RGB LED Driver Chips. Addressible LED RGB Ribbon and LED Driver WS2811 The most reliable LED RGB RF Driver
RGB LED ribbons are conveniently used for decorative backlight showcases, machine salon, signs ... with them it is easy to work, unlike simple LEDsbecause Current limiters are already standing, it is enough to simply apply the required voltage. The ability to cut into segments, gives flexible possibilities when installing.
What if you want more? What if you need to control each diode separately? You can put MK, but not every microcontroller alone will pull a lot of three-color diodes, you can try to put to each. For such purposes there are special LED drivers, some of which are provided with the ability to be managed with one common, or consistently passing through drivers, bus. Somewhere went further, and such a driver was built directly in RGB LED, which is needed by a minimum of external strapping. Next, the connectedly connected such diodes were placed on the LED tape - and in the end we received the addressable LED tape.
How it is not difficult to guess, the article will be discussed about LED RGB Drivere - WS2811, which are connected sequentially and controlled by a single-wire data line. And addressable LED ribbon on combined RGB diodes with such drivers.
As can be seen in the photo - such a LED tape consists of a plurality of series connected RGB LEDs with built-in WS2811 drivers (small black point in the middle). From the strapping, such a chip, when nutrition from 5V, only one condenser is required at 0.1MKF in the input of the power supply, a 3-volume resistor on the data line is still recommended, which, apparently, has missed the manufacturer.
All diodes are sitting sequentially on the same line. To change their displayed color and its intensity, you need to send the parcel to each of the diodes on the tape. The first driver receives the entire parcel and transmits it further than a deduction of the last package, which he writes off at his own expense. Similarly, the LED drivers remains with all the remaining assemblies. The parcel is completed special Team RES, which is highlighted by a long-term signal, having received it - all diodes will apply their new states.
Each package consists of 24 bits - 8 bits per channel, as a result we have 255 gradations of each color or 16 million colors. Each bit contains a positive and negative half-period, zero or unit coding is carried out by the duration of half-periods.
To work with the addressable LED ribbon, the controller was collected based on the microcontroller Pic16F688 and on a specially previously harvested universal workpiece of the board (), so I will not lead the sector.
Such a LED tape is very voracious, its meter with 60 LEDs at the maximum eats more than 2 amps, so you need a good and powerful power source. You can give her a smaller current, but then it will be lit with the predominance of red shades.
The firmware has written on an ambulance hand. The following algorithm of work was implemented: First, the entire package drops into the microcontroller from the computer and only after that it displays it. Due to the small amount of RAM memory of a weak microcontroller, it turned out to implement a buffer only on 60 addressed LEDs with WS2811 drivers. Due to the average UART speed in 38400, the speed of updating the entire tape is approximately 50 ms, i.e. The maximum permissible update frequency came out 20 frames / second. What to demonstrate the possibility of the tape I was enough. Generation of all effects is engaged special program On PC, which the same wrote on an ambulance hand.
The format of the sent commands to the controller:
Sending to be done on the UART at the speed of 38400 8N1.
- The first byte - space (32 ASCII INT code)
- The second byte - the length of the transmitted parcel (the number of LEDs), from 0 to 60 (transmitted by byte)
- Next, 3 bytes, in the order of GRB (green, red, blue), are transmitted PWM values \u200b\u200bfor each LED starting from the opposite end of the tape.
The controller responds on the start of the UArt ASCII exchange symbol ! , on the successful completion of sending a package ASCII symbol b. .
Based on similar lED tapes You can implement small video screens and various installations.
Supplement from 09.09.2015
For ease of testing, add a firmware to an article with an autonomous smooth sequential pseudo-random overflow (up to 60 LEDs). If one of this effect is sufficient, then you can simplify the scheme of removing CP2102 from it.
The most optimal way to connect to 220V, 12B is the use of current stabilizer, LED driver. In the language of the alleged opponent, "LED Driver" is written. By adding the desired power to this request, you can easily find suitable items on Aliexpress or eBay.
