LT8644S

Name: LT8644S
Brand: Analog Devices
Price: 4.62 USD
Availability: InStock

RECOMMENDED FOR NEW DESIGNS

8V, 16A Synchronous Step-Down Silent Switcher 2

Data Sheet (Rev. A) Product Selection Table

Part Models: 4
1ku List Price: Starting From $4.62

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Overview

Silent Switcher^®2 Architecture
- Ultralow EMI Emissions on Any PCB
- Internal Bypass Capacitors Reduce Radiated EMI
- Optional Spread Spectrum Modulation
High Efficiency at High Frequency
- Up to 94% Efficiency at 2MHz, 3.3V_IN to 1.2V_OUT
- Up to 93% Efficiency at 2MHz, 5V_IN to 1.2V_OUT
PV_IN Range: 1.5V to 8V, SV_IN Range: 2.7V to 8V
V_OUT Range: 0.6V to V_IN
Reference Accuracy: ±0.8% Over Temperature

PolyPhase^® Operation: Up to 12 Phases
Fast Transient Response with External Compensation
Forced Continuous Mode Operation
Low Quiescent Current Burst Mode^® Operation
- 180μA I_Q Regulating 5V_IN to 1.2V_OUT
- Output Ripple < 10mV_P-P
Fast Minimum Switch On-Time: 20ns
Adjustable and Synchronizable: 300kHz to 3.5MHz
Output Soft-Start and Power Good
Small 24-Lead 4mm × 4mm LQFN Package
AEC-Q100 Qualified for Automotive Applications

Part Models: 4
1ku List Price: Starting From $4.62

Documentation

Data Sheet 1

LT8644S: 8V, 16A Synchronous Step-Down Silent Switcher 2 Data Sheet (Rev.A) 10/18/2021

User Guide 1

DC2779A - Demo Manual (Rev.0) 10/22/2021

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT8644SIV#TRMPBF	24-Lead LQFN Package (4mm × 4mm × 0.95mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8644SIV#TRPBF	24-Lead LQFN Package (4mm × 4mm × 0.95mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8644SIV#WTRMPBF	24-Lead LQFN Package (4mm × 4mm × 0.95mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8644SIV#WTRPBF	24-Lead LQFN Package (4mm × 4mm × 0.95mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Apr 16, 2024 - 24_0033 Qualification of Cu pillar diameter change, SMT paste, and Die thickness change for LT8644S
		PCN24_0033_Form Material_Report Other
LT8644SIV#TRMPBF	PRODUCTION
LT8644SIV#TRPBF	PRODUCTION
LT8644SIV#WTRMPBF	PRODUCTION
LT8644SIV#WTRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

LT8644S

LTpowerCAD 1

LT8644S Project - 2.7-8Vin to 1.2Vout, 16A, 2MHz

Design tools for the following parts are available in LTpowerCAD:

LT8644S

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.

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.

Evaluation Kits

LT8644S | 8V, 16A Synchronous Step-Down Silent Switcher 2

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Product Details

Demonstration circuit 2779A is an 8V, 16A synchronous step-down Silent Switcher® 2 with spread spectrum frequency modulation featuring the LT8644S. The demo board is designed for 1.2V output from a 2.7V to 8V input. The LT8644S is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic stepdown switching regulator. The integrated bypass capacitors optimize all the fast current loops and make it easier to minimize EMI emissions by reducing layout sensitivity. Selectable spread spectrum mode further improves EMI performance, making it perfect solution to the noise sensitive applications.

Peak current mode control with minimum on-time of as low as 20ns allows high step-down conversion even at high frequency. The LT8644S switching frequency can be programmed either via an external resistor or an external clock over a 300kHz to 3.5MHz range. The default frequency of demo circuit 2779A is 2MHz.

The SYNC/MODE pin on the demo board DC2779A is grounded (JP1 at BURST position) by default for low ripple Burst Mode^® operation. It can be configured into different operation modes through JP1 and SYNC terminal (Table 1 in the demo manual).

Figure 4 in the demo manual shows the efficiency of the circuit at 3.3V input and 5V input in force continuous mode operation (input from VIN terminal). To get accurate efficiency measurement, measure the input voltage at the VIN_SENSE/GND terminals and measure the output voltage at the VOUT+ SENSE/VOUT– SENSE terminals. Figure 5 shows the LT8644S temperature rise on DC2779A demo board at 3.3V input and 5V input in forced continuous mode.

The LT8644S is assembled in a 4mm × 4mm LQFN package with exposed pads for low thermal resistance. The rated maximum continuous load current is 16A, while derating may be necessary for certain input voltage and thermal conditions.

The demo board has an EMI filter installed. This EMI filter can be included by applying the input voltage at the VEMI terminal. The EMI performance of the board (with EMI filter) is shown on Figure 6 in the demo manual. The red lines in EMI Performance are CISPR25 Class 5 limits. The figure shows that the LT8644S circuit passes the test with a wide margin. To achieve EMI performance as shown in Figure 6, the input EMI filter is required and the input voltage should be applied to VEMI terminal, and the test setup can be referred to the CISPR25 standards. If the input is applied to VIN terminal, the EMI filter is bypassed.

The LT8644S data sheet gives a complete description of the part, the operation and application information. The data sheet must be read in conjunction with the demo manual for demo circuit 2779A. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout and Thermal Considerations. Contact ADI applications engineer for support.