CN109960304B - Temperature detection circuit and implantable medical device using same - Google Patents
Temperature detection circuit and implantable medical device using same Download PDFInfo
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- CN109960304B CN109960304B CN201810297871.2A CN201810297871A CN109960304B CN 109960304 B CN109960304 B CN 109960304B CN 201810297871 A CN201810297871 A CN 201810297871A CN 109960304 B CN109960304 B CN 109960304B
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- 238000001514 detection method Methods 0.000 title claims abstract description 57
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/567—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for temperature compensation
Abstract
The invention discloses a temperature detection circuit, which comprises: a temperature sensing circuit for acquiring temperature and voltage; a reference current generation circuit for acquiring a reference current with a zero temperature coefficient; trimming circuit for proportionally mirroring the reference current to trimming current; a voltage generation circuit that generates a reference voltage and a threshold voltage corresponding to a first threshold temperature; a comparison circuit comparing the temperature voltage with the threshold voltage, outputting a first control signal if the temperature voltage is greater than the threshold voltage, and outputting a second control signal if the temperature voltage is less than or equal to the threshold voltage; after the temperature detection circuit provided by the invention generates the reference current with adjustable temperature coefficient, the reference current is mirrored in the reference voltage circuit and the threshold voltage circuit in proportion through the trimming circuit and the voltage generation circuit so as to correspondingly generate the reference voltage and the threshold voltage which are not influenced by temperature change, so that the comparison result of the comparison circuit is more accurate, and the energy consumption of the whole circuit is reduced.
Description
Technical Field
The invention belongs to the field of implantable medical devices, and particularly relates to a temperature detection circuit and an implantable medical device using the same.
Background
Among implantable medical devices, neurostimulators effectively control symptoms of functional neurological and psychiatric disorders by chronically electrically stimulating target nerves, such as pacemakers for treating cardiac arrhythmias, defibrillators for treating cardiac fibrillation, retinal stimulators for treating ocular blindness, muscle stimulators for producing coordinated limb movements, and the like.
Generally, components of an implantable neurostimulator include a stimulation chip, a stimulation controller, a wireless communication module, a voltage conversion module, a wireless charging module, a battery, and the like. The implantable neurostimulator consumes electrical energy during normal operation, and the more functions consume more electrical energy. The battery with the electric quantity of 5000mAh can be used for 5 years under normal conditions, if the electric quantity of the battery is exhausted, the stimulator needs to be replaced by a new operation, so that the pain of a patient is increased, and the financial burden of the patient is increased.
In order to solve the problems, the implantable stimulator supporting wireless charging becomes a research hot spot, and the device can be directly charged without replacing a battery, thereby reducing financial burden of a patient and greatly avoiding pain caused by secondary operation of the patient. Meanwhile, because the battery is small in size, the monitoring items of the stimulator are increased conveniently and rapidly due to wireless charging, medical staff can better solve the condition of patients, and a better treatment effect is achieved.
The wireless charging electric energy has energy loss in the transmission process, wherein a part of energy is released in a heat energy form, and the problem is that the temperature of the part of the human body where the stimulator is implanted is increased. If the temperature is continuously increased and exceeds the human body temperature by a certain value, the human body feels uncomfortable, and the human body tissues can be damaged under extreme conditions; in order to realize temperature monitoring, a thermistor is generally integrated in a PCB to be used for temperature detection in the prior art, but because the thermistor has large error and is easy to absorb current, the temperature monitoring accuracy is reduced, meanwhile, the burden of a battery is also increased, and the thermistor is used as an external device, so that the possibility of being damaged by an instrument is high, the occupied space is large, and the smaller implantation device is not beneficial to manufacture.
Disclosure of Invention
In order to solve the above-described problems, the present invention proposes a temperature detection circuit including:
a temperature sensing circuit configured to acquire a temperature voltage that varies with temperature;
a reference current generation circuit including a current source and a temperature coefficient adjustment circuit connected to an output of the current source, the temperature coefficient adjustment circuit configured to adjust a current generated by the current source to a reference current having a temperature coefficient of zero;
a trimming circuit comprising a first mirror circuit configured to mirror the reference current in proportion to a trimming current;
a voltage generation circuit including a reference voltage circuit, a threshold voltage circuit, and a second mirroring circuit configured to mirror the trimming current to the reference voltage circuit and the threshold voltage circuit to generate a reference voltage having a temperature coefficient of zero and a threshold voltage corresponding to a first threshold temperature;
and a comparison circuit configured to compare the temperature voltage with a threshold voltage, output a first control signal if the temperature voltage is greater than the threshold voltage, and output a second control signal if the temperature voltage is less than or equal to the threshold voltage.
