Multimode LED drive circuit based on LT3902 chip

Abstract

The utility model relates to the technical field of circuits for electric illumination light sources, and discloses a multimode LED drive circuit based on an LT3902 chip. The circuit comprises a mode selection switch, a current control circuit, a voltage control circuit and a PWM control circuit. The preceding stage of the current control circuit is connected with the voltage control circuit; the preceding stage of the voltage control circuit is connected with the PWM control circuit; the number of the mode selection switches is three, and the mode selection switches are respectively connected with control signals and respectively control on-off of working loops of the current control circuit, the voltage control circuit and the PWM control circuit. And the current control circuit realizes control through an LT3902 chip. According to the utility model, different LED driving requirements of various devices can be met, the functions are rich, the overall circuit redundancy is extremely low, different LED driving control requirements of various devices can be met, and the adaptability is extremely good, so that the maintenance cost and the management cost are greatly reduced; and on the whole, the integration degree is high, the connection functions are complete and diversified, the circuit is reasonable and compact, and the market prospect is excellent.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits used for electric lighting sources, in particular to the technical field of circuit devices used for operating light emitting diodes. Background Art

[0002] There are various requirements for LED drivers in medical devices in the prior art. For example, for calcium imaging devices, since the LEDs used in calcium imaging require a constant current, PWM modulation dimming cannot be used, and only a constant current source can be used. In practice, the LED driver requirements for adjusting LEDs in medical devices include at least constant adjustment of current, constant adjustment of voltage, and constant adjustment of PWM duty cycle. Some devices also involve the need to combine the two adjustment methods. This situation often requires different LED drive circuits for different devices in practice, making the maintenance and matching of the equipment particularly troublesome. Utility Model Content

[0003] The purpose of the utility model is to provide a multi-mode LED driving circuit based on the LT3902 chip, so that a set of LED driving circuits can adapt to different LED driving requirements of various devices, with rich functions and extremely low overall circuit redundancy and excellent adaptability, thereby greatly reducing maintenance costs and management costs.

[0004] The utility model is realized through the following technical solutions.

[0005] The utility model provides a multi-mode LED driving circuit based on the LT3902 chip, comprising:

[0006] Mode selection switch, current control circuit, voltage control circuit, PWM control circuit;

[0007] The front stage of the current control circuit is connected to the voltage control circuit;

[0008] The front stage of the voltage control circuit is connected to the PWM control circuit;

[0009] There are three mode selection switches, which are connected to control signals respectively to control the on and off of the working circuits of the current control circuit, the voltage control circuit, and the PWM control circuit;

[0010] The current control circuit is controlled by the LT3902 chip.

[0011] The current control circuit is a series-connected LT3902 chip, and a mode selection switch is connected in parallel to the LT3902 chip.

[0012] The voltage control circuit includes a digital variable resistor connected in parallel to the positive and negative outputs, and the digital variable resistor is connected in series with a mode selection switch.

[0013] The digital resistor adopts AD5271 chip.

[0014] The digital variable resistor is connected in series with a resistor for current limiting.

[0015] The PWM control circuit comprises a front-stage PWM chip and a rear-stage optocoupler circuit, and a mode selection switch is connected in parallel to the branch where the PWM chip and the optocoupler circuit are located.

[0016] The PWM chip adopts TL494 chip.

[0017] The output positive circuit of the optocoupler circuit is connected in series with a resistor for current limiting.

[0018] Compared with the prior art, the utility model can adapt to the different LED driving requirements of various devices, has rich functions and extremely low overall circuit redundancy, can meet the different LED driving control requirements of various devices, and has excellent adaptability, thereby greatly reducing maintenance costs and management costs; overall, it has a high degree of integration, complete and diverse connection functions, a reasonable and compact circuit, and excellent market prospects.

[0019] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0021] Figure 1 It is a connection diagram of at least one implementation mode of the utility model. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the utility model clearer, each embodiment of the utility model will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in each embodiment of the utility model, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the utility model. The various embodiments can be combined with each other and referenced to each other without contradiction.

