LT3965/LT3965-1
8-Switch Matrix LED Dimmer
FEATURES
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DESCRIPTION
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
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Eight Independent 17V 330mΩ NMOS Switches
Independent On/Off/Dimming Control of 1 to 4 LEDs
for Each Switch
I
2
C Multidrop Serial Interface with Programmable
Open LED and Shorted LED Fault Reporting
16 Unique I
2
C Addresses
V
DD
Range: 2.7V to 5.5V and V
IN
Range: 8V to 60V
Digital Programmable 256:1 PWM Dimming
Fade Transition Between PWM Dimming States
Optional Internal Clock Generator or External Clock
Source for PWM Dimming
Open LED Overvoltage Protection
Flicker Free PWM Dimming
APPLICATIONS
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Automotive LED Headlight Clusters
Large LED Displays
Automated Camera Flash Equipment
RGBW Color Mixing Lighting
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog
Devices, Inc. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Matrix LED Dimmer Powered by a Buck Mode LED Driver
750
Q1
1k
M1
LED
+
Q2
1k
D4
BIAS UVLO DETECT
BIAS
49.9k
BIAS
1µF
100V
D2
V
IN
EN/UVLO
PWM
2.2nF
V
REF
CTRL
1µF
50V
PGND
RT
LT3955
ISP
ISN
INTV
CC
PWMOUT
SYNC
VMODE
FB
GND
GNDK
DIM/SS
SW
VC
0.01µF
D1
IN4148
28k
L1
33µH
D5
LED
–
500mA
V
LED
26V
1µF
20k
0.1µF
100V
D3
DRN8
SRC8
DRN7
SRC7
DRN6
SRC6
DRN5
SRC5
DRN4
SRC4
DRN3
SRC3
DRN2
SRC2
DRN1
SRC1
V
IN
V
DD
0.1µF
LT3965/
LT3965-1
SDA
SCL
ALERT
EN/UVLO
RTCLK
ADDR1
ADDR2
ADDR3
ADDR4
GND
LEDREF
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
3965 TA01
EN/UVLO
28k
500Hz DIMMING FREQUENCY
10k
10k
10k
SDA
SCL
ALERT
V
CC
5V
LED
+
1k
Q3
EN/UVLO
9.09k
V
IN
40V
0.5
28.7k
375kHz
0.1µF
39651fa
For more information
www.linear.com/LT3965
1
LT3965/LT3965-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
DRN8
V
IN
EN/UVLO
ALERT
SCL
SDA
V
DD
RTCLK
ADDR1
1
2
3
4
5
6
7
8
9
29
GND
28 SRC8
27 DRN7
26 SRC7
25 DRN6
24 SRC6
23 DRN5
22 SRC5
21 DRN4
20 SRC4
19 DRN3
18 SRC3
17 DRN2
16 SRC2
15 DRN1
V
IN
............................................................................60V
V
IN
-SRC[8:1] ..........................................................–0.3V
DRN[8:1] ...................................................................60V
SRC[8:1]....................................................................60V
LEDREF .....................................................................60V
DRN[8:1]-SRC[8:1] (Each Channel) ................–0.3V, 25V
EN/UVLO ...................................................................12V
V
DD
.............................................................................6V
SDA, SCL,
ALERT
............................ –0.3V to V
DD
+ 0.3V
RTCLK.........................................................................6V
ADDR[4:1] ...................................................................6V
Operating Junction Temperature Range (Note 2)
LT3965E/LT3965E-1/LT3965I/LT3965I-1 –40 to 125°C
Storage Temperature Range .................. –65°C to 150°C
ADDR2 10
ADDR3 11
ADDR4 12
LEDREF 13
SRC1 14
FE PACKAGE
28-LEAD PLASTIC TSSOP
θ
JC
= 10°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT3965EFE#PBF
LT3965EFE-1#PBF
LT3965IFE#PBF
LT3965IFE-1#PBF
TAPE AND REEL
LT3965EFE#TRPBF
LT3965EFE-1#TRPBF
LT3965IFE#TRPBF
LT3965IFE-1#TRPBF
http://www.linear.com/product/LT3965#orderinfo
PART MARKING*
LT3965FE
LT39651FE
LT3965FE
LT39651FE
PACKAGE DESCRIPTION
28-Lead Plastic TSSOP
28-Lead Plastic TSSOP
28-Lead Plastic TSSOP
28-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
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39651fa
For more information
www.linear.com/LT3965
LT3965/LT3965-1
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 40V, V
DD
= EN/UVLO = 5V, LEDREF = 3V, SRC = 0V, ADDR[4:1] not
connected, unless otherwise noted.
