LT3965/LT3965-1
1
39651fa
For more information www.linear.com/LT3965
TYPICAL APPLICATION
FEATURES DESCRIPTION
8-Switch Matrix LED Dimmer
The LT
®
3965/LT3965-1 is an LED bypass switching device
for dimming individual LEDs in a string using a common
current source. It features eight individually controlled
floating source 17V/330mΩ NMOS switches. The eight
switches can be connected in parallel and/or in series to
bypass current around one or more LEDs in a string. The
LT3965 is initialized with all switches off (LEDs on), and
the LT3965-1 is initialized with all switches on (LEDs off)
The LT3965/LT3965-1 uses the I
2
C serial interface to
communicate with the microcontroller. Each of the eight
channels can be independently programmed to bypass
the LED string in constant on or off, or PWM dimming
with or without fade transition. Using the fade option
provides 11-bit resolution logarithmic transition between
PWM dimming states. The LT3965/LT3965-1 provides
an internal clock generator and also supports external
clock source for PWM dimming. The LT3965/LT3965-1
reports fault conditions for each channel such as open
LED and shorted LED. The four address select pins allow
16 LT3965/LT3965-1 devices to share the I
2
C bus. The
device is available in a 28-lead TSSOP package
APPLICATIONS
n
Eight Independent 17V 330mΩ NMOS Switches
n
Independent On/Off/Dimming Control of 1 to 4 LEDs
for Each Switch
n
I
2
C Multidrop Serial Interface with Programmable
Open LED and Shorted LED Fault Reporting
n
16 Unique I
2
C Addresses
n
V
DD
Range: 2.7V to 5.5V and V
IN
Range: 8V to 60V
n
Digital Programmable 256:1 PWM Dimming
n
Fade Transition Between PWM Dimming States
n
Optional Internal Clock Generator or External Clock
Source for PWM Dimming
n
Open LED Overvoltage Protection
n
Flicker Free PWM Dimming
n
Automotive LED Headlight Clusters
n
Large LED Displays
n
Automated Camera Flash Equipment
n
RGBW Color Mixing Lighting
L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks of Analog
Devices, Inc. All other trademarks are the property of their respective owners.
3965 TA01
L1
33µH
D1
D2 D3
D4
D5
500mA
LED
+
LED
+
LED
–
V
LED
26V
V
IN
0.01µF
V
IN
ISP
0.5Ω
ISN
RT
DIM/SS VC
LT3955
EN/UVLO
PWM
V
REF
CTRL
PGND
INTV
CC
PWMOUT
SYNC
VMODE
FB
GND
GNDK
SW
28.7k
375kHz
V
CC
5V
SDA
SCL
ALERT
28k
500Hz DIMMING FREQUENCY
L1: WURTH 744066330
D1: DFLS260
D2, D3: CMSD6263S 2 IN 1 PACKAGE
D4, D5: PMEG6010CEH
M1: VISHAY Si7309DN
Q1, Q3: ZETEX FMMT593
Q2: ZETEX FMMT493
10k10k10k
1k
20k
1µF
50V
2.2nF
1µF
0.1µF
100V
0.1µF
28k
49.9k
EN/UVLO
BIAS
BIAS
9.09k
1k
IN4148
Q1
M1
Q2
1k
GND
LT3965/
LT3965-1
V
DD
EN/UVLO EN/UVLO
SDA
SCL
ALERT
RTCLK
ADDR1
ADDR2
ADDR3
ADDR4
LEDREF
DRN8
DRN7
SRC8
DRN6
SRC7
DRN5
SRC6
DRN4
SRC5
DRN3
SRC4
DRN2
SRC3
DRN1
SRC2
SRC1
V
IN
0.1µF
1µF
100V
Q3
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