CN207069898U

CN207069898U - One kind trembles frequency control circuit

Info

Publication number: CN207069898U
Application number: CN201720868569.9U
Authority: CN
Inventors: 唐盛斌; 符威
Original assignee: Shenzhen Nanyun Microelectronic Co Ltd; Mornsun Guangzhou Science and Technology Ltd
Current assignee: Shenzhen Nanyun Microelectronic Co Ltd; Mornsun Guangzhou Science and Technology Ltd
Priority date: 2017-07-18
Filing date: 2017-07-18
Publication date: 2018-03-02
Anticipated expiration: 2027-07-18

Abstract

The utility model discloses one kind to tremble frequency control circuit, including detection module and enabled module, frequency control circuit is trembled by detecting pin state, decide whether that frequency function is trembled in addition, the utility model controling circuit structure is simple, easy to use, can integrated level it is high, Application Engineer can choose whether, using frequency function is trembled, to reduce the design difficulty of Application Engineer, simplify design procedure if need to only increasing or decreasing a peripheral cell (such as electric capacity).

Description

One kind trembles frequency control circuit

Technical field

Electromagnetic technology field is the utility model is related to, more particularly to one kind trembles frequency control circuit.

Background technology

Now, more and more Switching Power Supply manufacturers reduce electromagnetic interference (EMI) using frequency jitter technique.Frequency jitter technique passes through Switching frequency is modulated appropriately, makes radiant energy distribution in wider frequency range, reducing harmonic amplitude makes its smoothened, So as to reduce EMI.

But not only advantage is immaculate for frequency jitter technique, in some application environments, such as in low-power small size Application in, due to output capacitance very little, insufferable output ripple can usually be brought using frequency jitter technique；Also at some In communication power supply standard, frequency jitter technique cannot be used by being distinctly claimed, therefore is often given up those in such application and integrated The chip of frequency jitter technique, and use common chip to carry out PWM controls, which limits the application of the integrated chip for trembling frequency function Scope.

On the basis of existing technology, set to meet that needs tremble frequency with two kinds of application demands of frequency, chip need not be trembled Meter person has to individually designed two classes chip, or the extra pin of increase is so done undoubtedly again as the enabled pin for trembling frequency Add the design and manufacturing cost of chip design vendors；And for chip application manufacturer, in order to meet above two not Same application demand, they have to develop the different scheme of two classes respectively using two class chips, increase the product of application vendor The cost of design and the management of product, or the additional enabled enabled circuit in pin design periphery is individually for, this periphery is enabled Circuit is often more complicated, so can increase design difficulty and PCB layout area again.

Utility model content

Have in view of that, the technical problems to be solved in the utility model is to provide one kind and trembles frequency control circuit, can integrate and both Can multiplexing pins are realized and tremble the enabled of frequency, and can allows chip application engineer according to practical application request, only increase or decrease compared with Few peripheral cell just can be completed whether to add the selection of frequency jitter technique.

The technical scheme that the utility model solves above-mentioned first technical problem is：

One kind trembles frequency control circuit, applied to Switching Power Supply control chip, it is characterised in that：Including the detection being sequentially connected with Pin, detection module, enabled module and enable signal output end；Detect pin multiplexing Switching Power Supply control chip pin it One, detection module is charged to pin, and detects the pin and obtain voltage signal, and voltage signal then is sent into enabled module； Enabled module judges the whether external electric capacity of the pin, then passes through enable signal output end according to the voltage signal received Whether output adds the enable signal for trembling frequency function.

Preferably, module is enabled by the way that within a specified time, voltage signal and predeterminated voltage are contrasted, and judges that detection is drawn The whether external electric capacity of pin

Preferably, specified time is that chip starts moment or each cycle power tube opens moment.

Preferably, the set of frequency functional pin that pin is chip is detected.

