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CXLE88147N: Detailed explanation of high-performance LED driver and keyboard scanning control chip

        In today's increasingly popular smart home appliances and digital display devices, efficient and stable display drivers and control chips have become one of the key components. CXLE88147N is a dedicated control chip that integrates LED driver, keyboard scanning, data latch, and serial communication. This article will comprehensively introduce the characteristics, pin definitions, instruction system, application circuits, and electrical parameters of the chip, helping developers to deeply understand and efficiently apply it.KNV嘉泰姆

1、 Product Overview

      CXLE88147N is a highly integrated LED driver control chip based on CMOS technology, with built-in MCU digital interface, data latch, LED driver circuit, and keyboard scanning module. Its excellent anti-interference ability and stability make it widely used in digital tubes or LED display modules of smart water heaters, microwave ovens, washing machines, air conditioners, induction cookers, set-top boxes, electronic scales, smart meters and other devices.KNV嘉泰姆

2、 Main characteristics

▲ CMOS processLow power consumption, high integration;KNV嘉泰姆

▲ Display capability: 10 paragraphs× 8-bit LED driver;KNV嘉泰姆

▲ Keyboard scanning: Supports 8× 3 matrix keyboard input;KNV嘉泰姆

▲ Brightness adjustment8-level duty cycle adjustable, supporting brightness control;KNV嘉泰姆

▲ Communication interfaceThree wire serial interface (CLK, STB, DIO);KNV嘉泰姆

▲ Oscillation modeBuilt in RC oscillator, no need for external crystal oscillator;KNV嘉泰姆

▲ Packaging form：SOP28， Suitable for compact design.KNV嘉泰姆

3、 Detailed explanation of pin functions

4、 Instruction System Description

    If the STB is set to high level during instruction or data transmission, serial communication is initialized, and the instruction or data being transmitted is invalid (before that)KNV嘉泰姆
The instructions or data sent remain valid.KNV嘉泰姆

4.1 Data Command Settings: Used forSet data read and write modes, address growth methods, etc.KNV嘉泰姆
This instruction is used to set data write and read, and bits B1 and B0 do not allow setting 01 or 11.KNV嘉泰姆

4.2 Address Command Settings:Set the starting address of the display register, supporting 16 addresses from 00H to 0FH.KNV嘉泰姆

This instruction is used to set the address of the display register.KNV嘉泰姆
If the address is set to 10H or higher, the data is ignored until a valid address is set. When powered on, the address is set to 00H by default.KNV嘉泰姆

4.3 Display control commands:Set the display switch and brightness level (1/16~14/16 duty cycle).KNV嘉泰姆
                                  MSB                                                                                          LSBKNV嘉泰姆

5、 Display registers and driving methods

The chip has a built-in 16 byte display register with addresses 00H~0FH, each corresponding to an SEG/GRID driver output. Supports two types of digital tube drivers: co yin and co yang:KNV嘉泰姆

5.1. Common cathode digital tubeSEG is connected to the anode, and GRID is connected to the cathode;KNV嘉泰姆
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      Figure 7 shows a schematic diagram of the connection of a common cathode digital tube. If the digital tube displays“ 0” Just need to start from the lower order in the 00H (GRID1) addressKNV嘉泰姆
Start writing 0x3F data, and the data for each SEG1-SEG8 corresponding to 00H is shown in the table below.KNV嘉泰姆

5.1. Gongyang Digital TubeSEG is connected to the cathode, and GRID is connected to the anode (requiring an external current limiting resistor).KNV嘉泰姆
KNV嘉泰姆
Figure 8 shows the schematic diagram of the connection of the common anode digital tube. If the digital tube displays“ 0” , need to address units 00H (GRID1), 02H (GRID2)KNV嘉泰姆
Write data 01H in 04H (GRID3), 06H (GRID4), 08H (GRID5), and 0AH (GRID6) respectively, and the remaining addresses 0CH (GRID7) and 0EH (GRID8)KNV嘉泰姆
All units are written with data 00H. The data corresponding to each SEG1-SEG8 is shown in the table below.KNV嘉泰姆
 KNV嘉泰姆

AttentionAfter power on, the display register content is random. It is recommended to reset all values before sending the display data to avoid garbled characters. Whether driving a common cathode digital tube or a common anode digital tube, the SEG pin can only be connected to the anode of the LED, and the GRID pin can only be connected to the cathode of the LED and cannot be reversed.KNV嘉泰姆

6、 Keyboard scanning function

          Supports 3× 8-matrix keyboard scan, capable of reading up to 4 bytes of key value data. Key values are read in order from BYTE1 to BYTE4, and cross byte reading is not supported. Combination keys only support key combinations of the same KS line and different K lines.KNV嘉泰姆

