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CXLE88143N: analysis of high-performance LED driver and keyboard scanning control chip

I. Overview

CXLE88143N is a special integrated circuit for LED driver control integrated with keyboard scanning interface. It is manufactured by CMOS technology and has multiple functions such as MCU digital interface, data latch, LED driver and keyboard scanning. With its high reliability, excellent stability and strong anti-interference capability, the chip is widely used in intelligent water heaters, microwave ovens, washing machines, air conditioners, induction cookers and other household appliances, as well as set-top boxes, electronic scales, smart meter and other digital tube or LED display devices.jsD嘉泰姆

II. Main features

1. Display capability: supports 16-segment × 8-bit LED displayjsD嘉泰姆

2. Keyboard matrix: supports up to 8 × 4 matrix buttonjsD嘉泰姆

3. Brightness adjustment: 8-level duty cycle adjustable, support brightness controljsD嘉泰姆

4. Communication interface: Serial Interface (CLK, STB, DIN, DOUT), supports data read/write and button scanjsD嘉泰姆

5. Built-in functions: RC oscillator, power-on reset circuit, data latchjsD嘉泰姆

6. Anti-interference design: optimize the circuit to prevent dark and bright problems caused by LED reverse bias and leakagejsD嘉泰姆

7. Encapsulation form: LQFP44 package, suitable for high-density PCB layoutjsD嘉泰姆

3. Detailed explanation of pin functions

There are 44 pins in CXLE88143N, including the following categories:jsD嘉泰姆

IV. Instruction system and communication protocol

Commands are used to set the display mode and the status of the LED driver.jsD嘉泰姆
The first byte entered by DIN after STB failling edge is used as the instruction. After decoding, the highest bits of B7 and B are taken to distinguish different instructions.jsD嘉泰姆

CXLE88143N receive commands through the serial interface in the following format:jsD嘉泰姆

4.1. Data command settings (B7 = 0, B6 = 1)

4.1.1) write display data: B1B0 = 00jsD嘉泰姆

4.1.2) read key scan data: B1B0 = 10jsD嘉泰姆

4.1.3) address mode: B0 = 0 (auto-increment), B0 = 1 (fixed address)jsD嘉泰姆

4.1.4) mode setting: B0 = 0 (normal mode)jsD嘉泰姆
Commands are used to set data write and read. Bits B1 and B0 cannot be set to 01 or 11.jsD嘉泰姆
jsD嘉泰姆

4.2. Display control commands (B7 = 1, B6 = 0)

4.2.1) brightness adjustment: B2 ~ B0 control 8-level duty cycle (1/16~14/16)jsD嘉泰姆

4.2.2) Display switch: B3 = 0 (off), B3 = 1 (on)jsD嘉泰姆

This command is used to set the Display switch and display brightness adjustment. A total of 8 levels of brightness are available for adjustment.jsD嘉泰姆

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4.3. Address command (B7 = 1, B6 = 1)

Set the display register address (00H ~ 0FH), a total of 16 bytes, corresponding to 8 bits × 16 segments of display data.jsD嘉泰姆
This command is used to set the address of the display register. The maximum valid address is 16 bits (00H-0FH). If the address is set to 10h or higher, datajsD嘉泰姆
Ignored until the valid address is set. When power on, the address is set to 00h by default.jsD嘉泰姆

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V. Display driver and button scan

5.1. Display driver

5.1.1) co-negative digital tube: SEG is connected to the anode, GRID is connected to the cathode, and the corresponding segment selection data can be written to display.jsD嘉泰姆
jsD嘉泰姆
Figure 7 shows the connection diagram of the common cathode digital tube. If the digital tube is displayed as "0", only the 00h (GRID1) address needs to be removed from the low position.jsD嘉泰姆
Start writing 0x3F data. At this time, the data corresponding to each SEG1-SEG8 is as follows.jsD嘉泰姆
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5.1.2) Gongyang digital tube: You must write segment selection data to the corresponding GRID address and write 00h to the rest address.jsD嘉泰姆
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Figure 8 shows the connection diagram of the common anode digital tube. If the digital tube is displayed as "0", the address units 00H(GRID1), 02H(GRID2),jsD嘉泰姆
04H(GRID3), 06H(GRID4), 08H(GRID5), 0AH(GRID6) write data for 01h, the rest of the addresses 0CH(GRID7), 0EH(GRID8)jsD嘉泰姆
The unit writes all data for 00 hours. The data corresponding to each SEG1-SEG8 is shown in the following table.jsD嘉泰姆
jsD嘉泰姆
▲Note: whether driving the common cathode digital tube or driving the common anode digital tube, SEG pin can only be connected to the LED anode, GRID can only be connected to the LED cathode, nojsD嘉泰姆
It can be connected in reverse.jsD嘉泰姆

