CN204993961U - LED driver chip's peak current detection circuitry and use thereof - Google Patents
LED driver chip's peak current detection circuitry and use thereof Download PDFInfo
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- CN204993961U CN204993961U CN201520538848.XU CN201520538848U CN204993961U CN 204993961 U CN204993961 U CN 204993961U CN 201520538848 U CN201520538848 U CN 201520538848U CN 204993961 U CN204993961 U CN 204993961U
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- peak current
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Abstract
The utility model provides a critical mode LED driver chip's of three pins peak current detection circuitry, logic control circuit's output signal, control signal switch are received to the phase inverter, signal switch's one end links to each other with operational amplifier's non inverting input end, the other end is through linking to each other with the VCC end, still link to each other with the CS end through second resistance with first resistance, operational amplifier's non inverting input end is connected through fourth electric capacity and CS end, the inverting input end is connected through third resistance and VCC end, still links to each other through the output of fourth resistance with operational amplifier, output peak current detection circuitry's output voltage. Its advantage lies in that the CS who realizes the critical mode LED driver chip of three wiring ends holds both junction current sampling resistors, regards as 0 current potential of reference of chip again.
Description
Technical field
The utility model relates to power supply circuits, is specifically related to a kind of peak current detection circuit, is particularly useful for the peak current detection circuit of three pin critical conduction mode LED drive chip.
Background technology
The function of LED drive chip is for LED load provides constant electric current, and due to the advantage that precision is high and efficiency is high, critical current control model is usually used in the output constant current control of open loop.In critical conduction mode, the average current Iavg of load is determined by following formula:
Wherein, Ipk is the peak current of inductance, and Ivy is the lowest point electric current of inductance.In order to accurate control Iavg, in critical conduction mode, Ivy is set to 0.Can obtain thus:
Therefore, how accurately detection Ipk and inductive current zero crossing just become the key of constant current output in critical conduction mode.
Utility model content
For solving the problem, the utility model provides a kind of peak current detection circuit of LED drive chip, to overcome the defect of prior art.
The utility model provides a kind of peak current detection circuit of LED drive chip to comprise: operational amplifier B1, inverter B2, signaling switch K, the 4th electric capacity C4, the first resistance R1, the second resistance R2, the 3rd resistance R3 and the 4th resistance R4; The output signal of inverter B2 receive logic control circuit, control signal K switch; One end of signaling switch K is connected with the in-phase input end of operational amplifier B1; The other end is connected by holding with the first resistance R1 and VCC, it is connected also to be held by the second resistance R2 and CS; The in-phase input end of operational amplifier B1 is held by the 4th electric capacity C4 and CS and is connected; Inverting input is held by the 3rd resistance R3 and VCC and is connected, and is also connected with the output of operational amplifier B1 by the 4th resistance R4; Output exports the output voltage of peak current detection circuit.
In addition, the utility model provides a kind of three pin critical conduction mode LED drive chip to comprise: peak current detection circuit B, low-voltage power supply circuit A, comparator C, logic control circuit D, metal-oxide-semiconductor drive circuit E, zero current cross testing circuit F and metal-oxide-semiconductor M, and has VCC end, DRN end and CS end; Low-voltage power supply circuit A, from DRN end input high pressure, exports low pressure and holds to the power supply of chip internal to VCC; Peak current detection circuit B detects and calculates the peak current of inductance, and exports peak current representative voltage; Voltage comparator C compares and exports peak current representative voltage and peak current detection setting voltage and export peak current arriving signal; Zero current cross testing circuit F detects inductive current zero crossing and outputting inductance current zero-crossing signal; Logic control circuit D input signal peak current arriving signal and inductive current zero cross signal also control the on off state of metal-oxide-semiconductor M by metal-oxide-semiconductor drive circuit E; Logic control circuit E also controls the operating state of low-voltage power supply circuit A by output signal.
Further, the utility model provides a kind of three pin critical conduction mode LED drive chip, also has such feature: logic control circuit E also controls the operating state of low-voltage power supply circuit A by output logic control signal.
