DC1947A: Demo Board for the LT3799-1 Offline Isolated Flyback LED Controller with Active PFC.

DC507A: Demo Board for the LT1937 White LED Step-Up Converter in SC70 and ThinSOT.

DC871A-A: Demo Board for the LTC3215 700mA Low Noise High Current LED Charge Pump.

Demonstration circuit 2788A is a boost LED driver featuring the LT®3950. This demonstration circuit powers a string of LEDs at 330mA. The step-up topology can be used to drive a string of up to 28V of LEDs as assembled. The maximum output voltage capability of the LT3950 is 60V. DC2788A runs from an input voltage range of 6V to 24V as built. It also runs at 2MHz and has the capability to turn on spread spectrum frequency modulation (SSFM) for a frequency range of 2.0MHz to 2.5MHz. Dimming control can be achieved with analog dimming or PWM dimming—either from an external or internally-generated clock source. DC2788A features undervoltage lockout (UVLO) set at 6.6V with a 1.0V hysteresis for turn-on. The UVLO voltage, LED current, output voltage range, switching frequency, brightness control, SSFM, and the topology can all be adjusted with simple modifications to the demonstration circuit. LT3950 is a monolithic 1.5A peak switch current, 60V LED driver. The guaranteed peak switch current rating of the IC is 1.5A and this is important to know when calculating maximum output current at a given LED voltage and input voltage for a boost converter. The LT3950 features SSFM and a well-controlled SW node for low emissions. A frequency range of 200kHz to 2MHz and a high-side PWMTG PWM-dimming MOSFET makes this a very versatile IC for many applications. It can be used for boost, buck-boost mode and buck mode LED driver applications. The PWMTG MOSFET not only provides high PWM dimming ratio capability, but it also serves as a short-circuit protection device. The FAULT flag indicates when there is either a short-circuit or open-LED fault at the output. The demo circuit is designed to be easily reconfigured to suit other applications, including the example schematics in the data sheet. Consult technical support for assistance. High voltage operation, 3V input voltage operation, multiple topologies, small-and-compact size, fault protection, low EMI, and multiple brightness control options make the LT3950 flexible and powerful for compact, noise-sensitive LED driver solutions. The LT3950JMSE featured on this demo circuit is available in a thermally enhanced 16-lead plastic MSOP package. The LT3950 data sheet must be read in conjunction with this demo manual to properly use or modify demo circuit DC2788A.

The ADP8860SHIELD-EVALZ and the ADP8861SHIELD-EVALZ incorporate light emitting diodes (LEDs) for quick and easy evaluation of the ADP8860 and the ADP8861. Note that only the ADP8860SHIELD-EVALZ has dual light intensity sensors. The ADP8860SHIELD-EVALZ and the ADP8861SHIELD-EVALZ follow the form factor of a regular Arduino® shield to allow compatibility with microcontroller boards that use the same interface. These evaluation boards also incorporate a separate header dedicated to I2C communications. The ADP8860 and the ADP8861 are 7-channel LED drivers that utilizes a charge pump with selective gain for maximum efficiency. The LEDs driven by either device are programmable for maximum current and fade in and out times via the I2C interface. Only the ADP8860 has a programable light intensity threshold that can be set via the I2C interface of the device. Each channel can handle up to 30 mA (typical), except for the seventh channel, which can handle 60 mA (typical). Each channel can be unified to have the same fade in time and fade out time, or each channel can have an individual fade in time and fade out time for greater flexibility. For full details on the ADP8860 and the ADP8861, see the ADP8860 and the ADP8861 data sheets, which should be consulted in conjunction with the user guide when using these evaluation boards.

Demonstration Circuit 1279 is a full-featured, multitopology LED driver with 1.5A switch current featuring the LT3518. The board is optimized to drive a 330mA LED string with a total LED voltage between the input voltage and 40V in a boost topology. The input voltage range (VIN) is 3V to 30V, and the supply pin that powers the switcher (PVIN) has an input voltage range of 3V to 40V.

Demonstration circuit 1831A is a high power constant current, constant voltage synchronous buck controller featuring the LT3763. The input of the demo board is up to 60V. The output is optimized for 10V, 10A as a LED driver. The input voltage range of the LT3763 itself is 6V to 60V. The demo board input range is 12V to 60V, therefore, the demo board utilizes 80V MOSFETs. If an application has a maximum input voltage of 48V, 60V MOSFETs such as BSC100N06LS3, can be used for better efficiency at lower voltage range.

