out beyond a specified limit, the microcontroller (101), shuts down the PC (106) running programmes before shutting down the PC (106) and monitor(107). Thus safeguarding the PC software getting corrupted due to abrupt power shut down.

We claims:-
1. A device in an electronic apparatus to maintain uninterrupted power
supply during AC-mains failure, comprising:
- a switch mode power supply (SMPS) charger block providing a DC output with constant charging current for low-high voltage mains operation, the SMPS being incorporated in the apparatus;
- a controller block to control data flow between the electronic circuits;
- a DC-DC converter block that generates a 250v DC during the back-up mode; and
- a 12v battery enabled to receive power from mains AC supply through the converter block and provide power to the converter block during AC-mains failure.

2. The device as claimed in claim 1, wherein the controller block comprises a micro-controller with a charger.
3. The device as claimed in claim 1, wherein the electronic apparatus is a computer apparatus having a display.
4. The device as claimed in claim 1 or 2, wherein the microcontroller is configured in ten different sections constituting a battery sensing section,

a voltage regulation section, a buzzer sounding section, a switching relay section, a protection section, a power MOSFET section, a no-load shutdown section, a display section, a comparator section, and a communication section.
5. The device as claimed in claim 1, wherein the DC-DC converter is configured with push pull converter topology, and comprising at least one transformer and a PWM-controlled charge controller that generates 250 DC during back-up mode, wherein the microcontroller charger prevents a regulated power supply to the converter from the AC main in absence of power supply or when the voltage fluctuations of the mains supply reach beyond a specified limit, and wherein the microcontroller charger supplying a regulated supply of 12v DC from the mains to the converter and to the internal battery.
6. The device as claimed in claim 1 or 5, wherein the converter converts 12v DC to 240v DC and feeds to the apparatus, and wherein the converter in absence of power from the mains receives 12v DC from the battery and upon boosting up to 240v DC feeds to the apparatus.
7. The device as claimed in claim 1 or 2, wherein the microcontroller is configured to monitor the output from the DC-DC converter to the SMPS, and wherein the microcontroller upon detection of non-supply of 240v DC from the converter activates an auto bypass relay.

8. The device as claimed in claim 7, wherein the auto bypass relay comprises a first contact connecting the AC mains to the SMPS, and a second contact disconnecting 12v input to the DC-DC converter from the microcontroller charger, and wherein the SMPS while operating on mains supplies power to the apparatus.
9. The device as claimed in any one of the preceding claims, wherein when the internal battery gets drained out due to prolonged back-up supply, the microcontroller is enabled to command a shut-down of the programme running on the computer apparatus followed by shutting down of the apparatus.
10.The device as claimed in claim 4, wherein the positive end of the battery sensing section eliminates noise signals and detects the desired battery voltage.
11.The device as claimed in claim 4, wherein the voltage regulation section is provided with a three terminal positive linear regulator to convert the battery generated voltage from 12v to 5v.
12.The device as claimed in claim 4, wherein the buzzer sounding section produces a sound indication when the battery provides back-up supply, or the battery is on the verge of fully discharged, or the battery is fully discharged.

13.The device as claimed in claim 12, wherein the buzzer section comprises a Zener diode to maintain a constant voltage of 5v, and upon the voltage fluctuating beyond the referenced value of 5v, the buzzer sounding an indication.
*14.The device as claimed in claim 4, wherein the switching relay section comprises a single pole double throw (SPDT) relay, and wherein the relay coil is activated by a transistor and a series-connected fast switching diode.
15. The device as claimed in claim 4, wherein the protection section comprises at least two fuses, and wherein the first fuse is disposed in the battery path and the second fuse is disposed on AC mains input.
16.The device as claimed in claim 4, wherein the power MOSFET section comprises at least one power MOSFET, and wherein a combination of NPN and PNP transistors amplifies the received current and supplies to the gate terminal of the power MOSFET.
17.The device as claimed in claim 1 or 4, wherein the display section comprises at least one Green LED and one Red LEED which respectively indicates during the charging mode that supply is thorough the mains, or the UPS operating on battery mode.

18.The device as claimed in claim 1 or 4, wherein the comparator section comprises at least four internally compensated operational amplifiers (OPAMP) operable form a single power supply over a wide range of voltage, wherein at least two OPAMP are used as a set reference value to compare the voltage supplied from the mains, and wherein when the mains average voltage is less than the set average value, the comparator section transmits signals to the microcontroller to operate the power supply in battery mode.
19.The device as claimed in claim 4, wherein the communication section is enabled to transmit and receive data to and from the microcontroller.
20.The device as claimed in claim 4, wherein each of the plurality of sections forming the microcontroller is connected to specified pins of the microcontroller.