New Content (2)
Technical ArticlesSelf-Driving Cars—Are Power Systems up to the Task?
Rarely Asked QuestionsOptimized Power Supply Measurement Setup
Features and Benefits
- Wide Input Voltage Range: 3V to 60V
- Fast Minimum Switch-On Time: 30ns
- Ultralow Quiescent Current Burst Mode Operation:
- 6μA IQ Regulating 12VIN to 3.3VOUT
- 10mVP-P Output Ripple at No Load
- Synchronizable/Programmable Fixed Frequency Forced Continuous Mode Operation: 300kHz to 2.2MHz
- High Efficiency Synchronous Operation:
- 92% Efficiency at 0.5A, 5VOUT from 12VIN
- 90% Efficiency at 0.5A, 3.3VOUT from 12VIN
- Low Dropout: 360mV at 0.5A
- Low EMI
- Accurate 1V Enable Pin Threshold
- Internal Soft-Start and Compensation
- Power Good Flag
- Small Thermally Enhanced 16-Lead MSOP Package and 10-Lead (3mm × 3mm) DFN Packages
The LT8619 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 6μA of quiescent current. The LT8619 can deliver 1.2A of continuous current. Top and bottom power switches are included with all necessary circuitry to minimize the need for external components. Low ripple Burst Mode® operation enables high efficiency down to very low output currents while keeping the output ripple to 10mVP-P. A SYNC pin allows forced continuous mode operation synchronized to an external clock. Internal compensation with peak current mode topology allows the use of small inductors and results in fast transient response and good loop stability. The EN/UV pin has an accurate 1V threshold and can be used to program VIN undervoltage lockout or to shut down the LT8619, reducing the input supply current to below 0.6μA. The PG flag signals when VOUT is within ±7.5% of the programmed output voltage. The LT8619 is available in a small 16-lead MSOP and 10-lead 3mm × 3mm DFN packages with exposed pad for low thermal resistance.
- 12V Automotive Systems
- 12V and 24V Commercial Vehicles
- 48V Electric and Hybrid Vehicles
- Industrial Supplies
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 2137A is a monolithic step-down DC/DC switching regulator featuring the LT®8619. The LT8619 is a high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 6µA of quiescent current. The demo circuit is designed for 5V, 1.2A output from 6V to 48V input with the transient input voltage up to 60V. The wide input range makes it suitable for regulating power from a wide variety of sources, including automotive, industrial systems and telecom supplies. The power switch, compensation and other necessary circuits are inside of the LT8619 to minimize external components and simplify design.
The LT8619 switching frequency can be programmed either via oscillator resistor or external clock over a 300kHz to 2.2MHz range. The default frequency of demo circuit 2137A is 2MHz. The SYNC pin on the demo board is grounded (JP1 at BURST position) by default for low ripple Burst Mode® operation. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC terminal. The RT resistor (R4) should be chosen to set the LT8619 internal switching frequency equal or below the lowest synchronization input. During clock synchronization, the controller enters forced continuous mode. Pulse-skipping mode and forced continuous mode can be selected respectively by moving JP1 shunt.
Low ripple Burst Mode operation increases the efficiency at the light load while keeping the output ripple low. Figure 1 shows the efficiency of the circuit at 12V and 24V input in Burst Mode operation (input from VIN terminal to bypass the EMI filter).
The demo board has an EMI filter installed. The EMI performance of the board (with EMI filter) is shown on Figure 2. The red line in Radiated EMI Performance is CISPR25 Class 5 peak limit. The figure shows that the circuit passes the test with a wide margin. 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 LT8619 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 2137A. The LT8619 is assembled in a small 16-lead MSOP and 10-lead 3mm × 3mm DFN packages with exposed pad. Proper board layout is essential for both low EMI operation and maximum thermal performance. See the data sheet sections for details.
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.
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.
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.