Each technical scheme of circuit of the present utility model and the principle of technical characteristic, effect etc. are analyzed above, it is existing The beneficial effects of the utility model are summarized as follows：

1st, when frequency control circuit is trembled in design, as long as rationally designing described particular moment, it is functional to handle pin well The work schedule problem judged with trembling frequency, it is possible to realize pin multiplexing, save pin for chip, saved to chip Chevron Research Company (CRC) Cost.

2nd, described particular state and preparatory condition are rationally designed, Application Engineer can be made only to increase or decrease outside one Element is enclosed with regard to that can choose whether that frequency function is trembled in addition, without using two different classes of chip, core according to application demand Piece Chevron Research Company (CRC) is also without individually designed two classes chip, while the producing line for reducing chip application company and Chevron Research Company (CRC) is safeguarded Cost and design cost.

Brief description of the drawings

Fig. 1 is the circuit block diagram for trembling frequency control circuit 100 of the utility model embodiment 1；

Fig. 2 is the application circuit schematic diagram of the chip 10 for trembling frequency control circuit 100 of integrated the utility model embodiment 1.

Embodiment

In order that the purpose of this utility model, technical scheme and advantage are more clearly understood, below in conjunction with accompanying drawing and implementation Example, the utility model is further described.It should be appreciated that specific embodiment described herein is only explaining this reality With new, it is not used to limit the utility model.

Embodiment 1

Fig. 1 is a kind of circuit block diagram for trembling frequency control circuit 100 provided by the utility model.As shown in figure 1, tremble frequency control Circuit 100 includes detection pin 3, detection module 110, enabled module 120 and the enable signal EN output ends being sequentially connected with, detection One end of module 110 is that RI pins are connected with the set of frequency pin of chip 10, that is, detects the multiplex switch power supply core of pin 3 The set of frequency pin of piece is RI, and the other end of detection module 110 is connected to form RI pins sampling electricity with one end of enabled module 120 Press Vs node；The other end of enabled module 120 is connected with the frequency module 200 of trembling of chip 10, forms output enable signal EN's Node, i.e. enable signal EN output ends.Hereinafter the implication of the title with identical English code name is identical.

After chip 10 has started timing 2us, detection module 110 starts to detect the voltage of RI pins, generates sampled voltage Vs is sent to enabled module 120；Enabled module 120 makes comparisons the sampled voltage Vs received with predeterminated voltage V1, if sampling Voltage Vs is less than predeterminated voltage V1, then sends enable signal EN, enabled to tremble frequency module 200, will tremble in frequency function addition system.It is aobvious So, in the utility model embodiment 1, choose whether addition tremble frequency function can by RI pins add or be not added with electric capacity C1 come Realize, i.e., powered up in RI pins and hold C1, then the RI pin voltages rate of rise can reduce, then after defined 2us, sampled voltage Vs can be less than predeterminated voltage V1, and system adds and trembles frequency function；Conversely, then it is added without.Because 2us time is very short, pass through Rational design, it is only necessary to which a less low-voltage capacitance (nF levels) is with regard to that can choose whether that frequency function, circuit system letter are trembled in addition It is single.

Employ it is of the present utility model tremble frequency control program after, high is required to volume and output ripple at some, EMI characteristics Less demanding or product standard is distinctly claimed to use and trembled in the application of frequency, Application Engineer can by be not added with electric capacity C1 come Complete design；And it is just sufficiently large in some output capacitances itself, EMI requires high, can use and tremble in the application that frequency reduces EMI, C1 can be held by powering up come complete design.So Application Engineer avoids the need for different classes of using two according to application demand Chip, chip Chevron Research Company (CRC) reduces chip application company and Chevron Research Company (CRC) also without individually designed two classes chip Producing line maintenance cost and design cost.At the same time, moreover it is possible to realize pin multiplexing, reduce the costs such as the encapsulation of chip.

