LC78857V Datasheet, PDF (5/11 Pages) Sanyo Semicon Device – Digital Audio D/A Converter IC with On-Chip Digital Filters

LC78857V
Circuit Operation
The LC78857V consists of three main blocks: the digital filter block, the sigma-delta D/A converter block, and the
analog filter block.
[Digital Filter Block]
The LC78857V performs the following calculations.
• Normal speed mode:
Input
Attenuator
Deemphas
is first-
order IIR
filter
31st-order
FIR filter
11th-order
FIR filter
3rd-order
FIR filter
To the sigma-delta
D/A converter
• Double speed mode:
This mode is used, for example, when dubbing a CD to cassette tape at double speed. Although the XIN has the same
frequency as normal speed mode, BCLK, LRCK, and DATA are input at twice the rate used in normal speed.
Input
Attenuator
Deemphas
is first-
order IIR
filter
31st-order
FIR filter
3rd-order
FIR filter
fs* = double speed input = 2 × fs.
To the sigma-delta
D/A converter
[Sigma-Delta D/A Converter Block]
This circuit accepts 8fs data input and outputs a 384fs 1-bit data sequence.
From the
digital filters
Front-end
interpolation
3rd-order
noise
shaper
PWM D/A
converter
1-bit output A
1-bit output B
[Analog Low-Pass Filter Block]
This block consists of an analog low-pass filter that consists of on-chip resistors, capacitors, and operational amplifiers.
This block converts the 384fs 1-bit data streams A and B directly to an analog voltage output.
1-bit output A
1-bit output B
No. 5537-5/11