- 1. Features Chinese
- 2. Service life
- 3. Ice Driver for 220V
- 4. RGB driver for 220V
- 5. Module for assembly
- 6. Driver for LED Luminaires
- 7. Power supply for LED tape
- 8. LED Driver do it yourself
- 9. Low-voltage
- 10. Brightness adjustment
Features Chinese
Many love to buy on the largest Chinese market for Aliexpress. Prices and range are pleased. LED DRIVER is most often choosing due to low cost and good characteristics.
But with an increase in the dollar, buying the Chinese has become unprofitable, the cost comes from the Russian, while there is no guarantee and the possibility of exchanging. For cheap electronics, the characteristics are always overestimated. For example, if the power of 50 watts is indicated, at best, this is the maximum short-term power, and not constant. Nominal will be 35W - 40W.
In addition, they are much saved on the stuffing to reduce the price. Some where there is not enough items that provide stable operation. The cheapest components are applied, with a short service life and low quality, so the percentage of marriage is relatively high. As a rule, components work at the limit of their parameters, without any stock.
If the manufacturer is not specified, he does not need to be responsible for the quality and feedback about his goods will not write. And the same item produces several factories in different configurations. For good items, a brand must be specified, which means it is not afraid to respond for the quality of its products.
One of the best is the MEANWELL brand, which values \u200b\u200bthe quality of its products and does not release junk.
Life time
Like anyone electronic device The LED driver has a service life that depends on the operating conditions. Branded modern LEDs are already working up to 50-100 thousand hours, so food fails before.
Classification:
- consumer goods up to 20.000h.;
- secondary quality up to 50.000h.;
- up to 70.000h. Power supply on high-quality Japanese components.
This indicator is important when calculating payback to the long-term perspective. For domestic use, there is enough swirpotreb. Although the miser pays twice, and in LED searchlights and lamps it works great.
Ice driver for 220V
Modern LED drivers are structurally performed on the PWM controller, which can be very good to stabilize the current.
Main settings:
- rated power;
- working current;
- the number of connected LEDs;
- degree of protection against moisture and dust
- power factor;
- KPD stabilizer.
The housings for street use are performed from metal or shockproof plastic. In the manufacture of aluminum housing, it can act as a cooling system for electronic filling. This is especially true when filling the housing compound.
On labeling often indicate how many LEDs can be connected and what power. This value may not only be fixed, but also in the form of a range. For example, it is possible from 4 to 7 pieces of 1W. It depends on the design electrical circuit LED driver.
RGB driver for 220V
The tricolor RGB LEDs differ from one-color in order to contain in one body crystals of different colors red, blue, green. To manage them, each color must be lit separately. Diode tapes are used by the RGB controller and power supply.
If the RGB of the LED is the power of 50w, then this is total for all 3 colors. To learn an approximate load on each channel, divide 50w to 3, we get about 17w.
In addition to powerful LED Driver there are 1W, 3W, 5W, 10W.
Consoles remote control (DU) There are 2 types. With infrared management, like a TV. With the control of radio channel, do not need to be directed to the signal receiver.
Module for assembly
If you are interested in ice driver for assembling with your own hands of the LED searchlight or lamp, you can use the LED Driver without a case.
Before making LED Driver 50W with your own hands, it is worth a little search, for example, there is in every diode lamp. If you have a faulty light bulb, which has a malfunction in diodes, then you can use Driver from it.
Low-voltage
In detail we analyze the types of low-voltage ice drivers running from voltage up to 40 volts. Our Chinese brothers in mind offer many options. On the basis of PWM controllers, voltage stabilizers and current stabilizers are produced. The main difference, the module with the ability to stabilize current on the board is 2-3 blue regulators, in the form of variable resistors.
