WM8772EFT – 32 LEAD TQFP
Production Data
SUGGESTED ANALOGUE LOW PASS POST DAC FILTERS
It is recommended that a lowpass filter be applied to the output from each DAC channel for Hi Fi applications. Typically a
second order filter is suitable and provides sufficient attenuation of high frequency components (the unique low order, high
bit count multi-bit sigma delta DAC structure used in WM8772EFT produces much less high frequency output noise than
normal sigma delta DACs. This filter is typically also used to provide the 2x gain needed to provide the standard 2Vrms
output level from most consumer equipment.
Figure 59 shows a suitable post DAC filter circuit, with 2x gain. Alternative inverting filter architectures might also be used
with as good results.
1.0nF
10uF
1.8k
Ω
7.5kΩ
51Ω
VOUT1L
10kΩ
680pF
4.7kΩ
4.7kΩ
OP_FIL
VOUT1R
VOUT2L
VOUT2R
VOUT3L
VOUT3R
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
Figure 59 Recommended Post DAC Filter Circuit
PD Rev 4.2 October 2005
70
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
