CN202602282U - Circuit with function of preventing reverse current of power MOSFET - Google Patents
Circuit with function of preventing reverse current of power MOSFET Download PDFInfo
- Publication number
- CN202602282U CN202602282U CN 201220242419 CN201220242419U CN202602282U CN 202602282 U CN202602282 U CN 202602282U CN 201220242419 CN201220242419 CN 201220242419 CN 201220242419 U CN201220242419 U CN 201220242419U CN 202602282 U CN202602282 U CN 202602282U
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- schottky diode
- circuit
- type mosfet
- power mosfet
- current source
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- 239000000758 substrate Substances 0.000 claims abstract description 20
- 230000000903 blocking effect Effects 0.000 abstract 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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Abstract
A circuit having a function of blocking a reverse current of a power MOSFET is disclosed. The circuit comprises an N-type power MOSFET, a Schottky diode and a current source. The source electrode of the N-type power MOSFET is connected with the cathode of the Schottky diode; the substrate of the N-type power MOSFET is connected with the anode of the Schottky diode; one end of the current source receives the power supply input of the current source, and the other end of the current source is connected with the anode of the Schottky diode. The circuit can effectively prevent reverse current of the MOSFET, and can obtain smaller threshold voltage.
Description
Technical field
The embodiment of the utility model relates to a kind of electronic circuit, particularly relates to a kind of tool. the circuit that stops power MOSFET reverse current function is arranged.
Background technology
In the circuit design of battery charger chip or USB distribute power formula switch, under the situation that switching device turn-offs,, there is the reverse current that is back to input by output through power tube as output voltage V out during greater than input voltage vin.Reverse current will cause situation such as charger electric leakage, the damage of input power supply, the reverse current of therefore need taking measures to prevent.
As shown in Figure 1, in the prior art, for MOSFET pipe 10, for reducing the body bias effect and the conducting resistance of substrate, the source electrode with MOSFET 10 links to each other with substrate usually.Under the situation of not taking the measure that prevents, as Vout>during Vin, be back to input from output through the body diode 101 between substrate and the drain electrode with having reverse current.
A kind of mode of disclosed prevention reverse current is to adopt the switches set structure.As shown in Figure 2, N type power mosfet switch group 200 comprises a N type power MOSFET tube 21 and a N type power MOSFET tube 22.The grid of N type MOSFET pipe 21 links to each other with the grid of N type MOSFET pipe 22, and the substrate of N type MOSFET pipe 21 links to each other with the source electrode of N type MOSFET pipe 22.Power switch pipe group 200 receives an input voltage vin, and input links to each other with the drain electrode of N type MOSFET pipe 21.The power switch pipe group has an output, and output links to each other with the source electrode of N type MOSFET pipe 21 and the drain electrode of N type MOSFET pipe 22.N type MOSFET pipe 21 self has body diode with N type MOSFET pipe 22.N type MOSFET pipe 21 has body diode 201 and body diode 202.The substrate and the source electrode of N type MOSFET pipe 22 join, and therefore the body diode from the substrate to the source electrode is not played a role by short circuit, stays body diode 203 and plays a role.
During operate as normal, grid level is put height, Vin>Vout, N type MOSFET manages 21 conductings, and electric current directly flows to Vout from Vin.At this moment, because N type MOSFET pipe 22 has higher grid voltage equally, therefore form inversion channel.But because the no current path, the source voltage of N type MOSFET pipe 22 is Vout, and promptly the underlayer voltage of N type MOSFET pipe 21 is Vout, so N type MOSFET does not have the body bias effect when managing 21 operate as normal.When grid voltage less than turning-on voltage, and Vout during Vin, N type MOSFET pipe 21 does not form raceway groove with N type MOSFET pipe 22, and the PN junction body diode 202, body diode 203 reverse bias that form, current path is blocked, and can stop reverse current.But when adopting switches set to stop reverse current, threshold voltage and conducting resistance Ron are all bigger, and the package dimension of switches set is also bigger simultaneously, have reduced the efficient of voltage conversion device.
The utility model content
The purpose of the utility model is to provide a kind of circuit of the MOSFET of prevention reverse current, and this circuit can effectively stop reverse current, and obtains less threshold voltage.
The utility model provides a kind of circuit on the one hand, and this circuit comprises N type power MOSFET tube, Schottky diode and current source.Wherein, the negative electrode of the source electrode of N type power MOSFET tube and Schottky diode links to each other; The substrate of N type power MOSFET tube and the anode of Schottky diode link to each other; Current source one termination is received the current source supply input, and the other end links to each other with the anode of Schottky diode.
The circuit that the utility model is mentioned, wherein, the drain electrode of this N type power MOSFET tube receives input voltage; The source electrode of N type MOSFET pipe receives output voltage.
