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
- 2A DC from Each Channel Simultaneously
- Up to 3A on Either Channel
- Ultralow Quiescent Current Burst Mode® Operation:
- 6.2μA IQ Regulating 12VIN to 5VOUT1 and 3.3VOUT2
- Output Ripple < 10mVP–P
- Optional External VC Pin: Fast Transient Response
- Forced Continuous Mode
- High Efficiency at High Frequency
- 94.1% Efficiency at 1A, 5VOUT from 12VIN at 2MHz
- Pin-Selectable Fixed Output Voltages: 5V, 3.3V, 1.8V
- Fast Minimum Switch-On Time: 30ns
- Wide Input Voltage Range: 3.0V to 42V
- Adjustable and Synchronizable: 300kHz to 3MHz
- Fixed Output Pin Strap Options
- Internal 2MHz fSW with Fast Internal Compensation
- Small 4mm × 3mm 20-Pin LQFN Package
- AEC-Q100 Automotive Qualification in Progress
The LT8653S is a dual step-down regulator that delivers up to 2A of continuous current from both channels and supports loads up to 3A from each channel. The LT8653S 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 solution size with wide control loop bandwidth for fast transient response. Burst Mode operation enables ultralow standby current consumption or forced continuous mode can be used to control frequency harmonics across the entire output load range. The LT8653S is a full featured, customizable voltage regulator, but also has several pin strap options to select internal 2MHz switching frequency, internal compensation and internal feedback resistor divider options to create a simple, compact two output voltage regulator with only five external components.
- General Purpose Step-Down
- Automotive and Industrial Supplies
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 2535A is a 42V, dual channel, 2A synchronous step-down regulator featuring the LT8653S. The LT8653S is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator which features the second generation Silent Switcher® technology that minimizes EMI and reduces PCB layout sensitivity. The demo board is designed for two outputs: 5V and 3.3V from a 5.5V to 42V input. Each output can source up to 2A continuous current at the same time. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The integrated power switches and other necessary circuitry reduce the external component count and simplify design. Selectable spread spectrum mode of operation can further improve EMI/EMC performance. Ultralow quiescent current in Burst Mode® operation achieves high efficiency at very light loads.
The DC2535A demo board is 3" by 3" in size and has four layers with 2oz copper on the outer layers and 1oz copper on the inner layers. The DC2535A operates at 2MHz switching frequency by default to minimize solution size. The LT8653S is assembled in a small thermally enhanced 4mm × 3mm LQFN package. The IC temperature rises about 50°C when both channels operate at full load, 2A each, with the default switching frequency of 2MHz.
The jumper JP2 on the demo board determines the configuration of the SYNC pin of the LT8653S. By default, the SYNC pin on the demo board is grounded for low ripple Burst Mode operation. Moving JP2 to FCM W/SSM enables the spread spectrum mode of operation by tying the SYNC pin to VCC pin. To synchronize to an external clock, move JP2 to FCM W/O SSM OR SYNC position and apply the external clock on the SYNC turret.
The jumpers JP3 and JP4 on the demo board determine the configuration of the output voltage select bit pins D0 and D1. On the DC2535A, the D0 and D1 pins are by default floating. This combination connects internal feedback resistor divider between the FB1/FB2 pins and the error amplifier which means that FB1 and FB2 pins are regulated to 5V and 3.3V respectively. On the DC2535A, FB1/FB2 pins are by default connected through 0Ω resistors to the output nodes. Refer to the LT8653S data sheet for more information on the D0 and D1 pin settings.
The demo board has an EMI filter installed. The EMI performance of the demo board (with EMI filter) is shown in Figure 1 and Figure 2. The black lines in Figure 2 are CISPR 25 class 5 limits. To achieve EMI/EMC performance as shown in Figure 2, the input EMI filter is required and the input voltage should be applied at VEMI terminal.
The LT8653S data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this manual for demo circuit 2535A.
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.
Models for the following parts are available in LTspice:
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:
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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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.