KR100665286B1 - A power backup circuit of gps module for mobile terminal - Google Patents

Abstract

A power backup circuit of a GPS module of a mobile terminal is provided to stably provide power and lengthen an operation time of an RTC(Real Time Clock) unit. The first diode(D21) supplies the first operation voltage(Vdd1) from a GPS power source unit(10) uni-directionally. The second diode(D22) supplies the second operation voltage(Vdd2) from a main power source unit(40) uni-directionally. A VD(Voltage Detector)(110) detects the first operation voltage(Vdd1) through the first diode(D21) and/or the second operation voltage(Vdd2) through the second diode(D22), and supplies the detected voltage to an RTC unit(31). A battery charges the first operation voltage(Vdd1) through the first diode(D21) and/or the second operation voltage(Vdd2) through the second diode(D22).

Description

A POWER BACKUP CIRCUIT OF GPS MODULE FOR MOBILE TERMINAL}

1 is a block diagram of a conventional portable terminal.

2 is an operation time chart when the GPS module of FIG. 1 is turned off.

3 is a block diagram of a mobile terminal according to the present invention;

4 is an operation time chart when the GPS module of FIG. 3 is turned off.

Explanation of symbols on the main parts of the drawings

10: GPS power supply unit 30: GPS module

31: real time clock part 40: main power supply part

100: power supply backup circuit 110: voltage detector

D21: first diode D22: second diode

Vdd1: first operating voltage Vdd2: second operating voltage

R20: protective resistor BAT20: battery

The present invention relates to a power supply backup circuit of a GPS module for a mobile terminal such as a mobile phone, and in particular, by implementing the power supply to the real time clock part of the GPS module using the main power supply of the portable terminal, thereby providing a stable real time clock ( The present invention relates to a power supply backup circuit of a GPS module for a mobile terminal, which can supply an RTC), reduce an initial positioning time (TTFF), and reduce costs when a battery and an associated circuit element are not used.

In general, the Global Positioning System (GPS) is an all-nation radio navigation satellite system developed and promoted by the Department of Defense (DOD) and is a medium- and high-orbit navigation satellite system NAVSTAR (NAVigation System with Time). And Ranging) is also called NAVSTAR / GPS in the sense of the system using. The system consists of a total of 24 navigating satellites, each of which was launched on six circular orbits at an altitude of approximately 20,000 km, a period of about 12 hours, and an orbital inclination of 55 degrees, a ground control station that manages satellites, and a user's mobile station. Each satellite is equipped with an atomic clock. Since the system is arranged so that at least two satellites are in the field of view at all times around the globe, the user can select four of these satellites and measure each distance using visual signals contained in the GPS signal from this selected satellite. do. Since the positions of the four satellites are known, these measurements show the user's latitude, warning, and altitude in three-dimensional positions and the visual deviation of the field of view. The transmission frequency from the satellite is two waves of L1 band L1 (1,575.42MHz) and L2 (1,227.6MHz), and these two waves compensate for ionospheric delay.

Such GPS receivers measure latitude, longitude, altitude, speed and time using GPS data transmitted from satellites. At this time, the GPS data includes detailed satellite orbit information (Ephemeris), simple satellite orbit information (Almanac) and time (Time). Here, the detailed satellite orbit information (Ephemeris) is the orbital orbit information of each GPS satellite, and includes not only previous and current orbit information, but also future orbit estimates. The simplified satellite orbit information Almanac is a simplified form of the detailed satellite orbit information Ephemeris and includes approximate location information of all GPS satellites.

On the other hand, in the GPS receiver, according to the first determination time (TTFF: Time to first fix) for positioning (at the time of position fix), the cold start, the warm start and the hot start In the case of the cold start (in case of GPS data over 4 hours), the first determination time takes about 55 seconds, and in the case of warm start (in the case of GPS data over 4 hours), It can take up to 34 seconds, or up to 8 seconds for Hot Start (for GPS data older than 30 minutes).

That is, the GPS module includes simple satellite orbit information (Almanac), detailed satellite orbit information (Ephemers), time and position, etc., which are information for determining position, speed, and time in a memory in the initial state of the navigation operation. Cold start to perform position fix without any information of position and position using LKG (Last Known Good) data and time information saved during position fix. A warm start is made to make the decision.

