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CXLE87191 18 channel LED driver chip: an ideal solution for precision lighting control

            In today's smart devices and home appliances, LED lighting has become a key element in enhancing user experience. Jiataim Semiconductor has launchedCXLE87191  The 18 channel constant current LED driver chip provides a complete LED driving solution for mobile devices, smart home appliances, and decorative lighting with its precise current control, flexible dimming function, and compact packaging design. This chip supports 256 order linear current regulation, with a maximum output of 38mA per channel. It achieves precise brightness control through a standard I2C interface, meeting the needs of various high-end lighting applications.QAH嘉泰姆

1、 Product Overview and Core Advantages

          CXLE87191 is a high-performance constant current driver chip that integrates 18 independent LED driver channels and is manufactured using advanced power CMOS technology. Each channel has independent PWM control capability, supports 256 level brightness adjustment, and can achieve smooth brightness transition and complex lighting effects. The working voltage range of the chip is from 2.7V to 5.5V, compatible with various mobile devices and battery powered applications.QAH嘉泰姆

The chip has a built-in reset register and address auto add function, and supports flexible configuration through the I2C interface. Users can accurately set the maximum output current through an external resistor, and with PWM duty cycle adjustment, achieve precise control from complete shutdown to maximum brightness. The chip offers two packaging forms, QFN-24 (4mm× 4mm) and SOP-24, to meet the space requirements of different application scenarios.QAH嘉泰姆

2、 Key characteristics and technical parameters

2.1  Precision Drive and Control

•       number of channels18 independent constant current output channelsQAH嘉泰姆

•       current regulation256 order linear PWM regulation for precise brightness controlQAH嘉泰姆

•       maximum outputMaximum 38mA constant current output per channelQAH嘉泰姆

•       current settingAccurately set the maximum current through an external resistor (R_EXT)QAH嘉泰姆

•       Power supply rangeOperating at a wide voltage range of 2.7V to 5.5VQAH嘉泰姆

2.2    Intelligent interface and efficient control

•       control interfaceStandard I2C interface, maximum communication rate of 400kHzQAH嘉泰姆

•       slave addressFixed address "; 1010 1000" Support cascading of multiple devicesQAH嘉泰姆

•       Address self addingAutomatic address increment, simplifying multi byte data transmissionQAH嘉泰姆

•       Off modeSupports software and hardware shutdown, with a shutdown current of only 3.1 AQAH嘉泰姆

2.3    Reliability and compatibility

•       Operating TemperatureIndustrial grade temperature range: -40 ℃ to+85 ℃QAH嘉泰姆

•      ESD protection: 4kV HBM electrostatic protection levelQAH嘉泰姆

•       Encapsulation optionsQFN-24 and SOP-24 packaging optionsQAH嘉泰姆

•       thermal managementQFN packaging provides heat dissipation pads to optimize thermal performanceQAH嘉泰姆

3、 Register Structure and Control Logic

CXLE87191 achieves flexible LED control through a carefully designed register system:QAH嘉泰姆

3.1.    Core Function Register

•       Turn off register (00h)Control the soft shutdown mode to achieve ultra-low power standbyQAH嘉泰姆

•       PWM register (01h-12h)256 level brightness control with 18 channelsQAH嘉泰姆

•       LED control register (13h-15h)Control of switch status for each channelQAH嘉泰姆

•       Update Register (16h)Trigger configuration update to ensure synchronized outputQAH嘉泰姆

•       Reset register (17h)Global reset function, restoring default stateQAH嘉泰姆

3.2.  Current calculation formula

The maximum output current is precisely set by the external resistor R_EXT:QAH嘉泰姆

Among them, VEXT=1.3V, and the recommended minimum value of R_EXT is 2kΩ.QAH嘉泰姆

Calculation of average output current under PWM dimming:QAH嘉泰姆

4、 Typical application scenarios

CXLE87191 demonstrates strong advantages in multiple fields with its excellent performance and flexible configuration capabilities:QAH嘉泰姆