As a further improvement of the present invention, the temperature coefficient adjusting circuit includes a first branch and a second branch, the first branch is configured with a first MOS transistor and a first bipolar transistor, and the second branch is configured with a second MOS transistor and a second bipolar transistor; the output ends of the first MOS tube and the second MOS tube are correspondingly connected with the input ends of the first bipolar transistor and the second bipolar transistor respectively.
As a further improvement of the present invention, the temperature coefficient adjusting circuit further includes a third branch configured with a first adjusting resistor connected between the output end of the first MOS transistor and the ground end of the temperature detecting circuit; and a second adjusting resistor connected between the output end of the first MOS tube and the input end of the first bipolar transistor is arranged on the first branch, and the temperature coefficient of the reference current is adjusted by changing the resistance values of the first adjusting resistor and the second adjusting resistor.
As a further improvement of the invention, the area ratio of the grid electrodes of the first MOS tube and the second MOS tube is set to be a first preset area ratio.
As a further improvement of the present invention, the area ratio of the emitters of the first bipolar transistor and the second bipolar transistor is set to a second preset area ratio.
As a further improvement of the invention, the first mirror circuit comprises a first trimming transistor and a second trimming transistor, and the grid electrode of the second trimming transistor is correspondingly connected with the grid electrode of the first trimming transistor.
As a further improvement of the present invention, the trimming circuit changes the transistor number ratio of the second trimming transistor to the first trimming transistor by connecting a plurality of the second trimming transistors in parallel to mirror-trim the reference current to a trimming current in proportion.
As a further improvement of the invention, the threshold voltage circuit comprises a threshold resistor, which is arranged as an adjustable resistor to generate a corresponding threshold voltage in cooperation with the trimming current.
As a further improvement of the present invention, the threshold voltage circuit further includes a hysteresis circuit configured to generate a hysteresis voltage, the hysteresis circuit is activated after the second control signal is generated to convert the threshold voltage into a hysteresis voltage corresponding to a second threshold temperature, the temperature voltage and the hysteresis voltage are compared by a comparison circuit, if the temperature voltage is less than or equal to the hysteresis voltage, the comparison circuit continuously outputs the second control signal, and if the temperature voltage is greater than the hysteresis voltage, the comparison circuit outputs the first control signal.
As a further improvement of the invention, the hysteresis circuit comprises a hysteresis resistor, and after the second control signal activates the hysteresis circuit, the hysteresis resistor is connected into the threshold voltage circuit to generate a hysteresis voltage in cooperation with the trimming current.
As a further improvement of the invention, the comparison circuit comprises a filter circuit and a voltage comparator, wherein the output end of the filter circuit is connected with the input end of the voltage comparator, and the filter circuit is used for removing transient signals of the voltage entering the voltage comparator and smoothing the value of the voltage.
As a further improvement of the invention, the output end of the voltage comparator is connected with two voltage inverters in series, and the output signal of the voltage comparator is shaped and balanced for signal delay.
As a further improvement of the invention, the temperature detection circuit further comprises a starting circuit, wherein the starting circuit comprises a first switch MOS tube and a second switch MOS tube, and when the first switch MOS tube is conducted, the reference current generation circuit is conducted, so that the second switch MOS tube is conducted; and after the second switch MOS tube is conducted, the first switch MOS tube is closed, so that the starting circuit is closed.
As a further improvement of the invention, the temperature sensing circuit comprises a temperature sensing element configured as a set of transistors with collectors connected to the base stage.
As a further improvement of the present invention, the second mirror circuit is further configured to mirror the trimming current to the temperature sensing circuit to generate a temperature voltage in cooperation with the set of transistors.