As technical characteristics The entire module indicates the parameters of the PWM chip on which it is assembled. For example, an outdated but popular LM2596 according to specifications is holding up to 3 amps. But without a radiator, it will endure only 1 amp.
A more modern option with improved efficiency is a PWM XL4015 controller designed for 5a. With a miniature cooling system, it can work up to 2,5A.
If you have very powerful supermarket LEDs, then you need a LED driver for LED lamps. Two radiator cooled the diode and the XL4015 chip. In such configuration, it is capable of working up to 5a with voltage up to 35V. It is desirable that he does not work in the limit modes, it is significantly improved its reliability and service life.
If you have a small lamp or a pocket spotlight, then you will fit the miniature voltage stabilizer, with a current to 1,5a. Input voltage from 5 to 23V, output to 17B.
Brightness adjustment
To regulate the brightness of the LED, you can use compact LED dimmers that have recently appeared. If its power is not enough, you can put a dimmer more. They usually work in two ranges on 12V and 24V.
You can manage using infrared or radioperate remote control (DB). They cost from 100 rubles for a simple model and from 200 rub model with remote control. Basically, such consoles are used for 12V diode tapes. But it can easily be put to a low-voltage driver.
Dimmation can be analog in the form of a spinning handle and digital in the form of buttons.
However, I used more powerful components and another chip.
Datashet can be downloaded. The LED current is installed through the control resistor that is sensitive to the current. The output current i is equal to 0.1 / RS. I needed to get a current of about 300 mA for each channel, so I chose a resistor with a par value of 0.33 ohms. For the value of 350 mA, select the resistor with a par value of 0.27 ohms.
Each channel is monitored using the PWM signal, for example, from the Arduino microcontroller (you will need to solder the PAP / Mom plot connectors on the board).
You can use the input voltage up to 30 V and control the 3W / 10W / 20W LEDs.
Required components:
- Tantalum capacitorsC.1, C.2, C.3 : Capacity 22MKF.
- D.1, D.2, D.3 ; Schottky 2A diode in SMA housing
- L.1, L.2, L.3 : Powerful chokes of 68 μg, 0.7A
- R.1, R.2, R.3 : Resistors with denominations 0.33 Ohm, body 0805.
- 4 x. screw clamp, 3.5 mm (can be purchased in Tayda Electronics)
- 3X. pT4115 drivers.
- 1x 4-out + 1x 2-pin pin connector "Dad" or "Mom".
The photo above shows a fully assembled driver.
List of radio elements
| Designation | A type | Nominal | number | Note | Score | My notebook |
|---|---|---|---|---|---|---|
| IC1-1C3 | LED Driver | PT4115 | 3 | In notebook | ||
| D. | Diode Schottki | 2 A. | 3 | Any | In notebook | |
| C1-C3. | Capacitor | 22 μF | 3 | Any | In notebook | |
| R1- | Resistor | 0.33 Ohm. | 3 | Any | In notebook | |
| D1 | Inductor | 68 μH | 3 | Any per current 0.7 a | In notebook | |
| J1. | Pin pin | 2 PIN | 1 | In notebook | ||
| J. | Pin pin | 4 PIN | 1 | In notebook | ||
| JP1-JP3. | Screw clamp | 2 PIN | 3 |
In small-sized equipment, up to MP3 players and cell phones, three-color RGB-LEDs are increasingly used, and the so-called RGB clusters are used in different lighting equipment and decorative luminaires. For optimal brightness and color management, specialized drivers are used in such devices, many of which are managed by an external controller. Some of them will be discussed in this article. The author is considering a number of microcircuits on ON SEMICONDUCTOR, STMICROELECONICS and NATIONAL SEMICONDUCTOR.
RGB Driver LEDs with Cat4109 Stabilization (On Semiconductor)
The CAT4109 microcircuit is a driver for control of three sequential (R, G and B) chains of LEDs with current stabilization, separate installation and wired brightness of the luminance of these chains of LEDs. Cat4109 is manufactured in a miniature 11116-pin SOIC-16 case for surface mounting. The purpose of the chip conclusions is shown in Table 1, the inclusion scheme is shown in Fig. 1, and the functional scheme - in fig. 2.