However, in order to obtain such valid time information, a battery for supplying power to the real time clock part that generates the real time clock is required, and the battery life of each battery is about 1000 times. Different from each other, in order to increase the capacity of such a battery, a large capacity battery (Battery) should be used, but this has a limitation in using a large capacity battery due to limitations in the charge space, size and thickness of the GPS module.

1 is a block diagram of a conventional portable terminal.

The conventional portable terminal shown in FIG. 1 supplies a GPS power supply unit 10 for supplying an operating voltage Vdd for a GPS module, and an operating voltage Vdd from the GPS power supply unit 10 as a real time clock voltage. And a power backup circuit 20 which charges the operating voltage Vdd to a rechargeable battery and supplies the voltage charged to the battery as a real time clock voltage when the operating voltage Vdd is blocked. The GPS module 30 includes a real time clock unit 31 that receives an operating voltage from the circuit 20 and generates a real time clock.

The power backup circuit 20 includes a diode D1 for detecting an operating voltage Vdd from the GPS power supply unit 10 and a battery for charging the voltage from the diode D1 through a resistor R1 ( BAT1 and a voltage detector 21 which detects a voltage at a connection point between the diode D1 and the battery BAT1 and supplies it to the GPS module 30.

For example, in order to apply power to the GPS module, 3.0VDC power is applied to the operating voltage Vdd, and the battery is charged through the diode D1 and the resistor R1 to prevent reverse current. At the same time, the RTC unit 31 operates by being applied to a real time clock unit (RTC unit) 31 in the GPS module 30 via a voltage detector.

In addition, when the operating voltage Vdd is turned off, the voltage charged in the battery is transferred to the real of the GPS module 20 through the voltage detector 21 through the resistor R1. The real time clock unit 31 is applied to the time clock unit (RTC unit) 31.

However, in such a conventional mobile terminal, in the power backup circuit 20, the battery BAT1 should supply a voltage even when the GPS module is in the off state for a long time. As shown in FIG. When discharged, there is a case in which a voltage cannot be supplied during a charged time for hot start or warm start, and in this case, since the real time clock part does not operate, there is a problem in that the GPS module is switched to cold start. .

For example, referring to FIG. 2, FIG. 2 is an operation time chart when the GPS module of FIG. 1 is turned off. In FIG. 2, when the supply of the operating voltage Vdd is stopped at the same time as the GPS module is turned off, a voltage is supplied from the battery BAT1 to the GPS module. If the battery is discharged, the voltage of the battery is quickly discharged. This completes the supply of voltage for a sufficient time for the real time clock portion of the GPS module. Accordingly, since the real time clock cannot generate a real time clock, the time check fails.

As such, when the time check fails, the GPS module performs a cold start irrespective of the GPS module operation off time, which causes a problem in that a large amount of time is required for positioning.

The present invention has been proposed to solve the above problems, the object of which is to implement a stable real time clock (RTC) by implementing a power supply to the real time clock portion of the GPS module using the main power of the portable terminal at all times The present invention provides a power supply backup circuit for a GPS module for a portable terminal that can be supplied, can reduce initial positioning time (TTFF), and can reduce costs when a battery and related circuit elements are not used.

In order to achieve the above object of the present invention, the power backup circuit of the GPS module for a portable terminal of the present invention is applied to a portable terminal including a GPS power supply unit, a GPS module including a real time clock unit and a main power supply unit. A power backup circuit for supplying a voltage from a power supply unit to the GPS module, comprising: a first diode for unidirectionally supplying a first operating voltage from the GPS power supply unit; A second diode which supplies a second operating voltage from the main power supply unit in a unidirectional direction; And a voltage detector for detecting a first operating voltage through the first diode and / or a second operating voltage through the second diode and supplying the detected voltage to the real time clock unit.

The power backup circuit may further include a battery configured to charge a first operating voltage through the first diode and / or a second operating voltage through the second diode.

The second diode is characterized in that the anode terminal is connected to the second operating voltage terminal of the main power supply unit, the cathode terminal is connected to the positive electrode of the battery.

