tc9455f TOSHIBA Semiconductor CORPORATION, tc9455f Datasheet - Page 5

• Manufacturer Part Number: tc9455f
• Description: Digital Echo Ic For Karaoke
• Manufacturer: TOSHIBA Semiconductor CORPORATION

3.
AD/DA converter and digital delay circuit
Figure 3 is a block diagram of the echo circuit.
The AD/DA converter is a 12-bit successive comparison type. The sampling frequency when the system
clock operates at 4 MHz is 32 kHz.
The analog signal input from the AD converter is converted to 12-bit digital data. The digital delay circuit
compresses the 12-bit signal to 4-bit, writes it to delay RAM, then reads it. The 4-bit data read from delay
RAM is de-compressed to 12-bit. The 12-bit data are converted to analog signals by the DA converter and
output.
The area for delay RAM memory is 4096 words × 4 bits.
The echo delay time is 4096 words × (1/32 kHz) = 128 ms.
Figure 3 Block diagram of echo circuit
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TC9455,88F/N
2002-02-05