Fig. 1. CAT4109 microcircuit inclusion scheme
Fig. 2. CAT4109 microcircuit functional diagram
Table 1. Purpose of CAT4109 chip conclusions
| Output № | Designation | Purpose |
| "Earth" of the power part |
||
| Inputs of PWM management for LED3, LED2 and LED1 |
||
| LED3, LED2 and LED1 installation settings |
||
| Not used |
||
| Permissions. Active level - high |
||
| Power supply voltage 3 ... 5.5 V |
A feature of the inclusion circuit Cat4109 microcircuit is the lack of choke and the minimum of the details of the strapping. The supply voltage Cat4109 lies within 3 ... 5.5 V, and the supply voltage of the LED chains - 5 ... 25 V.
Each of the three LED control channels consists of an adjustable current source and a maximum current setting scheme (see Fig. 2). Common for all channels is a source of reference voltage (ion) 1.2 V.
VIN power supply voltage is determined maximum amount LEDs in each of the chains. The maximum current of each of the consecutive chains of LEDs can reach 175 mA. LED current creates a small voltage drop in the open output keys (0.4 V). The maximum values \u200b\u200bof the currents of the chains of the LEDs are set by external resistors R1, R2 and R3 (RSET1-RSET3 conclusions of the chip). Table 2 shows the dependence of these values \u200b\u200bfrom the resistance of the corresponding installation resistors R1-R3.
Table 2. Dependence of currents of chains of LEDs from the resistance of the corresponding installation resistor
| LED current (MA) | Rset Resistor (com) |
The external control of the CAT4109 microcircuit is carried out by the controller through the OE inputs (output 15), PWM1 (out. 5), Pwm2 (4) and PWM3 (out. 3). The permission to turn on LEDs is carried out by a high level of voltage (≥1.2 V) at the input OE (15). Cat4109 microcircuit time charts are shown in Fig. 3.
Fig. 3. Temporary Cat4109 chipworking diagrams
The microcircuit time from the shutdown mode (Shutdown) to the included state (T PS) is 1.4 μs. Turning off LEDs at the OE resolution input is carried out by low level (≤0.4 V) at this inlet with a delay T p2 \u003d 0.6 μs, and the re-inclusion is a high level with a delay T p1 \u003d 0.3 μs. To transfer the SHutDown Mode, you must support the output. 15 (OE) Low potential for 4 ... 8 μs (t pwrdwn). In this mode, the current current does not exceed 1 μA.
PWM1 inputs (out. 5), PWM2 (out. 4) and PWM3 (out. 3) are used for separate adjustment of the brightness of the luminosity of the LED chains by the PWM method at a high voltage level at the OE input (out. 15). For group adjustment of the brightness of the glow of all LEDs, you can file from the PWM controller signal to the OE input. In order not to disturb the color balance, the frequency of this PWM signal should be an order of magnitude lower than the PWM signal at the PWM1-PWM3 inputs.
Cat4109 chip has a temperature protection with a three-time threshold of 150 ° C and hysteresis 20 ° C, as well as protection against low supply voltage with a trigger threshold of 1.8 V.
RGB Driver LED with CAT4103 Stabilization (On Semiconductor)
The CAT4103 microcircuit is also designed to control the three sequential RGB-chains of LEDs with current stabilization, with a separate installation and wired brightness adjustment of their glow. It is produced in the SOIC-16 housing. The main feature of this chip is the possibility of separate management of each individual LED chain using a serial interface. Another feature of Cat4103 is the possibility of a cascade inclusion of multiple chips, which increases the number of controlled LEDs from one controller on a 4-pro-water interface. The assignment of the conclusions of this chip is shown in Table 3, the functional diagram is shown in Fig. 4, and the inclusion scheme is in fig. five.
