2002 May 22 7
Philips Semiconductors Product specification
Low power audio DAC UDA1334BT
8 FUNCTIONAL DESCRIPTION
8.1 System clock
TheUDA1334BT operates in slave mode only; this means
thatin all applications the system must provide the system
clock and the digital audio interface signals
(BCK and WS).
Thesystem clock must be locked in frequency to the digital
interface signals.
The UDA1334BT automatically detects the ratio between
the SYSCLK and WS frequencies.
The BCK clock can be up to 64fs, or in other words the
BCK frequency is 64 times the Word Select (WS)
frequency or less: fBCK ≤64 ×fWS.
Remarks:
1. The WS edge MUST fall on the negative edge of the
BCK at all times for proper operation of the digital I/O
data interface
2. For LSB-justified formats it is important to have a WS
signal with a duty factor of 50%.
The modes which are supported are given in Table 1.
Table 1 Supported sampling ranges
Notes
1. This mode can only be supported for power supply
voltages down to 2.4 V. For lower voltages, in
192fsmode the sampling frequency should be limited
to 55 kHz.
2. Not supported in the low sampling frequency mode.
An example is given in Table 2 for a 12.228 MHz system
clock input.
Table 2 Example using a 12.228 MHz system clock
Note
1. This mode can only be supported for power supply
voltages down to 2.4 V. For lower voltages, in 192fs
mode the sampling frequency should be limited to
55 kHz.
8.2 Interpolation filter
The interpolation digital filter interpolates from 1fsto 64fs
by cascading FIR filters (see Table 3).
Table 3 Interpolation filter characteristics
8.3 Noise shaper
The 5th-order noise shaper operates at 64fs. It shifts
in-band quantization noise to frequencies well above the
audio band. This noise shaping technique enables high
signal-to-noise ratios to be achieved. The noise shaper
output is converted into an analog signal using a
Filter Stream DAC (FSDAC).
CLOCK MODE SAMPLING RANGE
768fs8to55kHz
512fs8 to 100 kHz
384fs8 to 100 kHz
256fs8 to 100 kHz
192fs8 to 100 kHz(1)(2)
128fs8 to 100 kHz(2)
CLOCK MODE SAMPLING FREQUENCY
128fs96 kHz
192fs64 kHz(1)
256fs48 kHz
384fs32 kHz
512fs24 kHz
768fs16 kHz
ITEM CONDITION VALUE (dB)
Pass-band ripple 0to 0.45fs±0.02
Stop band >0.55fs−50
Dynamic range 0to 0.45fs>114