CN202737836U - Soft start circuit - Google Patents
Soft start circuit Download PDFInfo
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- CN202737836U CN202737836U CN 201220337064 CN201220337064U CN202737836U CN 202737836 U CN202737836 U CN 202737836U CN 201220337064 CN201220337064 CN 201220337064 CN 201220337064 U CN201220337064 U CN 201220337064U CN 202737836 U CN202737836 U CN 202737836U
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Abstract
Disclosed is a soft start circuit, comprising a current source, an energy storage unit connected with the current source, a first switch unit connected between the current source and the energy storage unit, and a control unit which is connected with the first switch unit and used for controlling the current source to periodically charge the energy storage unit. The soft start circuit of the utility model solves the problem that the production cost of the conventional soft start circuit is relatively high, thereby realizing the effect of decreasing the production cost of the soft start circuit.
Description
Technical field
The utility model relates to integrated circuit fields, in particular to a kind of soft starting circuit.
Background technology
In order to suppress output voltage or the output current overshoots of Circuits System in start-up course such as voltage source, current source, led drive circuit or motor drive circuit, usually in these Circuits System, use soft starting circuit, its principle is to control the rate of climb of output voltage and output current by the rate of climb of departure element reference voltage, prevents that overshoot from damaging device.
Analog soft start and digital soft start dual mode when being controlled, the rate of climb of error element reference voltage are generally arranged in the prior art, wherein the analog soft start device as shown in Figure 1a, the analog soft start device is when starting, enable signal EN and reference voltage SS oscillogram are shown in Fig. 1 b, the startup stage, the reference voltage by the departure adder reaches the overshoot that suppresses output voltage or output current.This device can be realized with increase charging capacitor C1 by reducing charging current I1 usually in order to obtain enough start-up times.There is following drawback in this kind device: charging current I1 is less, and precision is lower, and antijamming capability is more weak; Charging capacitor C1 is larger, and shared chip area is larger, and cost is higher.The digital soft start device is shown in Fig. 2 a, and the digital soft start device is when starting, and enable signal EN and reference voltage SS oscillogram are shown in Fig. 2 b, and this kind controlled K with the device of digital form departure element reference voltage by clock pulse
1, K
2..., K
N, wherein N clock opened K
N, can control accurately like this rate of climb of reference voltage SS, however the spent cost of clock circuit and current source almost be equal to Fig. 1 a shown device, still have the shortcoming that shared chip area is large, cost is high.
For the higher problem of soft starting circuit production cost in the correlation technique, effective solution is proposed not yet at present.
The utility model content
Main purpose of the present utility model is to provide a kind of soft starting circuit, to solve the higher problem of soft starting circuit production cost in the prior art.
To achieve these goals, according to the utility model, provide a kind of soft starting circuit, having comprised: current source; Energy-storage units is connected with current source; The first switch element is connected between current source and the energy-storage units; And control unit, be connected with the first switch element, be used for the control current source and periodically charge to energy-storage units.
Further, control unit comprises: the first drive circuit is connected with the first switch element, for generation of the first pulse drive signal of control the first switch element break-make.
Further, the first pulse drive signal comprises the first high level signal and the first low level signal, and wherein, the conducting when receiving the first high level signal of the first switch element ends when receiving the first low level signal; Or first switch element when receiving the first high level signal, end conducting when receiving the first low level signal.
Further, control circuit also comprises: the second switch unit, and first end is connected to first node, the second end ground connection, wherein, first node is the node between energy-storage units and the first switch element.
Further, control unit also comprises: the second drive circuit is connected with the second switch unit, for generation of the second pulse drive signal of control second switch unit break-make.
Further, the second pulse drive signal comprises the second high level signal and the second low level signal, and wherein, the conducting when receiving the second high level signal of second switch unit ends when receiving the second low level signal; Or the second switch unit ends conducting when receiving the second low level signal when receiving the second high level signal.
By the utility model, adopt the soft starting circuit that comprises following structure: current source; Energy-storage units is connected with current source; The first switch element is connected between current source and the energy-storage units; And control unit, be connected with the first switch element, be used for the control current source and periodically charge to energy-storage units.By the first switch element is set between current source and energy-storage units, and realize that by the break-make that control unit is controlled the first switch element the control current source periodically charges to energy-storage units, periodically charge to realize that to energy-storage units the voltage at energy-storage units two ends slowly raises by the control current source, to reach output voltage and the output current overshoot of Circuits System in start-up course that suppresses to use soft starting circuit, realize the output voltage of Circuits System and/or the effect that output current slowly raises, this kind soft starting circuit only needs that the first switch element is set and gets final product between current source and energy-storage units, integrated circuit area occupied and the production cost of relative soft starting circuit, the area change that the first switch element that increases brings and cost drop into and almost can ignore, solve the higher problem of soft starting circuit production cost in the prior art, and then reached the effect that reduces the soft starting circuit production cost.