The utility model also provides a kind of constant current LED drive circuit to comprise: rectifier bridge, the first electric capacity C1, inductance L 1, LED load, three pin critical conduction mode LED drive chip as claimed in claim 2 or claim 3, the second electric capacity C2, current sense resistor Rcs, sustained diode 5 and the 3rd electric capacity C3; Interchange input after inputting the first electric capacity C1 filtering, produces a direct voltage and powers to LED load after rectifier bridge; Inductance L 1 one end connects the negative terminal of LED load, and the other end connects the DRN end of driving chip; Second electric capacity C2 one end is held with VCC and is connected, other end ground connection; Current sense resistor Rcs one end is held with CS and is connected, other end ground connection; 3rd electric capacity C3 and sustained diode 5 all in parallel with LED load.
Accompanying drawing explanation
Fig. 1 is a kind of constant current LED drive circuit.
Fig. 2 is the circuit diagram of three pin critical conduction mode LED drive chip.
Fig. 3 is the peak current detection circuit figure of three pin critical conduction mode LED drive chip.
Fig. 4 is constant current LED drive circuit from oscillogram when being conducting to shutoff.
Embodiment
Below in conjunction with the drawings and specific embodiments, the utility model is further described.
Fig. 1 is a kind of constant current LED drive circuit.
As shown in Figure 1, a kind of constant current LED drive circuit comprises: rectifier bridge, the first electric capacity C1, inductance L 1, LED load, three pin critical conduction mode LED drive chip, the second electric capacity C2, current sense resistor Rcs, sustained diode 5 and the 3rd electric capacity C3.
Interchange input after inputting the first electric capacity C1 filtering, produces a direct voltage VDCIN and powers to LED load after rectifier bridge.Rectifier bridge is made up of four diodes D1, D2, D3 and D4.Inductance L 1 one end connects the negative terminal of LED load, and the other end connects the DRN end of driving chip.Second electric capacity C2 is storage capacitor, and one end is held with VCC and is connected, other end ground connection.Current sense resistor Rcs one end is held with CS and is connected, other end ground connection.3rd electric capacity C3 and sustained diode 5 all in parallel with LED load.3rd electric capacity C3 is exactly output capacitance.
Fig. 2 is the circuit diagram of three pin critical conduction mode LED drive chip.
As shown in Figure 2, three pin critical conduction mode LED drive chip comprise: peak current detection circuit B, low-voltage power supply circuit A, comparator C, logic control circuit D, metal-oxide-semiconductor drive circuit E, zero current cross testing circuit F and metal-oxide-semiconductor M, and have VCC end, DRN end and CS end.
Low-voltage power supply circuit A, from DRN end input high pressure, exports low pressure and holds also energy storage in the second electric capacity C2 to the power supply of chip internal to VCC.
Peak current detection circuit B detects and calculates the peak current of inductance L 1, and exports peak current representative voltage VA.Voltage comparator C compares output peak current representative voltage VA and peak current detection setting voltage Vref_pk, and exports peak current arriving signal Vpk.Zero current cross testing circuit F detects inductive current zero crossing and outputting inductance current zero-crossing signal ZCD.
Logic control circuit D input signal peak current arriving signal Vpk and inductive current zero cross signal ZCD, and the on off state being controlled metal-oxide-semiconductor M by metal-oxide-semiconductor drive circuit E, to reach the object of constant current output.Logic control circuit E also controls the operating state of low-voltage power supply circuit A by output signal.
Logic control circuit E also controls the operating state of low-voltage power supply circuit A by output logic control signal PWM_ON.
Fig. 3 is the peak current detection circuit figure of three pin critical conduction mode LED drive chip.
Peak current detection circuit comprises: operational amplifier B1, inverter B2, signaling switch K, the 4th electric capacity C4, the first resistance R1, the second resistance R2, the 3rd resistance R3 and the 4th resistance R4.
The output signal of inverter B2 receive logic control circuit, control signal K switch.One end of signaling switch K is connected with the in-phase input end of operational amplifier B1; The other end is connected by holding with the first resistance R1 and VCC, it is connected also to be held by the second resistance R2 and CS.The in-phase input end of operational amplifier B1 is held by the 4th electric capacity C4 and CS and is connected; Inverting input is held by the 3rd resistance R3 and VCC and is connected, and is also connected with the output of operational amplifier B1 by the 4th resistance R4; Output exports the output voltage of peak current detection circuit.
