CN207516773U - VOA driving circuits - Google Patents

VOA driving circuits Download PDF

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Publication number
CN207516773U
CN207516773U CN201721766850.8U CN201721766850U CN207516773U CN 207516773 U CN207516773 U CN 207516773U CN 201721766850 U CN201721766850 U CN 201721766850U CN 207516773 U CN207516773 U CN 207516773U
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China
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circuit
circuits
output
chips
connection
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CN201721766850.8U
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Chinese (zh)
Inventor
吕斌
蒋昌明
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Taicang T&W Electronics Co Ltd
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Taicang T&W Electronics Co Ltd
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Abstract

The utility model discloses a kind of VOA driving circuits, including MCU circuits, D/A converting circuit, DC DC circuits, wherein, the input of the output connection D/A converting circuit of MCU circuits, the input of the output connection DC DC circuits of D/A converting circuit, the voltage driving end of the output connection VOA devices of DC DC circuits, MCU circuit output digital voltage signals are converted to analog voltage signal through D/A converting circuit, analog voltage signal inputs DC DC circuits, controls the output voltage of DC DC circuits.The utility model controls DAC chip output voltage using MCU, and so as to control DC DC chip feedback pin voltages, the characteristic using DC DC chip feedback pin voltage constants causes DC DC circuit output adjustable voltages.Circuit structure is simple, and control accuracy is high, and precision can accomplish 0.01db;Not only measuring accuracy is high, but also easily calibrates, and calibration accuracy is high, and calibration speed is fast;High-operational amplifier and power supply chip are eliminated, power supply only needs two or even a power supply, and of low cost, reliability is also high, fast response time.