Description of drawings
The accompanying drawing that consists of the application's a part is used to provide further understanding of the present utility model, and illustrative examples of the present utility model and explanation thereof are used for explaining the utility model, do not consist of improper restriction of the present utility model.In the accompanying drawings:
Fig. 1 a is the circuit diagram according to the analog soft start circuit of correlation technique;
Fig. 1 b is according to the driving signal of the analog soft start circuit of correlation technique and the schematic diagram of tank voltage;
Fig. 2 a is the circuit diagram according to the digital soft start circuit of correlation technique;
Fig. 2 b is according to the driving signal of the digital soft start circuit of correlation technique and the schematic diagram of tank voltage;
Fig. 3 a is the schematic diagram according to the soft starting circuit of the utility model embodiment;
Fig. 3 b is the oscillogram that drives signal according to first of the soft starting circuit of the utility model embodiment; And
Fig. 3 c is the oscillogram that drives signal and tank voltage according to second of the soft starting circuit of the utility model embodiment.
Embodiment
Need to prove, in the situation that do not conflict, embodiment and the feature among the embodiment among the application can make up mutually.Describe below with reference to the accompanying drawings and in conjunction with the embodiments the utility model in detail.
The utility model embodiment provides a kind of soft starting circuit, below soft starting circuit that the utility model embodiment is provided be specifically introduced:
Fig. 3 a is the circuit diagram according to the soft starting circuit of the utility model embodiment, and shown in Fig. 3 a, the soft starting circuit of the utility model embodiment comprises current source, energy-storage units, the first switch element K1 and control unit (not shown).Wherein, the first switch element K1 is connected between current source and the energy-storage units, to realize disconnection or the conducting of charge circuit, control unit is connected with the first switch element K1, be used for sending drive control signal to the first switch element K1, realize periodically adhesive or open of control the first switch element K1, periodically charge to energy-storage units to realize the control current source.
The soft starting circuit of the utility model embodiment is by arranging the first switch element between current source and energy-storage units, and realize that by the break-make that control unit is controlled the first switch element the control current source periodically charges to energy-storage units, periodically charge to realize that to energy-storage units the voltage at energy-storage units two ends slowly raises by the control current source, to reach output voltage and the output current overshoot that suppresses to use in the soft start-up process Circuits System of soft starting circuit, realize the output voltage of Circuits System and/or the effect that output current slowly raises, this kind soft starting circuit only needs that the first switch element is set and gets final product between current source and energy-storage units, integrated circuit area occupied and the production cost of relative soft starting circuit, the area change that the first switch element that increases brings and cost drop into and almost can ignore, solve the higher problem of soft starting circuit production cost in the prior art, and then reached the effect that reduces the soft starting circuit production cost.
Particularly, control unit comprises the first drive circuit that is connected with the first switch element K1, this first drive circuit is for generation of the first pulse drive signal Vclk of control the first switch element K1 break-make, wherein, the first pulse drive signal can be the high-low level signal, the first switch element K1 can conducting when receiving high level signal, correspondingly ends when receiving low level signal; Perhaps the first switch element K1 can end when receiving high level signal, correspondingly conducting when receiving low level signal.With first switch element K1 conducting when receiving high level signal, cut-off is illustrated the soft start principle of soft starting circuit when receiving low level signal, it is the oscillogram of the first drive pulse signal shown in Fig. 3 b, when the drive pulse signal of control the first switch element K1 becomes high level, the K1 conducting, this moment, current source I1 was to energy-storage units (but energy-storage units can be charge and discharge capacitance C1) charging, and then in each pulse period, charging raises the voltage at C1 two ends to current source to C1
Wherein, t
dBe that high level signal is held time in the first pulse drive signal one-period T.When the first switch element K1 receives low level signal, the K1 cut-off, this moment, I1 stopped the charging to C1, and C1 keeps current voltage until next high level signal pulse arrives.If the reference voltage of output was raised to Vss after the definition soft start was finished, then the whole soft-start time T of soft starting circuit
SsFor:
Define the duty ratio of the first drive pulse signal
Substitution formula 1.1:
Can be found out if reduce K by formula 1.2, namely reduce the duty ratio of pulse signal, the speed of the soft start that can slow down.In other words, under the certain prerequisite of soft start speed, can increase by reducing duty ratio K value the charging current I1 of current source, realize improving precision and the antijamming capability of soft start, can reduce C1 by reducing duty ratio K value simultaneously, realize that the cost that reduces soft starting circuit drops into.
