LT8645S - 65V, 8A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current

Features

  • Silent Switcher® 2 Architecture
  • Ultralow EMI/EMC 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
  • Output Ripple < 10mVP-P
  • Fast Minimum Switch On-Time: 40ns
  • Low Dropout Under All Conditions: 60mV at 1A
  • Safely Tolerates Inductor Saturation in Overload
  • Adjustable and Synchronizable: 200kHz to 2.2MHz
  • Peak Current Mode Operation
  • Output Soft-Start and Tracking
  • Small 32-Lead 6mm × 4mm LQFN Package
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT8645S Typical Application
LT8645S Typical Application

Description

The LT®8645S synchronous step-down regulator features second generation Silent Switcher architecture designed to minimize EMI/EMC 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. This performance makes the LT8645S ideal for noise sensitive applications and environments.

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.

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/EMC emissions. Soft-start and tracking functionality is accessed via the TR/SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin. A CLKOUT pin enables synchronizing other regulators to the LT8645S.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT8645SEV#PBF 6mm × 4mm × 0.94mm LQFN LQFN E 05-08-1512 Yes
LT8645SIV#PBF 6mm × 4mm × 0.94mm LQFN LQFN I 05-08-1512 Yes


LT8645S Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT8645SEV#PBF 6mm × 4mm × 0.94mm LQFN E $8.50 $5.95 Yes
LT8645SIV#PBF 6mm × 4mm × 0.94mm LQFN I $9.36 $6.55 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2468A LT8645S Demo Board | Sync Buck Silent Switcher, 5.6V ≤ VIN ≤ 65V, VOUT = 5V @ 8A, fSW=2MHz $275.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT8645SIV#PBF 6mm × 4mm × 0.94mm LQFN I $9.36 $6.55 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

  • Automotive and Industrial Supplies
  • General Purpose Step-Down
  • GSM Power Supplies

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.

Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

Models for the following parts are available in LTspice:
LT8645S

Technical Support