Furthermore, the invention also provides an implantable medical device, which comprises a charging module with a wireless charging function, wherein the charging module comprises a control unit and a temperature detection unit which are in communication connection, the temperature detection unit comprises any one of the temperature detection circuits, and when the temperature detection unit detects that the current temperature is smaller than a first threshold temperature, the control unit controls the charging module to start the wireless charging function; when the temperature detection unit detects that the current temperature is greater than or equal to a first threshold temperature, the control unit controls the charging module to close the wireless charging function.
As a further improvement of the present invention, the temperature detection unit includes a hysteresis comparison unit that converts a first threshold temperature to a second threshold temperature when the charging module turns off a wireless charging function; when the temperature detection unit detects that the current temperature is greater than or equal to a second threshold temperature, the control unit controls the charging module to keep the wireless charging function closed; when the temperature detection unit detects that the current temperature is smaller than the second threshold temperature, the control unit controls the wireless charging module to start a wireless charging function.
The technical effects are as follows: according to the temperature detection circuit provided by the invention, the reference current with adjustable temperature coefficient is generated through the reference current generation circuit, and then the reference current is mirrored in proportion to the reference voltage circuit and the threshold voltage circuit through the first mirroring circuit of the trimming circuit and the second mirroring circuit of the voltage generation circuit so as to correspondingly generate the reference voltage and the threshold voltage which are not influenced by temperature change, so that the comparison result of the comparison circuit is more accurate, and the energy consumption of the whole circuit is reduced.
Drawings
FIG. 1 is a circuit diagram of a temperature detection circuit in an embodiment of the invention;
FIG. 2 is a circuit diagram of a threshold voltage versus temperature voltage comparison circuit according to an embodiment of the invention;
FIG. 3 is a circuit diagram of a hysteresis voltage versus temperature voltage comparison circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram showing the correspondence between voltage and temperature according to an embodiment of the present invention;
fig. 5 is a control flow diagram of an embodiment of the present invention.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Specific embodiments of the technical scheme of the present invention are described in detail below:
the invention provides an implantable medical device and a temperature detection circuit in an integrated circuit thereof.
Specifically, referring to fig. 1 and 2, the temperature detection circuit provided by the present invention includes a temperature sensing circuit 100 for acquiring a temperature voltage Vsense, a reference current generating circuit 200 for generating a reference current Iref, a trimming circuit 300 for generating a trimming current Io, a voltage generating circuit 400 for generating a reference voltage Vbg and a threshold voltage Vref, and a comparing circuit 500 for comparing the temperature voltage Vsense with the voltage value of the threshold voltage Vref, wherein the first control signal Vo1 is output if the temperature voltage Vsense is greater than the threshold voltage Vref, and the second control signal Vo2 is output if the temperature voltage Vsense is less than or equal to the threshold voltage Vref.
The generation of the temperature voltage Vsense, the reference current Iref, the reference voltage Vbg, and the threshold voltage Vref in the present invention will be further described with reference to the circuit diagram of fig. 1:
the temperature sensing circuit 100 includes temperature sensing elements connected in series, in which the temperature sensing elements are configured such that a collector is connected to a triode Q3 and a triode Q4, and an emitter of the triode Q3 is connected to a collector of the triode Q4, and when the temperature changes, a forward voltage drop of the triode decreases with an increase in temperature, that is, when the temperature increases, a temperature voltage Vsense decreases according to characteristics of the triode.
The reference current generating circuit 200 includes a current source and a temperature coefficient adjusting circuit connected to an output terminal of the current source, and the temperature coefficient adjusting circuit includes a first branch 210, a second branch 220, and a third branch 230.
Further, the current source includes PM2, PM3 disposed in the third branch 230, PM4, PM5 disposed in the first branch 210, and PM6, PM7 disposed in the second branch 220, wherein PM2 and PM4, PM3 and PM5, PM4 and PM6, PM5 and PM7 are current mirrors, which together mirror the reference current Iref to the first branch 210, the second branch 220 and the third branch 230, so that the current in each branch is more stable, and the overall power consumption of the reference current generating circuit 200 is reduced.
The temperature coefficient adjusting circuit includes a first MOS transistor NM5, a first bipolar transistor Q1, and a first adjusting resistor R5 disposed in the first branch 210, a second MOS transistor NM6, a second bipolar transistor Q0 disposed in the second branch 220, and a second adjusting resistor R4 disposed in the third branch 230; the source electrode of NM5 is connected with the collector electrode of Q1 through R5, the source electrode of NM6 is connected with the collector electrode of Q0, and meanwhile, R4 is connected between the drain electrode of NM5 and the ground terminal.
