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ECB and LCD Display Bias Supply with Accurate Output Voltage and Temperature Compensation

High-Accuracy Bias Supply Enables Use of Low-Cost Color ECB LCDs

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • High-Accuracy Reference Voltage (±1%)
  • ±11ppm/°C Output Voltage Drift
  • On-Chip Temperature Sensor Output
  • Accurate Voltage and Temperature Provide:
    • Consistent ECB Colors
    • Consistent LCD Gray-Scale Contrast
  • +2.7V to +5.5V Input Voltage Range
  • Output Voltage Range
    • +2.5V to +16V in Internal Feedback Mode
    • Programmable in External Feedback Mode
  • Dynamic Control of the Output Voltage
  • 67µA Supply Current
  • 0.4µA Shutdown Current
  • 10-Pin µMAX Package (1.09mm max height)
  • Evaluation Kit Available (MAX1729EVKIT)

Applications/Uses

  • Cell Phones
  • ECB Display Bias and Color Adjustment
  • LCD Display Bias and Contrast Adjustment
  • PDAs and Other Handheld Devices

Description

The MAX1729 micropower step-up/step-down DC-DC converter is ideally suited for electrically controlled birefringence (ECB) and liquid-crystal-display (LCD) bias-supply generation. It provides step-up/step-down voltage conversion and reduces output ripple by using a step-up DC-DC converter followed by a linear regulator. This architecture permits a physically smaller inductor than those used in competing SEPIC and flyback topologies. This device features low quiescent current (67µA typical). A logic-controlled shutdown mode further reduces quiescent current to 0.4µA typical.

The MAX1729 features an input that dynamically adjusts the output voltage to control display color or contrast. It offers two feedback modes: internal and external. Internal feedback mode allows output voltages between 2.5V and 16V, and is specifically designed to hold temperature drift to ±11ppm/°C. External feedback mode allows the MAX1729 output voltage range to be tailored for various displays.

An on-chip temperature sensor with a positive temperature coefficient provides compensation for LCD/ECB display temperature characteristics. In internal feedback mode, the buffered temperature sensor output is read and used to adjust the output voltage via a digital control signal. External feedback mode features an additional compensation method in which the temperature output is summed directly into the feedback network to provide first-order negative temperature compensation of the output voltage. The MAX1729 is available in the space-saving 10-pin µMAX package.

Simplified Block Diagram

MAX1729: Typical Operating Circuit MAX1729: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.