Quick Start Procedure - Linear Technology LT3755 Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1268A-A, 1268A-B
Table 1.
Typical Performance Summary for DC1268A-A/B
PARAMETER
Input Voltage PVIN Range
Switching Frequency
I
LED
Maximum Output Voltage - Open LED Voltage
Efficiency
Under Voltage Lockout
Peak Switch Current Limit

QUICK START PROCEDURE

Demonstration circuit 1268A-A, 1268A-B is easy to
set up to evaluate the performance of the LT3755,
LT3755-1. Follow the procedure below:
Make sure that the PVIN DC input voltage
NOTE:
does not exceed 40V.
Connect a string of LEDs with forward voltage
1.
less than 55V, but greater than the PVIN voltage,
to the LED+ and LED- (Boost) terminals on the
PCB as shown in Figure 1.
Connect the shutdown terminal to GND.
2.
HIGH VOLTAGE LED CONTROLLER
CONDITION
Operating
R8 = 28.7k
PVIN=12V V =50V I =1A
LED LED
RS1 = 0.015
With power off, connect the PVIN power supply
3.
to the PVIN and GND terminals within the ranges
specified on the PCB.
Connect the PWM terminal. If PWM is not used,
4.
connect PWM to a 5V source or to IntVcc on the
PCB. PWM must be pulled high to work. For –B,
the SYNC input can be left floating.
Turn the PVIN power supply on.
5.
Release the shutdown/GND connection.
6.
Observe the LED string running at the pro-
7.
grammed LED current.
For PWM dimming, connect a PWM 100Hz or
8.
higher signal to the PWM terminal.
Observe the reduction of brightness in the LED
9.
string when PWM dimming.
VALUE (TYPICAL)
8V-40V
400kHz
1A
56V
93%
8V
6.6A
2