Summary of the invention
The object of the present invention is to provide a kind of new LED display driver circuit, being intended to, when keeping output number constant, output interface is reduced one times.
The present invention is achieved in that a kind of LED display driver circuit, comprises the power end of series connection, three-state driver, driver module and earth terminal, and described three-state driver has output high level, output low level and output high resistance three kinds of states.Described three-state driver refers to a kind of driver having three kinds of states at least, namely has 0 state, 1 state and Z state respectively, and what wherein 1 state referred to output is high level; What 0 state referred to output is low level; And driver exports high resistant when Z state, now the electric current of driver port both cannot flow into and also cannot flow out.
Further technical scheme of the present invention is: described driver module comprises a LED port, the 2nd LED port, a LED, the 2nd LED, the 3rd LED, the 4th LED and earth terminal, the input of a described LED is contacted mutually with a described LED port, the input of described 2nd LED is contacted mutually with a described LED port, input and the described 2nd LED port of described 3rd LED are in series, and input and the described 2nd LED port of described 4th LED are in series; A described 2nd LED and described LED is in parallel, described 3rd LED and described 4th LED is in parallel, the output of described 4th LED and the parallel circuits of a described LED and described 2nd LED are in series, and the output of described 2nd LED and the input of described 3rd LED are in series; The output of a described LED is connected with described earth terminal, and the output of described ground three LED is connected with described earth terminal.
Further technical scheme of the present invention is: described driver module comprises a LED port, 2nd LED port, one LED, 2nd LED, 3rd LED, 4th LED and power end, described power end is connected with the input of a described LED, described power end is connected with the input of described 3rd LED, the output of a described LED is contacted mutually with a described LED port, the output of described 2nd LED is contacted mutually with a described LED port, output and the described 2nd LED port of described 3rd LED are in series, output and the described 2nd LED port of described 4th LED are in series, the series circuit of a described LED and described 2nd LED and the 3rd LED is in parallel, and the series circuit of described 3rd LED and a described LED and described 4th LED is in parallel, and the output of described 3rd LED and the input of described 2nd LED are in series.
Further technical scheme of the present invention is: described three-state driver state driver comprises interconnective first P-type mos effect transistor and the first N-type metal-oxide semiconductor (MOS) effect transistor.By controlling the circuit state control LED port circuit situation of two transistors.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the second P-type mos effect transistor be in parallel with described first P-type mos effect transistor.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the first switch be in series with described first P-type mos effect transistor.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the second switch be in series with described second P-type mos effect transistor.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the second N-type metal-oxide semiconductor (MOS) effect transistor be in parallel with described first N-type metal-oxide semiconductor (MOS) effect transistor.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the first switch be in series with described first N-type metal-oxide semiconductor (MOS) effect transistor.
Further technical scheme of the present invention is: described LED display driver circuit also comprises the second switch be in series with described second P-type mos effect transistor.
The invention has the beneficial effects as follows: the circuit of driving four LED that could realize originally needing four LED ports makes into only to need two, save the I/O resource of 50%, this greatly reduces cost, meanwhile, LED provided by the invention drives display circuit can realize more function when LED port number is constant.
Embodiment
Fig. 3 shows the LED display driver circuit that this specific embodiment provides.As seen from Figure 3, described LED display driver circuit comprises the power end of series connection, three-state driver, driver module and earth terminal, and described three-state driver has output high level, output low level and output high resistance three kinds of states.In this specific embodiment, three-state driver is composed in series by a P-type mos effect transistor and a N-type metal-oxide semiconductor (MOS) effect transistor, by the different conditions of the different conditions control LED port of described P-type mos effect transistor and described N-type metal-oxide semiconductor (MOS) effect transistor, thus reach the object controlling drive circuit.
Fig. 4 is the anode drive module that the embodiment of the present invention provides.Described anode drive module comprises a LED port, the 2nd LED port, a LED, the 2nd LED, the 3rd LED, the 4th LED and earth terminal, the input of a described LED is contacted mutually with a described LED port, the input of described 2nd LED is contacted mutually with a described LED port, input and the described 2nd LED port of described 3rd LED are in series, and input and the described 2nd LED port of described 4th LED are in series; A described 2nd LED and described LED is in parallel, described 3rd LED and described 4th LED is in parallel, the output of described 4th LED and the parallel circuits of a described LED and described 2nd LED are in series, and the output of described 2nd LED and the input of described 3rd LED are in series; The output of a described LED is connected with described earth terminal, and the output of described ground three LED is connected with described earth terminal.
In this specific embodiment, described three-state driver state driver comprises interconnective first P-type mos effect transistor and the first N-type metal-oxide semiconductor (MOS) effect transistor.
By by 4 LED and two metal-oxide semiconductor (MOS) effect transistors: a LED, the 2nd LED, the 3rd LED, the 4th LED, 1 P-type mos effect transistor and 1 N-type metal-oxide semiconductor (MOS) effect transistor combine with shown connected mode, only need two LED interfaces, namely a LED port and the 2nd LED port two output interfaces coordinate ground wire or power line just can complete display.This traditional LED driver module provided relative to Fig. 1 and Fig. 2 decreases two LED output ports, and advantage clearly.
