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PDF LT3797 Data sheet ( Hoja de datos )
| Número de pieza | LT3797 | |
| Descripción | Triple Output LED Driver Controller | |
| Fabricantes | Linear | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT3797 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
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FEATURES
n Three Independent LED Driver Channels
n Wide Input Voltage Range: 2.5V to 40V
n VIN Transient Ride-Through Up to 60V
n Rail-to-Rail LED Current Sense: 0V to 100V
n 3000:1 PWM Dimming
n TG Drivers for PMOS LED Disconnection
n Operates in Boost, Buck Mode, Buck-Boost Mode,
SEPIC or Flyback Topology
n Open-LED Protection
n Short-Circuit Protected Boost Capable
n Fault Flags for Independent Channels
n Programmable VIN Undervoltage and Overvoltage
Lockout
n Adjustable Switching Frequency: 100kHz to 1MHz
n Synchronizeable to an External Clock
n CTRL Pins Provide Analog Dimming
n Programmable Soft-Start
n 52-Lead QFN Package
APPLICATIONS
n Automotive and Industrial Lighting
n RGB Lighting
n Billboards and Large Displays
LT3797
Triple Output LED Driver
Controller
DESCRIPTION
The LT®3797 is a triple output DC/DC controller designed
to drive three strings of LEDs. The fixed frequency, current
mode architecture results in stable operation over a wide
range of supply and output voltages. The LT3797 includes
an integrated DC/DC converter to produce a regulated 7.5V
supply for the N-channel MOSFET gate drivers of the three
channels. This high efficiency converter enables the part to
operate from a wide input voltage range from 2.5V to 40V.
The LT3797 is designed so that each converter can use the
most suitable configuration to drive its LED load, whether
step-up, step-down or a combination. Two key features
enable this flexibility: first the LT3797 can sense output
current at the high side of the LED string; and second, the
voltage feedback pin, FBH, is referred to the ISP current
sensing input. The CTRL inputs provide output current
analog dimming capability. The TG drivers level shift the
PWM signals to drive the gates of external LED-disconnect
P-channel MOSFETs, allowing high PWM dimming range,
and providing LED overcurrent protection and short-circuit
protected boost capability.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 7199560, 7321203, 7746300.
TYPICAL APPLICATION
VIN
2.5V TO 40V
(60V TRANSIENT,
41V INTERNAL
OVLO PROTECTION)
4.7µF
×3
Triple Boost LED Driver
10µH
ISP1
250mΩ
ISN1
4.7µF
100V
×2
10µH
ISP2
250mΩ
ISN2
4.7µF
100V
×2
10µH
ISP3
250mΩ
ISN3
4.7µF
100V
×2
0.1µF 8mΩ
1A
50V 0.1µF 8mΩ
1A
50V 0.1µF 8mΩ
1A
50V
GATE1 SENSEP1 SENSEN1 TG1
VIN
1µF 47.5k
GATE2 SENSEP2 SENSEN2 TG2
LT3797
GATE3 SENSEP3 SENSEN3 TG3 ISN1-3
ISP1-3
20.5k
EN/UVLO
FBH1-3
49.9k
OVLO VREF CTRL1-3 PWM1-3 RT
SYNC SS1-3 FLT1-3 SW1 SW2 BOOST INTVCC GND
VC1-3
VIN 487k 75k
48.7k
300kHz
0.1µF
47µH 10µF
0.1µF
4.7k
10nF
1M
3797 TA01
For more information www.linear.com/LT3797
3797f
1
1 page  
LT3797
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature
PWM3 = 2V;
