SN28835 1/2-INCH NTSC TIMER

SOCS023B - FEBRUARY 1991

features

• NTSC-Timing Operation
• Solid-State Reliability
• Color and Monochrome Operation
• Four Selectable Antiblooming Modes
• Variable-Integration-Time Option
• Surface-Mount Package
• Clamp Pulse-Select Option
• Horizontal and Vertical Resets for External Synchronization

description

The SN28835 is a monolithic integrated circuit designed to supply timing signals for the Texas Instruments 8-mm TC242/TC244 color and TC243/TC245 monochrome CCD image sensors. The SN28835 supplies both CCD-drive signals and NTSC-television synchronization signals at standard video rates. It requires a single 5-V supply voltage and a 14.318-MHz crystal oscillator input. The SN28835 provides the user with several options including multiple antiblooming modes, variable integration time, external synchronization, and delayed horizontal transfer.

The SN28835 is designed to drive the CCD image sensor through intermediary level-shifting devices such as the TI TMS3473B parallel driver and the SN28846 serial driver. It also supplies sample-and-hold signals for the TI TL1593 3-channel sample-and-hold circuit and multiplex signals for the TI TL1051 video preprocessor. The SN28835 NTSC synchronization-signal outputs include composite sync, composite blank, clamp, subcarrier, subcarrier delayed by 90 degrees, and burst flag.

The SN28835 is supplied in a 44-pin plastic flat package and is characterized for operation from -20°C to 45°C.

This device contains circuits to protect its inputs and outputs against damage due to high static voltages or electrostatic fields. These circuits have been qualified to protect this device against electrostatic discharges (ESD) of up to 2 kV according to MIL-STD-883C, Method 3015; however, precautions should be taken to avoid application of any voltage higher than maximum-rated voltages to these high-impedance circuits. 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 an appropriated logic voltage level, preferably either V_CC or ground. 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.

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