CXLE87182 is an integrated high-voltage driver circuit of LED constant current driver chip, suitable for all kinds of LED lighting system. Its design is simple, without any peripheral devices can achieve a stable constant current output, greatly simplifying the circuit design, reducing the cost of the system. The chip is available in a variety of package forms, including SOT-23, large SOT-23, T0-92 and SOD-123, to meet the installation and heat dissipation needs of different application scenarios.
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[ CXLE87182-X ]"
CXLE87182 Single Channel LEDConstant current driveChip Details
In modern lighting systems, LED is widely used because of its high efficiency, energy saving, long life and other advantages. And the LED'sStabledrive, can not be separated from the high-performanceConstant current driveChip.CXLE87182 is a single channel designed for LEDConstant current driveIntegrated circuits, manufactured using high-voltage power CMOS technology, have excellent performance and reliability, and are widely used in various LED lighting scenarios. This article will detailCXLE87182 features, functions,Electrical parametersand application solutions to help engineers better understand and use the chip.
1. Product Overview
CXLE87182 is an integrated high-voltage drive circuit LEDConstant current driveChip, suitable for all kinds of LED lighting system. Its design is simple and can be realized without any peripheral devicesStableThe constant current output greatly simplifies the circuit design and reduces the system cost. The chip is available in a variety of package forms, including SOT-23, large SOT-23, T0-92 and SOD-123, to meet the installation and heat dissipation needs of different application scenarios.
2. core features
• High Pressure Process: Using high-voltage power CMOS process, the output port withstand voltage exceeds 30V, which is suitable for high-voltage working environment.
• High accuracy of constant current：CXLE87182-2 output constant current 20mA(± 5%),CXLE87182-3 Output 30mA(± 5%), CurrentStableSex is strong.
• No peripheral devicesBuilt-in complete drive circuit, no external components, simplify PCB layout.
• Multiple package selection: Support SOT-23, T0-92, SOD-123 and other packages to adapt to different heat dissipation and space requirements.
• Temperature negative feedback: Built-intemperature compensationmechanism to enhance work at high temperaturesStableSex.
3. internal structure and pin description
3.2. CXLE87182 Internal integrated temperature negative feedback mechanism to ensure that it can be maintained at different temperaturesStableoutput current. Its pin definition is clear, compatible with a variety of packages:
Attention：CXLE87182 For electrostatic sensitive devices, it is recommended to take anti-static measures in a dry environment to avoid performance degradation or damage due to ESD.
4.Electrical parametersDetailed explanation
4.1. Limit parameters (Ta = 25 ℃)
| Parameters | Symbol | Numerical | Unit |
|---|---|---|---|
| Output port withstand voltage | Vout | 30 | V |
| Power loss | PD | 400 | mW |
| Working temperature | Topt | -40~ 85 | ℃ |
| Storage temperature | Tstg | -65~ 150 | ℃ |
Tip: It is not recommended to approach or exceed the limit parameters for a long time in actual use, so as not to affect the life of the device.
(1) If the chip works for a long time under the above-mentioned limit parameters, it may cause the reliability of the device to be reduced or permanently damaged.
Which parameter meets or exceeds these limit values.
(2) All voltage values are tested relative to the system ground
4.2. Normal Scope of Work
|
Parameters |
Symbol |
Minimum |
Typical |
Max. |
Unit |
Condition |
|---|---|---|---|---|---|---|
|
Logic supply voltage |
OUT |
2.2 |
3 |
30 |
V |
Constant current output |
Note:CXLE87182 is a temperature negative feedback device, which can work under a short pulse width voltage of 30V. When the junction temperature of the chip does not exceed 80°C, it may
A current value reduction of up to 2mA is produced. The sustainable time of channel opening and the heat dissipation conditions at the bottom of the chip, ambient temperature, voltage pulse width time,
shape and frequency.
CXLE87182 With temperature negative feedback characteristics, when the chip junction temperature does not exceed 80 ℃, the current change is controlled within 2mA, which is suitable for short-term high-voltage pulse scenarios.
5. typicalapplication circuitDesign
5.1. BasicConstant current driveCircuit
As shown in the following figure, connect the LEDs in series to the OUT pin. The power supply voltage should ensure that the OUT pin voltage is greater than 2.2V. It is recommended to control around 3.0V in practical applications to ensure that the chipStableWork in constant current state.