Fig. 4 is constant current LED drive circuit from oscillogram when being conducting to shutoff.
Operation principle is as follows: when the Gate of signal logic control signal PWM_ON and metal-oxide-semiconductor is by low uprising, metal-oxide-semiconductor becomes conducting state from off state, and electric current is by VDCIN through LED load, and inductance L 1, metal-oxide-semiconductor M and current sense resistor Rcs flows into ground.Current sense resistor Rcs two ends pressure drop Vcs ton within the time period of M conducting, along with inductive current Iind rises by 0 voltage, magnitude of voltage is as follows,
V
cs＝I
ind·R
cs。
Meanwhile, the output signal PWM_ON of logic control circuit D controls low-voltage power supply circuit A ton within the time period of M conducting, stops rushing electricity to the second electric capacity C2.Owing to there is energy storage second electric capacity C2, ton within the time period of M conducting between VCC end and ground, its two ends pressure drop Vcc remains unchanged.But because reference 0 current potential of chip is Vcs, so within the ton time period, peak current detection circuit X2 is input as:
Vcc-V
cs。
When the output signal PWM_ON signal of logic control circuit D is by low uprising, K switch becomes off state from conducting state, so before Vcs rises by 0 voltage, the voltage of the positive input of operational amplifier B1 is stored on electric capacity C4.
Within the ton time period, because the voltage of the positive input terminal of operational amplifier B1 is saved, and the voltage of negative input end changes with the change of Vcs, and the output voltage that can obtain operational amplifier B1 is reference point is pin CS.
V
A＝V
cc-(V
cc-V
cs)＝V
cs
Thus, current sense resistor Rcs two ends pressure drop Vcs (reference point is ground) is copied to the peak current detection circuit output voltage VA reference point of operational amplifier B1 is pin CS.Subsequently, peak current detection circuit output voltage VA is sent to the positive input of voltage comparator C, compares with the peak current detection setting voltage Vref_pk being connected negative input.When VA rises to Vref_pk, the output Vpk of voltage comparator C can be from low to high.Logic control circuit (D) receives Vpk by after the low action uprised, and just can PWM_ON signal be become from height low, thus make metal-oxide-semiconductor become off state from conducting state.Obtain set peak current as follows,
Attached parameter is defined as follows:
VDCIN--input direct voltage
Vled--LED load two ends pressure drop
Iind--inductive current
The inductance value of Lm--inductance L 1
Vcs--current sense resistor Rs two ends pressure drop reference point is ground
Vcc--storage capacitor C2 two ends pressure drop reference point is ground
VA--peak current detection circuit output voltage (reference point is ground pin CS)
Vref_pk--peak current detection setting voltage (reference point is ground pin CS)
The signal of Gate--MOS pipe M
The output signal of PWM_ON--logic control circuit
ZCD--inductive current zero cross signal ZCD
Vpk--peak current arriving signal
Claims (4)
1. the peak current detection circuit of a LED drive chip, it is characterized in that: comprise, operational amplifier (B1), inverter (B2), signaling switch (K), the 4th electric capacity (C4), the first resistance (R1), the second resistance (R2), the 3rd resistance (R3) and the 4th resistance (R4);
The output signal of inverter (B2) receive logic control circuit, control signal switch (K);
One end of signaling switch (K) is connected with the in-phase input end of operational amplifier (B1); The other end is connected by holding with VCC with the first resistance (R1), also to be held with CS by the second resistance (R2) and be connected;
The in-phase input end of operational amplifier (B1) is held with CS by the 4th electric capacity (C4) and is connected; Inverting input is held with VCC by the 3rd resistance (R3) and is connected, and is also connected with the output of operational amplifier (B1) by the 4th resistance (R4); Output exports the output voltage of peak current detection circuit.
