LED driver chip, in fact, is a PWM control chip, in the composition of the circuit after normal operation, through the back of the current detection resistor to detect the LED current and get the voltage feedback to the chip, control the internal PWM duty cycle to adapt to changes in the LED's own characteristics caused by the current, voltage fluctuations, so that the LED to maintain a constant current.
led is our common light-emitting diode, it has three built-in driver types, one is constant voltage, the second is cross-current type, and the last is a pulse driver. Either kind of led driver can help us solve the current can not control the problem, after all, the diode is necessary to connect the power supply, often dealing with "electricity" Oh, therefore, the most indispensable is the built-in driver.
LED driver is a circuit used to control LED lights, it can provide a stable voltage and current to ensure the normal operation of LED lights. LED driver is usually composed of power supply, control circuit and output circuit, it can adjust the brightness and color of LED lights according to the input signal.
led driver power supply is used to supply power to led lamps and lanterns, so how to choose the right led strip driver according to the need?
1. According to the power selection: various specifications of constant-current and constant-voltage switching power supply sold on the market have a variety of different output voltage, current and output power to choose from, so you can choose according to the actual needs of use; in addition, some products have a variety of different frequencies of the input signal to choose from. For example
Some switching power supply can produce 50hz60hz100khz and other different frequencies of AC mains or DC (dcac) signal source, so that it can be easily used with the dimming station.
2. According to the load characteristics: choose the appropriate load characteristics to ensure the stability of the system and reduce the system power consumption is important. Generally speaking, the maximum allowable continuous operating time and the average trouble-free time under rated operating conditions as short as possible; and the average trouble-free working time is the cumulative working time between two failures within a certain period of time.
3. According to the use and environmental conditions: choose the appropriate way of heat dissipation, the choice of heat dissipation depends mainly on the type of driven parts and its working environment temperature and the structure of the heat sink form and material and several other factors.
For high-power led driver should try to use passive heat sink; and for small power removable controller should use active heat sink to improve its thermal effect and extend its life. In addition should also consider the temperature and humidity of the surrounding environment, dust, vibration and other factors.
4. Selection on demand: In the purchase should be fully considered whether the selected equipment can meet the functional requirements of the design requirements and use requirements, but also to consider whether the cost of the selected equipment is reasonable and other factors to consider the purchase.
5. Technical indicators: when selecting the purchase to read in detail the technical parameters and precautions in the product manual and other content.
LED driver features are mainly.
Stable output voltage, which can provide stable voltage and current.
adjustable output current, you can adjust the brightness and color of the LED lights according to the input signal.
energy-saving effect, can effectively reduce the power consumption of the LED lamp.
Safe and reliable, can protect the LED lamp from overload, short circuit and other damage.
The role of the LED driver is to control the brightness and color of the LED lamp so as to meet different lighting needs.
1. Because LED is a characteristic sensitive semiconductor devices, and has a negative temperature characteristics, LED driver power supply (also called driver) is the protection of its stable working condition in the application process.
2. LED devices on the drive power requirements are close to demanding, LED is not like ordinary incandescent bulbs, can be directly connected to 220V AC mains. LED is a low-voltage drive, you must design a complex conversion circuit, different uses of LED lights, to be equipped with different power adapters.
Design a good power supply must take into account the efficiency conversion, effective power, constant current accuracy, power supply life, electromagnetic compatibility of these factors, because the role of the power supply in the entire lamp is as important as the heart of a person.
LED drivers can be used in a variety of lighting applications, such as home lighting, commercial lighting, automotive lighting, etc.. In addition, LED drivers can also be applied to displays, projectors, smart homes and other fields.
AMC7150: Low price, you can choose it in the design parameters are not high requirements of low-voltage 4-25V products, the basic driving ability in the application design below 3W. For example, 1W string 3pcs or 3W 1pcs LED design is stable.
CAT4201: This IC drives 1-7 1W LEDs. efficiency up to 92%, 6-28V voltage input range buck drive application design. The biggest advantage over the previous two ICs is the SOT23 package size, the circuit profile, which meets the current requirements of most small volume lamp cup designs.
Large resistance range current regulation, can potentiometer wide resistance range to adjust the brightness, such as when the design of table lamps and other products need such.
ZXLD1350: This IC is currently a good market response, but also the SOT23 small volume package, input 7-30V voltage buck constant current drive 1-7psc LED, the line is simple and practical. Design Rs to be close to the IC to avoid supply voltage does not move significantly, which will affect the effect of constant current.
The overall electronic material cost is slightly higher than the previous IC.
LM3402 market feedback is good, the input voltage range covers the entire automotive applications, built-in MOS tube can be up to 15 LEDs, 1-3 LEDs is feeling a little expensive, more than 5 when the cost performance is very good. Currently in contact with the customer engineer evaluation is very high, accepting a relatively wide range of lines simple and practical.