Specifically, the derivation process of the reference current Iref is as follows:
where NM5 and NM6 are NMOS transistors, vgs5 represents the voltage difference from the gate Vg to the source V1 of NM5, vgs6 represents the voltage difference from the gate Vg to the source Vbe0 of NM6, vth represents the nominal turn-on voltage to the NMOS transistor, and k=0.5×μ×cox, K represents the cross-over coefficient, which is generally related to the process, W represents the channel width of the transistor, and L represents the channel length of the transistor.
Further, the areas of the gates of the first MOS transistor NM5 and the second MOS transistor NM6 are provided with a first preset area ratio, and in this embodiment, the first preset area ratio is set to 1:2, so that under the action of the current mirrors PM2 and PM4, PM3 and PM5, PM4 and PM6, and PM5 and PM7, the currents of the first branch 210 and the third branch 230 are Iref, and the current of the second branch 220 is 2Iref.
Meanwhile, it can be further deduced from the formula (1):
Vgs5＝Vgs6，V 1 ＝Vbe0 (2)
further, the first bipolar transistor Q1 and the second bipolar transistor Q0 are transistors, and the emitter areas of the first bipolar transistor Q1 and the second bipolar transistor Q0 are provided with a second preset area ratio, in this embodiment, the second preset area ratio is set to 24:1, and according to the current characteristics of the transistors, it is possible to obtain:
where Iq1 represents the emitter current of Q1, iq0 represents the emitter current of Q0, is represents the transistor transfer characteristic constant in the forward amplifying region of the transistor, V T Represents the thermal voltage value, and V T =kt/q, k is boltzmann constant: k=1.38×10 -28 J/K, q is charge level: q=1.6x10-19 coulombs, T representing the current temperature (kelvin temperature).
From equation (3), it can be derived that:
and then deducing that:
Vbe0-Vbe1＝V τ *ln24 (4)
the derived formula for Iref can be derived by referring to the first leg 210 and combining formula (4):
in equation (5), the voltage of Vbe0 is inversely proportional to temperature, and V is known from the thermal voltage equation as varying with temperature at a rate of about-2.0 mV/. Degree.C T The temperature coefficient of Iref can be regulated by regulating the resistance values of the first regulating resistor R5 and the second regulating resistor R4 in proportion to the temperature, and the effect that the temperature coefficient of Iref is zero, namely the temperature coefficient is not changed along with the temperature change is finally realized; specifically, the values of R4 and R5 are chosen to limit the temperature coefficient of Iref, and further ensure low power consumption of the whole circuit, so as to reduce the power consumption of the battery, in this embodiment, r4=2.4mΩ, r5=350kΩ are chosen, and finally, the reference current iref=250na is obtained.
Further, trimming circuit 300 includes a first mirror circuit configured to mirror the reference current Iref to a trimming current Io in proportion, wherein a scaling factor of Iref and Io is set to a, and io=a×iref.
Specifically, the first mirror circuit includes a first trimming transistor and a second trimming transistor, where in this embodiment, the first trimming transistor includes NM7 and NM8 set as NMOS transistors, and the second trimming transistor includes NM9 and NM10 set as NMOS transistors; wherein the gates of NM9 and NM10 are correspondingly connected to the gates of NM7 and NM8, and the drains of NM7 and NM8 are connected to the gates, and NM9 is changed by modifying the number of NM9 and NM10 transistors: NM7 and NM10: the proportional relation of NM8 affects the value of the scaling factor a, and further adjusts the reference current Iref to be the trimming current Io, in this embodiment, a=2 and io=2 Iref are selected.
Further, the voltage generation circuit 400 includes a reference voltage circuit, a threshold voltage circuit, and a second mirror circuit; the second mirror circuit includes PM12, PM13, PM14, PM15, PM16, and PM17, and mirrors the trimming current Io to the reference voltage circuit, the threshold voltage circuit, and the temperature-temperature sensing circuit 100 through the second mirror circuit to generate the reference voltage Vbg, the threshold voltage Vref, and the temperature voltage Vsense, respectively.