CAT4103 microcircuit control channels are similar to the corresponding Cat4109 channels, but the Cat4103 chip has one important feature, the essence of which is that the PWM signals for controlling the brightness of the LEDs are formed in the chip from the signals from the controller. To do this, the chip was introduced three-bit RAM (see Fig. 4), which consists of three triggers-latch (3-bit register "Latch") and a 3-bit shift register. The actual shift register ensures the conversion of the sequential code of the input signal to the parallel, which is remembered in the latch register.
Fig. 4. CAT4103 microcircuit functional scheme
Fig. 5. CAT4103 microcircuit inclusion scheme
Table 3. Appointment of CAT4103 chip conclusions
| Output № | Designation | Purpose |
| Input of the valve signal. Active level - high |
||
| Signal input "Latching" (memorization) of data |
||
| Data input |
||
| Tail pulse entrance (frequency up to 25 MHz) |
||
| Connections Connecting current resistors LED3, LED2 and LED1 |
||
| Connections of connecting cathodes LED3, LED2 and LED1 |
||
| Turning pulse output (frequency up to 25 MHz) |
||
| Data output |
||
| Signal output "Latching" (memorization) of data |
||
| Output signal damage |
||
| Power voltage input |
In order to control the following cascade inclusion chip, four buffer amplifiers are used and the delay trigger (D-trigger).
Let us give a description of the CAT4103 MS outputs, through which the control controller and the following chip are connected to it when cascading.
Conclusion 4 (SIN) - sequential data input.
The output 5 (CIN) is the entry of the clock pulses by a frequency of up to 25 MHz. This dynamic entrance is triggered along the clock pulse front (transition from log. "0" on the log. "1"). At the same time, the logical level from the SIN input is written to the shear register.
Output 3 (LIN) - Input of the data memorization command. When moving a signal with a log. "0" on the log. "1" At this input, the states of the shift register triggers are recorded in the latch register, where they are stored until the next pulse is coming to the LIN input.
Conclusions 13 (SOUT), 12 (COUT) and 14 (LOUT) - Outputs of the corresponding interface signals to the following CAT4103 chip with cascading inclusion. In this case, the Sout output signal changes (clocked) a slice of a clock pulse (signal transition from log. "1" on the log. "0").
Conclusion 2 (BIN) - the entrance is used to quenitize all LEDs, but does not affect the content of the latch register. The arrangement of LEDs is carried out by a high level (log. "1") at the BIN input.
The output 15 (BOUT) is the output of the extinguishing signal to the next CAT4103 chip during cascading inclusion.
The dependences of the currents of the chains of the LEDs from the resistors of the installation resistors of the CAT4103 chip are similar to the appropriate dependencies, we are tested above for the CAT4109 IC. In addition, the CAT4103 microcircuit has the same protection as CAT4109.
24-channel RGB driver STP24DP05 (STMicroelectronics)
STP24DP05 - This is one of the Power Logic (STP) driver of the POWER Logic driver (STP), is designed specifically to control color information displays on discrete RGB LEDs.
The basis of MS STP24DP05, as well as all the drivers of this family, are the shift register and the latch register, as well as the CAT4109 chip viewed above. The STP24DP05 microcircuit has three shifting registers and three latch register, one on the LEDs of each color (R, G and B).
In total, the STP24DP05 contains 24 LED control channels that are divided into three interface ports (R, G, B) of 8 channels in each. That is, the STP24DP05 chip is three conventional 8-channel monochrome drivers embedded in a small-sized TQFP48 case with a size of 7x7 mm and supplemented by the diagnostic diagnostic diagnostic schemes and closure of outputs with the body and power supply. Alarms about the detection of accidents enters the control controller in the form of special error codes through the serial interface.
