DC1470A

Demonstration circuit 1470A is a high current synchronous step-down LED driver with three-state control featuring the LT®3743EUFD. The demo board is optimized for 20A output from a 12V input. Being an LED driver, the output current is being regulated until the output voltage reaches a programmed voltage limit. This voltage limit on this demo board is set to around 6V by R5 and R6. The 6V is chosen because of the 6.3V voltage rating of the output capacitors. The ideal load to be used with this demo board is a single LED, such as PT120 from Luminus Devices. Smaller LEDs may not be able to handle the high current, even for a short period of time. At 20A, the demo circuit can operate continuously. However, it is necessary to mount the LED load on a proper heat sink and possibly with a fan to avoid exceeding its maximum temperate rating. The DC470A will drive a LED with its cathode grounded. Grounding cathode of the LED allows customers to use positive input supply.

• Uses a split output capacitor configuration to achieve <lt/>2μs current rise time from 0A to 20A
• Input supply range of 12V typical (PVIN = VIN)
• Typical output voltage of 4.5V (with one PT120 LED, 6V is the overvoltage limit)
• Output current of 20A (CTRL-SEL <gt/> 1V)
• Switching frequency of 430KHz
• Current rise time of 2μs
• Efficiency at DC is 94% (VIN = 12V, VOUT = 5V, IOUT = 20A)

Notes

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