The current mirror, the first mirror circuit and the second mirror circuit of the current source mirror reference current Iref and trimming current Io, so that the whole circuit is simple in structure and easy to integrate, and relatively stable image current can be obtained, and meanwhile, the power consumption of the circuit is reduced.
Further, the reference voltage circuit is provided with a resistor R7, and when the trimming current Io on the reference voltage circuit flows through R7, the reference voltage Vbg is generated, that is:
as can be seen from the combination of the formula (5) and the formula (6), since the temperature coefficient of Iref is adjustable and the resistor R7 has the temperature coefficient, the temperature coefficient of Iref is matched with the temperature coefficient of R7 by adjusting the resistance values of R4 and R5, so that the temperature coefficient of the reference voltage Vbg is finally made to be0, and even if the voltage value of the reference voltage Vbg is not affected by the temperature change, the voltage value of the reference voltage Vbg is always kept constant for calibration.
The threshold voltage circuit is provided with a threshold resistor R8 with an adjustable resistance value, in order to enable the threshold voltage Vref to be more accurate, the threshold resistor R8 is trimmed by 6 bits, trimming precision is +/-1 mV, and the trimming precision is equal to +/-0.25 ℃ when the temperature is affected by temperature change.
In this embodiment, R8 is connected to the ground through a switch NMOS NM11, and when the comparison circuit 500 outputs the first control signal Vo1, NM11 is in an on state, that is:
similarly, in this embodiment, a=2, the same principle as the reference voltage Vbg, because the temperature coefficient of Iref is adjustable, and then according to the temperature coefficient of R8, the resistance values of R4 and R5 are adjusted in a combined manner, so that the temperature coefficient of Iref is matched with the temperature coefficient of R8, and finally the temperature coefficient of the threshold voltage Vref is 0, even if the noise immunity of the threshold voltage Vref is stronger, the voltage value of the threshold voltage Vref is not affected by temperature change, the accuracy of the temperature comparison result of the temperature detection circuit is increased, and the temperature drift amount is reduced.
Because the voltage value of the reference voltage Vbg is a voltage which is generated by the reference voltage generating circuit in cooperation with the trimming current Io and does not change with the power supply voltage and the temperature, the external PAD can be connected for testing and trimming, and the threshold voltage Vref is equivalent to a replica voltage proportional to the reference voltage Vbg, and is directly used for comparing with the temperature voltage Vsense in the comparison circuit 500, if the external PAD test may be disturbed.
And because the PM12, the PM14, the PM13 and the PM15 are subjected to matching processing, the deviation of the threshold voltage Vref relative to the reference voltage Vbg is controlled within +/-1%, and the residual deviation of the threshold voltage Vref can be regulated to an accurate value through the threshold resistor R8. Meanwhile, the deviation of the reference voltage Vbg may reach +/-25% due to the process of components in the circuit, so that the deviation of the reference voltage Vbg needs to be controlled within +/-1% by adjusting the number of NM9 and NM10, and when the reference voltage Vbg is modified, the PAD can be directly modified by being connected with the outside through a test.
Further, the threshold voltage circuit further includes a hysteresis circuit configured to generate a hysteresis voltage vref_ hys corresponding to the second threshold temperature, the hysteresis circuit includes hysteresis resistors, the hysteresis resistors in this embodiment are set to R9 and R10, after the comparison circuit 500 outputs the second control signal, the hysteresis circuit is activated, NM11 becomes an off state, at this time, the hysteresis resistors R9 and R10 are connected into the threshold voltage circuit and are connected in series with the threshold resistor R8, and together cooperate with the trimming current Io to generate the hysteresis voltage vref_ hys, at this time, the hysteresis voltage vref_ hys is:
Vref_hys＝a*Iref*(R8+R9+R10)(8)
specifically, the two ends of the hysteresis resistor R10 are also connected in parallel with a control switch NM12, the control switch NM12 is set as an NMOS tube, and according to the actual tuning requirement, the gate of the control switch NM12 can be connected through a system register, and whether the control switch NM12 is turned on or not is selected by outputting a high level or a low level, so that whether the hysteresis resistor R10 is in short circuit or not is realized to change the voltage value of the hysteresis voltage vref_ hys.