Although according to the connected mode of LED display driver circuit in this specific embodiment, there is the problem that the 2nd LED and the 4th LED can not light separately, when namely wanting to light the 2nd LED, a LED must light, and when wanting to light the 4th LED, the 3rd LED must light.But consider the physical quantity in quite a few reality, as speed, the application of temperature etc. is existence order, higher numerical digit effectively must be based upon low level effectively on basis.Although so think that this type of drive has certain limitation, still a lot of application can be met.
In order to solve the problem that in above-mentioned LED display driver circuit, four LED cannot light simultaneously, the method for time-sharing operation can be used, utilize the afterglow effect of LED and human eye vision to persist, the object that " simultaneously " is lighted can be reached.
In this specific embodiment, LED port has three kinds of circuit states, 1 state, 0 state and Z state respectively, when the level of P-type mos effect transistor is high, when the level of N-type metal-oxide semiconductor (MOS) effect transistor is low, LED port is shown as Z state, when the level of P-type mos effect transistor is low, when the level of N-type metal-oxide semiconductor (MOS) effect transistor is also low, LED port is 1 signal; When the level of P-type mos effect transistor is high, when the level of N-type metal-oxide semiconductor (MOS) effect transistor is also high, LED port is 0 signal.
In this specific embodiment anode driving circuit, the relation of the situation of lighting of LED and LED port as shown in Table 1.
Table one: in anode driving circuit, LED lights situation and LED interface relationship
LED |
One LED port |
2nd LED port |
1 |
1 |
Z |
1+2 |
1 |
0 |
3 |
Z |
1 |
3+4 |
0 |
1 |
When a LED port is 1 state, when the 2nd LED port is Z state, the first LED is bright;
When a LED port is 1 state, when the 2nd LED port is 0 state, bright the while of a LED and the second LED;
When a LED port is Z state, when the 2nd LED port is 1 state, the 3rd LED is bright;
When a LED port is 0 state, when the 2nd LED port is 1 state, bright the while of the 3rd LED and the 4th LED.
When the LED used in this LED display driver circuit is all identical, light a LED and the 2nd LED to a LED port simultaneously, but the constant electric current being assigned to each LED of output current reduces by half, consistent in order to realize brightness, show anode driving circuit to LED to improve, as shown in Figure 6, increase SW1 and SW2 two switches and a second P-type mos effect transistor DP2 make fan-out capability can increase when needed to modified LED display driver circuit.For this improved circuit, the Z state of LED end is that NMOS closes, and now closes without the need to P-type mos effect transistor, as long as the extra switch of connecting with this PMOS disconnects, all the other.
Easily the anode drive module converts shown in Fig. 4 can be become the negative electrode driver module of its equivalence.Fig. 5 is the negative electrode driver module that the embodiment of the present invention provides.Described driver module comprises a LED port, the 2nd LED port, a LED, the 2nd LED, the 3rd LED, the 4th LED and power end, described power end is connected with the input of a described LED, described power end is connected with the input of described 3rd LED, the output of a described LED is contacted mutually with a described LED port, the output of described 2nd LED is contacted mutually with a described LED port, output and the described 2nd LED port of described 3rd LED are in series, and output and the described 2nd LED port of described 4th LED are in series; The series circuit of a described LED and described 2nd LED and the 3rd LED is in parallel, and the series circuit of described 3rd LED and a described LED and described 4th LED is in parallel, and the output of described 3rd LED and the input of described 2nd LED are in series.
According to identical principle, in this specific embodiment negative electrode drive circuit, the relation of the situation of lighting of LED and LED interface is as shown in Table 2:
Table two: in negative electrode drive circuit, LED lights situation and LED interface relationship
LED |
One LED port |
2nd LED port |
1 |
0 |
Z |
1+2 |
0 |
1 |
3 |
Z |
0 |
3+4 |
1 |
0 |
When a LED port is 0 state, when the 2nd LED port is Z state, the first LED is bright;
When a LED port is 0 state, when the 2nd LED port is 1 state, bright the while of a LED and the 3rd LED;
When a LED port is Z state, when the 2nd LED port is 0 state, the 3rd LED is bright;
When a LED port is 1 state, when the 2nd LED port is 0 state, bright the while of the 3rd LED and the 4th LED.
Same, described modified model LED in Fig. 6 shows the negative electrode drive circuit that anode driving circuit also can be converted into equivalence, modified LED shows negative electrode drive circuit as shown in Figure 7, and increase SW1 and SW2 two switches and a N-type metal-oxide semiconductor (MOS) effect transistor DN2 make fan-out capability can increase when needed.The improved anode drive circuit that other principles all provide with Fig. 6 is identical.
Can find out that LED display driver circuit provided by the invention can complete wiring by one side PCB from this specific embodiment.
The beneficial effect of this specific embodiment is the circuit of driving four LED originally needing four LED ports to realize to make into only to need two, save the I/O resource of 50%, this greatly reduces cost, meanwhile, LED provided by the invention drives display circuit can realize more function when LED port number is constant.
In addition; it should be noted that; employ 2 LED ports in the specific embodiment of the invention and achieve driving four LED, but the scheme of the LED of other quantity of LED port driver of any use other quantity similar to this programme thinking is also within the protection range of this programme.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.