If the power supply voltage is high or the LED string voltage is reduced, it is recommended to connect the voltage divider resistor R1 in series in the circuit, and the calculation formula is as follows:
• CXLE87182-2R = (supply voltage-LED total voltage drop -3.0V)/0.02A
• CXLE87182-3R = (supply voltage-LED total voltage drop -3.0V)/0.03A
Examples: Use 24V power supply to drive 5 white LEDs (each with a voltage drop of 3.0V)CXLE87182-2:
R = (24W - 15W - 3.0W) / 0.02A = 300 kW
As shown in Figure 1, to makeCXLE87182 Working in constant current state, the voltage on the chip OUT pin should be greater than 2.2V, I .e. 2 and 3 of the chip
The voltage between the feet should reach more than 2.2V. In application, the voltage applied to the OUT pin after the power supply is connected to the LED lamp in series is recommended to be about 3.0V.
If the chip continues to work in the rated constant current state,CXLE87182-2 andCXLE8718The OUT pin voltage of 2-3 should be 12.0V and 8.0V respectively
Within is appropriate.
If the chip OUT pin maintains a high voltage for a long time, the chip itself consumes a lot of power and may generate heat significantly, resulting in chip damage,
The device parameters should be reasonably configured according to the actual use. If the supply voltage is high or the number of LEDs connected in series is small, it will causeCXLE87182
When the working voltage of the OUT pin is too high, it is recommended to connect resistors with appropriate resistance and package power in series for voltage division, as shown in Figure 2 below:
In fig. 2, the resistance value of resistor R1 should be calculated according to the power supply voltage, the voltage drop of LED lamps used, and the number of LED lamps connected in series,
The specific calculation formula is as follows (setCXLE8718The operating voltage of the OUT pin of 2 is 3.0V):
UseCXLE87182-2: R = (supply voltage-LED lamp voltage drop x number of series -3.0V)/0.02A
UseCXLE87182-3: R = (supply voltage-LED lamp voltage drop x number of series -3.0V)/0.03A
For example: when the power supply voltage is DC24V, useCXLE87182-2 makeConstant current driveWhen 5 white LED lamp beads are connected in series, the resistance meter of R
Calculated as follows:
R =(24V-3.0V x 5-3.0V)/0.020A = 300Ω
Note: The voltage drop of red LED lamp is generally calculated at 2.0V, and the voltage drop of green and blue LED lamp is generally calculated at 3.0V, which should be based on the actual
The parameters and specifications of the LED lamp beads used in the world are determined.
Tip: Red LED voltage drop is about 2.0V, green/blue light is about 3.0V, the specific specifications shall prevail.
5.2. PWM DimmingApplication
Through the PWM signal control chip on-off, can realize the LED brightness adjustment. During the PWM off period, the OUT pin withstand voltage can reach 24V. The recommended duty cycle control is as follows:
• CXLE87182-2: Duty cycle <50%
• CXLE87182-3: Duty cycle <30%
If the total voltage difference between the power supply voltage and the LED is large, it is recommended to connect the voltage divider resistor in series to share the power.
As shown in Figure 3, the PWM signal is controlled by the switch circuit.CXLE87182 on and off, so that the chip works in a periodic on-off state.
when,CXLE8718The OUT pin of 2 can withstand 24V, that is, when the PWM signal is turned offCXLE8718The OUT pin voltage of 2 can be DC24.0V, but it is turned on.
The duty cycle should not be too high, the specific application reference is as follows:
CXLE87182-2: On-time duty cycle less than 50%
CXLE87182-3: On-time duty cycle less than 30%
If the remaining voltage is higher after the power supply voltage minus the total voltage drop of the LED lights connected in series, the voltage dividing resistor should be connected in series in the circuit as shown in fig. 3.
R1 for voltage and power sharing.
5.3. PCB Design Recommendations
In order to improve the heat dissipation effect, it is recommended to expand the copper foil area connected to the chip pins in the design to speed up heat conduction and ensure that the chip lasts for a long time.StableWork.
reduced.CXLE87182 The temperature when the chip is working, when designing the PCB, it should be comparedCXLE87182 pin connection PCB copper foil surface
The product is expanded as much as possible to achieve good and fast heat dissipation. Refer to the following figure:
6. Package Schematic Overview
CXLE87182 Provide four standard packages with accurate dimensions, suitable for automatic patch and manual welding. Please refer to the detailed illustration in the data sheet for specific dimensions.
7. epilogue
CXLE87182 As a high-performance, high-reliability LEDConstant current driveWith its simple design, flexible packaging options and excellent temperature characteristics, it has become an ideal choice for various LED lighting applications. Whether it is general lighting, decorative light strips orPWM Dimmingsystem,CXLE87182 can be provided.StableEfficient driver support.
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Keywords：CXLE87182, LEDConstant current drive, High-voltage CMOS, no peripheral devices, temperature negative feedback,PWM Dimming, SOT-23, T0-92, SOD-123, jtm-ic.com