Furthermore, the temperature detection circuit provided by the invention further comprises a starting circuit, wherein the starting circuit comprises a first switch MOS tube NM0 and a second switch MOS tube NM1.
Specifically, after Vdd is powered on, a high level voltage is provided for the gate of the first switch MOS transistor NM0 through R1, so that NM0 is turned on, and then the voltage of Vb1 is pulled down, so that PM1, PM2, PM4, PM6 and PM8 are turned on, and when PM1 is turned on, a high voltage is provided for the gates of NM3 and NM2, so that NM3 and NM2 are turned on simultaneously, and since NM2 is turned on, the voltage of Vb0 is pulled down, so that PM0, PM3, PM5, PM7 and PM9 are turned on; since PM4, PM5, PM6 and PM7 are all turned on, thereby pulling up the Vg voltage, making NM5 and NM6 turned on, starting to generate the reference current Iref, and simultaneously since the gate of the second switching MOS transistor NM1 is connected to the high voltage, making NM1 turned on, and Q2 is set to be a P-channel transistor and in the on state, after NM1 is turned on, the gate voltage of the first switching MOS transistor NM0 is pulled down, thereby turning NM0 off, and turning off the start circuit.
By setting the starting circuit, the power consumption of the temperature detection circuit is reduced, meanwhile, the second switch MOS tube NM1 is kept on, R1 is used as a current limiting resistor, and in order to reduce the battery power consumption, the resistance value of 10MΩ is selected in the embodiment.
Further, the comparison circuit 500 in the present embodiment includes a filter circuit 510 and a voltage comparator 520 electrically connected to each other; wherein the filter circuit 510 is configured as a low pass filter LPF for removing transient signals of the temperature voltage Vsense, the threshold voltage Vref, and the hysteresis voltage vref_ hys that enter the comparison circuit 500 and smoothing the voltage values; since the low pass filter LPF is a passive device and therefore consumes no power, the voltage comparator 520 in the comparison circuit 500 may employ a low power comparator because the conversion speed is not required high, thereby reducing the power consumption of the entire temperature detection circuit.
Further, the comparison circuit 500 is further provided with two voltage inverters 530 electrically connected to the output end of the voltage comparator 520, and the output result of the voltage comparator 520 passes through the two voltage inverters 530, so as to perform the functions of shaping and balancing the signal delay on the output signal of the voltage comparator 520.
The specific temperature detection process in this embodiment will be further described with reference to fig. 2, 3 and 4:
the threshold voltage Vref is adjusted to a voltage value corresponding to a first threshold temperature, in this embodiment, the first threshold temperature is set to 40 ℃, and when the temperature voltage Vsense is higher than the threshold voltage Vref, i.e. the current temperature is lower than 40 ℃, the comparison circuit 500 continuously outputs the first control signal Vo1;
since the voltage value of the temperature voltage Vsense decreases with an increase in temperature, the temperature voltage Vsense decreases as the temperature increases, and when the temperature voltage Vsense is less than or equal to the threshold voltage Vref, that is, the current temperature is greater than or equal to 40 ℃, the comparison circuit 500 outputs the second control signal Vo2;
the second control signal Vo2 activates the hysteresis circuit to convert the threshold voltage Vref into a hysteresis voltage vref_ hys corresponding to a second threshold temperature, in this embodiment, the second threshold temperature is set to 38 ℃, the hysteresis voltage vref_ hys is compared with the temperature voltage Vsense by the comparison circuit 500, and if the current temperature voltage Vsense is less than or equal to the hysteresis voltage vref_ hys, that is, the current temperature is greater than or equal to 38 ℃, the comparison circuit 500 continuously outputs the second control signal Vo2;
if the current temperature voltage Vsense is greater than the hysteresis voltage vref_ hys, i.e. the current temperature is reduced to less than 38 ℃, the comparator resumes outputting the first control signal Vo1, and at the same time the hysteresis circuit is turned off, and the hysteresis voltage vref_ hys is converted into the threshold voltage Vref.