Preferably, soft starting circuit also comprises the second switch unit K2 that is connected between signal ground and the first node.Wherein, first node is the node between energy-storage units C1 and the first switch element K1.Whether the two ends that the two ends of second switch unit K2 are connected to energy-storage units C1 discharge the energy among the energy-storage units C1 with realization, wherein, when the K2 conducting of second switch unit, signal ground is directly accessed at the two ends of energy-storage units C1, realization discharges the energy among the energy-storage units C1, when second switch unit K2 opened, energy-storage units C1 stopped to release energy.Wherein, can before the energy-storage units charging, control second switch unit K2 conducting at current source, so that energy-storage units C1 is carried out initialization, then when beginning is charged to energy-storage units, open second switch unit K2.Particularly, the signal of control second switch unit K2 conducting or cut-off can be produced by the second drive circuit in the control unit, the second drive circuit is connected with second switch unit K2, control the K2 conducting of second switch unit or cut-off by sending the second drive pulse signal EN to second switch unit K2, wherein, the second pulse drive signal EN can be high level for the starting stage, maintenance stage is low level signal, can be low level for the starting stage also, maintenance stage is the signal of high level, namely, can control the conducting when receiving high level signal of second switch unit, when receiving low level signal, end; Or control second switch unit ends conducting when receiving low level signal when receiving high level signal.Take the second pulse drive signal EN starting stage as low level signal, the maintenance stage as high level signal as exemplifying the soft start principle of example explanation soft starting circuit, it is the oscillogram of the voltage at the second drive pulse signal and energy-storage units two ends shown in Fig. 3 c, when the second pulse drive signal EN is low level signal, the K2 conducting of second switch unit is carried out discharge process to energy-storage units C1; When the second pulse drive signal EN becomes high level signal, control unit is also controlled the first switch element K1 conducting, at this moment, current source begins under the conducting of K1 switch or cut-off energy-storage units to be carried out the periodicity charging, realizes that the voltage SS at energy-storage units two ends slowly raises.
By the second switch unit is set in soft starting circuit, realized before the energy-storage units charging, energy-storage units being carried out initialization at current source, avoided energy-storage units because reset condition just stores voltage and/or the current over pulse that higher electric weight causes.
Operation principle below in conjunction with the soft starting circuit of the utility model embodiment illustrates soft starting circuit of the present utility model further, the soft starting circuit that the startup control method of this soft starting circuit can provide by the utility model embodiment foregoing is carried out, below the operation principle of soft starting circuit that the utility model embodiment is provided be specifically introduced:
When the soft starting circuit soft start, periodically charge so that the voltage at energy-storage units two ends raises gradually by the energy-storage units of control current source to soft starting circuit.Wherein, mainly realize charging to the periodicity of energy-storage units by the break-make of controlling the charge circuit between current source and the energy-storage units.Particularly, the first switch element is set between current source and energy-storage units, realizes the break-make of charge circuit by sending the first pulse drive signal to the first switch element to control the first switch element break-make.
The startup control method of the utility model embodiment periodically charges to realize that to energy-storage units the voltage at energy-storage units two ends slowly raises by the control current source, to reach output voltage and the output current overshoot of Circuits System in start-up course that suppresses to use soft starting circuit, realize the soft start effect of Circuits System, this kind soft starting circuit only needs that the first switch element is set and gets final product between current source and energy-storage units, integrated circuit area occupied and the production cost of relative soft starting circuit, the area change that the first switch element that increases brings and cost drop into and almost can ignore, solve the higher problem of soft starting circuit production cost in the prior art, and then reached the effect that reduces the soft starting circuit production cost.
Further, before current source periodically charged to the energy-storage units of soft starting circuit, the startup control method of the utility model embodiment also comprised: energy-storage units is discharged.
By energy-storage units is discharged, realized before the energy-storage units charging, energy-storage units being carried out initialization at current source, avoided energy-storage units because reset condition just stores voltage and/or the current over pulse that higher electric weight causes.
The above is preferred embodiment of the present utility model only, is not limited to the utility model, and for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., all should be included within the protection range of the present utility model.
Claims (4)
1. a soft starting circuit is characterized in that, comprising:
Current source;
Energy-storage units is connected with described current source;
The first switch element is connected between described current source and the described energy-storage units; And
Control unit is connected with described the first switch element, is used for controlling described current source and periodically charges to described energy-storage units.
2. soft starting circuit according to claim 1 is characterized in that, described control unit comprises:
The first drive circuit is connected with described the first switch element, for generation of the first pulse drive signal of described the first switch element break-make of control.
3. soft starting circuit according to claim 1 is characterized in that, described control circuit also comprises:
The second switch unit, first end is connected to first node, the second end ground connection, wherein, described first node is the node between described energy-storage units and described the first switch element.
4. soft starting circuit according to claim 3 is characterized in that, described control unit also comprises:
The second drive circuit is connected with described second switch unit, for generation of the second pulse drive signal of the described second switch of control unit break-make.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220337064 CN202737836U (en) | 2012-07-11 | 2012-07-11 | Soft start circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220337064 CN202737836U (en) | 2012-07-11 | 2012-07-11 | Soft start circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202737836U true CN202737836U (en) | 2013-02-13 |
Family
ID=47663492
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220337064 Expired - Lifetime CN202737836U (en) | 2012-07-11 | 2012-07-11 | Soft start circuit |
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| Country | Link |
|---|---|
| CN (1) | CN202737836U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751859A (en) * | 2012-07-11 | 2012-10-24 | 圣邦微电子（北京）股份有限公司 | Soft start circuit and start control method thereof |
-
2012
- 2012-07-11 CN CN 201220337064 patent/CN202737836U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751859A (en) * | 2012-07-11 | 2012-10-24 | 圣邦微电子（北京）股份有限公司 | Soft start circuit and start control method thereof |
| CN102751859B (en) * | 2012-07-11 | 2015-06-03 | 圣邦微电子（北京）股份有限公司 | Soft start circuit and start control method thereof |
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Granted publication date: 20130213 |