Description

VOA driving circuits
Technical field
The utility model belongs to electronic circuit technology field, and in particular to a kind of VOA driving circuits.
Background technology
In optical communication industry, optical module, GPON, EPON, etc. the various equipment for being related to opto-electronic conversion be required for test connect Receive sensitivity.It is good and bad that receiving sensitivity characterizes performance of the equipment after certain distance is transmitted.In order to simulate optical transport, in test Often a VOA (Variable Optical Attenuator, adjustable optical attenuator) is connected in optical link carry out simulated light Loss of the signal after transmission.Traditional VOA is using technology is manually adjusted, and not only precision is low but also inefficient.Current one The program-controlled adjustable VOA driving circuits of a little manufacturer's exploitations are also excessively complicated, driven using motor, of high cost, and low precision is safeguarded and is stranded It is difficult.
At present on the market common VOA driving circuits all by the way of amplifier.Multichannel amplifier is needed to cascade, circuit design It is complicated;Then various quiescent points are set, add various temperature-compensation circuits, calibration is inconvenient.Need a few road amplifiers same simultaneously When work could meet demand, since multichannel amplifier interacts, low precision, circuit is complicated, of high cost, and it is inconvenient to safeguard, by It is more fragile in amplifier, it is easily damaged, as long as certain, amplifier goes wrong and can not use, while also need to Multi-path electricity as long as equipment all the way Source, 5V, 15V, 3.3V etc..
Utility model content
The utility model technical issues that need to address are to provide a kind of precision height, and consistency is good, facilitates calibration and test And only need the VOA driving circuits of one to two kinds of power supplys.
To solve the above problems, technical solution adopted in the utility model is:
A kind of VOA driving circuits, including MCU circuits, D/A converting circuit, DC-DC circuit, wherein, the output of MCU circuits Connect the input of D/A converting circuit, the input of the output connection DC-DC circuit of D/A converting circuit, the output of DC-DC circuit The voltage driving end of VOA devices is connected, MCU circuit outputs digital voltage signal is converted to analog voltage through D/A converting circuit to be believed Number, analog voltage signal inputs DC-DC circuit, controls the output voltage of DC-DC circuit.
Further, the DC-DC circuit includes DC-DC chips and its peripheral circuit, and the DC-DC chips are with anti- Present the chip of controlling switch.
Further, the DC-DC circuit includes DC-DC chips U1, inductance L1, diode D1, resistance R1-R4, In, the VIN pins 5 of one end connection power supply VCC and DC-DC chip U1 of inductance L1, and through resistance R1 connection DC-DC chips U1 SHDN pins 4, inductance L1 the other end connection DC-DC chips U1 SW pins 1 simultaneously through diode connect power output end Vout, earthing power supply output end vo ut are concatenated resistance R2, resistance the R3 ground connection of connection, the GND pin of DC-DC chips U1 successively 2 ground connection, the FB pins 1 of DC-DC chips U1 connect the node that resistance R2 is connect with resistance R3, and through resistance R4 connection digital-to-analogue conversions The output terminal of circuit.
Further, the D/A converting circuit is using analog-digital chip U2 as the circuit of core, analog-digital chip U2 is 16 DAC chips.
It is using advantageous effect caused by above-mentioned technical proposal:
The utility model controls DAC chip output voltage using MCU, so as to control DC-DC chip feedback pin voltages, profit DC-DC circuit is caused to export adjustable voltage with the characteristic of DC-DC chip feedback pin voltage constants.Circuit structure is simple, control Precision is high, and precision can accomplish 0.01db;Not only measuring accuracy is high, but also easily calibrates, and calibration accuracy is high, calibration speed Soon;High-operational amplifier and power supply chip are eliminated, power supply only needs two or even a power supply, of low cost, reliability Height, fast response time.
Description of the drawings
Fig. 1 is the utility model circuit block diagram;
Fig. 2 is the utility model circuit diagram;
Specific embodiment
Utility model is described in further detail below in conjunction with the accompanying drawings:
The utility model is a kind of driving circuit of VOA devices, has that circuit structure is simple, measuring accuracy is high, and stabilization can By the features such as.
As shown in Figure 1, the utility model include MCU circuits, D/A converting circuit, DC-DC circuit, wherein, MCU circuits The input of output connection D/A converting circuit, the input of the output connection DC-DC circuit of D/A converting circuit, DC-DC circuit The voltage driving end of output connection VOA devices, MCU circuit outputs digital voltage signal are converted to simulation electricity through D/A converting circuit Signal is pressed, analog voltage signal inputs DC-DC circuit, controls the output voltage of DC-DC circuit.The DC-DC circuit includes DC- DC chips and its peripheral circuit, the DC-DC chips are the chip with feedback control pin.
As shown in Fig. 2, the DC-DC circuit includes DC-DC chips U1, inductance L1, diode D1, resistance R1-R4, In, the VIN pins 5 of one end connection power supply VCC and DC-DC chip U1 of inductance L1, and through resistance R1 connection DC-DC chips U1 SHDN pins 4, inductance L1 the other end connection DC-DC chips U1 SW pins 1 simultaneously through diode connect power output end Vout, earthing power supply output end vo ut are concatenated resistance R2, resistance the R3 ground connection of connection, the GND pin of DC-DC chips U1 successively 2 ground connection, the FB pins 1 of DC-DC chips U1 connect the node that resistance R2 is connect with resistance R3, and through resistance R4 connection digital-to-analogue conversions The output terminal of circuit.Filter capacitor C1, C2, the FB of power output end Vout and DC-DC chips U1 are connected between power supply VCC and ground Pin 1 is direct and meets filter capacitor C3.The D/A converting circuit is using analog-digital chip U2 as the circuit of core, and digital-to-analogue turns Chip U2 is changed as 16 DAC (digital-to-analogue conversion) chips.In above-described embodiment, power supply VCC is 3.3v, and DAC chip power supply is 5v, altogether Two kinds of power supplys are counted, certainly, DAC chip can also use the chip of 3.3v power supplies, thus only need a 3.3v power supply.
Operation principle explanation:
VOA devices are voltage driver part, and with the increase of voltage, attenuation can also increase.The drive voltage range of VOA About 3V to 15V.Therefore the adjustable circuits of 3V to 15V can be generated, and circuit must be very fine by needing one, to ensure The precision of attenuation.
The utility model forms the driving circuit using MCU, DAC chip and DC-DC chips, and MCU can for providing The digital voltage of programming is exported to DAC chip, and in order to ensure degree of regulation, DAC chip uses the DAC chip of 16, with reference to electricity It presses as 2.5V, precision can reach 2.5V/ (2^16)=0.0000305V.Such precision is enough VOA is allowed to be accurate to 0.01db Regulated quantity.
The adjusting of DC-DC circuit output voltage is realized using the principle of DC-DC chips FB feedback foot voltage constants.It is former Reason is as follows:
If without the intervention of DAC chip output voltage.The output voltage Vout=Vfb (1+R2/R3) of DC-DC circuit, The electric current for flowing through R2, R3 is equal, I2=I3, Vfb=I3*R3.After the intervention of DAC chip output voltage, DAC chip output electricity It forces down in FB pin voltages, electric current is absorbed at FB points by resistance R4, at this point, I2=I3+I4, if Vfb will be remained unchanged, It is necessary that I3 is constant, and I3 has become smaller, Vout can be automatically increased to ensure at this time because walking one part of current by I4 points Vfb's is constant.Conversely, the voltage that DAC chip exports is made to can be achieved with the effect of decompression higher than FB pin voltages.Therefore it only needs Change DAC chip output or absorb electric current number, can both realize the variation of Vout.Vout=((Vfb/R3)+ ((Vfb-Vdac)/R4)) * R2+Vfb=Vfb (1+R2/R3)+(R2/R4) (Vfb-Vdac).