According to the temperature detection circuit provided by the invention, the reference current with adjustable temperature coefficient is generated through the reference current generation circuit 200, and then the reference current is mirrored in proportion to the reference voltage circuit and the threshold voltage circuit through the first mirroring circuit of the trimming circuit 300 and the second mirroring circuit of the voltage generation circuit 400 so as to correspondingly generate the reference voltage and the threshold voltage which are not influenced by temperature change, so that the comparison result of the comparison circuit 500 is more accurate and the energy consumption of the whole circuit is reduced.
Further, as shown in fig. 5, the present invention further provides an implantable medical device, which includes a charging module having a wireless charging function, where the charging module includes a control unit and a temperature detection unit that are in communication connection, the temperature detection unit includes any one of the temperature detection circuits described above, and when the temperature detection unit detects that the current temperature is less than the first threshold temperature, the control unit controls the charging module to start the wireless charging function; when the temperature detection unit detects that the current temperature is greater than or equal to a first threshold temperature, the control unit controls the charging module to close the wireless charging function; in this embodiment, the first threshold temperature is set to 40 ℃.
Meanwhile, the temperature detection unit further comprises a hysteresis comparison unit, and when the wireless charging function of the charging module is closed, the hysteresis comparison unit converts the first threshold temperature into the second threshold temperature; when the temperature detection unit detects that the current temperature is greater than or equal to a second threshold temperature, the control unit controls the charging module to keep the wireless charging function closed; when the temperature detection unit detects that the current temperature is smaller than the second threshold temperature, the control unit controls the wireless charging module to start a wireless charging function; in this embodiment, the second threshold temperature is set at 38 ℃.
According to the implanted medical device, the situation that the implanted person is injured due to the fact that the temperature is too high in the charging process is avoided while the wireless charging function is achieved, meanwhile, the hysteresis comparison unit is set, the wireless charging function is started when the temperature is reduced to the second threshold temperature, the situation that the charging function is repeatedly started and stopped due to disturbance in the charging process is avoided, and the safety is improved while the energy consumption is reduced.
It should be understood that although the present disclosure describes embodiments in terms of examples, not every embodiment is provided with a single embodiment, and that this description is for clarity only, and that the skilled artisan should recognize that the embodiments may be combined appropriately to form other embodiments that will be understood by those skilled in the art.
The above list of detailed descriptions is only specific to practical embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.
Claims (17)
1. A temperature detection circuit, the temperature detection circuit comprising:
a temperature sensing circuit configured to acquire a temperature voltage that varies with temperature;
a reference current generation circuit including a current source and a temperature coefficient adjustment circuit connected to an output of the current source, the temperature coefficient adjustment circuit configured to adjust a current generated by the current source to a reference current having a temperature coefficient of zero;
a trimming circuit comprising a first mirror circuit configured to mirror the reference current in proportion to a trimming current;
a voltage generation circuit including a reference voltage circuit, a threshold voltage circuit, and a second mirroring circuit configured to mirror the trimming current to the reference voltage circuit and the threshold voltage circuit to generate a reference voltage having a temperature coefficient of zero and a threshold voltage corresponding to a first threshold temperature;
and a comparison circuit configured to compare the temperature voltage with a threshold voltage, output a first control signal if the temperature voltage is greater than the threshold voltage, and output a second control signal if the temperature voltage is less than or equal to the threshold voltage.
2. The temperature detection circuit of claim 1, wherein the temperature coefficient adjustment circuit comprises a first leg configured with a first MOS transistor and a first bipolar transistor and a second leg configured with a second MOS transistor and a second bipolar transistor; the output ends of the first MOS tube and the second MOS tube are correspondingly connected with the input ends of the first bipolar transistor and the second bipolar transistor respectively.
3. The temperature detection circuit of claim 2, wherein the temperature coefficient adjustment circuit further comprises a third branch configured with a first adjustment resistor connected between the output of the first MOS transistor and a ground of the temperature detection circuit; and a second adjusting resistor connected between the output end of the first MOS tube and the input end of the first bipolar transistor is arranged on the first branch, and the temperature coefficient of the reference current is adjusted by changing the resistance values of the first adjusting resistor and the second adjusting resistor.
4. The temperature detection circuit of claim 2, wherein the area ratio of the gates of the first MOS transistor and the second MOS transistor is set to a first preset area ratio.
5. The temperature detection circuit according to claim 2, wherein an area ratio of emitters of the first bipolar transistor and the second bipolar transistor is set to a second preset area ratio.