4.1  Mobile devices and consumer electronics

♦     smartphoneBreathing light, notification indicator light, backlight controlQAH嘉泰姆

♦     tablet: Status indication, decorative lightingQAH嘉泰姆

♦     wearable devicesColorful indicator lights, user feedbackQAH嘉泰姆

4.2    Smart Home Appliances and Home Furnishings

♦    Home appliance panel: Operation instructions, status displayQAH嘉泰姆

♦    smart home: Environmental lighting, scene modeQAH嘉泰姆

♦    gaming peripheralsRGB lighting effects, custom lightingQAH嘉泰姆

4.3    Professional Display and Decoration

♦    instrumentation and metersMulti state indication and alarm displayQAH嘉泰姆

♦    advertising decorationDot matrix display, color variationQAH嘉泰姆

♦    architectural lighting: Contour decoration, color controlQAH嘉泰姆

4.4 PWM controlQAH嘉泰姆

(1) The PWM register (01h~12h) can modulate the LED brightness of 18 channels through 256 levels. For example, if the PWM registerQAH嘉泰姆
The data is“ 0000 0100” Then PWM is the fourth level.QAH嘉泰姆
(2) Continuously writing new data into the register can modulate the brightness of the LED to achieve breathing effects.QAH嘉泰姆
(3) The maximum output current of OUT1~OUT18 can be adjusted through an external resistor REXT, as described belowQAH嘉泰姆
Formula (2).QAH嘉泰姆

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x = 58.5, VOUT = 0.8V, VEXT = 1.3V。    QAH嘉泰姆
The recommended minimum value for REXT is 2kΩQAH嘉泰姆

4.5. Brightness correctionQAH嘉泰姆

      In order to achieve better visual LED breathing effect, we recommend using PWM values with brightness correction to set the LED intensity. Not only canQAH嘉泰姆
Reduce the number of steps required to set LED intensity and make the intensity changes appear more linear to the naked eye.QAH嘉泰姆
Brightness correction (also known as brightness compression or encoding) is used to encode linear brightness to match the nonlinear characteristics of displays. Due to CXLE87191QAH嘉泰姆
The brightness of the LED can be modulated in 256 steps. When calculating the intensity settings for each subsequent LED, the brightness correction function can be applied to adjust the brightnessQAH嘉泰姆
The change matches the brightness curve of the human eye.QAH嘉泰姆
Table 7; Match 256 PWM levels with 32 levels of brightness levelQAH嘉泰姆
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        Choosing more levels of brightness can provide a more linear breathing effect. This is very useful for long-term respiratory circulation. Recommended configuration by HuQAH嘉泰姆
Definition of suction cycle T. When T=1s, select a brightness level of 32, and when T=2s, select a brightness level of 64. Users must make a decisionQAH嘉泰姆
The final brightness level should not only be determined by the LED itself, but also by the visual performance of the finished product.QAH嘉泰姆
Table 8  Match 64 levels of brightness levels with 256 PWM levelsQAH嘉泰姆
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Note: The data for the 32 level brightness level is the standard value, while the data for the 64 level brightness level is the recommended value.QAH嘉泰姆

4.6. Shutdown modeQAH嘉泰姆

The shutdown mode can be used as a means to reduce power consumption or generate flashing displays (repeatedly entering and exiting the shutdown mode). In the shutdown mode,QAH嘉泰姆
All registers retain their data.QAH嘉泰姆

4.7 Software shutdownQAH嘉泰姆

      By setting the SSD bit of the configuration register (00h) to“ 0” ， CXLE87191 will operate in software shutdown mode, where they onlyQAH嘉泰姆
Consume 3.1 A (typical value) of current. When CXLE87191 is in software shutdown mode, all current sources will be turned off.QAH嘉泰姆

4.8. Hardware shutdownQAH嘉泰姆

When the SDB pin is pulled low, the chip enters hardware shutdown mode.QAH嘉泰姆

5、 Radiance correction and visual effect optimization

        To achieve brightness changes that are more in line with human perception, CXLE87191 supports brightness correction function. This function uses non-linear brightness encoding to make the brightness changes of LED more linear and natural in human perception.QAH嘉泰姆

