Datasheet LT8645S-2 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 65V, 8A Synchronous Step-Down Silent Switcher with 2.5µA Quiescent Current |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTION. Silent Switcher® Architecture. Ultralow EMI … |
| File Format / Size | PDF / 2.1 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Silent Switcher® Architecture. Ultralow EMI Emissions. Optional Spread Spectrum Modulation
Text Version of Document
LT8645S-2 65V, 8A Synchronous Step-Down Silent Switcher with 2.5µA Quiescent Current
FEATURES DESCRIPTION
n
Silent Switcher® Architecture
The LT®8645S-2 synchronous step-down regulator features n
Ultralow EMI Emissions
Silent Switcher architecture designed to minimize EMI n
Optional Spread Spectrum Modulation
emissions while delivering high efficiency at high switch- n
High Efficiency at High Frequency
ing frequencies. This performance makes the LT8645S-2 n
Up to 95% Efficiency at 1MHz, 12VIN to 5VOUT
ideal for noise sensitive applications and environments. n
Up to 94% Efficiency at 2MHz, 12VIN to 5VOUT
The fast, clean, low-overshoot switching edges enable n
Wide Input Voltage Range: 3.4V to 65V
high efficiency operation even at high switching frequen- n
Ultralow Quiescent Current Burst Mode Operation
cies, leading to a small overall solution size. Peak current n
2.5μA IQ Regulating 12VIN to 3.3VOUT
mode control with a 40ns minimum on-time allows high n
Output Ripple < 10mVP-P
step-down ratios even at high switching frequencies. n Fast Minimum Switch On-Time: 40ns n Low Dropout Under All Conditions: 60mV at 1A Burst Mode® operation enables ultralow standby current n Adjustable and Synchronizable: 200kHz to 2.2MHz consumption, pulse-skipping mode allows full switching n Peak Current Mode Operation frequency at lower output loads, or spread spectrum n Output Soft-Start and Tracking operation can further reduce EMI emissions. n Small 32-Lead 6mm × 4mm LQFN Package
INTERNAL CAPS V
n
C COMP 150ºC GRADE
AEC-Q100 Qualification In Progress LT8645S* Yes Internal No LT8646S* Yes External No
APPLICATIONS
LT8645S-2 No Internal Yes n Automotive and Industrial Supplies *See LT8645S/LT8646S Datasheet n General Purpose Step-Down n GSM Power Supplies All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345.
TYPICAL APPLICATION 5V 8A Step-Down Converter 12VIN to 5VOUT Efficiency
VIN 5.5V TO 65V 100 4.0 4.7µF V EN/UV 3.5 IN VIN 95 0.47µF 0.47µF 90 EFFICIENCY 3.0 GND GND POWER LOSS (W) LT8645S-2 85 2.5 BST 0.1µF 2.2µH VOUT 80 2.0 SW 5V BIAS 8A 75 1.5 EFFICIENCY (%) POWER LOSS INTVCC 2.2pF 1M 70 1.0 1µF RT FB 100µF 65 1MHz, L = 2.2µH 0.5 41.2k GND 243k 2MHz, L = 1µH 60 0 1 2 3 4 5 6 7 8 f LOAD CURRENT (A) 8645S-2 TA01a SW = 1MHz 8645S-2 TA01b Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Applications Related Parts
FEATURES DESCRIPTION
n
Silent Switcher® Architecture
The LT®8645S-2 synchronous step-down regulator features n
Ultralow EMI Emissions
Silent Switcher architecture designed to minimize EMI n
Optional Spread Spectrum Modulation
emissions while delivering high efficiency at high switch- n
High Efficiency at High Frequency
ing frequencies. This performance makes the LT8645S-2 n
Up to 95% Efficiency at 1MHz, 12VIN to 5VOUT
ideal for noise sensitive applications and environments. n
Up to 94% Efficiency at 2MHz, 12VIN to 5VOUT
The fast, clean, low-overshoot switching edges enable n
Wide Input Voltage Range: 3.4V to 65V
high efficiency operation even at high switching frequen- n
Ultralow Quiescent Current Burst Mode Operation
cies, leading to a small overall solution size. Peak current n
2.5μA IQ Regulating 12VIN to 3.3VOUT
mode control with a 40ns minimum on-time allows high n
Output Ripple < 10mVP-P
step-down ratios even at high switching frequencies. n Fast Minimum Switch On-Time: 40ns n Low Dropout Under All Conditions: 60mV at 1A Burst Mode® operation enables ultralow standby current n Adjustable and Synchronizable: 200kHz to 2.2MHz consumption, pulse-skipping mode allows full switching n Peak Current Mode Operation frequency at lower output loads, or spread spectrum n Output Soft-Start and Tracking operation can further reduce EMI emissions. n Small 32-Lead 6mm × 4mm LQFN Package
INTERNAL CAPS V
n
C COMP 150ºC GRADE
AEC-Q100 Qualification In Progress LT8645S* Yes Internal No LT8646S* Yes External No
APPLICATIONS
LT8645S-2 No Internal Yes n Automotive and Industrial Supplies *See LT8645S/LT8646S Datasheet n General Purpose Step-Down n GSM Power Supplies All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345.
TYPICAL APPLICATION 5V 8A Step-Down Converter 12VIN to 5VOUT Efficiency
VIN 5.5V TO 65V 100 4.0 4.7µF V EN/UV 3.5 IN VIN 95 0.47µF 0.47µF 90 EFFICIENCY 3.0 GND GND POWER LOSS (W) LT8645S-2 85 2.5 BST 0.1µF 2.2µH VOUT 80 2.0 SW 5V BIAS 8A 75 1.5 EFFICIENCY (%) POWER LOSS INTVCC 2.2pF 1M 70 1.0 1µF RT FB 100µF 65 1MHz, L = 2.2µH 0.5 41.2k GND 243k 2MHz, L = 1µH 60 0 1 2 3 4 5 6 7 8 f LOAD CURRENT (A) 8645S-2 TA01a SW = 1MHz 8645S-2 TA01b Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Applications Related Parts
