LT8391
60V Synchronous 4-Switch
Buck-Boost LED Controller
with Spread Spectrum
FEATURES DESCRIPTION
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4-Switch Single Inductor Architecture Allows V The LT 8391 is a synchronous 4-switch buck-boost LED
IN
Above, Below or Equal to V controller that regulates LED current from input voltage
OUT
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Synchronous Switching: Up to 98% Efciency above, below or equal to the output voltage. The propri-
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Proprietary Peak-Buck Peak-Boost Current Mode etary peak-buck peak-boost current mode control scheme
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Wide V Range: 4V to 60V allows adjustable and synchronizable 150kHz to 650kHz
IN
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Wide V Range: 0V to 60V (51V LED) fixed frequency operation, or internal 15% triangle spread
OUT
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3% LED Current Accuracy spectrum operation for low EMI. With 4V to 60V input, 0V
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2000:1 External and 128:1 Internal PWM Dimming to 60V output, and seamless low noise transitions between
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High Side PMOS PWM Switch Driver operation regions, the LT8391 is ideal for LED driver and
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Integrated Bootstrap Diodes battery charger applications in automotive, industrial and
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No Top MOSFET Refresh Noise in Buck or Boost battery-powered systems.
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Adjustable and Synchronizable: 150kHz to 650kHz
The LT8391 provides both internal (up to 128:1) and
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Flicker-Free Spread Spectrum for Low EMI
external (up to 2000:1) LED current PWM dimming with
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Open and Short LED Protection with Fault Reporting
a high side PMOS switch. Two CTRL pins provide flexible
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Available in 28-Lead TSSOP with Exposed Pad and
20:1 analog dimming with 3% LED current accuracy at
28-Lead QFN (4mm 5mm)
100mV full scale. Fault protection is provided to detect
an open or short LED condition, during which the LT8391
APPLICATIONS
retries, latches off, or keeps running.
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Automotive Head Lamps/Running Lamps All registered trademarks and trademarks are the property of their respective owners.
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High Power LED Lighting
TYPICAL APPLICATION
98% Efficient 50W (25V, 2A) Buck-Boost LED Driver Efficiency vs V
IN
100
V
IN
4.7F 10F
6V TO 55V 98
BOOST
33F
100V 50V
BUCK
63V 1M 96
x2 x2
499k
V
IN
94
EN/UVLO BST1
BUCK-BOOST
INTV
CC 0.05 92
221k 34.8k
TG1 0.1F 0.1F
4.7F
100k 90
SW1
88
10H
FAULT FAULT
0.004
LSP
V LSN 86
REF
LT8391
0.47F 84
CTRL2 BG1
100k
82
GND
ANALOG DIM CTRL1
5.1 80
25V
PWM DIM PWM
BG2 0 10 20 30 40 50 60
2A
RP
SW2
INPUT VOLTAGE (V)
LED
SYNC/SPRD
TG2
RT 8391 TA01b
BST2
V
C
FB
SS
V
OUT
100k 2.2k
ISP
400kHz
0.1F
ISN
10nF
PWMTG
8391 TA01a
8391fa
1
For more information www.linear.com/LT8391
EFFICIENCY (%)LT8391
ABSOLUTE MAXIMUM RATINGS (Note 1)
V , EN/UVLO, V , ISP, ISN ...................................60V Operating Junction Temperature Range (Notes 2, 3)
IN OUT
(ISP-ISN) .........................................................1V to 1V LT8391E ............................................. 40C to 125C
BST1, BST2 ...............................................................66V LT8391I .............................................. 40C to 125C
SW1, SW2, LSP, LSN .................................... 6V to 60V LT8391H ............................................ 40C to 150C
INTV , (BST1-SW1), (BST2-SW2) .............................6V Storage Temperature Range .................. 65C to 150C
CC
(BST1-LSP), (BST1-LSN) ............................................6V
FB, PWM, SYNC/SPRD, CTRL1, CTRL2, FAULT ...........6V
PIN CONFIGURATION
TOP VIEW
TOP VIEW
1 28 BG2
BG1
BST1 2 27 BST2
28 27 26 25 24 23
3 26 SW2
SW1
TG1 1 22 TG2
4 TG2
TG1 25
LSP 2 21 V
LSP 5 24 V
OUT OUT
6 PWMTG LSN
LSN 23 3 20 PWMTG
V 7 22 SYNC/SPRD 29
29 V 4 19 SYNC/SPRD
IN IN
GND GND
8 RT
INTV 21
CC INTV 5 18 RT
CC
EN/UVLO 9 20 V
C
EN/UVLO 6 17 V
C
10 19 FB
RP
RP 7 16 FB
PWM 11 18 SS
PWM 8 15
SS
12 17 FAULT
V
REF
9 10 11 12 13 14
CTRL1 13 16 CTRL2
14 15 ISN
ISP
FE PACKAGE
UFD PACKAGE
28-LEAD PLASTIC TSSOP
28-LEAD (4mm 5mm) PLASTIC QFN
= 30C/W, = 5C/W
JA JC
= 34C/W, = 3.4C/W
JA JC
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
(