LTC6908 - Dual Output Oscillator with Spread Spectrum Modulation

Features

  • LTC6908-1: Complementary Outputs (0°/180°)
  • LTC6908-2: Quadrature Outputs (0°/90°)
  • 50kHz to 10MHz Frequency Range
  • One External Resistor Sets the Frequency
  • Optional Spread Spectrum Frequency Modulation for Improved EMC Performance
  • ±10% Frequency Spreading
  • 400µA Supply Current Typical (V+ = 5V, 50kHz)
  • Frequency Error ≤1.5% Max (TA = 25°C, V+ = 3V)
  • ±40ppm/°C Temperature Stability
  • Fast Start-Up Time: 260µs Typical (1MHz)
  • Outputs Muted Until Stable
  • Operates from a Single 2.7V to 5.5V Supply
  • Available in Low Profile (1mm) ThinSOT and DFN (2mm × 3mm) Packages
Designed for Automotive and Transportation Applications
AEC-Q100 data available for specific packages


Typical Application

LTC6908-1 Typical Application
LTC6908-1 Typical Application

Description

The LTC6908 is an easy-to-use precision oscillator that provides 2-outputs, shifted by either 180° or 90°. The oscillator frequency is programmed by a single external resistor (RSET) and spread spectrum frequency modulation (SSFM) can be activated for improved electromagnetic compatibility (EMC) performance. The LTC6908 operates with a single 2.7V to 5.5V supply and provides rail-to-rail, 50% duty cycle square wave outputs. A single resistor from 10k to 2M is used to select an oscillator frequency from 50kHz to 10MHz (5V supply). The oscillator can be easily programmed using the simple formula outlined below:

fOUT =10MHz • 10k/RSET

The LTC6908’s SSFM capability modulates the output frequency by a pseudorandom noise (PRN) signal to decrease the peak electromagnetic radiation level and improve EMC performance. The amount of frequency spreading is fi xed at ±10% of the center frequency. When SSFM is enabled, the rate of modulation is selected by the user. The three possible modulation rates are fOUT/16, fOUT/32 and fOUT/64.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC6908CDCB-1#PBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CDCB-1#TRMPBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CDCB-1#TRPBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CDCB-2#PBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CDCB-2#TRMPBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CDCB-2#TRPBF 2x3 DFN-6 DCB C 05-08-1715 Yes
LTC6908CS6-1#PBF SOT-23 S6 C 05-08-1636 Yes
LTC6908CS6-1#TRMPBF SOT-23 S6 C 05-08-1636 Yes
LTC6908CS6-1#TRPBF SOT-23 S6 C 05-08-1636 Yes
LTC6908CS6-2#PBF SOT-23 S6 C 05-08-1636 Yes
LTC6908CS6-2#TRMPBF SOT-23 S6 C 05-08-1636 Yes
LTC6908CS6-2#TRPBF SOT-23 S6 C 05-08-1636 Yes
LTC6908HS6-1#PBF SOT-23 S6 H 05-08-1636 Yes
LTC6908HS6-1#TRMPBF SOT-23 S6 H 05-08-1636 Yes
LTC6908HS6-1#TRPBF SOT-23 S6 H 05-08-1636 Yes
LTC6908HS6-2#PBF SOT-23 S6 H 05-08-1636 Yes
LTC6908HS6-2#TRMPBF SOT-23 S6 H 05-08-1636 Yes
LTC6908HS6-2#TRPBF SOT-23 S6 H 05-08-1636 Yes
LTC6908IDCB-1#PBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IDCB-1#TRMPBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IDCB-1#TRPBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IDCB-2#PBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IDCB-2#TRMPBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IDCB-2#TRPBF 2x3 DFN-6 DCB I 05-08-1715 Yes
LTC6908IS6-1#PBF SOT-23 S6 I 05-08-1636 Yes
LTC6908IS6-1#TRMPBF SOT-23 S6 I 05-08-1636 Yes
LTC6908IS6-1#TRPBF SOT-23 S6 I 05-08-1636 Yes
LTC6908IS6-2#PBF SOT-23 S6 I 05-08-1636 Yes
LTC6908IS6-2#TRMPBF SOT-23 S6 I 05-08-1636 Yes
LTC6908IS6-2#TRPBF SOT-23 S6 I 05-08-1636 Yes


