Datasheet LT8640, LT8640-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 42V, 5A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current |
| Pages / Page | 30 / 1 — FEATURES. DESCRIPTION. Silent Switcher. Architecture. Ultralow EMI/EMC … |
| Revision | C |
| File Format / Size | PDF / 1.9 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Silent Switcher. Architecture. Ultralow EMI/EMC Emissions. Spread Spectrum Frequency Modulation
Model Line for this Datasheet
Text Version of Document
LT8640/LT8640-1 42V, 5A Synchronous Step-Down Silent Switcher with 2.5µA Quiescent Current
FEATURES DESCRIPTION
n
Silent Switcher
®
Architecture
The LT®8640/LT8640-1 step-down regulator features Si- n
Ultralow EMI/EMC Emissions
lent Switcher architecture designed to minimize EMI/EMC n
Spread Spectrum Frequency Modulation
emissions while delivering high efficiency at frequencies up n
High Efficiency at High Frequency
to 3MHz. An ultralow 2.5µA quiescent current—with the n
Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
output in full regulation—enables applications requiring n
Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
highest efficiency at very small load currents. n
Wide Input Voltage Range: 3.4V to 42V
The LT8640/LT8640-1 al ows high V n IN to low VOUT conversion
5A Maximum Continuous Output, 7A Peak
at high frequency with a fast minimum top switch on-time of
Transient Output
30ns. The SYNC/MODE pin selects between Burst Mode n
Ultralow Quiescent Current Burst Mode
®
Operation
operation, spread spectrum mode, synchronization to n
2.5µA IQ Regulating 12VIN to 3.3VOUT
an external clock, and either pulse-skipping (LT8640) or n
Output Ripple < 10mVP-P
forced continuous mode (LT8640-1). n
Fast Minimum Switch On-Time: 30ns
n
Low Dropout Under All Conditions: 100mV at 1A SYNC/ INTERNAL
n
PACKAGE MODE ≠ 0 VC COMP H-GRADE CLKOUT CAPS Forced Continuous Mode (LT8640-1 Only)
n Safely Tolerates Inductor Saturation in Overload LT8640 QFN Pulse- Skipping Internal Yes No No n Adjustable and Synchronizable: 200kHz to 3MHz LT8640-1 QFN FCM Internal Yes No No n Peak Current Mode Operation LT8640S LQFN FCM Internal No Yes Yes n Output Soft-Start and Tracking LT8643S LQFN FCM External No Yes Yes n Small 18-Lead 3mm × 4mm QFN and Side Wettable QFN LT8640S-2 LQFN FCM Internal Yes Yes No LT8643S-2 LQFN FCM External Yes Yes No
APPLICATIONS
All registered trademarks and trademarks are the property of their respective owners. Protected n Automotive and Industrial Supplies by U.S. patents, including 8823345. n General Purpose Step-Down n GSM Power Supplies
TYPICAL APPLICATION 12VIN to 5VOUT Efficiency 5V 5A Step-Down Converter
100 3.00 V 95 2.63 IN 5.5V TO 42V 4.7µF EN/UV 90 EFFICIENCY 2.25 V POWER LOSS (W) IN1 VIN2 1µF 1µF 85 1.88 GND1 GND2 LT8640/ 80 1.50 PG LT8640-1 BST 0.1µF 3.3µH VOUT 10nF 75 1.13 SYNC/MODE SW 5V EFFICIENCY (%) TR/SS BIAS 5A POWER LOSS 70 0.75 1µF 4.7pF 1M 1MHz, L = 3.3µH INTV 65 0.38 CC FB 47µF 2MHz, L = 2.2µH 41.2k 3MHz, L = 1µH RT GND 243k 60 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 LOAD CURRENT (A) fSW = 1MHz 8640 TA01a 8640 TA01b Rev.C Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Silent Switcher
®
Architecture
The LT®8640/LT8640-1 step-down regulator features Si- n
Ultralow EMI/EMC Emissions
lent Switcher architecture designed to minimize EMI/EMC n
Spread Spectrum Frequency Modulation
emissions while delivering high efficiency at frequencies up n
High Efficiency at High Frequency
to 3MHz. An ultralow 2.5µA quiescent current—with the n
Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
output in full regulation—enables applications requiring n
Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
highest efficiency at very small load currents. n
Wide Input Voltage Range: 3.4V to 42V
The LT8640/LT8640-1 al ows high V n IN to low VOUT conversion
5A Maximum Continuous Output, 7A Peak
at high frequency with a fast minimum top switch on-time of
Transient Output
30ns. The SYNC/MODE pin selects between Burst Mode n
Ultralow Quiescent Current Burst Mode
®
Operation
operation, spread spectrum mode, synchronization to n
2.5µA IQ Regulating 12VIN to 3.3VOUT
an external clock, and either pulse-skipping (LT8640) or n
Output Ripple < 10mVP-P
forced continuous mode (LT8640-1). n
Fast Minimum Switch On-Time: 30ns
n
Low Dropout Under All Conditions: 100mV at 1A SYNC/ INTERNAL
n
PACKAGE MODE ≠ 0 VC COMP H-GRADE CLKOUT CAPS Forced Continuous Mode (LT8640-1 Only)
n Safely Tolerates Inductor Saturation in Overload LT8640 QFN Pulse- Skipping Internal Yes No No n Adjustable and Synchronizable: 200kHz to 3MHz LT8640-1 QFN FCM Internal Yes No No n Peak Current Mode Operation LT8640S LQFN FCM Internal No Yes Yes n Output Soft-Start and Tracking LT8643S LQFN FCM External No Yes Yes n Small 18-Lead 3mm × 4mm QFN and Side Wettable QFN LT8640S-2 LQFN FCM Internal Yes Yes No LT8643S-2 LQFN FCM External Yes Yes No
APPLICATIONS
All registered trademarks and trademarks are the property of their respective owners. Protected n Automotive and Industrial Supplies by U.S. patents, including 8823345. n General Purpose Step-Down n GSM Power Supplies
TYPICAL APPLICATION 12VIN to 5VOUT Efficiency 5V 5A Step-Down Converter
100 3.00 V 95 2.63 IN 5.5V TO 42V 4.7µF EN/UV 90 EFFICIENCY 2.25 V POWER LOSS (W) IN1 VIN2 1µF 1µF 85 1.88 GND1 GND2 LT8640/ 80 1.50 PG LT8640-1 BST 0.1µF 3.3µH VOUT 10nF 75 1.13 SYNC/MODE SW 5V EFFICIENCY (%) TR/SS BIAS 5A POWER LOSS 70 0.75 1µF 4.7pF 1M 1MHz, L = 3.3µH INTV 65 0.38 CC FB 47µF 2MHz, L = 2.2µH 41.2k 3MHz, L = 1µH RT GND 243k 60 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 LOAD CURRENT (A) fSW = 1MHz 8640 TA01a 8640 TA01b Rev.C Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
