TC245 (OBSOLETE)

786- X 488-Pixel CCD Image Sensor

 

Description

The TC245 is a frame-transfer charge-coupled device (CCD) image sensor designed for use in single-chip B/W NTSC TV applications. The device is intended to replace a 1/2-inch vidicon tube in applications requiring small size, high reliability, and low cost.

The image-sensing area of the TC245 is configured into 242 lines with 786 elements in each line. Twenty-nine elements are provided in each line for dark reference. The blooming-protection feature of the sensor is based on recombining excess charge with charge of opposite polarity in the substrate. This antiblooming is activated by supplying clocking pulses to the antiblooming gate, which is an integral part of each image-sensing element. The sensor is designed to operate in an interlace mode, electronically displacing the image-sensing elements in alternate fields by one-half of a vertical line during the charge integration period, effectively increasing the vertical resolution and minimizing aliasing. The device can also be operated as a 755 (H) by 242 (V) noninterlaced sensor with significant reduction in the dark signal.

A gated floating-diffusion detection structure with an automatic reset and voltage reference incorporated on-chip converts charge to signal voltage. The signal is further processed by a low-noise, state-of-the-art correlated clamp-sample-and-hold circuit. A low-noise, two-stage, source-follower amplifier buffers the output and provides high output-drive capability. The image is read out through three outputs, each of which reads out every third image column.

The TC245 is built using TI-proprietary virtual-phase technology, which provides devices with high blue response, low dark signal, good uniformity, and single-phase clocking. The TC245 is characterized for operation from -10°C to 45°C.

This MOS device contains limited built-in gate protection. During storage or handling, the device leads should be shorted together or the device should be placed in conductive foam. In a circuit, unused inputs should always be connected to SUB. Under no circumstances should pin voltages exceed absolute maximum ratings. Avoid shorting OUTn to ADB during operation to prevent damage to the amplifier. The device can also be damaged if the output terminals are reverse-biased and an excessive current is allowed to flow. Specific guidelines for handling devices of this type are contained in the publication Guidelines for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices and Assemblies available from Texas Instruments.

Features

  • High-Resolution, Solid-State Image Sensor for NTSC B/W TV Applications
  • 8-mm Image-Area Diagonal, Compatible With 1/2" Vidicon Optics
  • 755 (H) x 242 (V) Active Elements in Image-Sensing Area
  • Advanced On-Chip Signal Processing
  • Low Dark Current
  • Electron-Hole Recombination Antiblooming
  • Dynamic Range . . . More Than 70 dB
  • High Sensitivity
  • High Photoresponse Uniformity
  • High Blue Response
  • Single-Phase Clocking
  • Solid-State Reliability With No Image Burn-in, Residual Imaging, Image Distortion, Image Lag, or Microphonics

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