CPU COOLING CIRCUIT HAVING THERMOELECTRIC ELEMENT
A CPU cooling circuit for a CPU includes a thermoelectric element and a current source circuit. The thermoelectric element includes a first thermoelectric substrate attached to the CPU, a second thermoelectric substrate opposite to the first thermoelectric substrate, a plurality of n-type semiconductor units and p-type semiconductor units alternately sandwiched between the first and the second thermoelectric substrates and electrically connected in series between a positive power supply input and a negative power supply input. The current source circuit is configured for providing driving current to flow through the n-type semiconductor units and the p-type semiconductor units of the thermoelectric element according to a temperature of the CPU.
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1. Technical Field
The present disclosure relates to a central processing unit (CPU) cooling circuit, and more particularly, to CPU cooling circuit having thermoelectric element.
2. Description of Related Art
During operation of an electronic element of an electronic device, such as a central processing unit (CPU) of a computer, a large amount of heat is often produced. The heat must be quickly removed from the CPU to prevent unstable operation or damage to the CPU. Typically, a heat sink made of aluminum or copper is attached to an outer surface of the CPU to absorb the heat from the CPU. The heat absorbed by the heat sink is then dissipated to the ambient air via a fan attached on the heat sink. However, dissipating heat to air is slow and inefficient. In addition, when the temperature of the CPU is high, the fan will keep operating at a high-speed of rotation, which wastes electric power and shortens the life of the fan.
Therefore, a new system is desired to overcome the above-described shortcomings.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of at least one embodiment. In the drawings, like reference numerals designate corresponding parts throughout the various views.
Reference will now be made to the drawings to describe various disclosed embodiments of the present disclosure in detail, wherein like numerals refer to like elements throughout.
Referring to
As shown in
The thermoelectric element 10 further includes a positive power supply input 110 and an opposite negative power supply input 112 formed on the internal surface of the first substrate 11a for receiving a driving current from the current source circuit 20.
When current flows through the semiconductor units 101a and 101b, pn junctions of the semiconductor units 101a and 101b attached to the first substrate 11a have current flowing from the n-type semiconductor units 101a to the p-type semiconductor units 101b and form a cooler portion, whereas, other pn junctions of the semiconductor units 101a and 101b attached to the second substrate 11b have current flowing from the p-type semiconductor units 101b to the n-type semiconductor units 101a and form a heater portion. Therefore, heat can be conducted from the first substrate 11a to the opposite second substrate 11b via the semiconductor units 101a and 101b. A heat conductive efficiency of the thermoelectric element 10 is in direct proportion to the current flowing therethrough.
The circuit 20 includes a voltage comparator 21, a thermal resistor R1, a current division resistor R2, a plurality of current sampling resistors R3, and a plurality of switches Q.
In this embodiment, the voltage comparator 21 is an LM358DRG4 chip produced by Texas Instruments, Incorporated. The voltage comparator 21 includes a first input I1, a second input I2, a third input I3, a fourth input I4, a first output O1, and a second output O2.
The thermal resistor R1 has a negative temperature index and its resistance decreases with an increase its temperature. In this embodiment, the thermal resistor R1 connects in parallel with the current division resistor R2 between the first input I1 and an external power supply VCC. In one embodiment, the thermal resistor R1 is positioned adjacent to the first substrate 11a of the thermoelectric element 10 to sense a temperature of the thermoelectric element 10.
In this embodiment, as shown in
In this embodiment, as shown in
In operation, when a CPU attached to the first substrate 11a of the thermoelectric element 10 normally works it can make the temperature of the thermoelectric element 10 increase, the resistance of the thermal resistor R1 correspondingly decreases according to the increased temperature of the thermoelectric element 10. Thus, a current flowing through the thermal resistor R1 is increased to improve an output power of the current source circuit 20 to drive the thermoelectric element 10 for cooling the CPU. The voltage comparator 21 also increases a driving voltage to gate electrode G of each NMOS transistor Q to increase a current flowing through the thermoelectric element 10.
