CN204065897U - Output circuit - Google Patents
Output circuit Download PDFInfo
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- CN204065897U CN204065897U CN201420575318.8U CN201420575318U CN204065897U CN 204065897 U CN204065897 U CN 204065897U CN 201420575318 U CN201420575318 U CN 201420575318U CN 204065897 U CN204065897 U CN 204065897U
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Abstract
The utility model discloses a kind of output circuit.This output circuit can comprise clamping diode circuit and output transistor, it is characterized in that clamping diode circuit and output transistor are thermally coupled.This output circuit can maintain current limit effectively, thus can have overload protection more reliably, even if temperature changes.
Description
Technical field
The utility model relates to circuit field, more specifically, relates to the output circuit having and improve temperature performance.
Background technology
Output circuit is widely used in various application.Such as, output circuit can provide direct current (DC) supply voltage, with the externally power supply such as sensor, client's control system; Analog voltage can be provided to export, as the input of client's control system etc.; Numeral can be provided to export, to drive external loading as relay or the input as client's control system etc.In such output circuit, usually need overload protection function, to avoid damaging internal circuit when there is such as short circuit or Miswire.
Fig. 1 shows a kind of output circuit with overload protection.
As shown in Figure 1, this output circuit comprises power transistor T1, T2, clamping diode circuit D1, diode D2, resistor R1-R6 and capacitor C1.About the electrical connection between these elements, as shown in Figure 1, describe no longer one by one at this.
By output transistor T1, provide output at output node (collector corresponding to T1) place, such as 24V DC voltage.By applying control signal (such as, from microcontroller) at control end, the output of this output circuit can be turned on and off.
When such as making output transistor T1 conducting by control signal is set to high level, the voltage on the base-emitter of resistor R6 and output transistor T1 will be limited to clamp circuit D1, thus output current is roughly:
Wherein, I
maxrepresent the maximal value of output current, U
d1represent the voltage at clamp circuit D1 two ends, UBE
t1represent the base emitter voltage of output transistor T1, R6 represents the resistance value of resistor R6.
As long as the current needs of external loading is lower than I
max, the pressure drop on output transistor T1 is lower, and the base current that transmits due to resistor R3 and R5 of output transistor T1 and be in state of saturation.Therefore, the power consumption of output transistor T1 is lower, and junction temperature remains on security level.
Once the current needs of external loading (such as, due to faults such as short circuits) exceeds I
max, output circuit will be transformed into constant current source, and the voltage on output transistor T1 will increase, and cause the power consumption in transistor T1 to increase, and therefore junction temperature also rise.Higher junction temperature by causing the UBE that transistor T1 is shown to reduce, such as, is about 2mV/ DEG C again.On the other hand, the pressure drop on clamp circuit D1 keeps substantially constant, thus according to above formula, I
maxto increase.Such as, the intensification of 50 DEG C will cause UBE to reduce 100mV, such as, may be down to 650mV from 750mV, therefore at this " thermal runaway " stage final (short circuit) electric current by rising about 10%.Like this, if the design current limit value of circuit is 200mA, the so final short-circuit current value exported may reach about 225mA.
Utility model content
In view of the above problems, the purpose of this utility model is that providing a kind of has the output circuit improving temperature characterisitic at least in part.
According to an aspect of the present utility model, provide a kind of output circuit, comprise clamping diode circuit and output transistor, it is characterized in that clamping diode circuit and output transistor are thermally coupled.This output circuit such as can comprise DC output circuit.
According to an embodiment, between clamping diode circuit and output transistor, heat-conducting medium can be provided with.
According to an embodiment, clamping diode circuit and output transistor can be arranged close to each other.In one example, clamping diode circuit and output transistor can be arranged at the same side of printed circuit board (PCB).Such as, clamping diode circuit can be arranged on trace identical on printed circuit board (PCB) with output transistor.In another example, clamping diode circuit can be arranged on the relative both sides of printed circuit board (PCB) respectively with output transistor.Such as, clamping diode circuit can be arranged on the trace of the relative both sides of printed circuit board (PCB) respectively with output transistor, and trace can be communicated with by passage of heat.
According to an embodiment, output transistor can be contained in an encapsulation, and the collector of output transistor can be connected to a metal tap of this encapsulation, and clamping diode circuit can be set to and this metal tap thermal coupling.
According to an embodiment, clamping diode circuit can be contained in a diode package, and this diode package can also comprise miscellaneous part, and clamping diode circuit can via the miscellaneous part in this diode package and output transistor thermal coupling.This diode package such as can comprise BAV99s, BAV99U, BAV99BRW or BAV99STB6.Output transistor can be contained in an encapsulation, and the collector of output transistor can be connected to a metal tap of this encapsulation, and miscellaneous part in diode package can with metal tap thermal coupling.