PARAMETER
V
DD
Input Supply Voltage
V
DD
Operating I
Q
V
DD
Shutdown I
Q
V
IN
Operating Voltage
V
IN
Operating I
Q
(Channel Not Switching)
SCL = SDA =5V (I
2
C Bus Idle), R
TCLK
= 28k
EN/UVLO < 0.4V
EN/UVLO = 1.15V
All Channels V
OTH
[1:0] = V
STH
[1:0] = “00” (Note 3)
All Channels V
OTH
[1:0] = V
STH
[1:0] = “00”, LED ON
All Channels V
OTH
[1:0] = V
STH
[1:0] = “11”, LED OFF
All Channels V
OTH
[1:0] = “11”, V
STH
[1:0] = “00”,
LED ON
V
IN
Shutdown I
Q
DRN[8:1] Operating Voltage
SRC[8:1] Operating Voltage
Current Out of SRC[8:1] Pins (Each Channel)
Switch On-Resistance
Switch Leakage Current
Switch Transition Time (t
r
/t
f
)
DRN[8:1] to SRC[8:1] Crowbar Protection
Clamp Voltage
Response Time from SW Crowbar Protection
to SW Secure Protection
Programmable Open LED Threshold (V
OTH
)
DRN = 16V, V
OTH
[1:0] = 11
DRN to 10V through 50Ω Resistor
LED or Switch Bypass Current is 500mA
LED or Switch Bypass Current is 500mA
V
OTH
[1:0] = “00” (Note 3)
V
OTH
[1:0] = “01” (LT3965-1 POR State)
V
OTH
[1:0] = “10”
V
OTH
[1:0] = “11” (LT3965 POR State)
V
STH
[1:0] = “00” (Note 3)
V
STH
[1:0] = “01”
V
STH
[1:0] = “10”
V
STH
[1:0] = “11”
V
STH
[1:0] = “00” (Note 3)
V
STH
[1:0] = “01”
V
STH
[1:0] = “10”
V
STH
[1:0] = “11”
V
STH
[1:0] = “00” (Note 3)
V
STH
[1:0] = “01”
V
STH
[1:0] = “10”
V
STH
[1:0] = “11”
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
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1.3
0.1
MAX
5.5
1.8
1
8
60
1.4
3.3
2
1
V
IN
– 3V
V
IN
– 7.1V
UNITS
V
mA
µA
µA
V
mA
mA
mA
µA
V
V
µA
µA
mΩ
µA
µs
V
µs
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
mV
µA
nA
Hz
Hz
Hz
2.7
8
1
2.5
1.5
0.1
EN/UVLO < 1.15V
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Channel LED Is On (Channel Switch Is Off)
Channel LED Is Off (Channel Switch Is On)
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40
330
13
55
5
0.35
0.5
22
1
0.65
25
1.6
4.75
9.5
14.25
19
1.15
1.2
1.25
1.3
1.15
4.2
7.3
10.4
1.15
5.3
9.5
13.7
1.35
3.2
100
220
550
1250
4.25
8.5
12.75
17
0.85
0.85
0.85
0.85
0.85
3.8
6.7
9.6
0.85
4.7
8.5
12.3
1.15
2.2
4.5
9
13.5
18
1
1
1
1
1
4
7
10
1
5
9
13
1.24
10
2.7
10
Programmable Shorted LED Threshold (V
STH
)
for LEDREF = 0V
Programmable Shorted LED Threshold (V
STH
)
for LEDREF = 3V
Programmable Shorted LED Threshold (V
STH
)
for LEDREF ≥ 4V
EN/UVLO Threshold Voltage Falling
EN/UVLO Threshold Voltage Rising Hyst.
EN/UVLO Input Bias Current Low
EN/UVLO Input Bias Current High
LED PWM Dimming Frequency
(=RTCLK Programmed Oscillator
Frequency/2048 or External Clock
Frequency/2048)
EN/UVLO = 1.15V
EN/UVLO = 1.33V
R
TCLK
= 80.6kΩ
R
TCLK
= 28kΩ
R
TCLK
= 10kΩ
RTCLK Programmable Internal Oscillator or External Clock Source
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450
950
195
500
1090
39651fa
For more information
www.linear.com/LT3965
3
LT3965/LT3965-1
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 40V, V
DD
= EN/UVLO = 5V, LEDREF = 3V, SRC = 0V, ADDR[4:1] not
connected, unless otherwise noted.
