Features and Benefits
- Silent Switcher®2 Architecture:
- Ultralow EMI on Any PCB
- Eliminates PCB Layout Sensitivity
- Internal Bypass Capacitors Reduce Radiated EMI
- Optional Spread Spectrum Modulation
- 4A DC from Each Channel Simultaneously
- Up to 6A on Either Channel
- Ultralow Quiescent Current Burst Mode® Operation:
- 6.2μA IQ Regulating 12VIN to 5VOUT1 and 3.3VOUT2
- Output Ripple <10mVP-P
- Forced Continuous Mode
- Optional External VC Pin: Fast Transient Response and Current Sharing (Extra 50µA IQ/Channel)
- High Efficiency at High Frequency
- 94.6% Efficiency at 2A, 5VOUT from 12VIN at 2MHz
- 93.3% Efficiency at 4A, 5VOUT from 12VIN at 2MHz
- Fast Minimum Switch-On Time: 40ns
- Wide Input Voltage Range: 3.0V to 42V
- Adjustable and Synchronizable: 300kHz to 3MHz
- Small 4mm × 6mm 32-Pin LQFN Package
- AEC-Q100 Qualified for Automotive Applications
The LT8650S is a dual step-down regulator that delivers up to 4A of continuous current from both channels and supports loads up to 6A from each channel. The LT8650S features the second generation Silent Switcher architecture to minimize EMI emissions while delivering high efficiency at high switching frequencies. This includes integration of bypass capacitors to optimize high frequency current loops 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 at high switching frequencies.
Burst Mode operation features a 6.2μA quiescent current resulting in high efficiency at low output currents, forced continuous mode allows fixed switching frequency operation over the entire output load range, and spread spectrum operation can further reduce EMI emissions. External VC pins allow optimal loop compensation for fast transient response. The VC pins can also be used for current sharing and the CLKOUT pin enables synchronizing two LT8650S chips to generate a 4-phase, 16A supply.
- General Purpose Step-Down
- Automotive and Industrial Supplies
Markets and Technologies
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demonstration circuit 2407A is a dual channel 42V, 4A synchronous step-down Silent Switcher® with 6.2μA quiescent current featuring the LT8650S. The LT8650S is the second-generation Silent Switcher that minimizes EMI and reduces PCB layout sensitivity. The demonstration circuit has two outputs: 5V and 3.3V. Each output can source up to 4A continuous current at the same time. Figure 1 shows the conducted EMI measurements from 150kHz to 30MHz. Figure 2 shows the radiated EMI measurements from 30MHz to 1GHz. All measurements were tested per CISPR 25 specifications. The circuit passes the tests with wide margins.
Documentation & Resources
R585 Reliability Data4/13/2020
Active Rectifier Controller with Ultrafast Transient Response and Low Power Dissipation12/17/2018
Dual-Channel, 42 V, 4 A Monolithic Synchronous Step-Down Silent Switcher 2 with 6.2 μA Quiescent Current6/1/2018
DN1044 - Dual Channel 42V, 4A Monolithic Synchronous Step-Down Silent Switcher 2 with 6.2μA Quiescent Current11/14/2017
Optimizing Power Systems for the Signal Chain—Part 2: High Speed Data Converters4/9/2021 Analog Dialogue
Optimizing Power Systems for the Signal Chain—Part 1: How Much Power Supply Noise Is Tolerable?3/5/2021 Analog Dialogue
Self-Driving Cars—Are Power Systems up to the Task?9/1/2018
LT8650S Demo Board | Dual Channel 42V, 4A Synchronous Step-Down Silent Switcher 211/15/2017
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
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.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
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.
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.