2

dc1706af

DEMO MANUAL DC1706A

QUICK START PROCEDURE

DC1706A is easy to set up to evaluate the performance of

the LT3796. Follow the procedure below:

NOTE: PWM must be pulled high to run. If PWM is not

used, connect PWM to a 3.3V or 5V source or to VREF on

the PCB using 0Ω resistor R24.

1. Connect a string of LEDs that will run with forward volt-

and GND terminals on the PCB as shown in Figure 1.

2. Connect the EN/UVLO terminal to GND.

3. With power off, connect the input power supply to the

PVIN and GND terminals. Make sure that the PVIN DC

4. Connect the PWM terminal. If PWM is not used, connect

PWM to a 3.3V or 5V source or to VREF on the PCB us-

ing 0Ω resistor R24. PWM must be pulled high to run.

5. Turn the input power supply on and make sure the

6. Release the EN/UVLO-to-GND connection.

7. Observe the LED string running at the programmed

LED current.

8. Observe the CSOUT and ISMON input and output cur-

rent monitor voltages.

9. For PWM dimming, connect a PWM (100Hz or higher is

recommended) signal to the PWM terminal. For analog

dimming, connect a DC voltage between 0V and 2V to

the CTRL terminal.

10. Observe the reduction of brightness in the LED string

when PWM or analog dimming.

PARAMETER

CONDITIONS

UNITS

Input Voltage PVIN Range

Operating

Switching Frequency

R18 = 26.1k

300kHz

400mA

RS2 = 0.62Ω, PVIN = 8V

350mA

R5 = 1M, R9 = 13.7k

Open LED Voltage

R5 = 1M, R9 = 13.7k

92.5V

Typical Efficiency

93%

Under Voltage Lockout (Falling Turn-Off)

R1 = 499k and R8 = 100k

7.5V

Under Voltage Lockout (Rising Turn-On)

R1 = 499k and R8 = 100k

8.7V

Operating

7.7V

Peak Switch Current Limit

RS3 = 0.015Ω

6.6A

Suggested Maximum PWM Dimming Ratio

100:1