Linear Technology Corporation

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Linear Technology Corporation
LTC2656 Precision 16-Bit Octal DAC with 4LSB
INL and Internal Reference

• Dave QuarlesVice President of International Sales

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Closed Loop or Open Loop Application?

• Closed Loop Applications Includes a Feedback
  Path, so Good Differential Nonlinearity
  (Monotonicity) is important Integral
  Nonlinearity (INL) may not be as important
• Open Loop Applications Require Precision DC
  Specifications (INL, Offset Error, Gain Error)
  with Very Small Errors Over Temperature
• Linear Technology Offers DACs Good for Both
  Closed Loop and Open Loop Applications

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Closed Loop System Example
Motor
Power Amplifier
LTC2601
Digital I/O
Feed-forward linearity does not matter
mC
Rotation Signal
Digital I/O
ADC
Feedback linearity does matter
Tachometer

• Motor Control is One Example of a Closed Loop
  System
• A Closed Loop System Includes a Feedback Path,
  Whether its with an ADC, Visually, or Some Way
  to Detect an Error Signal and Make Corrections
  with the DAC

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Open Loop System Example
15V
IN
LT3080
LTC2656
0V to 5VOUT
OUT
SET
Digital I/O
4.7mF
1N4003
mC

• Using a DAC Output to Drive the Pin Voltage to
  Another IC is an Example of an Open-Loop System
• Examples Also Include Test Equipment and Data
  Acquisition Cards Where Absolute Accuracy is
  Essential
• The 16-bit LTC2656 Offers Eight DACs with 4LSB
  INL, 1LSB DNL

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LTC2656 Octal 16-/12-Bit VOUT DACs with Internal
Reference, 4LSB INL at 16 Bits

• Precision Internal Reference
• 10ppm/C (max) (1.25V or 2.048V) 2.5V or 4.096V
  DAC Full-Scale Output Ranges
• Precision DC Specifications
• 16-Bit INL 4LSB (max)
• 16-Bit DNL 1LSB (max)
• Low 2mV (max) Offset Error
• Low 0.1 (max) Gain Error
• 2.7V to 5.5V Supply Range
• Ultralow Crosstalk Between DACs (1nVs)
• Low 3nVs Glitch Impulse
• 50MHz SPI-Compatible Interface
• 20-Pin 4mm x 5mm QFN and TSSOP Packages

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LTC2656 Precision Octal 16-/12-Bit VOUT DACs

• LTC2656 is Similar to the LTC2600, But Offers an
  Internal Reference and Better DC Specifications
• Applications
• High-End Optical Networking
• Data Acquisition Modules
• Industrial Process Control
• Instrumentation
• ATE
• LTC2656 Target Markets Include Open-Loop
  Applications