One STP24DP05 chip controls eight LED RGB-Triads or TRADE groups of a colored LED screen. The supply voltage of the chip in the range of 3 ... 5.5 V, and the supply voltage of the LED chains can be selected up to 20 V, depending on the number of LEDs in the chains. Output current (current of each of the chains of LEDs) 5 ... 80 mA.
The flow diagram of the STP24DP05 microcircuit is shown in Fig. 6, Cascade inclusion scheme n chips of this type - in Fig. 7, and the assignment of the conclusions is shown in Table 4.
Fig. 6. Functional diagram of the STP24DP05 microcircuit
Fig. 7. Cascade Machining Scheme STP24DP05
Table 4. Purpose of the conclusions of the STP24DP05 chip
| Output № | Designation | Purpose |
| 1, 7, 12, 25, 30, 36 | ||
| Serial data input |
||
| Serial data output |
||
| Entrance of clock impulses |
||
| Input capture and dedule data |
||
| Log in to enable error definition mode |
||
| 13, 16, 19, 22, 39, 42, 45, 48 | Outputs of the 8-channel driver of red LEDs |
|
| Flag of excess temperature (outdoor outlet) |
||
| Error flag (outdoor outlet) |
||
| Gradual Delay (Gradual Delay) |
||
| 15, 17, 20, 23, 37, 40, 43, 46 | Outputs of the 8-channel drive of blue LEDs |
|
| Permissions for the exits B1-B8, G1-G8, R1-R8 (active level - low) |
||
| Inputs for setting currents for Outputs R1-R8, G1-G8, B1-B8 |
||
| 14, 18, 21, 24, 38, 41, 44, 47 | Outputs of the 8-channel drivers of green LEDs (G) |
|
| Inputs that determine the sequence r, G signals and B in the input code (see Table 8) |
||
| Supply voltage |
As noted above, the basis of the STP24DP05 microcircuit for controlling 8-channel RGB interfaces is a shift register of the RGB structure 8x3 (8 bit of 3 bits), which converts the sequential input code at the SDI input to three 8-bit parallel code. These codes are remembered in a 24-bit (8x3) latch register of RGB data. Each of the output cascades of the microcircuit (all of them 24 - eight for each color) is a stabilizer (source) of the current. In addition, for each color there is a solution scheme and discontinuity detector and short closures of output lines. Common for all channels are the control logic, temperature protection and protection against low supply voltage. At the conclusions 2, 3, 4, 32, 33 and 34 buffer cascades are installed.
Consider some features of the work of the STP24DP05 microcircuit. The clock frequency of this microcircuit can reach 25 MHz. LED current is programmed separately for each color using three external resistors that are connected to the output. 26, 27 and 28.
The dependence of the currents of the LEDs, as well as the threshold for the detection of the output lines of the output lines (LED lines) from the resistance of the corresponding setting resistor is shown in Table 5.
Table 5. The dependence of the currents of the LEDs and the threshold of the discharge detector of the output lines from the resistance of the corresponding mounting resistor
| The specified current of the LEDs, Ma | Rext, Oh. | The threshold of the discharge detector, ma |
When at the LEDM input (out. 3) high level, The "Latch" register captures data that pass through the shift register. When there is a low potential at this entrance, then the "latch" register holds (stores) them.
Low level At the OE-RDM inputs (out. 34), OE-G (out. 33) and OE-B (out. 32) permits the passage of data from the "latch" register at the output cascades of the chip, and high locks output cascades.
As is known, the greatest current consumption from the power source in any switching circuit occurs when transient processes at the time of switching. To facilitate current and thermal microcircuit modes, while on the simultaneous inclusion of all LEDs, as well as to reduce the level of pulsations, an extinct delay (gradual delay) of the turn on the LED, which is not noticeable to the eye is provided. It is submitted to the DG input (out. 9) of the log level. "0". The delay time for the inclusion of output cascades is shown in Table 6.
