STM32F071CB - High performance MCU
The STM32F071 microcontroller incorporates the high-performance Arm®Cortex®-M0 32-bit RISC core operating at up to 48 MHz frequency, high-speed embedded memories (up to 128 Kbytes of Flash memory and 16 Kbytes of SRAM), and an extensive range of enhanced peripherals and I/Os. This device offers standard communication interfaces (two I2Cs, two SPI/one I2S, one HDMI CEC and four USARTs), one 12-bit ADC, one 12-bit DAC with two channels, seven 16-bit timers, one 32-bit timer and an advanced-control PWM timer. Thanks to advanced timer, the solution implements LED dimming down to 0.5% level of the maximum brightness.
STD11N60M2-EP - High efficiency Power MOSFET
This device is an N-channel Power MOSFET developed using MDmesh™ M2 enhanced performance (EP) technology. Thanks to its strip layout and an improved vertical structure, the device exhibits low on-resistance, optimized switching characteristics with very low turn-off switching losses, rendering it suitable for the most demanding very high frequency converters. The device allows the achievement of high efficiency even at light load (dimming) conditions.
PM8841 - High efficiency low-side driver
The PM8841 is a high frequency single channel low-side MOSFET driver specifically designed to work with digital power conversion microcontrollers. The PM8841 output can sink 1 A and source 0.8A. The input levels of the driver are derived by the voltage present at the IN_TH pin (between 2 V and 5.5 V). This pin is typically connected at the same voltage of the microcontroller supply voltage. The PM8841 device includes both input and output pull-down resistors. UVLO circuitry for input and output stages prevent the IC from driving the external MOSFET in unsafe conditions. The device is available in SOT23-5 small package.
L6395 - High Voltage gate diver
The L6395 is a high voltage device manufactured with the BCD™ “offline” technology. It is a single chip high and low-side gate driver for N-channel power MOSFETs or IGBTs. The high-side (floating) section is designed to withstand a voltage rail up to 600 V. The logic inputs are CMOS/TTL compatible down to 3.3 V for easy microcontroller/DSP interfacing.
PM8834 - Dual low side driver
The PM8834 is a flexible, high-frequency dual low-side driver specifically designed to work with high capacitive MOSFETs and IGBTs. Both PM8834 outputs can sink and source 4 A independently. A higher driving current can be obtained by connecting the two PWM outputs in parallel. The PM8834 provides two enable pins which can be used to enable the operation of one or both the output lines. Both lines are used in this specific solution, one to drive the low-side MOSFET of the inverse buck, and one for the 0-10V dimming operation. The PM8834 works with a CMOS/TTL-compatible PWM signal. The device is available in an SO8 or an MSOP8 package with an exposed pad
VIPer012LS - High voltage converter
o The VIPer012 is a high voltage converter smartly integrating an 800 V avalanche-rugged power MOSFET with PWM current mode control. The power MOSFET with 800 V breakdown voltage allows the extended input voltage range to be applied, as well as the size of the DRAIN snubber circuit to be reduced. This IC meets the most stringent energy-saving standards as it has very low consumption and operates in pulse frequency modulation under light load. The design of flyback, buck and buck boost converters is supported. The integrated HV startup, sense-FET, error amplifier and oscillator with jitter allow a complete application to be designed with the minimum number of components.
- Wide input voltage range 85 – 265 VAC
- Transition Mode PFC
- Two constant current outputs working in transition mode based on different topologies:
- Buck topology
- Inverse buck topology
- Output current: 500 mA ±2.5%
- Number of LEDs connected at output: 16 – 24 white LEDs (3.3 V each)
- PFC > 0.97 and THD < 20% at full load with input voltage 85-265 VAC
- Peak Efficiency at maximum load ≅ 91%
- Comprehensive safety protections:
- Open/no-load circuit protection
- Short-/overload circuit protection
- Soft start implementation
- LED dimming range: 0.5% to 100%
- Analog dimming
- Digital dimming
- Dimming control options:
- Push button
- 0-10 V input
- Meets IEC55022 Class B EMI Standard
The 75W digitally controlled constant current LED driver (STEVAL-LLL004V1) features a PFC stage and two DC-DC converters designed to work in transition mode (TM) for optimized efficiency.