6. The temperature detection circuit of claim 1, wherein the first mirror circuit comprises a first trimming transistor and a second trimming transistor, a gate of the second trimming transistor being correspondingly connected to a gate of the first trimming transistor.
7. The temperature sensing circuit of claim 6, wherein the trimming circuit mirrors the reference current to a trimming current in proportion to a number ratio of transistors of the second trimming transistor to the first trimming transistor by connecting a plurality of the second trimming transistors in parallel.
8. The temperature detection circuit of claim 1, wherein the threshold voltage circuit comprises a threshold resistance configured as an adjustable resistance to cooperate with the trimming current to generate a corresponding threshold voltage.
9. The temperature detection circuit of claim 1, wherein the threshold voltage circuit further comprises a hysteresis circuit configured to generate a hysteresis voltage, wherein the second control signal is generated to activate the hysteresis circuit to convert the threshold voltage into a hysteresis voltage corresponding to a second threshold temperature, and wherein the comparison circuit is configured to compare the temperature voltage with the hysteresis voltage, wherein the comparison circuit is configured to continuously output the second control signal if the temperature voltage is less than or equal to the hysteresis voltage, and wherein the comparison circuit is configured to output the first control signal if the temperature voltage is greater than the hysteresis voltage.
10. The temperature detection circuit of claim 9, wherein the hysteresis circuit comprises a hysteresis resistor, and wherein after the second control signal activates the hysteresis circuit, the hysteresis resistor is connected to the threshold voltage circuit to generate a hysteresis voltage in cooperation with the trimming current.
11. The temperature detection circuit of claim 1, wherein the comparison circuit comprises a filter circuit and a voltage comparator, the output of the filter circuit being connected to the input of the voltage comparator, the filter circuit being configured to remove transient signals from the voltage entering the voltage comparator and to smooth the value of the voltage.
12. The temperature detection circuit of claim 11, wherein the output of the voltage comparator is connected in series with two voltage inverters to shape and balance the output signal of the voltage comparator.
13. The temperature detection circuit according to claim 1, further comprising a start-up circuit, wherein the start-up circuit comprises a first switch MOS transistor and a second switch MOS transistor, and when the first switch MOS transistor is turned on, the reference current generation circuit is turned on, so that the second switch MOS transistor is turned on; and after the second switch MOS tube is conducted, the first switch MOS tube is closed, so that the starting circuit is closed.
14. The temperature sensing circuit of claim 1, wherein the temperature sensing circuit comprises a temperature sensing element configured as a set of tertiary tubes with collectors connected to a base stage.
15. The temperature detection circuit of claim 14, wherein the second mirroring circuit is further configured to mirror the trimming current to the temperature sensing circuit to generate a temperature voltage in cooperation with the set of transistors.
16. An implantable medical device comprising a charging module with a wireless charging function, the charging module comprising a control unit and a temperature detection unit in communication connection, characterized in that the temperature detection unit comprises a temperature detection circuit according to any one of claims 1 to 15, and when the temperature detection unit detects that the current temperature is less than a first threshold temperature, the control unit controls the charging module to turn on the wireless charging function; when the temperature detection unit detects that the current temperature is greater than or equal to a first threshold temperature, the control unit controls the charging module to close the wireless charging function.
17. The implantable medical device according to claim 16, wherein the temperature detection unit comprises a hysteresis comparison unit that converts a first threshold temperature to a second threshold temperature when the charging module turns off a wireless charging function; when the temperature detection unit detects that the current temperature is greater than or equal to a second threshold temperature, the control unit controls the charging module to keep the wireless charging function closed; when the temperature detection unit detects that the current temperature is smaller than the second threshold temperature, the control unit controls the wireless charging module to start a wireless charging function.
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| CN109960304B (en) * | 2017-12-23 | 2024-02-06 | 景昱医疗科技（苏州）股份有限公司 | Temperature detection circuit and implantable medical device using same |
| CN114146308B (en) * | 2020-12-29 | 2022-11-04 | 江苏海莱新创医疗科技有限公司 | Temperature control device of electric field therapeutic apparatus and adjusting method thereof |
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| CN208335045U (en) | 2019-01-04 |
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