2002 May 22 7
Philips Semiconductors Product specification
Low power audio DAC UDA1334BT
8 FUNCTIONAL DESCRIPTION
8.1 System clock
The UDA1334BT operates in slave mode only; this means
that in all applications the system must provide the system
clock and the digital audio interface signals
(BCK and WS).
The system clock mustbe locked infrequency to the digital
interface signals.
The UDA1334BT automatically detects the ratio between
the SYSCLK and WS frequencies.
The BCK clock can be up to 64f
s
, or in other words the
BCK frequency is 64 times the Word Select (WS)
frequency or less: f
BCK
≤ 64 × f
WS
.
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
192f
s
mode 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 192f
s
mode the sampling frequency should be limited to
55 kHz.
8.2 Interpolation filter
The interpolation digital filter interpolates from 1f
s
to 64f
s
by cascading FIR filters (see Table 3).
Table 3 Interpolation filter characteristics
8.3 Noise shaper
The 5th-order noise shaper operates at 64f
s
. 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
768f
s
8to55kHz
512f
s
8 to 100 kHz
384f
s
8 to 100 kHz
256f
s
8 to 100 kHz
192f
s
8 to 100 kHz
(1)(2)
128f
s
8 to 100 kHz
(2)
CLOCK MODE SAMPLING FREQUENCY
128f
s
96 kHz
192f
s
64 kHz
(1)
256f
s
48 kHz
384f
s
32 kHz
512f
s
24 kHz
768f
s
16 kHz
ITEM CONDITION VALUE (dB)
Pass-band ripple 0 to 0.45f
s
±0.02
Stop band >0.55f
s
−50
Dynamic range 0 to 0.45f
s
>114