According to embodiment of the present utility model, clamping diode circuit can with output transistor thermal coupling, if thus the junction temperature of output transistor raise, so in clamp circuit, the junction temperature of diode also can raise.Output transistor junction temperature raises and its base-emitter voltage drop will be caused low on the one hand, and diode junction temperature rise will cause the voltage at clamp circuit two ends to reduce on the other hand.These two kinds of effect combined actions, can make the current limit of output circuit substantially remain unchanged.So this output circuit can maintain current limit effectively, thus overload protection more reliably can be had, even if temperature changes.
Accompanying drawing explanation
By referring to the description of accompanying drawing to the utility model embodiment, above-mentioned and other objects of the present utility model, feature and advantage will be more clear, in the accompanying drawings:
Fig. 1 is the circuit diagram diagrammatically illustrating conventional output circuit;
Fig. 2 shows the block diagram of the output circuit according to the utility model embodiment;
Fig. 3 shows the block diagram of the output circuit according to another embodiment of the utility model;
Fig. 4 shows the block diagram of the output circuit according to another embodiment of the utility model;
Fig. 5 shows the block diagram of the output circuit according to another embodiment of the utility model;
Fig. 6 shows the circuit diagram of the output circuit according to another embodiment of the utility model;
Fig. 7 shows the encapsulation figure of the clamping diode circuit according to the utility model embodiment.
Embodiment
Below, with reference to the accompanying drawings embodiment of the present utility model is described.But should be appreciated that, these describe just exemplary, and do not really want to limit scope of the present utility model.In addition, in the following description, the description to known features and technology is eliminated, to avoid unnecessarily obscuring concept of the present utility model.
Various structural representations according to the utility model embodiment shown in the drawings.These figure not draw in proportion, wherein in order to the object of clear expression, are exaggerated some details, and may eliminate some details.The shape of the various regions shown in figure, layer and the relative size between them, position relationship are only exemplary, in reality may due to manufacturing tolerance or technical limitation deviation to some extent, and those skilled in the art can design the regions/layers with difformity, size, relative position in addition needed for actual.
In context of the present utility model, when one deck/element is called be positioned at another layer/element " on " time, this layer/element can be located immediately on this another layer/element, or can there is intermediate layer/element between them.In addition, if one to be positioned at towards middle one deck/element another layer/element " on ", so when turn towards time, this layer/element can be positioned at this another layer/element D score.
According to embodiment of the present utility model, output circuit can comprise clamping diode circuit and output transistor.Such as, clamping diode circuit can be determined at its two ends pincers (roughly fixing) voltage, output transistor based on this voltage, can export certain electric current.This output circuit such as shown in Figure 1.As mentioned above, in such a circuit, when the junction temperature of output transistor rises, the limit value of output current will raise.
Inventor finds, clamping diode circuit can be thermally coupled to output transistor.Like this, the junction temperature of output transistor raises and the junction temperature of diode in clamp circuit will be caused to raise, and then this voltage that clamp circuit two ends institute pincers can be made again fixed reduces (such as, in the circuit shown in Fig. 1, owing to there are two PN junctions, voltage reduces about 4mV/ DEG C with temperature).Inventor finds, the current limit that this thermal coupling effectively can alleviate output circuit raises and the problem of rising with output transistor junction temperature.
Such as, can the above-mentioned design by following experimental verification.In the output circuit such as shown in Fig. 1, clamping diode circuit D1 is directly bonded at output transistor T1 top (particularly, the top of the encapsulation of output transistor T1).Find through experiment, even if the temperature of output transistor T1 rises tens of degree, " thermal runaway " phenomenon does not also occur, short-circuit current remains on initial value (value when output transistor T1 is low temperature such as room temperature) substantially.
At this, so-called " thermal coupling ", can refer to there is passage of heat.Thermal coupling can have numerous embodiments.Such as, Heat Conduction Material (such as, both being bonded to each other by heat-conducting glue) can be provided with between clamping diode circuit and output transistor; By clamping diode circuit and output transistor spatially (such as, adjacent) setting close to each other etc.
Design of the present utility model can present in many ways, below will describe some of them example.
Fig. 2 shows the block diagram of the output circuit according to the utility model embodiment.
As shown in Figure 2, this output circuit 10 can comprise output transistor 102 (such as, output transistor T1 in Fig. 1) and clamping diode circuit 104 is (such as, clamping diode circuit D1 in Fig. 1) and miscellaneous part 106 (T2, D2, C1, R1-R6 such as, in Fig. 1).These parts can be arranged on public substrate 108 as on printed circuit board (PCB) (PCB).Electric connecting relation in output circuit 10 between each parts can carry out in many ways, such as shown in Figure 1, makes output transistor 102 can produce output current based on the voltage that clamping diode circuit 104 pincers are fixed.
