WM8593 datasheet(95/98 Pages) WOLFSON

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WM8593

PP Rev 1.0 January 2007

RECOMMENDED ANALOGUE LOW PASS FILTER

Ω

Figure 72 Recommended Analogue Low Pass Filter (shown for VOUT1L/R)

Note: See WAN0176 for AC coupling capacitor selection information.

An external single pole RC filter is recommended (see Figure 72) if the device is driving a wideband

amplifier. Other filter architectures may provide equally good results.

EXTENDED INPUT IMPEDANCE CONFIGURATION

Ω

Figure 73 Extended Input Impedance Configuration

Note: See WAN0176 for AC coupling capacitor selection information.

The input impedance to the WM8593 is specified in the Electrical Characteristics section beginning

on p8, 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 73) is possible.

This configuration increases the input impedance to the WM8593 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:

•

If a 2VRMS signal is applied to VIN1L and VIN1R and routed to VOUT1L and VOUT1R using

PGA1L and PGA1R, then setting PGA1L_VOL[7:0] and PGA1R_VOL[7:0] =0x00 is necessary to

see 2VRMS at VOUT1L and VOUT1R.

•

If a 2VRMS signal is applied to VIN1L and VIN1R and routed to ADCL and ADCR, then setting

ADC_AMP_VOL[1:0]=10 is necessary to see 0dBFS at the ADC outputs.

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