TI TC281-30

TC281 is a frame-transfer charge-coupled device (CCD) image sensor that provides high-resolution image acquisition for image processing applications such as robotic vision, medical X-ray analysis, and metrology. The image sensing area measures 8mm horizontally and 8mm vertically, with an 11.3mm diagonal and 8μm square pixels. The image area contains 1000 active rows, each with 1000 active pixels. Dark reference signals are available from ten dark reference lines located between the image area and storage area, 28 dark reference pixels at the left edge of each horizontal line, and 8 dark reference pixels at the right edge of each horizontal line.

The storage section of the TC281 contains 1010 rows of 1036 pixels each, protected from light by a metal layer. Photocharge generated in the image area can be transferred to the storage section in less than 110μs. After image capture (integration time) and transfer to the storage area, readout is performed by shifting charge row by row into the serial register located below the storage area. The serial register contains 1036 active pixels and 9 dummy pixels, with a maximum data rate of 40 million pixels per second. When a full flush of the storage area is required, charge can be rapidly shifted through the serial register into a clear drain located below the register.

A high-performance bulk charge detection (BCD) node converts the charge from each pixel into an output voltage. A low-noise, two-stage source-follower amplifier further buffers the signal before it reaches the output pin. The device readily supports a 30-frames-per-second readout rate.

This MOS device incorporates limited gate protection. During storage or handling, device pins should be shorted together or the device placed in conductive foam. In circuit, unused inputs must always be connected to VSS. Under no circumstances should pin voltages exceed the absolute maximum ratings. Shorting OUT to VSS during operation should be avoided to prevent amplifier damage. The device may also be damaged if the output terminal is reverse biased and excessive current is allowed to flow. For specific guidelines on handling such devices, refer to the Electrostatic Discharge Sensitive (ESDS) Devices and Assemblies Handling Guide provided by Texas Instruments.

The sensor's anti-blooming protection is based on an advanced lateral overflow drain (ALOD). Anti-blooming is activated by applying an appropriate DC bias to the overflow drain pin. This type of anti-blooming protection also enables a full flush of charge from the image area, which can be accomplished by applying a single 10V pulse of at least 1μs duration to the overflow drain pin.

The TC281 image sensor employs Texas Instruments' proprietary advanced virtual phase (AVP) technology, advanced lateral overflow drain, and BCD detection node. These features give Texas Instruments imaging devices high blue response, high near-infrared sensitivity, low dark current, high photoresponse uniformity, and single-phase clocking. The TC281 operates over a temperature range of -10°C to 45°C.

The TC281 image sensor consists of five basic functional blocks: image sensing area, ALOD, storage area, serial register, and BCD node with buffered output amplifier.

The image sensing area contains 1036×1010 pixel cells. A metal light shield covers 28 pixels at the left edge, 8 pixels at the right edge, and 10 rows at the bottom of the sensing area. Dark pixel signals serve as black references during video signal processing. Dark references accumulate dark current at the same rate as active photosensitive sites, representing a true black-level signal. When light enters the active photosensitive sites of the image area, electron-hole pairs are generated and electrons are collected in the pixel potential wells. These potential wells have a finite charge storage capacity determined by the pixel design. When the number of electrons generated in an illuminated pixel exceeds this limit, electrons may overflow into adjacent pixels and cause blooming. To prevent this, each pair of horizontal pixels in the image sensing area shares a lateral overflow drain structure that provides up to 1000:1 anti-blooming capability.

• Low dark current
• Advanced lateral overflow drain for anti-blooming
• Single-pulse image area clearing capability
• Dynamic range exceeding 60dB
• High sensitivity and quantum efficiency
• Lossless charge detection via TI advanced BCD node technology
• High near-IR and blue light response
• Solid-state reliability — no image burn-in, image retention, image distortion, image lag, or microphonic effects