LTC6908-1 Package Drawing
LTC6908-1 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC6908CDCB-1#PBF 2x3 DFN-6 C $2.45 Yes
LTC6908CDCB-1#TRMPBF 2x3 DFN-6 C $2.45 $1.67 Yes
LTC6908CDCB-1#TRPBF 2x3 DFN-6 C $2.45 $1.65 Yes
LTC6908CDCB-2#PBF 2x3 DFN-6 C $2.45 Yes
LTC6908CDCB-2#TRMPBF 2x3 DFN-6 C $2.45 $1.67 Yes
LTC6908CDCB-2#TRPBF 2x3 DFN-6 C $2.45 $1.65 Yes
LTC6908CS6-1#PBF SOT-23 C $2.43 Yes
LTC6908CS6-1#TRMPBF SOT-23 C $2.43 $1.67 Yes
LTC6908CS6-1#TRPBF SOT-23 C $2.43 $1.65 Yes
LTC6908CS6-2#PBF SOT-23 C $2.43 Yes
LTC6908CS6-2#TRMPBF SOT-23 C $2.43 $1.67 Yes
LTC6908CS6-2#TRPBF SOT-23 C $2.43 $1.65 Yes
LTC6908HS6-1#PBF SOT-23 H $3.46 Yes
LTC6908HS6-1#TRMPBF SOT-23 H $3.46 $2.46 Yes
LTC6908HS6-1#TRPBF SOT-23 H $3.46 $2.44 Yes
LTC6908HS6-2#PBF SOT-23 H $3.46 Yes
LTC6908HS6-2#TRMPBF SOT-23 H $3.46 $2.46 Yes
LTC6908HS6-2#TRPBF SOT-23 H $3.46 $2.44 Yes
LTC6908IDCB-1#PBF 2x3 DFN-6 I $2.92 Yes
LTC6908IDCB-1#TRMPBF 2x3 DFN-6 I $2.92 $2.06 Yes
LTC6908IDCB-1#TRPBF 2x3 DFN-6 I $2.92 $2.04 Yes
LTC6908IDCB-2#PBF 2x3 DFN-6 I $2.92 Yes
LTC6908IDCB-2#TRMPBF 2x3 DFN-6 I $2.92 $2.06 Yes
LTC6908IDCB-2#TRPBF 2x3 DFN-6 I $2.92 $2.04 Yes
LTC6908IS6-1#PBF SOT-23 I $2.90 Yes
LTC6908IS6-1#TRMPBF SOT-23 I $2.90 $2.06 Yes
LTC6908IS6-1#TRPBF SOT-23 I $2.90 $2.04 Yes
LTC6908IS6-2#PBF SOT-23 I $2.90 Yes
LTC6908IS6-2#TRMPBF SOT-23 I $2.90 $2.06 Yes
LTC6908IS6-2#TRPBF SOT-23 I $2.90 $2.04 Yes
Buy NowRequest Samples
* 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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2073A-J LTC6908-1 Silicon Oscillator Demo Board $50.00
DC2073B-B LTC1799 Silicon Oscillator Demo Board $50.00
DC2073B-H LTC6906 Silicon Oscillator Demo Board $50.00
DC814A2-K LTC6908-2 DEMO BOARD | BUFFER BOARD W/ ASSOCIATED DIP8 CLOCK BOARD Contact Factory
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC6908HS6-1#PBF SOT-23 H $3.46 Yes
LTC6908HS6-1#TRMPBF SOT-23 H $3.46 $2.46 Yes
LTC6908HS6-1#TRPBF SOT-23 H $3.46 $2.44 Yes
LTC6908HS6-2#PBF SOT-23 H $3.46 Yes
LTC6908HS6-2#TRMPBF SOT-23 H $3.46 $2.46 Yes
LTC6908HS6-2#TRPBF SOT-23 H $3.46 $2.44 Yes
LTC6908IS6-1#PBF SOT-23 I $2.90 Yes
LTC6908IS6-1#TRMPBF SOT-23 I $2.90 $2.06 Yes
LTC6908IS6-1#TRPBF SOT-23 I $2.90 $2.04 Yes
LTC6908IS6-2#PBF SOT-23 I $2.90 Yes
LTC6908IS6-2#TRMPBF SOT-23 I $2.90 $2.06 Yes
LTC6908IS6-2#TRPBF SOT-23 I $2.90 $2.04 Yes
Buy NowRequest Samples
* 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 Linear Technology sales office or authorized distributor.

Applications

  • Switching Power Supply Clock Reference
  • Portable and Battery-Powered Equipment
  • Precision Programmable Oscillator
  • Charge Pump Driver

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

Models for the following parts are available in LTspice:
LTC6908-1
LTC6908-2

OscCalc, an Excel based selection and synthesis tool, allows you to choose and configure the Silicon Oscillator best suited for your application.

  • Download and open OscCalc
  • Enable Macros
  • Enter your desired switching frequency. Suitable silicon oscillators will be highlighted in green. Clicking on a part will show you the external component values and settings required to achieve your desired switching frequency.

Technical Support