5.2. Button scan

5.2.1) support 8 × 4 matrix button, automatic scanning, cycle is about 4.7ms.jsD嘉泰姆
Button scanning is automatically completed by CXLE88143N and is not controlled by users. Users only need to read key values according to the time series. Complete a key scanjsD嘉泰姆
One display cycle is required, and a display cycle is about T = 4.7ms. Two different button are pressed within 4.7ms. The key values read twice are alljsD嘉泰姆
The key value of the button pressed first.jsD嘉泰姆
CXLE88143N after power-on, the internal scanning waveform of SEG1/KS1-SEG8/KS8 is shown in figure (10):jsD嘉泰姆
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▲Note: a cycle time is related to the oscillation frequency of the IC, and the oscillation frequency of each IC is not completely consistent. The above data is for reference onlyjsD嘉泰姆
The actual measurement shall prevail.jsD嘉泰姆

5.2.2) key-value data is output in the order of BYTE1 to BYTE4, and each byte contains four key states.jsD嘉泰姆
Button reuse:The problem of composite button is abnormal: SEG1/KS1-SEG8/KS8 is reused by display and button scan. Take figure (12) as an example,jsD嘉泰姆
The display needs D1 to be on and D2 to be off. You need to set SEG1 to "0" and SEG2 to "1". If S1 and S2 are pressed at the same time, it is equivalent to SEG1 and SEG2 is short-circuited,jsD嘉泰姆
At this time, D1 and D2 are all lit up.jsD嘉泰姆

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Solution:jsD嘉泰姆
1. On the hardware, you can set the keys that need to be pressed at the same time on different k lines as shown in figure (13),jsD嘉泰姆
jsD嘉泰姆
2. The series diode is shown in figure (14).jsD嘉泰姆
jsD嘉泰姆
▲Note: We recommend that you use the same K key with different KS as the composite button.jsD嘉泰姆

5.3. Display register address:jsD嘉泰姆
This register stores data transmitted from external devices to CXLE88143N through the serial interface. The maximum valid address is 16 bytes from 00H-0FH,jsD嘉泰姆
Corresponding to the SEG and GRID pins of the chip respectively, the specific allocation is shown in figure (2):jsD嘉泰姆
When writing LED display data, it operates from low to high in the display address and from low to high in the data byte.jsD嘉泰姆

jsD嘉泰姆
▲Note: the value stored in the chip display register at the moment of power-on may be randomly uncertain. At this time, the customer directly sends the Open Screen command,jsD嘉泰姆
Garbled codes may appear. Therefore, we recommend that the customer power on the display register for clear operation, that is, the 16-bit memory address after power-on.jsD嘉泰姆
0x 00 is written to all data in (00H-0FH).jsD嘉泰姆

5.4. Serial data transmission format:jsD嘉泰姆

Read and receive 1 BIT are operating on the rising edge of the clockjsD嘉泰姆
jsD嘉泰姆
▲Note: 1. When reading data, you need to set the command from the 8th rising edge of the serial clock CLK to the CLK failling edge read data.jsD嘉泰姆
Wait time Twait (minimum 2 μs). For more information, see Time series feature table.jsD嘉泰姆
2. The above time series are DOUT and DIN shorted together as DIO usage.jsD嘉泰姆

5.5. Serial data transmission during application:jsD嘉泰姆
      5.5.1) address increase modejsD嘉泰姆
Using the automatic address plus 1 mode, setting the address is actually the starting address of the transmitted data stream. The start address command word has been sent,jsD嘉泰姆
STB does not need to be high to transmit data immediately. It can be up to 16 bytes at most.jsD嘉泰姆

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Command1: set data commandsjsD嘉泰姆
Command2: Set the display addressjsD嘉泰姆
Data1 ~ n: transmit display data to the Command2 address and the following address (up to 16bytes)jsD嘉泰姆
Command3: Display Control commandsjsD嘉泰姆

