Products
LT8646S
RECOMMENDED FOR NEW DESIGNS65V, 8A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current
- Part Models
- 8
- 1ku List Price
- Starting From $8.06
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Overview
- Silent Switcher®2 Architecture
- Ultralow EMI Emissions on Any PCB
- Eliminates PCB Layout Sensitivity
- Internal Bypass Capacitors Reduce Radiated EMI
- Optional Spread Spectrum Modulation
- High Efficiency at High Frequency
- Up to 95% Efficiency at 1MHz, 12VIN to 5VOUT
- Up to 94% Efficiency at 2MHz, 12VIN to 5VOUT
- Wide Input Voltage Range: 3.4V to 65V
- Ultralow Quiescent Current Burst Mode Operation
- 2.5μA IQ Regulating 12VIN to 3.3VOUT (LT8645S)
- Output Ripple < 10mVP-P
- External Compensation: Fast Transient Response and Current Sharing (LT8646S)
- Fast Minimum Switch On-Time: 40ns
- Low Dropout Under All Conditions: 60mV at 1A
- Adjustable and Synchronizable: 200kHz to 2.2MHz
- Peak Current Mode Operation
- Output Soft-Start and Tracking
- Small 32-Lead 6mm × 4mm LQFN Package
- AEC-Q100 Qualified for Automotive Applications
The LT8645S/LT8646S synchronous step-down regulator features second generation Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at high switching frequencies. This includes the integration of bypass capacitors to optimize all the fast current loops inside and make it easy to achieve advertised EMI performance by eliminating layout sensitivity.
The fast, clean, low-overshoot switching edges enable high efficiency operation even at high switching frequencies, leading to a small overall solution size. Peak current mode control with a 40ns minimum on-time allows high step-down ratios even at high switching frequencies. The LT8646S has external compensation to enable current sharing and fast transient response at high switching frequencies.
Burst Mode® operation enables ultralow standby current consumption, pulse-skipping mode allows full switching frequency at lower output loads, or spread spectrum operation can further reduce EMI emissions.
Applications
- Automotive and Industrial Supplies
- General Purpose Step-Down
- GSM Power Supplies
Documentation
Data Sheet 1
User Guide 1
Design Note 1
Technical Articles 1
Video 1
Book & eBook 1
Solutions Bulletin & Brochure 1
Webcast 1
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.
| Part Model | Pin/Package Drawing | Documentation | CAD Symbols, Footprints, and 3D Models |
|---|---|---|---|
| LT8646SEV#PBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SEV#TRPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SEV#WPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SEV#WTRPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SIV#PBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SIV#TRPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SIV#WPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) | ||
| LT8646SIV#WTRPBF | 32-Lead LQFN (6mm x 4mm x 0.94mm w/ EP) |
| Part Models | Product Lifecycle | PCN |
|---|---|---|
|
Sep 9, 2025 - 24_0002 Qualification of New Mold Compound, SMT Paste and Pillar Diameter Change for LT8645S, LT8645S-2, LT8646S |
||
| LT8646SEV#PBF | PRODUCTION | |
| LT8646SEV#TRPBF | PRODUCTION | |
| LT8646SEV#WPBF | PRODUCTION | |
| LT8646SEV#WTRPBF | PRODUCTION | |
| LT8646SIV#PBF | PRODUCTION | |
| LT8646SIV#TRPBF | PRODUCTION | |
| LT8646SIV#WPBF | PRODUCTION | |
| LT8646SIV#WTRPBF | PRODUCTION | |
|
Apr 11, 2019 - 19_0067 Notification of Wafer Fab Location Change for 0.35 BCD Process |
||
| LT8646SEV#PBF | PRODUCTION | |
| LT8646SIV#PBF | PRODUCTION | |
This is the most up-to-date revision of the Data Sheet.
Software Resources
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Tools & Simulations
LTspice
Models for the following parts are available in LTspice:
- LT8646S
- LT8646SA
LTpowerCAD 1
Design tools for the following parts are available in LTpowerCAD:
- LT8646S
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
Evaluation Kits
LT8646S Demo Board | 65V, 8A Synchronous Step-Down Silent Switcher 2