[0023] The first embodiment of the present invention relates to Figure 1 A multi-mode LED driving circuit based on the LT3902 chip is shown, comprising:

[0024] Mode selection switch, current control circuit, voltage control circuit, PWM control circuit;

[0025] The front stage of the current control circuit is connected to the voltage control circuit;

[0026] The front stage of the voltage control circuit is connected to the PWM control circuit;

[0027] There are three mode selection switches, which are connected to control signals respectively to control the on and off of the working circuits of the current control circuit, the voltage control circuit, and the PWM control circuit;

[0028] The current control circuit is controlled by the LT3902 chip.

[0029] Therefore, based on the mode selection switch to control the on and off, and the settings of the current control circuit, voltage control circuit, and PWM control circuit, the LED drive control method can be more diverse and the overall circuit redundancy is extremely low, which can meet the different LED drive control requirements of various devices. Overall, the integration is high, the connection functions are complete and diverse, the circuit is reasonable and compact, and the market prospect is excellent.

[0030] The second embodiment of the present invention is substantially the same as the first embodiment, mainly in that the current control circuit is a series-connected LT3902 chip, and a mode selection switch is connected in parallel to the LT3902 chip.

[0031] Furthermore, the voltage control circuit includes a digital variable resistor connected in parallel to the positive and negative outputs, and the digital variable resistor is connected in series with a mode selection switch.

[0032] Preferably, the digital rheostat uses an AD5271 chip.

[0033] Furthermore, the digital variable resistor is connected in series with a resistor for current limiting.

[0034] Furthermore, the PWM control circuit includes a front-stage PWM chip and a rear-stage optocoupler circuit, and the mode selection switch is connected in parallel to the branch where the PWM chip and the optocoupler circuit are located.

[0035] Preferably, the PWM chip is a TL494 chip.

[0036] Furthermore, a resistor is connected in series to the output positive circuit of the optocoupler circuit for current limiting.

[0037] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A multi-mode LED driving circuit based on LT3902 chip, characterized in that: include: Mode selection switch, current control circuit, voltage control circuit, PWM control circuit; The front stage of the current control circuit is connected to the voltage control circuit; The front stage of the voltage control circuit is connected to the PWM control circuit; There are three mode selection switches, which are connected to control signals respectively to control the on and off of the working circuits of the current control circuit, the voltage control circuit, and the PWM control circuit; The current control circuit is controlled by the LT3902 chip.

2. The multi-mode LED driving circuit based on the LT3902 chip according to claim 1 is characterized in that: The current control circuit is a series-connected LT3902 chip, and a mode selection switch is connected in parallel to the LT3902 chip.

3. The multi-mode LED driving circuit based on the LT3902 chip according to claim 1, characterized in that: The voltage control circuit includes a digital variable resistor connected in parallel to the positive and negative outputs, and the digital variable resistor is connected in series with a mode selection switch.

4. The multi-mode LED driving circuit based on the LT3902 chip according to claim 3 is characterized in that: The digital resistor adopts AD5271 chip.

5. The multi-mode LED driving circuit based on the LT3902 chip according to claim 3 is characterized in that: The digital variable resistor is connected in series with a resistor for current limiting.

6. The multi-mode LED driving circuit based on the LT3902 chip according to claim 1, characterized in that: The PWM control circuit comprises a front-stage PWM chip and a rear-stage optocoupler circuit, and a mode selection switch is connected in parallel to the branch where the PWM chip and the optocoupler circuit are located.

7. The multi-mode LED driving circuit based on the LT3902 chip according to claim 6, characterized in that: The PWM chip adopts TL494 chip.

8. The multi-mode LED driving circuit based on the LT3902 chip according to claim 6, characterized in that: The output positive circuit of the optocoupler circuit is connected in series with a resistor for current limiting.

Images