Datasheet LT8391 (Linear Technology)
| Manufacturer | Linear Technology |
| Description | 60V Synchronous 4-Switch Buck-Boost LED Controller with Spread Spectrum |
| Pages / Page | 34 / 1 — 4-Switch Single Inductor Architecture Allows VIN. Above, Below or Equal … |
| Revision | A |
| File Format / Size | PDF / 466 Kb |
| Document Language | English |
4-Switch Single Inductor Architecture Allows VIN. Above, Below or Equal to VOUT
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LT8391 60V Synchronous 4-Switch Buck-Boost LED Controller with Spread Spectrum FEATURES DESCRIPTION n
4-Switch Single Inductor Architecture Allows VIN
The LT®8391 is a synchronous 4-switch buck-boost LED
Above, Below or Equal to VOUT
controller that regulates LED current from input voltage n
Synchronous Switching: Up to 98% Efficiency
above, below or equal to the output voltage. The propri- n
Proprietary Peak-Buck Peak-Boost Current Mode
etary peak-buck peak-boost current mode control scheme n
Wide VIN Range: 4V to 60V
allows adjustable and synchronizable 150kHz to 650kHz n
Wide VOUT Range: 0V to 60V (51V LED)
fixed frequency operation, or internal ±15% triangle spread n
±3% LED Current Accuracy
spectrum operation for low EMI. With 4V to 60V input, 0V n 2000:1 External and 128:1 Internal PWM Dimming to 60V output, and seamless low noise transitions between n High Side PMOS PWM Switch Driver operation regions, the LT8391 is ideal for LED driver and n Integrated Bootstrap Diodes battery charger applications in automotive, industrial and n No Top MOSFET Refresh Noise in Buck or Boost battery-powered systems. n Adjustable and Synchronizable: 150kHz to 650kHz The LT8391 provides both internal (up to 128:1) and n Flicker-Free Spread Spectrum for Low EMI external (up to 2000:1) LED current PWM dimming with n Open and Short LED Protection with Fault Reporting a high side PMOS switch. Two CTRL pins provide flexible n 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. n Automotive Head Lamps/Running Lamps All registered trademarks and trademarks are the property of their respective owners. n High Power LED Lighting TYPICAL APPLICATION
98% Efficient 50W (25V, 2A) Buck-Boost LED Driver Efficiency vs VIN
V 100 IN 6V TO 55V 4.7µF 10µF 33µF 98 100V 50V BOOST 63V BUCK x2 96 499k x2 1M VIN EN/UVLO BST1 94 INTV BUCK-BOOST CC 0.05Ω 92 221k TG1 0.1µF 0.1µF 34.8k 4.7µF 100k 90 SW1 FAULT FAULT 88 0.004Ω 10µH LSP EFFICIENCY (%) VREF LSN 86 0.47µF LT8391 84 100k CTRL2 BG1 82 ANALOG DIM CTRL1 GND 5.1Ω PWM DIM PWM 25V 80 BG2 0 10 20 30 40 50 60 RP 2A SW2 SYNC/SPRD LED INPUT VOLTAGE (V) TG2 RT BST2 8391 TA01b VC FB SS 100k 2.2k VOUT 400kHz 0.1µF ISP 10nF ISN PWMTG 8391 TA01a 8391fa For more information www.linear.com/LT8391 1
4-Switch Single Inductor Architecture Allows VIN
The LT®8391 is a synchronous 4-switch buck-boost LED
Above, Below or Equal to VOUT
controller that regulates LED current from input voltage n
Synchronous Switching: Up to 98% Efficiency
above, below or equal to the output voltage. The propri- n
Proprietary Peak-Buck Peak-Boost Current Mode
etary peak-buck peak-boost current mode control scheme n
Wide VIN Range: 4V to 60V
allows adjustable and synchronizable 150kHz to 650kHz n
Wide VOUT Range: 0V to 60V (51V LED)
fixed frequency operation, or internal ±15% triangle spread n
±3% LED Current Accuracy
spectrum operation for low EMI. With 4V to 60V input, 0V n 2000:1 External and 128:1 Internal PWM Dimming to 60V output, and seamless low noise transitions between n High Side PMOS PWM Switch Driver operation regions, the LT8391 is ideal for LED driver and n Integrated Bootstrap Diodes battery charger applications in automotive, industrial and n No Top MOSFET Refresh Noise in Buck or Boost battery-powered systems. n Adjustable and Synchronizable: 150kHz to 650kHz The LT8391 provides both internal (up to 128:1) and n Flicker-Free Spread Spectrum for Low EMI external (up to 2000:1) LED current PWM dimming with n Open and Short LED Protection with Fault Reporting a high side PMOS switch. Two CTRL pins provide flexible n 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. n Automotive Head Lamps/Running Lamps All registered trademarks and trademarks are the property of their respective owners. n High Power LED Lighting TYPICAL APPLICATION
98% Efficient 50W (25V, 2A) Buck-Boost LED Driver Efficiency vs VIN
V 100 IN 6V TO 55V 4.7µF 10µF 33µF 98 100V 50V BOOST 63V BUCK x2 96 499k x2 1M VIN EN/UVLO BST1 94 INTV BUCK-BOOST CC 0.05Ω 92 221k TG1 0.1µF 0.1µF 34.8k 4.7µF 100k 90 SW1 FAULT FAULT 88 0.004Ω 10µH LSP EFFICIENCY (%) VREF LSN 86 0.47µF LT8391 84 100k CTRL2 BG1 82 ANALOG DIM CTRL1 GND 5.1Ω PWM DIM PWM 25V 80 BG2 0 10 20 30 40 50 60 RP 2A SW2 SYNC/SPRD LED INPUT VOLTAGE (V) TG2 RT BST2 8391 TA01b VC FB SS 100k 2.2k VOUT 400kHz 0.1µF ISP 10nF ISN PWMTG 8391 TA01a 8391fa For more information www.linear.com/LT8391 1