Table 6. Delayed on the inclusion of LEDs on the distribution log. 0 - Log. 1 at the inputs of permission depending on the logical level at the input of the gradual delay (Gradual Delay)
| Logical level at the entrance GD. | A trigger delay (NA) on log drops. "0" - log. "1" at the entrancesOexx |
|||||||
| R1, G1, B1 | R2, G2, B2 | R3, G3, B3 | R4, G4, B4 | R5, G5, B5 | R6, G6, B6 | R7, G7, B7 | R8, G8, B8 |
|
The STP24DP05 chip data signal (input and output output. 2 and 35) contains the RGB signal stream alternating with clock frequencyThe sequence of which is set by logical levels at the inputs DF0 and DF1 (see Table 7).
Table 7. Setting the Signal Sequence R, G and B in the code of input and output signals
Switching from the working mode to the error definition mode is carried out by the low potential input to the DM input (out. 5) or more than 1 μs on the OE-RDM input (out. 34). After that, within 24 hours, the error code arrives on the output bus.
The STP24DP05 microcircuit interface has two flags: TF (out. 29) - Flag of the temperature and EF (out. 8) - error flag. Both of these outputs are made according to the opening circuit, therefore, a pull-up resistor 10 kΩ is connected between each of these outputs and the power source. When an emergency situation occurs, the internal key of the microcircuit closes the corresponding output (29 or 8) to the "Earth". The level of log is thus obtained. "0" signals an external accident controller. If instead of pull-up resistors to the outputs, connect the LEDs (through limiting resistors), then the visual indication of an emergency is implemented.
Quad driver RGB LED with I2C LP55281 bus (National Semiconductor)
The LP55281 chip is a specialized RGB-backlight driver of small-sized liquid crystalline displays. It provides separate adjustment of the brightness of the luminescence and color shade for each of the four RGB LEDs from the external controller according to the standard serial interface I 2 C or SPI. The main use of the LP55281 chip is cell phones, communicators and MP3 players.
LP55281 contains four PWM channels for controlling the brightness and color of RGB-LED glow, synchronization audio channel for the background LED, as well as a built-in voltage converter, interfaces I 2 C and SPI. In addition, LP55281 provides through the serial interface testing of the LED cliff. The main parameters of the chip are shown in Table 8.
T. ababilica 8. Basic LP55281 chip parameters
| Parameter | Value |
| Supply voltage | |
| Number of control lines | |
| Turning on LEDs | Parallel |
| Deviation of the value of the output current of adjacent channels | |
| Maximum output voltage | |
| Type of raising converter | Inductive |
| Output voltage converter | Adjustable |
| Efficiency converter | |
| Consumption current | |
| Operating frequency of the converter | |
| Method of regulation | |
| Maximum LED current (general) | |
| Operating temperature range |
The microcircuit is made in miniature MicroSMD enclosures with a size of 3x3x0.6 mm and Micro SMDXT (3x3x0.65 mm) with 36 ball leads in 0.5 mm increments. The location of the LP55281 chip conclusions is shown in Fig. 8, and the assignment of the conclusions is reduced to Table 9.
Fig. 8. Location of the conclusions of the LP55281 chip
Table 9. Purpose of LP55281 chip conclusions
| Output № | Designation | Purpose |
| DC / DC Transducer Output to Choke |
||
| entrance feedback DC / DC converter |
||
| Exit to blue LED 3 |
||
| Output to LED R1 |
||
| Exit to LED G1 |
||
| Exit LED B1 |
||
| Output to LED R3 |
||
| Output to the G3 LED |
||
| Selection of MC Slave (SPI) or Line (Logging / Output) Tire Data I 2 C |
||
| Entry from the RGB Driver Offset Current Resistor |
||
| Audio input 2. |
||
| Serial SPI bus input or address selection inlet i 2 C |
||
| SPI SPI Tire Data Code Output |
||
| Output to red (R) LED R2 |
||
| Input asynchronous reset (active level - low) |
||
| Output to red (R) R4 LED |
||
| Supply voltage |
||
| Power supply for input and output cascades |
||
| Turning pulse entry for SPI and I2C interfaces |
||
| Output to the LED G2 |
||
| Output to LED AudioSynchronization |
||
| Exit to LED G4 |
||
| Audio input audio signal 1 |
||
| Resistor defining the frequency of the generator |
||
| Interface selection input (log. "1" - SPI, log. "0" - I 2 C) |
||
| Output to LED B2 |
||
| LED access B4 |
||
| "Earth" analog part |
||
| Outlet voltage output |
||
| The output of an internal supply source of the analog part 2.8 V |
||
| Power voltage input |
The functional circuit and the inclusion circuit of the LP55281 chip is shown in Fig. nine.
