CXLE87185-X is a single-channel LED constant current driver chip with high precision and no external resistor setting current. Its biggest feature is that it has 8 adjustable output currents, covering 10mA ~ 45mA. Users can flexibly set current values without external resistors, which greatly simplifies circuit design and material management.
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[ CXLE87185-X ]"
CXLE87185-X: High-performance single-channel LEDConstant current driveChip comprehensive analysis
In today's increasingly widespread application of LED lighting, an efficient,StableA highly integrated driver chip is essential to ensure the life and performance of the entire lighting system. Tianwei Electronics launchedCXLE87185-XSingle channel constant currentLED driver chipIt is an excellent solution designed to meet the needs of small and medium power LED lighting. This article will comprehensively introduce the technical characteristics, typical applications, design points and purchase suggestions of the chip, helping engineers to achieve more efficient and reliable LED driver design.
1. Chip Overview: Why ChooseCXLE87185-X？
CXLE8718The 5-X is aHigh precision, no external resistor setting currentSingle-channel LEDConstant current driveChip. Its biggest feature is to have8-speed adjustable output currentCoverage10mA~45mAUsers can flexibly set the current value without external resistance, which greatly simplifies the circuit design and material management.
The chip is in3V~40VWide input voltage range availableStableWork, VP port withstand voltage up to 40V, suitable for a variety of power supply environment. Its typical conversionEfficiencyUp98%The constant current inflection point voltage is extremely low, effectively reducing system power consumption and heating, and improving overall energy efficiency.
2. core features
• Accurate current output: High output current accuracy, chip-to-chip deviation <± 5%
• Low dropout constant current: The inflection point voltage is only 0.33V(@ 10mA) at the lowest and 0.51V(@ 45mA) at the highest
• PWM DimmingSupport: Suitable for intelligent dimming scenes, compatible with a variety of dimming signals
• Temperature protection mechanism: hasover-temperature protectionand negative temperature coefficient to enhance system reliability
• HighStableSex: The zero adjustment rate of power supply/load is only 0.1%/V, adapting to voltage fluctuation
• Environmentally friendly packaging: SOT23-3 lead-free package, in line with environmental standards
3. typical application areas
CXLE87185-X is widely used in the following lighting scenarios:
• Commercial sign lighting: mall LOGO, parking lot sign, warehouse logo, etc.
• Advertising and decorative lighting: luminous characters, advertising light box, landscape lights
• linear lighting systemLED light bar, soft light strip, cabinet lighting
• Industrial and civil lighting：Low voltage lightingSystems, portable lamps, low-voltage track lights
4. pin definitions and limit parameters
4.1 Pin Function (SOT23-3)
| Pin Name | Pin No. | Function Description |
|---|---|---|
| VP | 1 | Constant current output terminal, connected to LED anode |
| VDD | 2 | Chip power input (3~40V) |
| GND | 3 | Chip grounding |
4.2. Limit parameters (absolute maximum)
| Parameters | Symbol | Limit value | Unit |
|---|---|---|---|
| VP/VDD Voltage | VP/VDD | -0.3 ~ 40 | V |
| Output current | Ivp | 45 | mA |
| Total power consumption | PTOT | 300 (TS≤ 100 ℃) | mW |
| working junction temperature | Topt | -40 ~ 125 | ℃ |
Prompt: Exceeding the above limit value may cause permanent damage to the chip. It is recommended to keep enough margin during design.
5. electrical characteristics and performance advantages
5.1. Tested under the conditions of VP = 3.0V and TA = 25 ℃, the main electrical characteristics of the chip are as follows:
| Parameters | Test conditions | Typical value | Unit |
|---|---|---|---|
| Quiescent current | VDD=5V | 280 | µA |
| Constant current inflection point voltage | Ivp=10mA | 0.33 | V |
| Output current range | - | 10~45 | mA |
| Current deviation | Vvp=3~6V | <3 | % |
| temperature coefficient | TA=-40~85℃ | -2.0 | %/℃ |
The chip has excellent temperature characteristics and voltage adaptability to ensure that it can still be used in harsh environments.StableWork.