SraEnNgSeE,No1th,eSrEwNisSeENsp2e, cSiEfiNcaStEioNn3s=a0reV,autnTlAes=s2o5t°hCe.rwVIiNse=n2o4tVe;dE. N/UVLO
=
24V;
CTRL1,
CTRL2,
CTRL3,
PWM1,
PWM2,
PARAMETER
PWM1, PWM2, PWM3 Input High Voltage
PWM1, PWM2, PWM3 Input Low Voltage
PWM1, PWM2, PWM3 Resistance to GND
FLT1, FLT2, FLT3 Output Low
SS1, SS2, SS3 Sourcing Current
SS1, SS2, SS3 Sinking Current
SS1, SS2, SS3 Soft-Start Reset Threshold
SS1, SS2, SS3 Fault Reset Threshold
NMOS Gate Drivers
GATE1, GATE2, GATE3 Output Rise Time (tr)
GATE1, GATE2, GATE3 Output Fall Time (tf)
Gate Output Low (VOL)
Gate Output High (VOH)
PMOS Gate Drivers
TG1, TG2, TG3 Turn-On Time
TG1, TG2, TG3 Turn-Off Time
PMOS Gate On Voltage
(ISP1-TG1, ISP2-TG2, ISP3-TG3)
PMOS Gate Off Voltage
(ISP1-TG1, ISP2-TG2, ISP3-TG3)
CONDITIONS
IFLT =1mA
SS1, SS2, SS3 = 1V, Current Out of Pin
SS1, SS2, SS3 = 1V, OVLO =1.3V
Falling, Measured on SS1, SS2, SS3
Hysteresis
Measured on SS1, SS2, SS3
CGATE = 3300pF (Note 5)
CGATE = 3300pF (Note 5)
CTG = 1000pF (Note 6)
CTG = 1000pF (Note 6)
MIN
l
l 0.6
TYP
1.1
0.9
200
28
2.8
160
30
1.7
25
25
INTVCC –
0.05
200
70
6.5
MAX UNITS
1.4 V
V
kΩ
300 mV
µA
µA
mV
mV
V
ns
ns
0.1 V
V
ns
ns
V
0.3 V
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: Do not apply a positive or negative voltage or current source
to SW1, SW2, GATE1, GATE2, GATE3, TG1, TG2, TG3 pins, otherwise
permanent damage may occur.
Note 3: The LT3797E 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 LT3797I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 4: FBH(REG) denotes the regulation voltage (|ISP-FBH|) of the
corresponding FBH pin.
Note 5: Rise and fall times are measured at 10% and 90% levels.
Note 6: Gate turn-on/turn-off time is measured from 50% level of PWM
voltage to 90% level of gate on/off voltage.
For more information www.linear.com/LT3797
3797f
5
5 Page 
BLOCK DIAGRAM
R6 R5
– VFB1 +
RSW_SEN
LT3797
VOUT
D1
LED
M2 STRING
COUT
L1
VIN
CVIN2
RC
CC
CSS
VIN
R1
R2
17 16 15
FBH1 ISP1
ISN1
14
TG1
4
PWM1
PWM1 SS1 SHDN ISP1
G4
ISP1-6.5V
|ISP1 – FBH1|
A6
x4 + 0.2V
A7
OVI
PWMON
19 VC1 S1
8 CTRL1
1.2V
1.25V
20 SS1
150mV
3V 1.3V
12µA
–
A16
OVFB
+
++–
–
A8
A9
1A28µ+A=AAT8–
1A29µ+A=AAT9–
+
+ A11
–
CTRL_ON
Q4
CH1 SOFT-START
AND
FAULT PROTECTION
PWMON
CH1 FLT
+ A12
–
3V
25µA
S2
VISENSE1
1mA 2.5µA
G3 CTRL_ON
PROTECTION
SR1 INTVCC
G1 R O
S
G2 GATE1 23
SET
A13 +
–
A14 +
–
110mV
SENSEP1 22
SENSEN1 21
REPLICATED FOR EACH CHANNEL
1 FLT1
2 FLT2
3 FLT3
Q1
Q2
Q3
51 EN/UVLO
1.22V
IS1
2µA
VIN
OVLO
SHDN
FAULT
PROTECTION
AND REPORT
CH1 FLT
CH2 FLT
CH3 FLT
INTVCC A3
UVLO
41V
VIN
165°C THERMAL
SHUTDOWN
5.7V
INTVCC SET
+ A1
–
2V
+–
A2
–+
A4
1.05V
+ A5
–
1.25V
OVLO
52
VREF
7
R4 R3
VIN
RAMP
RAMP
GENERATOR
50kHz TO 1MHz
OSCILLATOR
SHDN SET
INTEGRATED
POWER
SUPPLY
VIN 50
BOOST 48
SW1 49
SW2 47
INTVCC
45, 46
GND 53
RT
11
SYNC
12
RT
SHARED COMPONENTS
3797 F01
M1
CSEN RSW_SEN
VIN
CVIN1
CBOOST
LPWR
CVCC
Figure 1. LT3797 Block Diagram Working in Boost Configuration (for Simplicity, Only Channel 1 Is Shown)
For more information www.linear.com/LT3797
3797f
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LT3797.PDF ] | |
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