PARAMETER
RTCLK Output Voltage (Using Internal
Oscillator)
RTCLK Input Low Threshold (RT
VIL
)
RTCLK Input High Threshold (RT
VIH
)
RTCLK Input Clock Frequency
RTCLK Input Clock Pulse Width High (T
RTH
)
RTCLK Input Clock Pulse Width Low (T
RTL
)
RTCLK Input Clock Ramp Time between RT
VIL
and RT
VIH
(T
RTRAMP
)
Address Select
ADDR[4:1] Input Low
ADDR[4:1] Input High
ADDR[4:1] Pull-Up Resistance to V
DD
Alert Status Output
ALERT
Output Low Voltage
ALERT
Output High Leakage Current
LEDREF Input Linear Range
LEDREF Input Bias Current
I
2
C Port (See Note 5 for I
2
C Timing Diagram)
SDA and SCL Input Threshold Rising
SDA and SCL Input Threshold Falling
SDA and SCL Input Hysteresis
SDA and SCL Input Current
SDA Output Low Voltage
SCL Clock Operating Frequency
(Repeated) Start Condition Hold Time (t
HD_STA
)
Repeated Start Condition Set-Up Time (t
SU_STA
)
Stop Condition Setup Time (t
SU_STO
)
Data Hold Time Output (t
HD_DAT(O)
)
Data Hold Time Input (t
HD_DAT(I)
)
Data Set-Up Time (t
SU_DAT
)
SCL Clock Low Period (t
LOW
)
SCL Clock High Period (t
HIGH
)
Data Rise Time (t
r
)
Data Fall Time (t
f
)
Input Spike Suppression Pulse Width (t
SP
)
Bus Free Time (t
BUF
)
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ELECTRICAL CHARACTERISTICS
CONDITIONS
R
TCLK
= 28kΩ
MIN
0.83
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TYP
0.88
MAX
0.93
0.4
UNITS
V
V
V
MHz
ns
ns
1.5
2.5
100
100
T
RTL
= 10µs
2.3
µs
0.25V
DD
0.75V
DD
300
500
0.3
700
0.4
0.1
0
4
100
V
V
kΩ
V
µA
V
nA
V
I
ALERT
= 3mA
ALERT
= 5.5V
External LED Reference Voltage for Shorted LED Detection
0V ≤ LEDREF ≤ 4V
–100
0.7V
DD
0.25V
DD
0.05V
DD
–250
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V
V
nA
V
kHz
μs
µs
μs
SDA = SCL = 0V to 5.5V
I
SDA
= 3mA
250
0.4
400
0.6
0.6
0.6
0
0
100
1.3
0.6
20 + 0.1C
B
20 + 0.1C
B
300
300
50
1.3
900
ns
ns
ns
µs
μs
ns
ns
ns
µs
C
B
= Capacitance of One BUS Line (pF) (Note 4)
C
B
= Capacitance of One BUS Line (pF) (Note 4)
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39651fa
For more information
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LT3965/LT3965-1
ELECTRICAL CHARACTERISTICS
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LT3965E/LT3965E-1 is guaranteed to meet performance
specifications from the 0°C to 125°C junction temperature. Specifications
over the –40°C to 125°C operating junction temperature range are
assured by design, characterization and correlation with statistical process
controls. The LT3965I/LT3965I-1 is guaranteed over the full –40°C to
125°C operating junction temperature range. High junction temperatures
degrade operating lifetimes. Operating lifetime is derated at junction
temperatures greater than 125°C.
Note 3:
V
OTH
[1:0] and V
STH
[1:0] register bits are set by LT3965/LT3965-1
I
2
C commands. V
OTH
/V
STH
programmed by V
OTH[1:0]
/V
STH[1:0]
refer to
the open/shorted LED threshold between DRN and SRC of a channel. For
a channel, V
IN
> V
SRC
+ V
OTH
+ 2.5V is required for accurate open LED
detection.
Note 4:
Rise and fall times are measured at 30% and 70% levels.
Note 5:
I
2
C interface timing diagram.
SDA
t
SU,DAT
t
HD,DATO
t
HD,DATI
t
SU,STA
t
SP
t
HD,STA
t
SP
t
SU,STO
t
BUF
3965 TD
SCL
t
HD,STA
REPEATED START
CONDITION
REPEATED START
CONDITION
STOP
CONDITION
START
CONDITION
TYPICAL PERFORMANCE CHARACTERISTICS
V
DD
Quiescent Current
vs Temperature
1.8
V
DD
= 5V
2.8
2.6
2.4
ALL SWITCHES ARE ON
V
DD
, I
Q
(mA)
V
IN
, I
Q
(mA)
1.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3965 G01
T
A
= 25°C, unless otherwise noted.
EN/UVLO Threshold
vs Temperature
1.27
1.26
EN/UVLO THRESHOLD (V)
1.25
1.24
1.23
1.22
1.21
–50 –25
FALLING
RISING
V
IN
Quiescent Current
vs Temperature
V
IN
= 40V, LEDREF = 3V
V
OTH[1:0]
= V
STH[1:0]
= 11,
SWITCHES ARE ON
1.6
1.2
ALL SWITCHES ARE OFF
1.0
V
OTH[1:0]
= 11, V
STH[1:0]
= 00,
SWITCHES ARE OFF
V
OTH[1:0]
= V
STH[1:0]
= 00,
SWITCHES ARE OFF
0.8
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3965 G02
0
25 50 75 100 125 150
TEMPERATURE (°C)
3965 G03
39651fa
For more information
www.linear.com/LT3965
5
Microchip MCU
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