6.1. The key scan matrix is 3× 8bit， As shown in Figure (3):KNV嘉泰姆
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The key scan data storage address is shown in Figure (4). First, send the read key command, and then start reading the key data BYTE1— BYTE4 bytes, read data fromKNV嘉泰姆
The output starts at a low position, and when the buttons corresponding to the K and KS pins of the chip are pressed, the BIT bit in the corresponding byte is 1.KNV嘉泰姆
 KNV嘉泰姆

▲ Note: 1. CXLE88147N can read up to 4 bytes and does not allow for multiple reads.KNV嘉泰姆
2. Read data bytes can only be read sequentially from BYTE1-BYTE4 and cannot be read across bytes. For example, on the hardware, press the corresponding button for K2 and KS8KNV嘉泰姆
At this time, in order to read the data of this button, it is necessary to read the 5th bit of the 4th byte before reading the data; When K1 and KS8, K2 and KS8KNV嘉泰姆
When two buttons are pressed simultaneously, the B5 and B6 bits of the data read by BYTE4 are both 1.KNV嘉泰姆
3. Combination keys can only be the same KS, and different K pins can be used as combination keys; The same K and different KS pins cannot be used as combination keys.KNV嘉泰姆

6.2. Key scanning and combination keys:KNV嘉泰姆

6.2.1) Key scanning:Key scanning is automatically completed by CXLE88147N and is not controlled by the user. Users only need to read key values in chronological order. Complete a key scan onceKNV嘉泰姆
One display cycle is required, and one display cycle takes approximately T=4.7ms. Within 4.7ms, two different keys were pressed successively, and the key values read twice wereKNV嘉泰姆
The key value of the button pressed first.KNV嘉泰姆
6.2.2) Combination buttons:KNV嘉泰姆
Abnormal problem with composite buttons: SEG1/KS1-SEG8/KS8 is a combination of display and button scanning. Taking Figure (12) as an example, D1 needs to be lit up for display, D2KNV嘉泰姆
Extinguish, SEG1 needs to be set to“ 0” , SEG2 is“ 1” If S1 and S2 are simultaneously pressed, it is equivalent to SEG1 and SEG2 being short circuited, and D1 and D2 are both activatedKNV嘉泰姆
Bright.KNV嘉泰姆
KNV嘉泰姆
Solution:KNV嘉泰姆
1. In terms of hardware, the keys that need to be pressed simultaneously can be set on different K-lines as shown in Figure (13),KNV嘉泰姆
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2. The series diode is shown in Figure (14).KNV嘉泰姆
KNV嘉泰姆
▲ Attention:Suggest using the same KS with different K keys as a composite key.KNV嘉泰姆

7、 Communication timing and data transmission

7.1 Automatic Address Addition Mode

Suitable for continuous writing of multi byte data with high efficiency. Using the address auto increment mode, setting the address is actually setting the starting address for storing the transmitted data stream. The starting address command word has been sent,“ STB” There is no need to set it high and transmit data immediately, up to 16BYTE. The data will only be transmitted after it is completed; STB” Set high.KNV嘉泰姆
KNV嘉泰姆
Command1: Set Data CommandKNV嘉泰姆
Command2: Set Display AddressKNV嘉泰姆
Data1~n: Transfer display data to Command2 address and subsequent addresses (up to 16 bytes)KNV嘉泰姆
Command3: Display Control CommandsKNV嘉泰姆

7.2 Fixed Address Mode

Suitable for random address writing, with high flexibility. 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” No need to set it high, immediately transmit 1BYTE data, and only after the data transmission is completed will it be sent; STB” Set high. Then reset the address where the second data needs to be stored,KNV嘉泰姆
Up to 16BYTE data transmission completed,“ STB” Set high.KNV嘉泰姆
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Command1: Set Data CommandKNV嘉泰姆
Command2: Set Display Address 1KNV嘉泰姆
Data1: Transfer display data 1 to Command2 addressKNV嘉泰姆
Command3: Set Display Address 2KNV嘉泰姆
Data2: Transfer display data 2 to Command3 addressKNV嘉泰姆
Command4: Display control commandsKNV嘉泰姆

7.3 Read key timing sequence

After sending the read key command, continuously read 4 bytes of key value data.KNV嘉泰姆
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Command1: Set the read button commandKNV嘉泰姆
Data1-4: Read key dataKNV嘉泰姆
7.4. Serial Data Transmission Format:KNV嘉泰姆
Reading and receiving one BIT are both performed on the rising edge of the clock.KNV嘉泰姆
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▲ Attention:1. When reading data, an equal interval is required between setting instructions from the 8th rising edge of the serial clock CLK and reading data from the falling edge of CLKKNV嘉泰姆
Wait for Twait (minimum 2μ S). Please refer to the timing characteristic table for specific parameters.KNV嘉泰姆
7.5. Program design flowchart using automatic address addition and fixed address methods:KNV嘉泰姆
     7.5.1) Use address auto add one program design flowchart:KNV嘉泰姆