The first diode is characterized in that the anode terminal is connected to the first operating voltage terminal of the GPS power supply unit, the cathode terminal is connected to the positive electrode of the battery through a protective resistor.

The voltage detector is connected to a first connection node between the cathode terminal of the first diode and the protection resistor, and detects a voltage of the first connection node.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

3 is a block diagram of a portable terminal according to the present invention.

Referring to FIG. 3, the portable terminal according to the present invention includes a GPS power supply unit 10, a GPS module 30 including a real time clock unit 31, a main power supply unit 40, and a power backup circuit 100. do.

The power backup circuit 100 includes a first diode D21 for supplying the first operating voltage Vdd1 from the GPS power supply 10 in one direction and a second operating voltage from the main power supply 40. The second diode D22 for supplying Vdd2 in one direction, the first operating voltage Vdd1 through the first diode D21 and / or the second operating voltage Vdd2 through the second diode D22. And a voltage detector 110 for supplying the detected voltage to the real time clock unit 31.

The power backup circuit may further include a battery BAT20 that charges the first operating voltage Vdd1 through the first diode D21 and / or the second operating voltage Vdd2 through the second diode D22. It may include.

The first diode D21 has an anode terminal connected to a first operating voltage Vdd1 terminal of the GPS power supply unit 10, and a cathode terminal of the first diode D21 is connected to a positive electrode of the battery BAT20 through a protective resistor R20. Connected.

The voltage detector 110 is connected to the first connection node N1 between the cathode terminal of the first diode D21 and the protection resistor R20 to detect the voltage of the first connection node.

The second diode D22 has an anode terminal connected to a second operating voltage Vdd2 terminal of the main power supply unit 40, and a cathode terminal of the second diode D22 is an anode of the battery BAT20, that is, the first protective resistor. And a second connection node N2 between R20 and the battery BAT20.

4 is an operation time chart when the GPS module of FIG. 3 is turned off.

In FIG. 4, when the GPS module is turned off, the first operating voltage Vdd1 of the GPS module is cut off and a second operating power supply Vdd2 is supplied to the GPS module. It can be seen that the first operating voltage Vdd1 and / or the second operating power source Vdd2 are supplied to generate a real time clock stably while the GPS module is turned off.

Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.

The power supply backup circuit of the GPS module for a mobile terminal of the present invention is applied to a mobile terminal such as a mobile phone, and when the GPS module is turned off, the operating voltage is always generated so that a real time clock necessary for time check for position calculation can be generated. Always supply

This will be described with reference to FIGS. 3 and 4.

Referring to FIG. 3, in the portable terminal to which the power backup circuit 100 of the present invention is applied, the GPS power supply unit 10 generates a first operating voltage Vdd1 while the GPS module is turned on. Supply to the backup circuit 100. When the portable terminal to which the power backup circuit 100 of the present invention is applied is in a power-on state, the main power supply 40 generates a second operating voltage Vdd2 and supplies it to the power backup circuit 100.

First, a description will be given of a power supply process in the GPS module 30 operating on state.

In the power supply backup circuit 100 of the present invention, the first diode D21 detects the first operating voltage Vdd1 from the GPS power supply unit 10. The voltage detector 110 of the present invention detects the first operating voltage Vdd1 detected by the first diode D21 and supplies the operating voltage to the real time clock unit 31 of the GPS module 30. do. Accordingly, the real time clock unit 31 normally generates a real time clock.

In addition, when the power backup circuit 100 of the present invention includes the battery BAT20 as shown in FIG. 3, the first operating voltage Vdd1 detected by the first diode D21 is a protection resistor ( The battery BAT20 is charged through R20.

As described above, looking at the path for supplying the voltage to the real time clock unit 31 of the GPS module, in order to apply power to the GPS module 30, the first operating voltage from the GPS power supply unit 10 ( A voltage of approximately 3.0 VDC, which is Vdd1), is applied and charged to the battery BAT20 through the protection resistor R20 after passing through the first diode D21 for preventing reverse current. At the same time, power is applied to the back-up through the voltage detector to operate the real time clock of the GPS module 30.

Next, a description will be given of the power supply process in the GPS module 30 in the operation off state.