The utility model also provides a kind of circuit on the other hand, and this circuit comprises P type power MOSFET tube, Schottky diode and current source.Wherein, the anode of the source electrode of P type power MOSFET tube and Schottky diode links to each other; The substrate of P type power MOSFET tube and the negative electrode of Schottky diode link to each other; Current source one termination is received the current source supply input, and the other end links to each other with the anode of Schottky diode.
The circuit that the utility model is mentioned, wherein, the source electrode of this P type MOSFET pipe receives input voltage; The drain electrode of P type MOSFET pipe receives output voltage.
Description of drawings
Accompanying drawing is as the part of specification, and embodiment describes to the utility model, and with embodiment the principle of the utility model is made an explanation.In order to understand the utility model better, will be described in detail the utility model according to following accompanying drawing.
Fig. 1 does not have the MOSFET pipe that stops the reverse current function in the prior art;
Fig. 2 is a kind of switch mosfet group structure that stops reverse current in the prior art;
Fig. 3 is the circuit structure diagram that stops N type MOSFET reverse current function according to having of the utility model one specific embodiment;
Fig. 4 is the circuit structure diagram that stops P type MOSFET reverse current function according to having of the utility model one specific embodiment;
Shown in Figure 5 is the conducting resistance R of N type MOSFET shown in Figure 3 and switches set shown in Figure 2
DSSimulation waveform contrast sketch map.
Embodiment
To describe the specific embodiment of the utility model below in detail, should be noted that the embodiments described herein only is used to illustrate, be not limited to the utility model.In the following description, for the thorough to the utility model is provided, a large amount of specific detail have been set forth.Yet it is obvious that for those of ordinary skills: needn't adopt these specific detail to carry out the utility model.
Fig. 3 is for having the circuit diagram 300 that stops N type MOSFET reverse current function according to the utility model one specific embodiment.Circuit 300 comprises a N type power MOSFET tube 31, Schottky diode 32 and current source 33.The drain electrode end of N type MOSFET pipe 31 receives input voltage vin, and the source terminal of N type MOSFET pipe 31 links to each other with output voltage V out.N type MOSFET pipe 31 self has body diode, comprises body diode 301 and body diode 302, and wherein substrate is as the anode of two diodes, and source terminal and drain electrode end are respectively as the negative electrode of diode 302 and 301.The anode of Schottky diode 32 links to each other with the substrate of N type MOSFET pipe 31, and the negative electrode of Schottky diode 32 links to each other with the source electrode of N type MOSFET pipe 31.Current source 33 1 terminations are received current source supply input V
A, the other end links to each other with the anode of Schottky diode 32 and the substrate of N type MOSFET pipe 31.
When circuit 300 work, current source 33 applies a constant current and flows through Schottky diode 32, Schottky diode 32 conductings.Because the conduction voltage drop of Schottky diode 32 is less than the pressure drop of the body diode 302 of N type MOSFET pipe 31 self, for example, common Schottky diode conduction voltage drop is 0.3V, and common body diode conduction voltage drop is 0.7V, base voltage V
BValue by Schottky diode 32 clampers at Vout+0.3V, therefore can avoid body diode 302 conductings.
During operate as normal, grid level is put height, Vin>Vout, this moment, N type MOSFET managed 31 conductings, and electric current directly flows to Vout from Vin.And when the turning-on voltage of grid voltage, and Vout less than MOSFET pipe 31>during Vin, N type MOSFET pipe 31 does not form raceway groove, and because Schottky diode 32 has stoped the path of body diode, so stoped all reverse currents of N type MOSFET pipe 31.
The threshold voltage V of N type MOSFET pipe 31
THFormula is following:
（1）
Wherein,
Be the Fermi potential of Semiconductor substrate,
Be body-effect coefficient, V
SBBe the electrical potential difference between source electrode and the substrate, V
TH0Be the electrical potential difference V between source electrode and substrate
SBBe zero (V
SB=0) threshold voltage the time.
After circuit 300 increases Schottky diode 32, electrical potential difference V
SBBe clamped at-0.3V,, can know, increase the threshold voltage V that Schottky diode 32 can reduce later N type MOSFET pipe 31 by formula (1) with respect to switches set circuit 200 shown in Figure 2
TH
As everyone knows, the conducting resistance R of MOSFET pipe
DSBe directly proportional with threshold voltage.Therefore N type MOSFET manages 31 threshold voltage V
THReduce to make that N type MOSFET manages 31 conducting resistance R
DSReduce.
Fig. 4 is for having the circuit diagram 400 that stops P type MOSFET reverse current function according to the utility model one specific embodiment.Circuit 400 comprises a power P type MOSFET pipe 41, Schottky diode 42 and current source 43.The source terminal of P type MOSFET pipe 41 receives input voltage vin, and the drain electrode end of P type MOSFET pipe 41 links to each other with output voltage V out.P type MOSFET pipe 41 self has body diode, and P type MOSFET pipe 41 comprises body diode 401 and body diode 402, and wherein substrate is as the negative electrode of two diodes, and source terminal and drain electrode end are respectively as the anode of diode 401 and 402.The anode of Schottky diode 42 links to each other with the source electrode of P type MOSFET pipe 41, and the negative electrode of Schottky diode 42 links to each other with the substrate of P type MOSFET pipe 41.Current source 43 1 terminations are received current source supply input V
A, the other end links to each other with the anode of Schottky diode 42 and the substrate of P type MOSFET pipe 41.
