New Content (2)
Features and Benefits
- 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
- Wide Input Voltage Range: 3.0V to 42V
- Ultralow Quiescent Current Burst Mode® Operation:
- <3μA IQ Regulating 12VIN to 3.3VOUT
- Output Ripple <10mVP-P
- High Efficiency 2MHz Synchronous Operation:
- >90% Efficiency at 0.75A, 5VOUT from 12VIN
- 1.5A Continuous Output Current
- Fast Minimum Switch-On Time: 35ns
- Adjustable and Synchronizable: 200kHz to 2.2MHz
- Allows Use of Small Inductors
- Low Dropout
- Peak Current Mode Operation
- Internal Compensation
- Output Soft-Start and Tracking
- Small 12-Lead LQFN Package
The LT8608S is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 1.7μA of quiescent current. The LT8608S can deliver 1.5A 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 below 10mV. A SYNC pin allows synchronization to an external clock, or spread spectrum modulation of switching frequencies for low EMI operation. 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 LT8608S reducing the input supply current to 1μA. A capacitor on the TR/SS pin programs the output voltage ramp rate during start-up while the PG flag signals when VOUT is within ±8.0% of the programmed output voltage as well as fault conditions. The LT8608S is available in a small 12-lead LQFN package.
- General Purpose Step Down
- Low EMI Step Down
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 2711A is a 42V, 1.5A synchronous step-down regulator featuring the LT8608S. The demo board is designed for 5V output from a 5.5V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8608S is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator with the second-generation Silent Switcher® structure that minimizes EMI and reduces PCB layout sensitivity. LT8608S consumes only 3μA of quiescent current when output is regulated at 5V. Top and bottom power switches, compensation components and other necessary circuits are inside of the LT8608S to minimize external components and simplify design.
The SYNC pin on the demo board is grounded by default for low ripple Burst Mode® operation. Move JP1 to PULSE SKIPPING position can change the operation mode to pulse-skipping operation. Once JP1 is on SPREAD SPECTRUM position, VCC is applied to the SYNC pin for low EMI spread spectrum operation. To synchronous to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Figure 1 in the demo manual shows the efficiency of the circuit.
The demo board has an EMI filter installed. The radiated EMI performances of the board (with EMI filter) are shown in Figure 2 and Figure 3 in the demo manual. The red lines in Figure 2 and Figure 3 are CISPR25 Class 5 peak limit. To use the EMI filter, the input should be tied to VEMI, not VIN. An inductor L2, which is shorted on the board by default now, can be added in the EMI filter to further reduce the conducted emission.
The LT8608S data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with the demo manual for DC2711A.
Documentation & Resources
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.View our quality and reliability program and certifications for more information.
|Part Number||Material Declaration||Reliability Data||Pin/Package Drawing||CAD Symbols, Footprints & 3D Models|
|LT8608SEV#TRMPBF||Material Declaration||Reliability Data||12-Lead LQFN (2mm x 3mm x 0.74mm)|
|LT8608SEV#TRPBF||Material Declaration||Reliability Data||12-Lead LQFN (2mm x 3mm x 0.74mm)|
|LT8608SIV#TRMPBF||Material Declaration||Reliability Data||12-Lead LQFN (2mm x 3mm x 0.74mm)|
|LT8608SIV#TRPBF||Material Declaration||Reliability Data||12-Lead LQFN (2mm x 3mm x 0.74mm)|
|Wafer Fabrication Data|
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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.