5.2. Limit parameters
(1) These levels in the above table, the chip may cause permanent damage to the device and reduce the reliability of the device under long-term use conditions. We do not recommend in its
It works under any condition that the chip exceeds these limit parameters;
(2) All voltage values are tested relative to the system ground.
5.3. Electrical characteristics
6. System Design Guide
6.1. LED series number calculation.
The number of LEDs in series NLED can be calculated by the following formula:
6.2 Design Example：
When VCC = 24V,VLED = 3V, VP = 1V is set:
Therefore, up7 LEDsto ensure that the VP port voltage is higher than the constant current knee voltage.
In the following figure, the current limiting resistor Rext of VDD: VCC = 24V, 10KΩ-15KΩ is recommended; VCC = 12V, 3KΩ-5KΩ is recommended.
VP Port Load Number of LEDs NLEDIt is calculated according to the voltage drop of LED, the voltage of VCC and the constant current voltage of VP terminal.
VP Port Load Number of LEDs NLEDThe calculation formula is as follows:
NLED=(VCC-VP)/VLED;
Example: VLED=3V,VCC= 24V, when Vp = 1V, NLED=(24V-1V)/3V=7.6,NLEDrepresents the number of LEDs in series,
That is, the number of series lamps does not exceed 7.
Vp representsCXLE8718The V of 5-XP The voltage between the port and the chip GND (VPshould be higher than I constant current inflection point voltage). In practical application,
When the light bar is long, VCC will drop at a position far away from the power access point. If Vp does not reach the constant current inflection point voltage, VCC will drop
If the rated constant current value is not reached, the Vp value can be increased by reducing the number of lamps in series, or the power access point can be increased.
Circuit application diagram as shown in figure (A), (B). If the consistent effect of the lamp at extremely low brightness is required to be high, it is recommended to use the following scheme (B).
Design recommendations：
When the light bar is longer and the terminal voltage drops, the number of series LEDs can be reduced or the power access point can be increased
VDD current limiting resistor recommendation: 10kΩ ~ 15kΩ for 24V system and 3kΩ ~ 5kΩ for 12V system
6.3. Expanding the flow scheme.
If the output current of the single chip is insufficient, it can be used.multi-chip parallelStructure (see Figure 4 in the data sheet for details) to achieve current superposition and meet the needs of high current drive.
6.4. PWM DimmingApplication
Through the external PWM signal control VP port, can achieve smooth brightness adjustment. It is recommended that the PWM frequency be set at 100Hz ~ 1kHz to take into account the response speed and flicker-free effect.
7.over-temperature protectionand reliability design
CXLE87185-X built-in perfectover-temperature protectionfunction. When the chip junction temperature exceeds the safety threshold, the output current will automatically drop, effectively preventing chip damage or LED light failure caused by overheating.
7.1. Thermal Design Recommendations：
• In high temperature environment or high current application, ensure that there is enough heat dissipation space around the chip
• Reasonable design of PCB copper foil area to improve heat dissipation effect
• Avoid the chip working near the limit parameters for a long time
7.2 over-temperature protection
CXLE87185-X hasover-temperature protectionfunction. High IC junction temperature may cause chip damage, system heat and fire, etc.
LossLost. Excessive junction temperature may be caused by high current operation, poor circuit board design or high ambient temperature.
7.3, constant current curve
1） CXLE87185-X can realize low voltage constant current opening and high output current accuracy, and the output current deviation between chips is less than ± 5%;
2) As shown in the figure below, after reaching the constant current inflection point, the output current is very little affected by the VP port voltage.
8. Encapsulation Information
Chip adopts standardSOT23-3Package, small size (about 2.92mm × 1.6mm), suitable for compact design with limited space. Refer to page 6 of the data sheet for specific mechanical dimensions.
9. epilogue
CXLE87185-X with itsHigh integration, high precision, wide voltage range and excellent temperature characteristicsIt is an ideal drive solution for small and medium power LED lighting systems. Whether it is commercial sign lighting, LED strip or intelligent dimming system, the chip can provideStableReliable performance support.
ProvideCXLE87185-X full range of productsofTechnical Support,Sample Applicationwith supply services. Welcome to visit our official website for more product information and application solutions
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