When circuit 400 work, current source 43 applies a constant current and flows through Schottky diode 42, Schottky diode 42 conductings.Because the conduction voltage drop of Schottky diode 42 is less than the pressure drop of the body diode 401 of P type MOSFET pipe 41 self, for example, common Schottky diode conduction voltage drop is 0.3V, and common body diode conduction voltage drop is 0.7V, base voltage V
BValue by Schottky diode 42 clampers at Vin-0.3V, therefore can avoid body diode 401 conductings.
During operate as normal, grid level is put low, Vin>Vout, this moment, P type MOSFET managed 41 conductings, and electric current directly flows to Vout from Vin.The turning-on voltage that is higher than MOSFET pipe 41 when grid voltage; And Vout>during Vin; P type MOSFET pipe 41 does not form raceway groove, and because Schottky diode 42 has stoped the backward channel of body diode 401, so stoped all reverse currents of P type MOSFET pipe 41.
In like manner, can know that the threshold voltage and the conducting resistance of this P type MOSFET pipe also can reduce by formula (1).
Shown in Figure 5 is the conducting resistance R of N type MOSFET and switches set shown in Figure 2 200 in the circuit 300 shown in Figure 3
DSSimulation waveform contrast sketch map.Wherein, solid line is depicted as the conducting resistance R of N type MOSFET in the circuit 300 shown in Figure 3
DSWith the variation of input voltage vin, dotted line is depicted as the conducting resistance R of switches set 200 shown in Figure 2
DSVariation with input voltage vin.Can find out by two wavy curves shown in Figure 5, behind the increase Schottky diode 32, the conducting resistance R of N type MOSFET pipe 31
DSConducting resistance less than switches set 200 shown in Figure 2.Be the low-pressure area of 1V-2V in input voltage vin particularly, this advantage is more obvious.Little conducting resistance R
DSHelp reducing the size of wafer, improve the efficient of voltage conversion device.
What need statement is that above-mentioned utility model content and embodiment are intended to prove the practical application of technical scheme that the utility model provides, and should not be construed as the qualification to the utility model protection range.Those skilled in the art are in the spirit and principle of the utility model, when doing various modifications, being equal to replacement or improvement.The protection range of the utility model is as the criterion with appended claims.
Claims (4)
1. a circuit is characterized in that, said circuit comprises N type power MOSFET tube, Schottky diode, and current source, wherein, the source electrode of said N type power MOSFET tube and the negative electrode of said Schottky diode link to each other; The substrate of said N type power MOSFET tube and the anode of said Schottky diode link to each other; Said current source one termination is received the current source supply input, and the other end links to each other with the anode of said Schottky diode.
2. circuit as claimed in claim 1 is characterized in that, the drain electrode of said N type power MOSFET tube receives input voltage; The source electrode of said N type MOSFET pipe receives output voltage.
3. a circuit is characterized in that, said circuit comprises P type power MOSFET tube, Schottky diode, and current source, wherein, the source electrode of said P type power MOSFET tube and the anode of said Schottky diode link to each other; The substrate of said P type power MOSFET tube and the negative electrode of said Schottky diode link to each other; Said current source one termination is received the current source supply input, and the other end links to each other with the anode of said Schottky diode.
4. circuit as claimed in claim 1 is characterized in that, the source electrode of said P type MOSFET pipe receives input voltage; The drain electrode of said P type MOSFET pipe receives output voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220242419 CN202602282U (en) | 2012-05-28 | 2012-05-28 | Circuit with function of preventing reverse current of power MOSFET |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220242419 CN202602282U (en) | 2012-05-28 | 2012-05-28 | Circuit with function of preventing reverse current of power MOSFET |
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| CN202602282U true CN202602282U (en) | 2012-12-12 |
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| CN 201220242419 Expired - Lifetime CN202602282U (en) | 2012-05-28 | 2012-05-28 | Circuit with function of preventing reverse current of power MOSFET |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110297187A (en) * | 2018-03-23 | 2019-10-01 | 本田技研工业株式会社 | The current leakage inspection method of fuel cell |
-
2012
- 2012-05-28 CN CN 201220242419 patent/CN202602282U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110297187A (en) * | 2018-03-23 | 2019-10-01 | 本田技研工业株式会社 | The current leakage inspection method of fuel cell |
| CN110297187B (en) * | 2018-03-23 | 2021-07-27 | 本田技研工业株式会社 | Current leakage inspection method for fuel cell |
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| GR01 | Patent grant | ||
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| CX01 | Expiry of patent term |
Granted publication date: 20121212 |