SAA4956TJ

The SAA4956TJ is a 2949264-bit field memory with an optional field based noise reduction designed for advanced TV applications such as 100/120 Hz TV, PALplus, PIP and 3D comb filter. The SAA4956TJ is functional and pin compatible with the SAA4955TJ. However, the SAA4956TJ has also, in addition to the field memory function, a field based noise reduction circuit. If this function is enabled it can be controlled via the I2C-bus. The maximum storage depth is 245772 words× 12 bits.

A FIFO operation with full word continuous read and write could be used as a data delay, for example. A FIFO operation with asynchronous read and write could be used as a data rate multiplier. Here the data is written once, then read as many times as required as long as new data is not written. In addition to the FIFO operations, a random block access mode is accessible during the pointer reset operation. When this mode is enabled, reading and/or writing may begin at, or proceed from, the start address of any of the 6144 blocks. Each block is 40 words in length. Two or more SAA4956TJs can be cascaded to provide a greater storage depth or a longer delay, without the need for additional circuitry.

The SAA4956TJ contains separate 12-bit wide serial ports for reading and writing. The ports are controlled and clocked separately, so asynchronous read and write operations are supported. Independent read and write clock rates are possible. Addressing is controlled by read and write address pointers. Before a controlled write operation can begin, the write pointer must be set to zero or to the beginning of a valid address block. Likewise, the read pointer must be set to zero or to the beginning of a valid address block before a controlled read operation can begin.