Fig. 2 is to integrate a kind of application circuit schematic diagram for the chip 10 for trembling frequency control circuit 100 provided by the utility model, What the circuit was applied is the DC-DC anti exciting converter schemes of inexpensive small size, and main power topology is known technology, by 9-36V The V of input_DC, output voltage V_out, electric capacity C_VIN, electric capacity C_ds, main power transformer, diode D_OUT, electric capacity C₂, inductance L₁, electric capacity C₃, resistance R₂, resistance R₃, resistance R₄, resistance R₅, resistance R₆, electric capacity C_C, the device such as TL431 composition.As shown in Fig. 2 chip 10 is logical VIN pins are crossed from input voltage V_DCPower taking, then the shunt capacitance C to VCC pin_BPAfter charging to the startup of chip 10, flow through The electric current of VIN pins is changed into the running current of chip 10, i.e. VIN pins continue from input voltage power taking to maintain chip just Often work；VFB pins are the feedback pin of chip 10, for receiving the feedback signal of optocoupler；VSS pins are that chip 10 refers to Ground；DRN pins are the drain electrodes of built-in chip type power tube, are connected for one end with transformer, realize that the energy of Switching Power Supply turns Change；RI is the set of frequency pin of chip 10, it is necessary to which outer meeting resistance R1 comes configuration switch frequency, specific method to set up to reference ground For the internal reference voltage V of chip 10_refBy the voltage clamping of RI pins it is V by a voltage follower_refSo that flow through resistance R1 electric current I_R1=V_ref/ R1, then chip 10 is by electric current I_R1Mirror image is to the RC oscillators inside chip 10 in proportion, as RC The bias current of oscillator is to set chip frequency.

In summary, in RI pin plug-in capacitor C1, only can lengthen RI pin voltages rises to V_refTime, can't Influence the former pin function of set of frequency.Therefore perfect can be realized using the control program of embodiment 1 tremble frequency selection function and The pin multiplexing of set of frequency function.

Embodiment 2

The circuit block diagram for trembling frequency control circuit and application circuit structure of embodiment 2 are identical with embodiment 1.Both Difference is that the preparatory condition of embodiment 2 is that sampled voltage Vs is more than predeterminated voltage V1, i.e., in example 2, if generation Sampled signal Vs be more than predeterminated voltage V1, then send enable signal EN, it is enabled to tremble frequency module 200, frequency function will be trembled and add system In system.

Therefore in example 2, electric capacity C1 is not added with, system adds and trembles frequency function；C1 is held in power-up, and system, which is added without, trembles frequency work( Energy.

Described above is preferred embodiments of the present utility model, it is noted that for the ordinary skill people of the art For member, on the premise of the utility model principle is not departed from, some improvements and modifications for making, as particular moment is set to chip After the preset time started or each cycle power tube start-up time, special time period are set to the preset time period that chip has started Interior or each cycle power tube was opened in the period, and special pin is set as other functional pins, and particular state is other shapes such as electric current State, change preparatory condition etc., also should be regarded as the scope of protection of the utility model.

Claims

1. one kind trembles frequency control circuit, applied to Switching Power Supply control chip, it is characterised in that：Detection including being sequentially connected with is drawn Pin, detection module, enabled module and enable signal output end；One of pin of pin multiplexing Switching Power Supply control chip is detected, Detection module is charged to pin, and detects the pin and obtain voltage signal, and voltage signal then is sent into enabled module；It is enabled Module judges the whether external electric capacity of the pin, then exported by enable signal output end according to the voltage signal received Whether the enable signal of frequency function is trembled in addition.

2. according to claim 1 tremble frequency control circuit, it is characterised in that：Enabled module is by within a specified time, inciting somebody to action Voltage signal contrasts with predeterminated voltage, judges to detect the whether external electric capacity of pin.

3. according to claim 2 tremble frequency control circuit, it is characterised in that：Specified time is for chip startup moment or weekly Phase power tube opens moment.

4. according to claim 1 tremble frequency control circuit, it is characterised in that：Detect the set of frequency function that pin is chip Pin.