Table of Contents
Advertisement
DP-7050
20
CIRCUIT DESCRIPTION
6. Digital Filter : SM5840CP (X32 : IC7)
Outline
This LSI is a digital filter for 8 times over-sampling
(interpolation) for a digital audio playback device. This is
LSI accepts not only 16 bit signals but also 18 bit sig-
nals, and outputs 16, 18 or 20 bit signals. Accordingly,
this LS! can be a wide interface.
In addition, this LSI has the digital de-emphasis
function matched to 3fs, the noise shaping function to
reduce re-quantized noises, etc.
Features and functions
* 2 channel processing
* §8 times over-sampling (interpolation) (Hereinafter
referred to as 8fs)
¢
Digital de-emphasis
(Matched
to 3fs of 48kHz,
44.1kHz and 32kHz)
¢ Serial input data
2's complementary, MSB first, selection of 16 or 18
bit signal.
¢ Serial output data
MSB first, 2's complementary, selection of 16 or 18
bit signal.
6-1. Block diagram
DE-EMPHASIS CONTROL
VO DATA
e Primary noise shaper (Turned on only when 16 or 18
bit signal is output)
Selection of system clock of 256fs or 384fs
Input / Output TTL compatible
Signal power source of 5V (Standard)
Can be operated with low voltage (3.2V)
18 pin plastic DIP
Composition of filter
e interpolation of filter (Straight line phase FIR filters
of 3 stages)
1st stage (fs —-=
2fs) : Degree 69
2nd stage (2fs —-~ 4fs) : Degree 13
3rd stage (4fs —=
8fs) : Degree 9
¢ De-emphasis filter
Accurate gain and phase characteristics are ob-
tained by the composition of IIR filter
e Highly accurate calculation with (19 x 14) bit parallel
multiplier and 24 bit accumulator
¢
Built in overflow limiter
INPUT DATA
INTERFACE
CALCULATOR BLOCK
INPUT OUTPUT DATA
INTERFACE
Advertisement
Table of Contents
