LTC3308B

RECOMMENDED FOR NEW DESIGNS

5V, 4A, 10MHz Synchronous Step-Down Silent Switcher in 2mm × 2mm LQFN

Data Sheet (Rev. 0) Product Selection Table
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Overview

  • Pin Compatible with LTC3307(3A) and LTC3309(6A)
  • High Efficiency: 8mΩ NMOS, 31mΩ PMOS
  • Programmable Frequency 3MHz to 10MHz
    • Tiny Inductor and Capacitors
  • Peak Current Mode Control
    • 22ns Minimum On-Time
    • Wide Bandwidth, Fast Transient Response
  • Silent Switcher® Architecture
    • Ultralow EMI Emissions
  • Low Ripple Burst Mode®Operation with IQ of 40μA
  • Safely Tolerates Inductor Saturation in Overload
  • VIN Range: 2.25V to 5.5V
  • VOUT Range: 0.5V to VIN
  • VOUT Accuracy: ±1% Over Temperature Range
  • Precision 400mV Enable Threshold, 1μA in Shutdown
  • Power Good, Internal Compensation and Soft-Start
  • Thermally Enhanced 2mm × 2mm LQFN Package
  • AEC-Q100 Qualified for Automotive Applications
LTC3308B
5V, 4A, 10MHz Synchronous Step-Down Silent Switcher in 2mm × 2mm LQFN
LTC3308B Application Circuit LTC3308B Performance Graph LTC3308B Pin Configuration
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Documentation

Data Sheet 1

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Software Resources

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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC3308A
  • LTC3308B

LTpowerCAD 1

Design tools for the following parts are available in LTpowerCAD:

  • LTC3308A
  • LTC3308B
LTspice

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

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

eval board
schematic 1
schematic 2
schematic 3
DC3054A-B

LTC3308B | 3.3V to 1.8V at 4A, 6.6MHz Low EMI Buck Regulator in a 0.47cm2 Solution

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Product Details

Demonstration circuit 3054A-B features the LTC3308B 5V, 4A synchronous step-down Silent Switcher® operating as a 6.6MHz, 3.3V to 1.8V 4A buck regulator. The LTC3308B supports adjustable output voltages from 0.5V to VIN, and operating frequencies from 3MHz up to 10MHz. The LTC3308B is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic step-down switching regulator. A minimum on-time of 22ns enables high VIN to low VOUT conversion ratios at high switching frequencies.

The DC3054A-B operating mode may be selected as Burst Mode® operation, skip or forced continuous (FC) mode. Setting JP1 to the FC/SYNC position will allow the LTC3308B to sync to a clock frequency from 3MHz to 10MHz. The LTC3308B operates in forced continuous mode when syncing to an external clock. The DC3054A-B is set to a fixed 6.6MHz.

The DC3054A-B is set to a fixed 6.6MHz frequency by connecting RT to VIN through a 0Ω resistor, R9. The frequency can be easily changed by removing R9 and setting an appropriate resistor in the R4 location to obtain the desired frequency. Refer to the LTC3308B data sheet for the proper RT value for a desired switching frequency. 

The LTC3308B data sheet gives a complete description of the device, operation and application information. The data sheet must be read in conjunction with the demo manual. The LTC3308B is assembled in a 2mm × 2mm LQFN package with exposed pads for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout.

eval board
schematic 4
schematic 5
schematic 6
DC3054A-B

LTC3308B | 3.3V to 1.8V at 4A, 6.6MHz Low EMI Buck Regulator in a 0.47cm2 Solution

Buy Now View Details

Product Details

Demonstration circuit 3054A-B features the LTC3308B 5V, 4A synchronous step-down Silent Switcher® operating as a 6.6MHz, 3.3V to 1.8V 4A buck regulator. The LTC3308B supports adjustable output voltages from 0.5V to VIN, and operating frequencies from 3MHz up to 10MHz. The LTC3308B is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic step-down switching regulator. A minimum on-time of 22ns enables high VIN to low VOUT conversion ratios at high switching frequencies.

The DC3054A-B operating mode may be selected as Burst Mode® operation, skip or forced continuous (FC) mode. Setting JP1 to the FC/SYNC position will allow the LTC3308B to sync to a clock frequency from 3MHz to 10MHz. The LTC3308B operates in forced continuous mode when syncing to an external clock. The DC3054A-B is set to a fixed 6.6MHz.

The DC3054A-B is set to a fixed 6.6MHz frequency by connecting RT to VIN through a 0Ω resistor, R9. The frequency can be easily changed by removing R9 and setting an appropriate resistor in the R4 location to obtain the desired frequency. Refer to the LTC3308B data sheet for the proper RT value for a desired switching frequency. 

The LTC3308B data sheet gives a complete description of the device, operation and application information. The data sheet must be read in conjunction with the demo manual. The LTC3308B is assembled in a 2mm × 2mm LQFN package with exposed pads for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout.
DC3054A-B
LTC3308B | 3.3V to 1.8V at 4A, 6.6MHz Low EMI Buck Regulator in a 0.47cm2 Solution
DC3054A-B Evaluation Board - Angle View DC3054A-B Evaluation Board - Top View DC3054A-B Evaluation Board - Bottom View
DC3054A-B
LTC3308B | 3.3V to 1.8V at 4A, 6.6MHz Low EMI Buck Regulator in a 0.47cm2 Solution
DC3054A-B Evaluation Board - Angle View DC3054A-B Evaluation Board - Top View DC3054A-B Evaluation Board - Bottom View

Reference Designs

ADPS43506-RD Power Tree
ADPS43506-RD Power Tree
ADPS43506-RD Board Illustration
ADPS43506-RD Communications Power Solution Circuits from the lab

Compact Multi-Rail Power Solution for Optical Transceiver Modules

View Detailed Reference Design

Features and Benefits

  • Removes existing power solutions' struggle with ripple, regulation, and load current constraints in compact form factors.
  • Silent Switcher technology enables high current delivery with ultra-clean, low-noise outputs.
  • SIMO architecture generates multiple rails without increasing component count or PCB footprint.
  • Combined approach enables a compact, efficient, and high-performance power delivery network.

Solution Specifications

Solution Requirements:

  • Operates from a 3.3 V ±5% input rail and generates four output voltages (0.85 V, 1.2 V, 1.5 V, and 1.8 V) with tolerances ranging from ±3.0% to ±5.0%, ensuring regulated and stable power delivery across all rails.
    • 0.85 V ± ~3.00% output voltage delivers up to 2.2 A output current with 21.25 mVpp voltage ripple.
    • 1.2 V ± 5.00% output voltage provides 350 mA maximum current with 30 mVpp ripple.
    • 1.5 V ± 3.33% output voltage provides 250 mA maximum current and achieves the lowest ripple performance (15 mVpp).
    • 1.8 V ± 5.00% output voltage supports 70 mA maximum current with 30 mVpp ripple.
  • Soft-start ramp times are 20 µs for the 0.85 V and 1.8 V rails, while the 1.2 V and 1.5 V rails start without additional programmed ramp delay.
  • All rails achieve greater than 80% efficiency, with the 0.85 V rail reaching approximately 90% efficiency at 1 A load.

Environmental Requirements:

  • Components -40°C to 105°C, system operation up to 85°C

Form Factor Requirements:

  • PCB size 10mm x 5mm for whole power solution

No input filter is needed or any other protection. Solution is considered as Point of Load supplies.
ADPS43506-RD Communications Power Solution
Compact Multi-Rail Power Solution for Optical Transceiver Modules
ADPS43506-RD Power Tree
ADPS43506-RD Board Illustration

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