Recommended Huijie configuration

►    32 level brightness levelSuitable for a 1-second breathing cycle, providing smooth brightness transitionsQAH嘉泰姆

►    64 level brightness levelSuitable for breathing cycles of 2 seconds or longer, achieving finer effectsQAH嘉泰姆

Brightness correction not only enhances visual effects, but also allows for optimization of brightness curves based on specific application requirements, ensuring the best visual experience in different lighting environments.QAH嘉泰姆

6、 System Design Guidelines

6.1.    Typical Application Circuit

In standard applications, it is recommended to use the following configuration:QAH嘉泰姆

♦     Power decouplingPlace 1μ F and 100nF capacitors near the VCC pinQAH嘉泰姆

♦     I2C pull-upSDA and SCL line configuration 4.7kΩ pull-up resistorQAH嘉泰姆

♦     current settingSelect the resistance value of R_EXT (2kΩ -10kΩ) according to the requirementsQAH嘉泰姆

♦     thermal managementThe heat dissipation pads of QFN packaging should be reliably groundedQAH嘉泰姆

6.2.    Layout suggestions

6.2.1.    Power integrityEnsure that the VCC and GND traces are wide enough to reduce voltage dropQAH嘉泰姆

6.2.2.  Signal IntegrityTry to keep the I2C signal line as short as possible to avoid parallel high-speed signalsQAH嘉泰姆

6.2.3.    thermal designProvide sufficient copper foil area for heat dissipation in high current applicationsQAH嘉泰姆

6.2.4.    EMI protectionChips should be kept away from interference sources such as high-frequency antennasQAH嘉泰姆

7、 Software implementation

Through the standard I2C protocol, various lighting effects can be easily achieved:QAH嘉泰姆

•    Breathing effectCycle changing PWM values to achieve smooth brightness changesQAH嘉泰姆

•    Chasing effectSwitching LED states sequentially between different channelsQAH嘉泰姆

•    Color MixingBy combining RGB channels, achieve full-color effectsQAH嘉泰姆

•    Scene ModePre stored multiple brightness configurations for quick switchingQAH嘉泰姆
7.1.    I2C bus description:QAH嘉泰姆

(1) CXLE87191 uses a serial bus that complies with the I2C protocol, with two control lines SDA and SCL. The slave address of CXLE87191 is“ one thousand and tenQAH嘉泰姆
1000”。 It only supports write operations.QAH嘉泰姆
(2) SCL line is unidirectional, SDA line is bidirectional (open drain output) with pull-up resistor (usually 4.7kΩ); ）. The I2C standard specifies the mostQAH嘉泰姆
The large clock frequency is 400kHz. The host is MCU and the slave is CXLE87191.QAH嘉泰姆
(3) The timing diagram of I2C is shown in Figure 3. SDA lock exists at the stable high level of SCL. When there is no interface activity, the SDA line should remain highQAH嘉泰姆
Level.QAH嘉泰姆
(4) The starting signal is generated by pulling down the SDA line when the SCL line is high. The start signal will alert all devices connected to the I2C busQAH嘉泰姆
Check the incoming address based on your own chip address.QAH嘉泰姆
(5) Next, send the 8-bit chip address, starting with the highest bit. When the SCL line is at a high level, each address bit must be stable.QAH嘉泰姆
(6) After the last chip address bit is sent, the host detects the response from CXLE87191. Then the host sends an SCL pulse.QAH嘉泰姆
If CXLE87191 has received the address correctly, then it keeps the SDA line low during the SCL pulse period. If the SDA line is not at a low level,QAH嘉泰姆
The host should send“ STOP” Signal (discussed later) and abort the transfer.QAH嘉泰姆
(7) After confirming the response of CXLE87191, send the register address byte, starting with the highest bit. CXLE87191 must generate another response indicating that it has been receivedQAH嘉泰姆
Received register address.QAH嘉泰姆
(8) Then send the 8-bit data byte, starting with the highest bit. When the SCL level stabilizes at a high level, each data bit should be valid.QAH嘉泰姆
After sending the data byte, CXLE87191 must generate another response indicating that the data has been received.QAH嘉泰姆
（9）“ STOP” The signal transmission has ended. Send out“ Stop” When the SCL signal is high, the SDA signal becomes high.QAH嘉泰姆

