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Features and Benefits
- Silent Switcher®2 Architecture:
- Ultralow EMI on Any PCB n 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 BurstMode® Operation:
- 6.2μA IQ Regulating 12VIN to 5VOUT1 and 3.3VOUT2
- Output Ripple <10mVP-P
- Optional External VC Pin: Fast Transient Response and Current Sharing (Extra 50µA IQ/Channel)
- Forced Continuous Mode
- 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
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
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Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
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.
Design Notes (3)
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.
Design tools for the following parts are available in LTpowerCAD:
Press Releases (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.
Sample & Buy
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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.