2. three pin critical conduction mode LED drive chip, is characterized in that:
Comprise peak current detection circuit as claimed in claim 1 (B), low-voltage power supply circuit (A), comparator (C), logic control circuit (D), metal-oxide-semiconductor drive circuit (E), zero current cross testing circuit (F) and metal-oxide-semiconductor (M), and there is VCC end, DRN end and CS end;
Low-voltage power supply circuit (A), from DRN end input high pressure, exports low pressure and holds to the power supply of chip internal to VCC;
Peak current detection circuit (B) detects and calculates the peak current of inductance, and exports peak current representative voltage;
Voltage comparator (C) compares and exports peak current representative voltage and peak current detection setting voltage and export peak current arriving signal;
Zero current cross testing circuit (F) detects inductive current zero crossing and outputting inductance current zero-crossing signal;
Logic control circuit (D) input signal peak current arriving signal and inductive current zero cross signal also control the on off state of metal-oxide-semiconductor (M) by metal-oxide-semiconductor drive circuit (E); Logic control circuit (E) also controls the operating state of low-voltage power supply circuit (A) by output signal.
3. three pin critical conduction mode LED drive chip according to claim 2, is characterized in that:
Logic control circuit (E) also controls the operating state of low-voltage power supply circuit (A) by output logic control signal.
4. a constant current LED drive circuit, is characterized in that: comprise rectifier bridge, the first electric capacity (C1), inductance (L1), LED load, three pin critical conduction mode LED drive chip as claimed in claim 2 or claim 3, the second electric capacity (C2), current sense resistor (Rcs), fly-wheel diode (D5) and the 3rd electric capacity (C3);
Interchange input after inputting the first electric capacity (C1) filtering, produces a direct voltage and powers to LED load after rectifier bridge;
Inductance (L1) one end connects the negative terminal of LED load, and the other end connects the DRN end of driving chip;
Second electric capacity (C2) one end is held with VCC and is connected, other end ground connection;
Current sense resistor (Rcs) one end is held with CS and is connected, other end ground connection;
3rd electric capacity (C3) and fly-wheel diode (D5) all in parallel with LED load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520538848.XU CN204993961U (en) | 2015-07-23 | 2015-07-23 | LED driver chip's peak current detection circuitry and use thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520538848.XU CN204993961U (en) | 2015-07-23 | 2015-07-23 | LED driver chip's peak current detection circuitry and use thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204993961U true CN204993961U (en) | 2016-01-20 |
Family
ID=55128277
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520538848.XU Withdrawn - After Issue CN204993961U (en) | 2015-07-23 | 2015-07-23 | LED driver chip's peak current detection circuitry and use thereof |
Country Status (1)
| Country | Link |
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| CN (1) | CN204993961U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105007658A (en) * | 2015-07-23 | 2015-10-28 | 宁波拓扑思科电子科技有限公司 | Peak current detection circuit of three-pin critical mode LED driver chip and application thereof |
| CN108333506A (en) * | 2018-04-08 | 2018-07-27 | 杭州欣美成套电器制造有限公司 | A kind of nearly zero-signal extraction and alternating-current switch position detecting circuit |
| CN115656770A (en) * | 2022-10-19 | 2023-01-31 | 杭州国磊半导体设备有限公司 | Method and device for testing power driving chip, computer equipment and storage medium |
-
2015
- 2015-07-23 CN CN201520538848.XU patent/CN204993961U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105007658A (en) * | 2015-07-23 | 2015-10-28 | 宁波拓扑思科电子科技有限公司 | Peak current detection circuit of three-pin critical mode LED driver chip and application thereof |
| CN105007658B (en) * | 2015-07-23 | 2017-11-28 | 宁波拓扑思科电子科技有限公司 | The peak current detection circuit of three pin critical conduction mode LED drive chips and its application |
| CN108333506A (en) * | 2018-04-08 | 2018-07-27 | 杭州欣美成套电器制造有限公司 | A kind of nearly zero-signal extraction and alternating-current switch position detecting circuit |
| CN115656770A (en) * | 2022-10-19 | 2023-01-31 | 杭州国磊半导体设备有限公司 | Method and device for testing power driving chip, computer equipment and storage medium |
| CN115656770B (en) * | 2022-10-19 | 2023-09-01 | 杭州国磊半导体设备有限公司 | Power supply driving chip testing method and device, computer equipment and storage medium |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20160120 Effective date of abandoning: 20171128 |
|
| AV01 | Patent right actively abandoned |