The fourth input I4 is used to detect the current flowing through the thermoelectric element 10 and compares the current flowing through the thermoelectric element 10 with a reference voltage Vref of the third input I3. In one embodiment, when the current flowing through the thermoelectric element 10 is over 20 amperes, the voltage comparator 21 control the first output I1 to turn off the switches Q for protecting the circuit 20 and send an alarm signal to an external device, such as a speaker, to warn of the over-current condition of the CPU cooling circuit 100.
It is to be understood, however, that even though numerous characteristics and advantages of certain inventive embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of arrangement of parts within the principles of present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Claims
1. A CPU cooling circuit for a CPU, comprising:
- a thermoelectric element comprising a first thermoelectric substrate attached to the CPU, a second thermoelectric substrate opposite to the first thermoelectric substrate, a plurality of n-type semiconductor units and p-type semiconductor units alternately sandwiched between the first and the second thermoelectric substrates and electrically connected in series between a positive power supply input and a negative power supply input; and
- a current source circuit configured for providing driving current to flow through the n-type semiconductor units and the p-type semiconductor units of the thermoelectric element according to a temperature of the CPU.
2. The CPU cooling circuit of claim 1, wherein pn junctions of the p-type and the n-type semiconductor units attached to the first thermoelectric substrate have current flowing from the n-type semiconductor units to the p-type semiconductor units.
3. The CPU cooling circuit of claim 2, wherein pn junctions of the p-type and the n-type semiconductor units attached to the second thermoelectric substrate have current flowing from the p-type semiconductor units to the n-type semiconductor units.
4. The CPU cooling circuit of claim 1, wherein a heat conductive efficiency of the thermoelectric element is in direct proportion to the current flowing through the p-type and the n-type semiconductor units.
5. The CPU cooling circuit of claim 1, further comprising a first electrically conductive pattern and a second electrically conductive pattern formed at internal surfaces of the first and the second thermoelectric substrates, respectively, the p-type semiconductor units and the n-type semiconductor units are electrically connected via the first conductive pattern and the second conductive pattern.
6. The CPU cooling circuit of claim 1, wherein the current source circuit comprises a voltage comparator, a thermal resistor, a plurality of switches, and a plurality of current sampling resistors, the voltage comparator comprises a first input configured for receiving an external power supply via the thermal resistor, and a first output configured for controlling the current provided from the external power supply to the positive power supply input via the plurality of switches, the negative power supply input is grounded via the current sampling resistors.
7. The CPU cooling circuit of claim 6, wherein the plurality of switches are n-channel metal-oxide-semiconductor (NMOS) transistors.
8. The CPU cooling circuit of claim 7, wherein the first output connected to a gate electrode of each NMOS transistor, the external power supply is connected to the positive power supply input via a drain electrode and a source electrode of each NMOS transistor.
9. The CPU cooling circuit of claim 8, wherein the voltage comparator further comprises a second input connected to source electrode of each NMOS transistor via a resistor.
10. The CPU cooling circuit of claim 6, wherein the plurality of switches are p-channel metal-oxide-semiconductor (PMOS) transistors.
11. The CPU cooling circuit of claim 6, wherein the plurality of switches are npn type bipolar transistors.
12. The CPU cooling circuit of claim 6, wherein the plurality of switches are pnp type bipolar transistors.
13. The CPU cooling circuit of claim 6, wherein the voltage comparator further comprises a third input configured for receiving a reference voltage and a fourth input connected to the negative power input terminal to detect the current flowing through the thermoelectric element by the current sampling resistors.
14. The CPU cooling circuit of claim 6, wherein the thermal resistor has a negative temperature index.
15. The CPU cooling circuit of claim 14, wherein further comprising a current division resistor connected in parallel with the thermal resistor.
Type: Application
Filed: Jun 21, 2010
Publication Date: Sep 22, 2011
Applicants: HONG FU JIN PRECISION INDUSTRY (ShenZhen) CO., LTD. (Shenzhen City), HON HAI PRECISION INDUSTRY CO., LTD. (Tu-Cheng)
Inventors: HAI-QING ZHOU (Shenzhen City), SONG-LIN TONG (Shenzhen City)
Application Number: 12/820,044
International Classification: F25B 21/02 (20060101);