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7.5.1) Flowchart of program design using fixed addresses:KNV嘉泰姆
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8、 Suggestions for Application Circuit Design

8.1. Common cathode digital tube circuitSEG directly drives the LED anode, while GRID drives the cathode;KNV嘉泰姆
KNV嘉泰姆

8.2. Gongyang Digital Tube CircuitExternal PNP transistor or common anode driving circuit is required;KNV嘉泰姆
KNV嘉泰姆

8.2. Filter capacitor100 μ F and 104 capacitors should be placed nearby between VDD and GND;KNV嘉泰姆

8.3. Communication line filteringDIO, CLK, and STB lines can be connected in series with 100pF capacitors for anti-interference;KNV嘉泰姆

8.4. Power Supply SuggestionsUse a 5V power supply to ensure the normal driving of the blue LED (3V voltage drop).KNV嘉泰姆

9、 Summary of Electrical Parameters

9.1. Limit parameter (VSS=0 V)

 

parameter

symbol

scope

unit

Logic power supply voltage

VDD

-0.5 ～+7.0

V

Logic input voltage

VI1

-0.5 ～ VDD + 0.5

V

LED Seg driver output current

IO1

-50

mA

LED Grid Drive Output Current

IO2

+200

mA

power loss

PD

four hundred

mW

Operating Temperature

Topt

-40 ～ +85

℃

Storage temperature

Tstg

-65 ～+150

℃

9.2. Normal operating range (VSS=0 V)

parameter

symbol

minimum

typical

maximum

unit

test conditions

Logic power supply voltage

VDD

five

V

-

High level input voltage

VIH

0.7 VDD

-

VDD

V

-

Low level input voltage

VIL

0

-

0.3 VDD

V

-

9.3. Electrical characteristics (VDD=4.5~  5.5 V, VSS=0 V)

parameter

symbol

minimum

typical

maximum

unit

test conditions

SEG Drive Pulling Current

Ioh1

twenty

twenty-five

forty

mA

SGE1～SEG10 Vo = VDD-2V

Ioh2

twenty

thirty

fifty

mA

SGE1～SEG10 Vo = VDD-3V

Grid driven current injection

IOL1

eighty

one hundred and forty

-

mA

GRID1-GRID8 Vo=0.3V

Output pull-down resistor

RL

ten

KΩ

K1～K3

input current

II

-

-

± one

μA

VI = VDD / VSS

High level input voltage

VIH

zero point sevenKNV嘉泰姆 VDD

-

V

CLK，DI0，STB

Low level input voltage

VIL

-

-

zero point threeKNV嘉泰姆 VDD

V

CLK，DI0，STB

Lagging voltage

VH

-

zero point three five

-

V

CLK，DI0，STB

Dynamic current loss

IDDdyn

-

-

five

mA

No load, display off

9.4. Switching characteristics (VDD=4.5~5.5 V)

parameter

symbol

minimum

typical

maximum

unit

test conditions

oscillation frequency

fosc

-

five hundred

-

KHz

R = 16.5 KΩ

Transmission delay time

tPLZ

-

-

three hundred

ns

CLK → DIOKNV嘉泰姆 CL = 15pF, RL = 10K Ω

tPZL

-

-

one hundred

ns

rise time

TTZH 1

-

-

two

μs

CL = 300p F

SEG1～SEG10

fall time

TTHZ

-

-

one hundred and twenty

μs

CL = 300pF，SEGN， GRIDN

Maximum clock frequency

Fmax

-

-

one

MHz

Duty cycle 50%

Input capacitor

CI

-

-

fifteen

pF

-

9.5. Timing Characteristics (VDD=4.5~5.5 V)

parameter

symbol

minimum

typical

maximum

unit

test conditions

Clock pulse width

PWCLK

four hundred

-

-

ns

-

Select pulse width

PWSTB

one

-

-

μs

-

Data establishment time

tSETUP

one hundred

-

-

ns

-

Data retention time

tHOLD

one hundred

-

-

ns

-

CLK → STB time

tCLK STB

one

-

-

μs

CLK↑ → STB↑

waiting time

tWAIT

one

-

-

μs

CLK↑ → CLK↓

9.6. Time series waveform diagram:KNV嘉泰姆

10、 Encapsulation information

        The chip is packaged in SOP28 and its size meets industry standards, making it suitable for automated surface mount production.KNV嘉泰姆

11、 Conclusion

CXLE88147N is an ideal choice for LED display and keyboard control due to its high integration, flexible control capabilities, and wide applicability. Through reasonable design and configuration, the display effect and interactive experience of the product can be greatly improved. Developers can refer to the circuit design and instruction instructions provided in this article to quickly implement product development and debugging.KNV嘉泰姆

For further information on detailed timing diagrams, packaging dimensions, or application cases, please contact technical support or refer to the official data manual.KNV嘉泰姆

12、 Selection Guide for Related Chips;                        More similar products ....KNV嘉泰姆

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