Datasheet LT8640S-2, LT8643S-2 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 42V, 6A Synchronous Step-Down Silent Switcher with 2.5µA Quiescent Current |
| Pages / Page | 30 / 1 — FEATURES. DESCRIPTION. Silent Switcher. Architecture. Ultralow EMI … |
| File Format / Size | PDF / 2.6 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Silent Switcher. Architecture. Ultralow EMI Emissions. Optional Spread Spectrum Modulation
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LT8640S-2/LT8643S-2 42V, 6A Synchronous Step-Down Silent Switcher with 2.5µA Quiescent Current
FEATURES DESCRIPTION
n
Silent Switcher
®
Architecture
The LT®8640S-2/LT8643S-2 synchronous step-down n
Ultralow EMI Emissions
regulator features Silent Switcher architecture designed n
Optional Spread Spectrum Modulation
to minimize EMI emissions while delivering high efficiency n
High Efficiency at High Frequency
at high switching frequencies. Peak current mode control n
Up to 96% Efficiency at 1MHz, 12V
with a 30ns minimum on-time allows high step-down
IN to 5VOUT
n
Up to 95% Efficiency at 2MHz, 12V
ratios even at high switching frequencies.The LT8643S-2
IN to 5VOUT
n has external compensation to enable current sharing and
Wide Input Voltage Range: 3.4V to 42V
n fast transient response at high switching frequencies.
6A Maximum Continuous, 7A Peak Output
n
Ultralow Quiescent Current Burst Mode
®
Operation
Burst Mode operation enables ultralow standby current n
2.5µA IQ Regulating 12VIN to 3.3VOUT (LT8640S-2)
consumption, forced continuous mode can control n
Output Ripple < 10mVP-P
frequency harmonics across the entire output load range, n
External Compensation: Fast Transient Response
or spread spectrum operation can further reduce EMI
and Current Sharing (LT8643S-2)
emissions. n Fast Minimum Switch On-Time: 30ns
SYNC/ INTERNAL
n Low Dropout Under All Conditions: 100mV at 1A
PACKAGE MODE ≠ 0 VC COMP H-GRADE CLKOUT CAPS
n Forced Continuous Mode LT8640 QFN Pulse- n Adjustable and Synchronizable: 200kHz to 3MHz Skipping Internal Yes No No n Output Soft-Start and Tracking LT8640-1 QFN FCM Internal Yes No No n Small 24-Lead 4mm × 4mm LQFN Package LT8640S LQFN FCM Internal No Yes Yes LT8643S LQFN FCM External No Yes Yes LT8640S-2 LQFN FCM Internal Yes Yes No
APPLICATIONS
LT8643S-2 LQFN FCM External Yes Yes No n Automotive and Industrial Supplies n General Purpose Step-Down All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345.
TYPICAL APPLICATION 5V, 6A Step-Down Converter 12VIN to 5VOUT Efficiency
100 3.2 VIN 5.7V TO 42V 95 2.8 4.7µF V EN/UV IN VIN 90 EFFICIENCY 2.4 1µF 1µF POWER LOSS (W) GND GND 85 2.0 LT8640S-2 BST 80 1.6 0.1µF 3.3µH VOUT SW 5V 75 1.2 EFFICIENCY (%) 6A POWER LOSS BIAS 70 0.8 INTVCC 10pF 1M 1MHz, L = 3.3µH 1µF 65 2MHz, L = 2.2µH 0.4 RT FB 100µF 3MHz, L = 1µH 60 0 41.2k GND 243k 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 LOAD CURRENT (A) 8640s2 TA01b f 8640s2 TA01a SW = 1MHz Rev 0 Document Feedback For more information www.analog.com 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION E LECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATIONS RELATED PARTS
FEATURES DESCRIPTION
n
Silent Switcher
®
Architecture
The LT®8640S-2/LT8643S-2 synchronous step-down n
Ultralow EMI Emissions
regulator features Silent Switcher architecture designed n
Optional Spread Spectrum Modulation
to minimize EMI emissions while delivering high efficiency n
High Efficiency at High Frequency
at high switching frequencies. Peak current mode control n
Up to 96% Efficiency at 1MHz, 12V
with a 30ns minimum on-time allows high step-down
IN to 5VOUT
n
Up to 95% Efficiency at 2MHz, 12V
ratios even at high switching frequencies.The LT8643S-2
IN to 5VOUT
n has external compensation to enable current sharing and
Wide Input Voltage Range: 3.4V to 42V
n fast transient response at high switching frequencies.
6A Maximum Continuous, 7A Peak Output
n
Ultralow Quiescent Current Burst Mode
®
Operation
Burst Mode operation enables ultralow standby current n
2.5µA IQ Regulating 12VIN to 3.3VOUT (LT8640S-2)
consumption, forced continuous mode can control n
Output Ripple < 10mVP-P
frequency harmonics across the entire output load range, n
External Compensation: Fast Transient Response
or spread spectrum operation can further reduce EMI
and Current Sharing (LT8643S-2)
emissions. n Fast Minimum Switch On-Time: 30ns
SYNC/ INTERNAL
n Low Dropout Under All Conditions: 100mV at 1A
PACKAGE MODE ≠ 0 VC COMP H-GRADE CLKOUT CAPS
n Forced Continuous Mode LT8640 QFN Pulse- n Adjustable and Synchronizable: 200kHz to 3MHz Skipping Internal Yes No No n Output Soft-Start and Tracking LT8640-1 QFN FCM Internal Yes No No n Small 24-Lead 4mm × 4mm LQFN Package LT8640S LQFN FCM Internal No Yes Yes LT8643S LQFN FCM External No Yes Yes LT8640S-2 LQFN FCM Internal Yes Yes No
APPLICATIONS
LT8643S-2 LQFN FCM External Yes Yes No n Automotive and Industrial Supplies n General Purpose Step-Down All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345.
TYPICAL APPLICATION 5V, 6A Step-Down Converter 12VIN to 5VOUT Efficiency
100 3.2 VIN 5.7V TO 42V 95 2.8 4.7µF V EN/UV IN VIN 90 EFFICIENCY 2.4 1µF 1µF POWER LOSS (W) GND GND 85 2.0 LT8640S-2 BST 80 1.6 0.1µF 3.3µH VOUT SW 5V 75 1.2 EFFICIENCY (%) 6A POWER LOSS BIAS 70 0.8 INTVCC 10pF 1M 1MHz, L = 3.3µH 1µF 65 2MHz, L = 2.2µH 0.4 RT FB 100µF 3MHz, L = 1µH 60 0 41.2k GND 243k 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 LOAD CURRENT (A) 8640s2 TA01b f 8640s2 TA01a SW = 1MHz Rev 0 Document Feedback For more information www.analog.com 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION E LECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATIONS RELATED PARTS
