Datasheet LT8642S (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 18V, 10A Synchronous Step-Down Silent Switcher 2 |
| Pages / Page | 26 / 1 — FEATURES. DESCRIPTION. Silent Switcher. 2 Architecture. Ultralow EMI … |
| File Format / Size | PDF / 1.4 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Silent Switcher. 2 Architecture. Ultralow EMI Emissions On Any PCB. Eliminates PCB Layout Sensitivity
Model Line for this Datasheet
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LT8642S 18V, 10A Synchronous Step-Down Silent Switcher 2
FEATURES DESCRIPTION
n
Silent Switcher
®
2 Architecture
The LT®8642S synchronous step-down regulator fea- n
Ultralow EMI Emissions On Any PCB
tures second generation Silent Switcher architecture n
Eliminates PCB Layout Sensitivity
designed to minimize EMI emissions while delivering n
Internal Bypass Capacitors Reduce Radiated EMI
high efficiency at high switching frequencies. This n
Optional Spread Spectrum Modulation
includes the integration of bypass capacitors to opti- n
High Efficiency at High Frequency
mize all the fast current loops inside and make it easy n
Up to 96% Efficiency at 1MHz, 12VIN to 3.3VOUT
to achieve advertised EMI performance by eliminating n
Up to 95% Efficiency at 2MHz, 12VIN to 3.3VOUT
layout sensitivity. This performance makes the LT8642S n
Wide Input Voltage Range: 2.8V to 18V
ideal for noise sensitive applications and environments. n
10A Output Current
The fast, clean, low-overshoot switching edges enable n
External Compensation: Fast Transient Response
high efficiency operation even at high switching frequen-
and Current Sharing
cies, leading to a small overall solution size. Peak current n Low Quiescent Current Burst Mode® Operation mode control with a 25ns minimum on-time al ows high n 240µA IQ Regulating 12VIN to 1.2VOUT step down ratios even at high switching frequencies. n Output Ripple < 10mVP-P External compensation via the VC pin al ows for fast n Fast Minimum Switch On-Time: 25ns transient response at high switching frequencies. The n Low Dropout Under All Conditions: 50mV at 1A VC pin also enables current sharing and a CLKOUT pin n Forced Continuous Mode enables synchronizing other regulators to the LT8642S. n Adjustable and Synchronizable: 200kHz to 3MHz n Output Soft-Start and Power Good Burst Mode operation enables low standby current con- n Small 24-Lead 4mm × 4mm LQFN Package sumption, forced continuous mode can control frequency harmonics across the entire output load range, or spread
APPLICATIONS
spectrum operation can further reduce EMI emissions. n Server Power Applications Soft-start and tracking functionality is accessed via the n General Purpose Step-Down SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin. All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents 8823345.
TYPICAL APPLICATION 12VIN to 1.2VOUT Efficiency
100 3.2
1.2V 10A Step-Down Converter
VBIAS = 3.3V 95 2.8 0.28µH VOUT VIN V 90 2.4 IN SW 1.2V 2.8V TO 18V POWER LOSS (W) 10A 10µF EN/UV 85 2.0 11k EFFICIENCY V LT8642S C 47pF 100k 80 1.6 RT FB 220µF 150pF ×2 75 1.2 EFFICIENCY (%) 17.8k GND 100k POWER LOSS 70 0.8 8642S TA01a f 1MHz, L = 0.56µH SW = 2MHz 65 2MHz, L = 0.28µH 0.4 3MHz, L = 0.28µH 60 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT (A) 8642S TA01b Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Applications Related Parts
FEATURES DESCRIPTION
n
Silent Switcher
®
2 Architecture
The LT®8642S synchronous step-down regulator fea- n
Ultralow EMI Emissions On Any PCB
tures second generation Silent Switcher architecture n
Eliminates PCB Layout Sensitivity
designed to minimize EMI emissions while delivering n
Internal Bypass Capacitors Reduce Radiated EMI
high efficiency at high switching frequencies. This n
Optional Spread Spectrum Modulation
includes the integration of bypass capacitors to opti- n
High Efficiency at High Frequency
mize all the fast current loops inside and make it easy n
Up to 96% Efficiency at 1MHz, 12VIN to 3.3VOUT
to achieve advertised EMI performance by eliminating n
Up to 95% Efficiency at 2MHz, 12VIN to 3.3VOUT
layout sensitivity. This performance makes the LT8642S n
Wide Input Voltage Range: 2.8V to 18V
ideal for noise sensitive applications and environments. n
10A Output Current
The fast, clean, low-overshoot switching edges enable n
External Compensation: Fast Transient Response
high efficiency operation even at high switching frequen-
and Current Sharing
cies, leading to a small overall solution size. Peak current n Low Quiescent Current Burst Mode® Operation mode control with a 25ns minimum on-time al ows high n 240µA IQ Regulating 12VIN to 1.2VOUT step down ratios even at high switching frequencies. n Output Ripple < 10mVP-P External compensation via the VC pin al ows for fast n Fast Minimum Switch On-Time: 25ns transient response at high switching frequencies. The n Low Dropout Under All Conditions: 50mV at 1A VC pin also enables current sharing and a CLKOUT pin n Forced Continuous Mode enables synchronizing other regulators to the LT8642S. n Adjustable and Synchronizable: 200kHz to 3MHz n Output Soft-Start and Power Good Burst Mode operation enables low standby current con- n Small 24-Lead 4mm × 4mm LQFN Package sumption, forced continuous mode can control frequency harmonics across the entire output load range, or spread
APPLICATIONS
spectrum operation can further reduce EMI emissions. n Server Power Applications Soft-start and tracking functionality is accessed via the n General Purpose Step-Down SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin. All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents 8823345.
TYPICAL APPLICATION 12VIN to 1.2VOUT Efficiency
100 3.2
1.2V 10A Step-Down Converter
VBIAS = 3.3V 95 2.8 0.28µH VOUT VIN V 90 2.4 IN SW 1.2V 2.8V TO 18V POWER LOSS (W) 10A 10µF EN/UV 85 2.0 11k EFFICIENCY V LT8642S C 47pF 100k 80 1.6 RT FB 220µF 150pF ×2 75 1.2 EFFICIENCY (%) 17.8k GND 100k POWER LOSS 70 0.8 8642S TA01a f 1MHz, L = 0.56µH SW = 2MHz 65 2MHz, L = 0.28µH 0.4 3MHz, L = 0.28µH 60 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT (A) 8642S TA01b Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Applications Related Parts
