WM8594_07 Wolfson Microelectronics Ltd., WM8594_07 Datasheet - Page 75

• Manufacturer Part Number: WM8594_07
• Description: 24-bit 192khz 2vrms Multi-channel Codec
• Manufacturer: Wolfson Microelectronics Ltd.

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RECOMMENDED ANALOGUE LOW PASS FILTER
EXTENDED INPUT IMPEDANCE CONFIGURATION
w
Note: See WAN0176 for AC coupling capacitor selection information.
An external single pole RC filter is recommended (see Figure 63) if the device is driving a wideband
amplifier. Other filter architectures may provide equally good results.
Note: See WAN0176 for AC coupling capacitor selection information.
The input impedance to the WM8594 is specified in the Electrical Characteristics section beginning
on p7, and is fixed across gain setting and signal routing options. If this input impedance is not
enough for the intended application, an alternative input configuration (Figure 64) is possible.
This configuration increases the input impedance to the WM8594 by 10kΩ, but reduces the overall
gain in the ADC and Bypass paths by -6dB. In order to compensate for this reduction in gain, +6dB
of gain should be set in the ADC Input PGA (by using ADC_AMP_VOL[1:0]) and in the bypass PGA
(by using PGAxx_VOL[7:0]).
Examples:
Figure 63 Recommended Analogue Low Pass Filter (shown for VOUT1L/R)
Figure 64 Extended Input Impedance Configuration
•
•
If a 2V
PGA1L and PGA1R, then setting PGA1L_VOL[7:0] and PGA1R_VOL[7:0] =0x00 is necessary to
see 2V
If a 2V
ADC_AMP_VOL[1:0]=10 is necessary to see 0dBFS at the ADC outputs.
RMS
RMS
RMS
at VOUT1L and VOUT1R.
signal is applied to VIN1L and VIN1R and routed to ADCL and ADCR, then setting
signal is applied to VIN1L and VIN1R and routed to VOUT1L and VOUT1R using
Ω
Ω
Ω
Ω
Ω
Ω
PP Rev 1.0 January 2007
WM8594
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