LT3965/LT3965-1
22
39651fa
For more information www.linear.com/LT3965
APPLICATIONS INFORMATION
the LT3965/LT3965-1 can control the LEDs through a 1
meter ribbon cable (9 wires total) passing 0.5A with no
false faults detected. The snubber value shown here is
good for most applications.
Schottky Clamping Diode for LT3965/LT3965-1
Protection
A Schottky clamping diode (D1 shown in Figure 15) con
-
necting the top of the LED string (LED
+
node) to the V
IN
pin is required to guarantee that the absolute maximum
rating V
IN
– SRC ≥ –0.3V is met.
Figure 14. RC Snubbers In Long Wire Application
Figure 15. Clamping Diode For LT3965/LT3965-1 Protection
For the boost-buck configuration, where the voltage at
the LED string bottom (LED
–
node) may go below 0V, a
Schottky clamping diode (D2 shown in Figure 15) con-
necting the
IC ground to the LED
–
node is required to
keep SRC ≥ –0.3V.
In applications with wires longer than 30cm, there is
potential for an open or shorted LED to cause ringing at
channel DRN-SRC beyond the absolute maximum rating of
–0.3V. The LT3965/LT3965-1 can be protected by placing
Schottky clamping diodes (D3 to D10 shown in Figure 15)
near the IC across channel pins.
GND
LT3965/
LT3965-1
DRN8
DRN7
SRC8
DRN6
SRC7
DRN5
SRC6
DRN4
SRC5
DRN3
SRC4
DRN2
SRC3
DRN1
SRC2
SRC1
V
IN
D3
D4
D5
D6
D7
D8
D9
D10
LED
IF NEEDED
LED
LT3965/LT3965-1
DRN8
DRN7
SRC8
DRN2
SRC3
DRN1
SRC2
SRC1
3965 F14
LED
D8
C9
10nF
R9
10Ω
D7
•
•
•
•
•
•
D3
D2
D1
–
UP TO 1 METER
C8
10nF
R8
10Ω
C2
10nF
R2
10Ω
C1
10nF
R1
10Ω