Fig. 9. Functional scheme and inclusion circuit LP55281 chip
The microcircuit contains an increase (boost) converter with a built-in output key on a MOSFET transistor, which can operate at a transformation frequency up to 2 MHz. The external LBOOST throttle for this transformation frequency should have an inductance of 4.7 microns, and for the frequency of conversion of 1 MHz - twice as much (approximately 10 μg). As a pulse rectifier, an external diode d1 with a small direct voltage drop (suits Schottky diodes with peak current of at least 1 A) is used. The output voltage of the converter is set by default 5 V, but it can be programmatically changed by control bus from 4 to 5.3 V in increments of 0.15 V.
Chip, and, therefore, the LEDs are managed by an external controller. It is not at all necessary that this control is carried out on all seven conductors, as shown in Fig. 9. So, for example, the IF_SEL interface selection input (out. 2b) can be connected directly to the "Earth" or a plus power source. In the first case, the interface of the bus I 2 C is turned on, and in the second - SPI. In any embodiment, the LP55281 microcircuit is used as a slave device. As you know, the bin interface i 2 with a two-wire (SCL clock line and SDA data line), and the SPI bus interface of the four-wire (SS is the selection of a slave chip, SCK - the input of the clock pulse, Si - data input and SO - data output).
When used in the device, i 2 C, the SO output will remain not connected (out. 4b).
In this case, the Si / A input (out. 4c) can be connected to "Earth" by selecting this 4ch chip address, and it is possible to the power source plus, which ensures 4DH address.
Output Cascades, which are regulated PWM stabilizers (sources or generators) current, to the outputs of which, except LEDs, a multiplexer is connected. He, at the moments of locking output cascades, provides alternate, periodic switching to the ADC input of the signal levels from the outputs of the microcircuit.
For normal work These levels are high, and in the event of a break of one of the LEDs or the sample of the output cascade, the voltage at the output of the multiplexer decreases, which will tell about the malfunction. The voltage from the release of a multiplexer is digitized into the ADC and through the control bus (I 2 C or SPI) enters the external controller.
The LP55281 chip is embedded in a channel, which is called the audio channel channel. It is used in cell phones, MP3 players, etc. As a "colorwoman" channel, providing flashing LEDs in the tact with a ringtone or a losing melody. This channel has two inputs (output. 2D and 4D) to which signals or stereo signal are supplied, with a scope of up to 1.6 V. They are mixed, and then the total signal is digitized, the AGC scheme and a digital peak detector passes. After that, there is a reverse conversion of a digital signal into analog. The resulting analog signal controls the output cascade (source of current), and hence the brightness of the luminescence of the background LED.
Literature and Internet Sources
1. www.monolithicpower.com - MONOLITHIC POWER SYSTEMS website.
2. Stmicroelectronics. STP24DP05. 24-Bit Constant Current Led Sink Driver With Output Error Detection. FIRST REELEASE. 2008.
3. www.st.com - Stmicroelectronics website.
4. National Semiconductor. LP55281. Quad RGB Driver. General Description. June 2007.
5. www.national.com - National Semiconductor Corporation site.