In addition, in this output circuit 10, output transistor 102 and clamping diode circuit 104 are arranged close to each other.Although they be depicted as adjacent each other in the drawings, the utility model is not limited thereto.Such as, they can separate certain distance, as long as the heat that output transistor 102 sends can effectively have influence on clamping diode circuit 104.Those skilled in the art can set this distance according to side circuit environment.Certainly, in order to better thermal coupling, their (such as, their encapsulation) should be as far as possible close.
Output transistor 102 can be power transistor, and has certain encapsulation, and such as DPAK encapsulation, SOT 223 encapsulate.Usually, in such encapsulation, the collector of power transistor can be connected to the metal tap of encapsulation, can be thermally coupled to encapsulating housing (such as in order to dispel the heat) well to make the knot of transistor.In addition, clamping diode circuit 104 can have certain encapsulation, such as BAV99 encapsulation.The encapsulation of output transistor 102 and the encapsulation of clamping diode circuit 104 can be arranged close to each other.
Fig. 3 shows the block diagram of the output circuit according to another embodiment of the utility model.
As shown in Figure 3, this output circuit 20 can comprise output transistor 202 (such as, output transistor T1 in Fig. 1) and clamping diode circuit 204 is (such as, clamping diode circuit D1 in Fig. 1) and miscellaneous part 206 (T2, D2, C1, R1-R6 such as, in Fig. 1).These parts can be arranged on public substrate 208 as on printed circuit board (PCB) (PCB).Electric connecting relation in output circuit 10 between each parts can carry out in many ways, such as shown in Figure 1, makes output transistor 202 can produce output current based on the voltage that clamping diode circuit 204 pincers are fixed.
In addition, in this output circuit 20, output transistor 202 and clamping diode circuit 104 are separately positioned on the relative both sides of substrate 108, and toward each other.Although they be depicted as aligned with each other in the drawings, the utility model is not limited thereto.Such as, they can also non-fully be aimed at, but can offset certain distance, as long as the heat that output transistor 202 sends can effectively have influence on clamping diode circuit 204.Those skilled in the art can set this offset distance according to side circuit environment.Certainly, in order to better thermal coupling, their (such as, their encapsulation) should be as far as possible close.
Fig. 4 shows the block diagram of the output circuit according to another embodiment of the utility model.In the diagram, for simplicity, illustrate only output transistor 302 and clamping diode circuit 304.
As shown in Figure 4, output transistor 302 and clamping diode circuit 304 can be arranged close to each other on the same side of PCB 308.In this example, they can also be arranged on the identical trace 310 (such as, Cu layer) of PCB 308, and this can improve the thermal coupling between them.
Fig. 5 shows the block diagram of the output circuit according to another embodiment of the utility model.In Figure 5, for simplicity, illustrate only output transistor 402 and clamping diode circuit 404.
As shown in Figure 5, output transistor 402 and clamping diode circuit 404 can be separately positioned on the relative both sides of PCB 408, toward each other.Such as, output transistor 402 can be arranged on trace 410-1 on first side (upside in Fig. 5) of PCB 408 (such as, Cu layer) on, and clamping diode circuit 404 can be arranged on the trace 410-2 (such as, Cu layer) on second side (downside in Fig. 5) of PCB 408.Conductive channel 412 can also be formed with in PCB 408.This conductive channel 412 such as can by forming the through hole filling Heat Conduction Material formation in through-holes that run through the first side and the second side in PCB 408.In one example, this conductive channel 412 such as can be formed by the electric via hole of PCB (such as the metal etc. of the conductive material generally speaking, in via hole is hot good conductor).
Fig. 6 shows the circuit diagram of the output circuit according to another embodiment of the utility model.
Output circuit shown in Fig. 6 is substantially the same with the output circuit shown in Fig. 1, except clamping diode circuit D1-1 is in except in different encapsulation.Particularly, in this example, clamping diode circuit D1-1 can have the encapsulation of BAV99s.Fig. 7 shows the schematic diagram of this encapsulation.As shown in Figure 7, can have four diodes in BAV99s encapsulation, wherein every two diodes are concatenated with one another, and their anode, negative electrode and common node are each other connected respectively to the respective terminal 1-6 of encapsulation.Illustrate in circuit at Fig. 6, clamping diode circuit D1-1 only make use of BAV99s encapsulation in two diodes (such as, the diode be connected with terminal 1,2,6), two other diode D1-2 (diode such as, be connected with terminal 3-5) is then idle.