5.5.2) fixed address modejsD嘉泰姆
Using the fixed address mode, setting the address is actually setting the address where the 1byte data to be transmitted is stored. The address has been sent, "STB"jsD嘉泰姆
You do not need to set the value to high. The data is transmitted immediately after 1byte. The STB value is set to high only after the data is transmitted. Then reset the address where the second data needs to be stored,jsD嘉泰姆
Up to 16 bytes of data has been transferred, and the STB is set to high.jsD嘉泰姆

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Command1: set data commandsjsD嘉泰姆
Command2: set display address 1jsD嘉泰姆
Data1: transfer display data from 1 to Command2 addressesjsD嘉泰姆
Command3: set display address 2jsD嘉泰姆
Data2: transfer display data from 2 to Command3 addressesjsD嘉泰姆
Command4: Display Control commandsjsD嘉泰姆

5.5.3) read button time seriesjsD嘉泰姆

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Command1: Set the read button commandjsD嘉泰姆
Data1 ~ 4: reads button datajsD嘉泰姆
▲Note: the above time series are DOUT and DIN shorted together as DIO usage.jsD嘉泰姆

5.5.4) program design flow chart using automatic address plus one and fixed address:jsD嘉泰姆

5.5.4.1) program design flow chart using automatic address plus one:jsD嘉泰姆
jsD嘉泰姆
5.5.4.2) program design flow chart with fixed address:jsD嘉泰姆
jsD嘉泰姆

VI. Application circuit design suggestions

6.1. Power filtering: add 100 LEDs F and 104 capacitors between VDD and GND, and place them close to the chip.jsD嘉泰姆

6.2. Communication anti-interference: DIO, SCLK, and STB lines are connected in series with 100pF capacitors.jsD嘉泰姆

6.3.LED type adaptation: blue LED is recommended to use 5V power supply.jsD嘉泰姆
6.4. Composite button processing: it is recommended to design composite keys on different k lines or series diodes to prevent short circuit.jsD嘉泰姆

6.5. Hardware circuit diagram of CXLE88143N driver co-Yin digital screenjsD嘉泰姆

jsD嘉泰姆

6.6.CXLE88143N drive co-Yang digital screen wiring circuit diagram (19)jsD嘉泰姆

jsD嘉泰姆
▲Note:1. The filter capacitor between VDD and GND should be placed as close as possible to CXLE88143N chips in PCB wiring to enhance the filtering effect.jsD嘉泰姆

2. Three 101(100pF) capacitors connected to the DIO(DIN, DOUT), SCLK, and STB communication ports can reduce the interference to the communication ports.jsD嘉泰姆
3. Since the conduction voltage of blue light digital tube is reduced by about 3V, 5V should be selected for CXLE88143N power supply.jsD嘉泰姆
4. It is recommended to use DIN and DOUT ports together as DIO in the actual circuit.jsD嘉泰姆

VII. Summary of electrical parameters

7.1. Working voltage: 5VjsD嘉泰姆

7.2. Driving current: SEG output 20-50ma, GRID output 80-140majsD嘉泰姆

7.3. Communication clock: up to 1MHzjsD嘉泰姆

7.4. Working temperature:-40 ℃ ~ 85 ℃jsD嘉泰姆
7.5. Limit parameters (Ta = 25℃, Vss = 0V)jsD嘉泰姆
jsD嘉泰姆
7.6. Normal operating range (Vss = 0V)jsD嘉泰姆
jsD嘉泰姆
7.7. Electrical characteristics (VDD = 5V, Vss = 0V)jsD嘉泰姆
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7.8. Switching characteristics (VDD = 5V)jsD嘉泰姆
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7.9. Time series characteristics (VDD = 5V)jsD嘉泰姆
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7.10. Time Series Waveform diagram:jsD嘉泰姆
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VIII. Summary

CXLE88143N is a fully functional and stable LED driver and keyboard scanning control chip, suitable for a variety of household appliances and industrial display scenarios. Its flexible instruction system, powerful driving ability and good anti-interference design make it an ideal choice for high reliability display control.jsD嘉泰姆

IX,Relevant chip selection guide             More similar products.....jsD嘉泰姆

 jsD嘉泰姆

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