wm9714l Wolfson Microelectronics plc, wm9714l Datasheet - Page 111

• Manufacturer Part Number: wm9714l
• Description: Ac?97 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
LINE OUTPUT
AC-COUPLED HEADPHONE OUTPUT
w
The headphone outputs, HPL and HPR, can be used as stereo line outputs. The speaker outputs,
SPKL and SPKR, can also be used as line outputs. Recommended external components are shown
below.
Figure 29 Recommended Circuit for Line Output
The DC blocking capacitors and the load resistance together determine the lower cut-off frequency,
fc. Assuming a 10 kΩ load and C1, C2 = 10µF:
fc = 1 / 2π (R
Increasing the capacitance lowers fc, improving the bass response. Smaller values of C1 and C2 will
diminish the bass response. The function of R1 and R2 is to protect the line outputs from damage
when used improperly.
The circuit diagram below shows how to connect a stereo headphone to the WM9714L.
Figure 30 Simple Headphone Output Circuit Diagram
The DC blocking capacitors C1 and C2 together with the load resistance determine the lower cut-off
frequency, fc. Increasing the capacitance lowers fc, improving the bass response. Smaller
capacitance values will diminish the bass response. For example, with a 16Ω load and C1 = 220µF:
fc = 1 / 2π R
L
L
C
+R
1
= 1 / (2π x 16Ω x 220µF) = 45 Hz
1
) C
1
= 1 / (2π x 10.1kΩ x 1µF) = 16 Hz
PP, Rev 3.2, October 2008
WM9714L
111