According to this embodiment, in BAV99s encapsulation, idle diode D1-2 can be thermally coupled to output transistor T1 (such as, its encapsulation).Due to space less in encapsulating, diode D1-2 idle in BAV99s encapsulation heat up (such as, because the output transistor T1 of thermal coupling with it heats up) will cause encapsulating in for two diodes intensifications of clamp circuit D1-1.That is, the diode in clamp circuit D1-1 via BAV99s encapsulation in miscellaneous part D1-2 and with output transistor T1 thermal coupling.
In one example, in BAV99s can being encapsulated, idle diode D1-2 is arranged near the encapsulation of output transistor T1, the metal tap that the collector even the 3-5 connecting terminals that BAV99s encapsulates can being received output transistor T1 is connected to, to realize thermal coupling.In figure 6, D1-2 is depicted as the collector being connected to transistor T1.
Although it is pointed out that at this and employ BAV99s encapsulation in the example of fig. 6, the utility model is not limited to this.Such as, other diode package can also be used, as BAV99U, BAV99BRW or BAV99STB6.Clamping diode circuit can use part (such as, the two) diode in these diode package, and the miscellaneous part in encapsulation can as mentioned above for thermal coupling.
Although below describe various features in various embodiments respectively, this does not also mean that these features can not advantageously be combined.
Above embodiment of the present utility model is described.But these embodiments are only used to the object illustrated, and are not intended to limit scope of the present utility model.Scope of the present utility model is by claims and equivalents thereof.Do not depart from scope of the present utility model, those skilled in the art can make multiple substituting and amendment, and these substitute and amendment all should drop within scope of the present utility model.
Claims (12)
1. an output circuit, comprises clamping diode circuit and output transistor, it is characterized in that, described clamping diode circuit and described output transistor are thermally coupled.
2. output circuit according to claim 1, is characterized in that, is provided with heat-conducting medium between described clamping diode circuit and described output transistor.
3. output circuit according to claim 1 and 2, is characterized in that, described clamping diode circuit and described output transistor are arranged close to each other.
4. output circuit according to claim 3, is characterized in that, described clamping diode circuit and described output transistor are arranged at the same side of printed circuit board (PCB).
5. output circuit according to claim 4, is characterized in that, described clamping diode circuit is arranged on trace identical on described printed circuit board (PCB) with described output transistor.
6. output circuit according to claim 3, is characterized in that, described clamping diode circuit is arranged on the relative both sides of printed circuit board (PCB) respectively with described output transistor.
7. output circuit according to claim 6, is characterized in that, described clamping diode circuit and described output transistor are arranged on the trace of the relative both sides of described printed circuit board (PCB) respectively, and described trace is communicated with by passage of heat.
8. output circuit according to claim 1, it is characterized in that, described output transistor is contained in an encapsulation, and the collector of described output transistor is connected to a metal tap of this encapsulation, and described clamping diode circuit is set to and this metal tap thermal coupling.
9. output circuit according to claim 1, it is characterized in that, described clamping diode circuit is contained in a diode package, and described diode package also comprises miscellaneous part, described clamping diode circuit is via the described miscellaneous part in described diode package and described output transistor thermal coupling.
10. output circuit according to claim 9, is characterized in that, described diode package comprises BAV99s, BAV99U, BAV99BRW or BAV99STB6.
11. output circuits according to claim 9, it is characterized in that, described output transistor is contained in an encapsulation, and the collector of described output transistor is connected to a metal tap of this encapsulation, and described miscellaneous part in described diode package and described metal tap thermal coupling.
12. output circuits according to claim 1, wherein said output circuit comprises DC output circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420575318.8U CN204065897U (en) | 2014-09-30 | 2014-09-30 | Output circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420575318.8U CN204065897U (en) | 2014-09-30 | 2014-09-30 | Output circuit |
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| Publication Number | Publication Date |
|---|---|
| CN204065897U true CN204065897U (en) | 2014-12-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420575318.8U Active CN204065897U (en) | 2014-09-30 | 2014-09-30 | Output circuit |
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| CN (1) | CN204065897U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110719095A (en) * | 2018-07-12 | 2020-01-21 | 浙江海利普电子科技有限公司 | Power supply circuit and method for monitoring state of load supplied by power supply circuit |
-
2014
- 2014-09-30 CN CN201420575318.8U patent/CN204065897U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110719095A (en) * | 2018-07-12 | 2020-01-21 | 浙江海利普电子科技有限公司 | Power supply circuit and method for monitoring state of load supplied by power supply circuit |
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| GR01 | Patent grant |