In the portable terminal to which the power backup circuit of the present invention is applied, when the operation of the GPS module is turned off, the first operating voltage Vdd1 is not supplied from the GPS power supply unit 10.

In this case, the voltage charged in the battery BAT20 is supplied to the real time clock part 31 of the GPS module 30 through the voltage detector 110.

If the voltage charged in the battery BAT20 is completely discharged, since the voltage cannot be supplied to the real time clock part 31 of the GPS module 30, the real time clock part 31 normally operates. You will not be able to create a real-time clock.

By the way, in the present invention, the first diode D21 detects the second operating voltage Vdd2 from the main power supply 40 of the portable terminal to which the present invention is applied. The voltage detector 110 of the present invention detects the second operating voltage Vdd2 detected by the second diode D22 and supplies the operating voltage to the real time clock unit 31 of the GPS module 30. do. Accordingly, in the state in which the GPS module 30 is turned off, the real time clock unit 31 normally generates a real time clock regardless of the state of the charging voltage of the battery BAT20.

In the present invention as described above, in the portable terminal to which the GPS module is applied, the backup battery of the GPS module uses a main power source, which is a high capacity battery of the main body of the mobile terminal, through an external main power input terminal (PIT) during over discharge, for a long time. Stable power supply enables normal real-time clock operation.

As shown in FIG. 4, in the portable terminal to which the present invention is applied, the first operating voltage Vdd1 of the GPS module is cut off at the time T0 when the GPS module is turned off, but at the same time, the second operating power source Vdd2 is blocked. ) Is supplied to the real time clock unit 31 of the GPS module, so that the real time clock unit 31 is continuously supplied with the operating voltage, and thus the real time clock is stably maintained in the off state of the GPS module. Since it is possible to check the normal time (T1, T2, T3, ...).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, but is defined by the claims, and the apparatus of the present invention may be substituted, modified, and modified in various ways without departing from the spirit of the present invention. It is apparent to those skilled in the art that modifications are possible.

According to the present invention as described above, in the power supply backup circuit of the GPS module for a portable terminal such as a mobile phone, by implementing the power to always supply the real time clock portion of the GPS module using the main power of the portable terminal, stable real Time clock (RTC) can be supplied, initial positioning time (TTFF) can be shortened, and the cost can be reduced when battery and related circuit devices are not used.

That is, in terms of performance, by adopting a circuit that uses a main power source, which is an external power source in common, it is possible to supply a more stable power supply, thereby extending the operating time of the real-time clock part, and thereby positioning for the first time. The time TTFF can be shortened. In addition, by adopting the external and internal dual input battery structure, more stable circuit operation is possible.

In terms of cost, 90% of the cost of the battery back-up circuit is the battery price, and the internal battery and the diode can be selectively used, and when the battery and the diode are not used, the cost is increased. Can be saved.

In addition, the product can respond to market needs and can be fully differentiated from competitors.

Claims (5)

In the power supply backup circuit is applied to a portable terminal including a GPS power supply unit, a GPS module including a real-time clock unit and a main power supply unit, the power backup circuit for supplying a voltage from each power supply unit to the GPS module,   A first diode which supplies a first operating voltage from the GPS power supply unit in one direction; A second diode which supplies a second operating voltage from the main power supply unit in a unidirectional direction; And A voltage detector for detecting a first operating voltage through the first diode and / or a second operating voltage through the second diode and supplying the detected voltage to the real time clock part Power backup circuit of the GPS module for a mobile terminal comprising a. The method of claim 1, wherein the power backup circuit, A battery charging a first operating voltage through the first diode and / or a second operating voltage through the second diode Power backup circuit of the GPS module for a mobile terminal further comprising a. The method of claim 1, wherein the second diode, And an anode terminal thereof is connected to the second operating voltage terminal of the main power supply unit, and a cathode terminal thereof is connected to the positive electrode of the battery. The method of claim 3, wherein the first diode, And an anode terminal thereof is connected to the first operating voltage terminal of the GPS power supply unit, and a cathode thereof is connected to the positive electrode of the battery through a protection resistor. The method of claim 4, wherein the voltage detector, And a voltage connected to the first connection node between the cathode terminal of the first diode and the protection resistor to detect the voltage of the first connection node.

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