Texas Instruments TC237H, TC237 Datasheet

TC237

680- × 500-PIXEL CCD IMAGE SENSOR

SOCS044B – JUNE 1994 – REVISED JUNE 1996

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Very High-Resolution, 1/3-in Solid-State Image Sensor for NTSC Black and White Applications

340,000 Pixels per Field

Frame Memory

658 (H) × 496 (V) Active Elements in Image Sensing Area Compatible With Electronic Centerin

Multimode Readout Capability – Progressive Scan – Interlaced Scan – Dual-Line Readout – Image-Area Line Summing – Smear Subtraction

Fast Single-Pulse Clear Capability

Continuous Electronic Exposure Control From 1/60 – 1/50,000 s

7.4-µm Square Pixels

Advanced Lateral-Overflow-Drain Antiblooming

Low Dark Current

High Dynamic Range

High Sensitivity

High Blue Response

Solid-State Reliability With No Image Burn-In, Residual Imaging, Image Distortion, Image Lag, or Microphonics

description

The TC237 is a frame-transfer, charge-coupled device (CCD) image sensor designed for use in single-chip black and white NTSC TV, computer, and special-purpose applications requiring low cost and small size.

The image-sensing area of the TC237 is configured into 500 lines with 680 elements in each line. Twenty-two elements are provided in each line for dark reference. The blooming-protection feature of the sensor is based on an advanced lateral-overflow-drain concept. The sensor can be operated in a true-interlace mode as a 658(H) × 496(V) sensor with a very low dark current. One important feature of the TC237 very high-resolution sensor is the ability to capture a full 340,000 pixels per field. The image sensor also provides high-speed imagetransfer capability. This capability allows for a continuous electronic exposure control without the loss of sensitivity and resolution inherent in other technologies. The charge is converted to signal voltage at 20 µV per electron by a high-performance structure with a reset and a voltage-reference generator. The signal is further buffered by a low-noise, two-stage, source-follower amplifier to provide high output-drive capability.

The TC237 is built using TI-proprietary advanced virtual-phase (A VP) technology , which provides devices with high blue response, low dark signal, good uniformity, and single-phase clocking. The TC237 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 VSS. Under no circumstances should pin voltages exceed absolute maximum ratings. Avoid shorting OUT to VSS 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.

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

DUAL-IN-LINE PACKAGE

(TOP VIEW)

ODB 1

IAG2 2

SUB 3

ADB 4 OUT1 5 OUT2 6

12 IAG1 11 SAG 10 SAG 9 SUB 8 SRG 7 RST

TC237 680- × 500-PIXEL CCD IMAGE SENSOR

SOCS044B – JUNE 1994 – REVISED JUNE 1996

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

functional block diagram

Image Area With

Blooming Protection

Dark Reference Elements

Storage Area

Clearing Drain

SUB

ODB

IAG2

ADB

OUT2

OUT1

Amplifiers

4 Dummy Elements

IAG1

SAG

SUB

SRG

RST

sensor topology diagram

Single-Phase Storage Area

Two-Phase Image-Sensing Area

422

Optical Black

(OPB)

4 22 658 Active Pixels

Dummy Pixels

658 Active Pixels

4 Dark Lines

22 Dark Reference Pixels

658 Active Pixels

496 Lines

500 Lines

TC237

680- × 500-PIXEL CCD IMAGE SENSOR

SOCS044B – JUNE 1994 – REVISED JUNE 1996

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Terminal Functions

TERMINAL

NAME NO.

I/O

DESCRIPTION

ADB 4 I Supply voltage for amplifier-drain bias IAG1 12 I Image-area gate 1 IAG2 2 I Image-area gate 2 ODB 1 I Supply voltage overflow-drain antiblooming bias OUT1 5 O Output signal 1 OUT2 6 O Output signal 2 RST 7 I Reset gate SAG 10, 11 I Storage-area gate SRG 8 I Serial-register gate SUB 3, 9 Substrate

detailed description

The TC237 consists of four basic functional blocks: the image-sensing area, the image-storage area, the serial register gates, and the low-noise signal processing amplifier block with charge-detection nodes and independent resets. The location of each of these blocks is identified in the functional block diagram.

image-sensing and storage areas

Figure 1 and Figure 2 show cross sections with potential-well diagrams and top views of the image-sensing and storage-area elements. As light enters the silicon in the image-sensing area, free electrons are generated and collected in the wells of the sensing elements. Blooming protection is provided by applying a dc bias to the overflow-drain bias pin. If it is necessary to clear the image before beginning a new integration time (for implementation of electronic fixed shutter or electronic auto-iris), it is possible to do so by applying a pulse at least 1 µs in duration to the overflow-drain bias. After integration is complete, the charge is transferred into the storage area; the transfer timing is dependent on whether the readout mode is interlace or progressive scan. If the progressive-scan readout mode is selected, the readout may be performed normally by utilizing one serial register or high speed by using both serial registers (see Figure 3 through Figure 5). A line-summing operation (which is useful in off-chip smear subtraction) may be implemented before the parallel transfer (see Figure 6 for line-summing timing).

There are 22 columns at the left edge of the image-sensing area that are shielded from incident light; these elements provide the dark reference used in subsequent video-processing circuits to restore the video black level. There are also four dark lines between the image-sensing and the image-storage area that prevent charge leakage from the image-sensing area into the image-storage area.

TC237 680- × 500-PIXEL CCD IMAGE SENSOR

SOCS044B – JUNE 1994 – REVISED JUNE 1996

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

3.8 µm

3.6 µm

7.4 µm

1.6 µm

Channel Stops

Including Metal Bus Lines

Clocked Barrier Clocked Well

Virtual Barrier

Antiblooming Device

Virtual Well Clocked Gate

Figure 1. Image-Area Pixel Structure

3.5 µm

7.4 µm

1.6 µm

Clocked Barrier

Clocked Well

Virtual Barrier

Virtual Well

Clocked Gate

1.6 µm

Channel Stops

Including Metal Bus Lines

Figure 2. Storage-Area Pixel Structure

TC237

680- × 500-PIXEL CCD IMAGE SENSOR

SOCS044B – JUNE 1994 – REVISED JUNE 1996

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Expanded Section of

Parallel Transfer

IAG1, 2

SAG

SRG

1 µs Minimum

684 Pulses

†

‡

ODB

IAG1, 2

SAG

SRG

RST

Clear Integrate Transfer to Memory Readout

250 Cycles

Figure 3. Interlace Timing

†

The number of parallel transfer pulses is field dependent. Field 1 has 500 pulses of IAG1, IAG2, SAG, and SRG with appropriate phasing. Field 2 has 501 pulses.

‡

The readout is from register 2.

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