WM8904ECSSLASHR datasheet(79/188 Pages) WOLFSON

79 / 188 page

Pre-Production

WM8904

PP, Rev 3.3, September 2012

ANALOGUE OUTPUTS

The WM8904 has four analogue output pins:



Headphone outputs, HPOUTL and HPOUTR, with feedback HPOUTFB



Line outputs, LINEOUTL and LINEOUTR, with feedback LINEOUTFB

The output signal paths and associated control registers are illustrated in Figure 37.

HEADPHONE OUTPUTS – HPOUTL AND HPOUTR

The headphone outputs are designed to drive 16Ω or 32Ω headphones. These outputs are ground-

referenced, i.e. no series capacitor is required between the pins and the headphone load. They are

outputs is controlled as shown in Table 45.

The ground-referenced outputs incorporates a common mode, or ground loop, feedback path which

provides rejection of system-related ground noise. The return path for the HPOUTL and HPOUTR

outputs is via HPOUTFB. This pin must be connected to ground for normal operation of the

headphone output. No register configuration is required.

LINE OUTPUTS – LINEOUTL AND LINEOUTR

The line outputs are identical to the headphone outputs in design. They are ground-referenced and

Table 46.

Note that these outputs are intended for driving line loads, as the charge pump powering both the

Headphone and Line outputs can only provide sufficient power to drive one set of headphones at any

given time.

The ground-referenced outputs incorporates a common mode, or ground loop, feedback path which

provides rejection of system-related ground noise. The return path for the LINEOUTL and LINEOUTR

outputs is via LINEOUTFB. This pin must be connected to ground for normal operation of the line

output. No register configuration is required.

WM8904ECS/R Datasheet(PDF) 79 Page - Wolfson Microelectronics plc