Claims (4)

1. a kind of VOA driving circuits, it is characterised in that:Including MCU circuits, D/A converting circuit, DC-DC circuit, wherein, MCU The input of the output connection D/A converting circuit of circuit, the input of the output connection DC-DC circuit of D/A converting circuit, DC-DC The voltage driving end of the output connection VOA devices of circuit, MCU circuit output digital voltage signals are converted to through D/A converting circuit Analog voltage signal, analog voltage signal input DC-DC circuit, control the output voltage of DC-DC circuit.
2. VOA driving circuits according to claim 1, it is characterised in that the DC-DC circuit include DC-DC chips and its Peripheral circuit, the DC-DC chips are the chip with feedback control pin.
3. VOA driving circuits according to claim 1 or 2, it is characterised in that the DC-DC circuit includes DC-DC chips U1, inductance L1, diode D1, resistance R1-R4, wherein, the VIN of one end connection power supply VCC and DC-DC chip U1 of inductance L1 Pin 5, and through the SHDN pins 4 of resistance R1 connection DC-DC chips U1, the DC-DC chips U1's of the other end connection of inductance L1 SW pins 1 and through diode connect power output end Vout, earthing power supply output end vo ut be concatenated successively connection resistance R2, Resistance R3 is grounded, and the GND pin 2 of DC-DC chips U1 is grounded, and the FB pins 1 of DC-DC chips U1 connect resistance R2 and resistance R3 and connect The node connect, and through the output terminal of resistance R4 connection D/A converting circuits.
4. VOA driving circuits according to claim 1 or 2, it is characterised in that the D/A converting circuit is to be turned with digital-to-analogue The circuit that chip U2 is core is changed, analog-digital chip U2 is 16 DAC chips.
CN201721766850.8U 2017-12-18 2017-12-18 VOA driving circuits Active CN207516773U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201721766850.8U CN207516773U (en) 2017-12-18 2017-12-18 VOA driving circuits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201721766850.8U CN207516773U (en) 2017-12-18 2017-12-18 VOA driving circuits

Publications (1)

Publication Number Publication Date
CN207516773U true CN207516773U (en) 2018-06-19

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN201721766850.8U Active CN207516773U (en) 2017-12-18 2017-12-18 VOA driving circuits

Country Status (1)

Country Link
CN (1) CN207516773U (en)

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