LM3404 and LM3402 line is the same, the difference is that the current can reach 1A, drive 1-15pcs LED cost-effective.
IC specifications listed above are built-in MOS tube, built-in MOS tube can simplify the line design, small size, reduce the overall cost of the design, the failure rate will also be reduced. Because of its current IC process made, cost and other reasons greater than 1A LED driver IC need external MOS tube.
In our daily product design often encounter high current design, such as 5W, 10W and other higher power design requirements, that can only choose the external MOS tube IC can. The next will be a comprehensive cost recommendation of several ICs, for the majority of engineers and friends to choose a convenient model.
MAX16819/MAX16820 work in the 4.5V to 28V input voltage range, and has a 5V/10mA on-chip regulator. Output current is regulated by a high-side current-sense resistor, and a dedicated PWM input (DIM) enables a wide range of pulsed brightness regulation.
The MAX16819/MAX16820 are ideal for applications that require a wide input voltage range. High-side current detection and built-in current-setting circuitry allow for a minimum number of external components and provide ±5% accuracy in LED current. The hysteresis control algorithm ensures excellent input power rejection and fast response during load switching and PWM brightness regulation.
The MAX16819 has a 30% inductor ripple current, while the MAX16820 has a 10% ripple current. These devices can operate at switching frequencies of up to 2MHz, allowing the use of small components.
The MAX16819/MAX16820 can operate over the -40°C to +125°C automotive-grade temperature range and are available in a 3mm x 3mm x 0. 8mm, 6-pin TDFN package.
Personally, I recommend 200-500Hz PWM grayscale frequency adjustment, 1-6pcs LEDs in series up to 25W product design, recommended about price around 0.5 USD.
LM3401 is the country half launched external MOS high-power LED driver, can be designed to drive current within 3A, input voltage up to 35V, can be connected in series more than 10 LEDs.
The MAX16802A/B is a high-brightness (HB) LED driver control IC that internally contains all the circuitry needed to design a wide-input-range LED driver for general-purpose lighting and display applications. It is suitable for low input voltage (10.8V DC to 24V DC) LED drivers. When precise regulation of LED current is required, an on-chip error amplifier and a 1% accuracy reference can be utilized. Low-frequency PWM brightness regulation enables a wide brightness adjustment range.
The MAX16802 features an input undervoltage lockout (UVLO) feature that sets the input start-up voltage and ensures proper operation in the event of a power dip.
The MAX16802 does not have this bootstrap circuitry internally and can be biased directly from +12V. The internally fine-tuned 262 kHz fixed switching frequency allows for optimal selection of magnetic and filter components, resulting in a compact, cost-effective LED driver.
The MAX16802A has a maximum duty cycle of 50 percent and the MAX16802B has a maximum duty cycle of 75 percent. These devices are available in 8-pin μMAX? packages and can operate over the -40°C to +85°C temperature range.
Personally, I recommend 200-500Hz PWM grayscale frequency adjustment, 1-6pcs LED string max 50W product design, about the price of about 1.4 USD.
The MAX16818 pulse-width modulated (PWM) LED driver controller comes in a compact package that provides high output current with minimal external components.
The MAX16818 is ideally suited for synchronous and asynchronous buck (buck) topologies, as well as boost, buck-boost, SEPIC, and buck LED driver architectures. Fast LED transients of up to 20A/μs and a brightness regulation frequency of 30kHz can be achieved.
The device uses average current mode control to minimize the need for an external heat sink even at output LED currents up to 30A by optimizing the use of MOSFETs with optimal charge and on-state resistance characteristics. True differential detection technology allows precise control of the LED current.
Wide range brightness adjustment can be easily achieved by external PWM signals. Internal regulators with simple external bias devices allow the device to operate over a wide input voltage range of 4. 75V to 5. 5V or 7V to 28V. The wide switching frequency range of up to 1.5MHz allows the use of small size inductors and capacitors.
The MAX16818 has a clock output with a 180° phase delay that can be used to control another LED driver operating in staggered phase to reduce input and output filter capacitor size and lower ripple current.
The MAX16818ETE+ is rated for extended-grade temperature range (-40°C to +85°C), while the MAX16818ATE+ operates in the automotive-grade temperature range (-40°C to +125°C). The LED driver controller is available in a lead-free, 0.8mm thick, 5mm x 5mm 28-pin TQFN package with exposed pads.
The high current LED driver controller ICs with output currents up to 30A are recommended for designing 50-300W ultra high power portable LED projectors, LCD TV and monitor backlights, front panel projectors/rear projection TVs, automotive, bus/truck exterior lights, automotive emergency lighting and symbol lights, and many more products.