The LED driver can dim LEDs down to 0.5% maximum brightness level via analog and digital control, and still retain flicker operation.
The principal design objectives of this LED driver solution are to deliver considerable performance in terms of efficiency (90%), power factor (>0.97), THD (<20%), wide dimming range (down to 0.5%) and EN55022 EMC pre-compliance, as well as facilitate design optimization over a wide range of operating points with little or no hardware configuration. A reference design based on digital algorithms supported by a programmable STM32 microcontroller is therefore the ideal solution.
The implementation of digital control as opposed to analog is gaining popularity in power conversion circles for its superior flexibility regarding control loop parameter and on-the-fly operating point adjustment for any given condition, without needing to modify the hardware. Additionally, digital control ensures greater stability under noisy conditions and tends to be less sensitive to component tolerances, temperature variations and voltage drift. An appropriate programmable digital controller can also simplify the implementation and customization of advanced lighting solution features like flicker-free, high-resolution dimming, connectivity for remote control and dimming, diagnostic protection and monitoring.
The PFC section, based on a boost converter, provides a regulated high-voltage DC rail and ensures the system complies with standard EN61000-3-2 (harmonic current distortion) for lighting equipment at an input active power above 25 W.
The two downstream DC-DC converters, buck and modified/inverse buck, are connected in parallel. The board is designed to allow evaluation of the advantages of buck and modified buck(Inverse buck) DC-DC conversion topologies by implementing both converters in parallel: the modified buck topology has the power switch connected to ground, rendering it is easier to control the switch, while the buck converter has the LEDs connected to the ground.
The MCU controls all three power stages in transition mode, turning ON MOSFET gate just after the inductor current
reaches zero. A proportional-integral (PI) control loop has been implemented for the PFC stage, improving control
loop stability, line transition and dimming steps behavior, and reducing current and voltage overshoot at start-up.
Buck and inverse buck converters work in hysteretic mode. The dimming technique and control can be selected from the toggle switches on the board. In either of the dimming technique selected the brightness can go down up to 0.5% of the maximum brightness.
The analog dimming is implemented using an MCU internal comparator and a digital to analog converter (DAC) peripheral. According to the dimming level, the current threshold (inductor peak current) at the non-inverting end of the internal comparator is adjusted with the help of the DAC.
The digital dimming is managed by varying the on and off intervals of the MOSFET, by using MCU timer peripheral running at 500Hz.
Dimming options are set by using on the board jumpers and switches, for selecting the dimming type and control, and for selecting either the 0-10 VDC or PWM (3.3 V) inputs for external signal dimming control.
|STSW-LLL004FW||75 W digitally controlled constant current HB LED driver||Active|
All Evaluation Features
- Input voltage range - 85 - 265 VAC
- Power factor at full load 85 -265 VAC > 0.96
- THD at full load 85 -265 VAC < 20%
- PFC output voltage - 450 V ±2.5%
- Peak Efficiency at maximum load ≅ 91%
- Min. PFC switching frequency Transition Mode 35 kHz
- Min. PFC switching frequency Discontinuous Mode 20 kHz
- Maximum output power Buck and inverse buck 75 W
- Output voltage (Vout) Buck 50 - 80 VDC
- Buck Converter switching frequency at full load Transition mode ~100 kHz
- Output current (Iout) Buck (CC) 500 mA ±5%
- Output voltage (Vout) Inverse-buck 50 - 80 VDC
- Inverse buck converter switching frequency at full load Transition Mode ~100 kHz
- Output current (Iout) Inverse buck (CC) 500 mA ±5%
- LEDs connected at output HB white LEDs 16 - 24 (3.3 V each)
- Digital dimming frequency - 500 Hz
- Default brightness level - 100%
- Minimum dimming level - 0.5%
Microcontrollers & Microprocessors
|STM32F071CB||主流ARM Cortex-M0基本型系列MCU，具有128 KB Flash、48 MHz CPU和CEC功能|
EDA Symbols, Footprints and 3D Models
STMicroelectronics - SL-LTILT04802V1
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