7.2.    Address automatically increasesQAH嘉泰姆

        To write multiple bytes of data to CXLE87191, load the address of the data register targeted by the first data byte. In CXLE87191QAH嘉泰姆
During the confirmation of receiving data bytes, the internal address pointer will increment by 1. The next data byte sent to CXLE87191 will be placed in the new address, according toQAH嘉泰姆
This type of promotion. As long as data is continuously written to CXLE87191, the address will automatically increment (Figure 6).QAH嘉泰姆

7.3.    Register DefinitionQAH嘉泰姆

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16h   PWM update registerQAH嘉泰姆
The data sent to the PWM register and LED control register will be stored in temporary registers. Need to write 8-bit values to update registersQAH嘉泰姆
Operate to update registers (01h~15h).QAH嘉泰姆
17h   Reset registerQAH嘉泰姆
After the user writes 8-bit data into the reset register, CXLE87191 will reset all registers to their default values. At the initial power on, CXLE87191QAH嘉泰姆
The register will be reset to its default value to display blank.QAH嘉泰姆

8、 Electrical characteristicsQAH嘉泰姆
       8.1.      Extreme working conditions

(1) If the chip operates for a long time under the above extreme parameter conditions, it may cause a decrease in device reliability or permanent damageQAH嘉泰姆
When any parameter reaches or exceeds these limit values in actual use.QAH嘉泰姆
(2) All voltage values are tested relative to the system ground.QAH嘉泰姆

8.2.      Electrical Characteristics

8.3.    Switch characteristics

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Note 1: The recommended minimum value for REXT is 2k Ω, otherwise it may result in a large currentQAH嘉泰姆
Note 2: Guaranteed by designQAH嘉泰姆
Note 3: Cb=total capacitance on a bus (pF). ISINK≤ 6mA. t and t were measured between 0.3 * VCC and 0.7 * VCC.

9、 Detailed explanation of performance advantages

8.1.  Accurate current matching

CXLE87191 provides excellent current consistency between channels, ensuring uniform LED brightness. Even when the output voltage changes, the constant current characteristic can maintain stable optical output.QAH嘉泰姆

8.2.  Efficient power management

The chip supports multiple low-power modes and only consumes 3.1 A of current in the off state, making it particularly suitable for battery powered devices. The software shutdown function allows entering a low-power state through software control without changing the hardware configuration.QAH嘉泰姆

8.3.  Flexible system expansion

Through the I2C address self add function, it is easy to achieve multi chip cascading and build large-scale LED array systems. Automatic shaping and forwarding ensure the integrity of signals during long-distance transmission.QAH嘉泰姆

10、 Encapsulation information

CXLE87191 offers two packaging options:QAH嘉泰姆

♦     QFN-24：4mm× 4mm ultra compact package, suitable for space constrained applicationsQAH嘉泰姆

♦     SOP-24Standard packaging for easy production and maintenanceQAH嘉泰姆

Both types of packaging comply with RoHS standards, providing excellent heat dissipation performance and welding reliability.QAH嘉泰姆
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11、 Conclusion

      The CXLE87191 18 channel LED constant current driver chip from Jiataim Semiconductor provides a complete and efficient solution for LED lighting in modern electronic devices with its precise current control, flexible dimming function, and compact packaging design. Whether it's simple status indication or complex decorative lighting, CXLE87191 can provide stable and reliable performance. Its 256 level PWM dimming, brightness correction, and low-power characteristics make it an ideal choice for high-end lighting applications.QAH嘉泰姆

      For detailed technical documentation, reference designs, or sample applications, please visit the official website of Jiataimu:jtm-ic.comOur technical team will provide you with professional technical support and comprehensive solutions.QAH嘉泰姆

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

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