Demonstration circuit DC2575A is a 60V 2MHz synchronous buck-boost LED driver featuring the LT8391A. It accepts an input voltage from 4V to 60V and drives a single string of LEDs up to 16V at 1.5A. DC2575A runs at 2MHz switching frequency and features spread spectrum frequency modulation (SSFM) which can be enabled with a simple jumper. SSFM spreads the switching frequency from fSW to fSW + 25% for reduced EMI. SSFM is not necessary in applications where EMI is not important.

Demonstration circuit 2404A is a 36V synchronous buckboost LED driver featuring the LT3942. It drives a single string of LEDs up to 14V at 1A when VIN is between 9V and 36V and will run down to 3VIN with reduced ILED. DC2404A runs at 2MHz switching frequency with spread spectrum frequency modulation (SSFM) disabled. When enabled, SSFM spreads the switching frequency of the LT3942 from fSW to fSW + 25% for reduced EMI performance. The LT3942 has an operating input voltage range of 3V to 36V. It has internal, synchronous 40V switches for high efficiency and small size. It has an adjustable switching frequency between 300kHz and 2MHz. The LT3942 can by synchronized to an external source, programmed with SSFM enabled for low EMI, or set to normal operation. The LT3942’s integrated PWMTG high-side PWM MOSFET driver assists with short-circuit protection of the output, as well as PWM dimming of the connected LEDs. The LED string can be PWM dimmed with an external PWM signal or can be dimmed using the internally generated PWM signal. DC2404A has jumpers that can be set to switch between internally and externally generated PWM signals. The external PWM setting defaults to 100% on with no PWM signal applied. The LT3942 can also be analog dimmed by placing a controllable DC voltage on the CTRL pin. When running PWM dimming with SSFM enabled, the SSFM aligns itself with the PWM signal for flicker free operation. This applies to both internal and external PWM dimming. Small ceramic input and output capacitors are used to save space and cost. The board is designed with tiny, high frequency capacitors placed near the PVIN and PVOUT pins for a reduction in radiated EMI. The open LED overvoltage protection uses the IC’s constant voltage regulation loop to regulate the output to approximately 17V peak if the LED string is opened. The output current can be monitored through the ISMON output pin. Undervoltage lockout can be adjusted on DC2404A with a few simple resistor choices. There is a small ferrite bead EMI filter on the input and output of DC2404A. These filters, combined with proper board layout and SSFM, are effective in reducing EMI. Please follow the recommended layout and four-layer PCB thickness of DC2404A for low EMI applications. The LT3942 can operate as a constant current LED driver as well as a constant voltage regulator. Small changes to the circuit allow for constant output voltage regulation. The LT3942 data sheet gives a complete description of the part, operation, and applications information. The data sheet must be read in conjunction with this demo manual for demonstration circuit 2404A. The LT3942EUFD is assembled in a 28-lead plastic QFN (UFD) package with a thermally enhanced exposed ground pad. Proper board layout is essential for maximum thermal performance. See the data sheet section Layout Considerations.

The ADP8860SHIELD-EVALZ and the ADP8861SHIELD-EVALZ incorporate light emitting diodes (LEDs) for quick and easy evaluation of the ADP8860 and the ADP8861. Note that only the ADP8860SHIELD-EVALZ has dual light intensity sensors. The ADP8860SHIELD-EVALZ and the ADP8861SHIELD-EVALZ follow the form factor of a regular Arduino® shield to allow compatibility with microcontroller boards that use the same interface. These evaluation boards also incorporate a separate header dedicated to I2C communications. The ADP8860 and the ADP8861 are 7-channel LED drivers that utilizes a charge pump with selective gain for maximum efficiency. The LEDs driven by either device are programmable for maximum current and fade in and out times via the I2C interface. Only the ADP8860 has a programable light intensity threshold that can be set via the I2C interface of the device. Each channel can handle up to 30 mA (typical), except for the seventh channel, which can handle 60 mA (typical). Each channel can be unified to have the same fade in time and fade out time, or each channel can have an individual fade in time and fade out time for greater flexibility. For full details on the ADP8860 and the ADP8861, see the ADP8860 and the ADP8861 data sheets, which should be consulted in conjunction with the user guide when using these evaluation boards.