Analog Devices LT3952 | Demoboard DC2361A

Description

Demonstration circuit DC2361A is a 2MHz 60V LED driver with internal 4A switch featuring the LT3952 monolithic LED driver. It accepts an input voltage from 8V to 28V (with transient to 36V) and boosts to a single string of LEDs up to 40V at 330mA. DC2361A features an integrated 4A switch, constant current and constant voltage output control as well as input current limit and monitoring.The LT3952 has a wide input voltage range down to 3V and up to 42V. It has adjustable switching frequency between 200kHz and 3MHz. It has an option for external frequency synchronization or spread spectrum frequencymodulation. It has high PWM dimming capability from an external signal and can be PWM dimmed with an internally generated PWM oscillator and analog input signal. It can be analog dimmed with a control voltage on its control pin. LT3952 features both open LED and short LED (LED+to GND) protection as well as fault output flags for each. Although DC2361A is assembled as a boost LED driver, it can be altered to be run as a buck mode, buck-boost mode or boost-buck LED driver.There is another demonstration circuit featuring LT3952 at 350kHz (DC2013A).DC2361A features an option to turn on spread spectrum by simply changing the position of a jumper from NO SPREAD to SPREAD or to EXTERNAL SYNC.Small ceramic input and output capacitors are used to save space and cost. The open LED overvoltage protection uses the IC’s constant voltage regulation loop to regulate the output to approximately 45V if the LED string is opened although it may reach 49V peak during transient fromrunning LEDs to open. There is a protection diode from LED+ to GND to prevent negative ringing during a shortcircuit with long wires.There is undervoltage and overvoltage lockout that can be adjusted on the circuit with a few simple resistor choices.There is a small EMI filter on the input of DC2361A. This EMI filter has a ferrite bead and very small cap to reduce high frequency EMI. The PCB layout contains a small hot-loop for minimized very high frequency EMI. The EMIfilter can be used by connecting to the ‘EMI VIN’ terminal. However, if the EMI filter is not needed, the input connection can be directly to the PVIN terminal. If the EMI filter is not used, it is recommended to remove the EMI filter if EMI measurements are being made from the PVIN terminal for base EMI testing. It can be replaced for EMI testing at the EMI VIN terminal.The LT3952 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 DC2361A. The LT3952EFE isassembled in a 28-lead plastic TSSOP (FE) package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the Layout Considerations section.

Typical applications

• Automotive,AvionicLighting
• DisplayBacklighting
• AccurateCurrent-Limited VoltageRegulators

More information

• Datasheet
• IC product information