CS42L55 Datasheet, PDF (30/73 Pages) Cirrus Logic – Ultra Low Power, Stereo CODEC w/Class H Headphone Amp

CS42L55
+VCP
Ideal Transition
+VCP
2
-VCP
2
Actual Transition caused
by VHPFILT Capacitor
Actual Transition caused
by VHPFILT Capacitor
Time
-VCP
Ideal Transition
Figure 15. VHPFILT Transitions
When the charge pump transitions from the higher set of rail voltages to the lower set, there is a one sec-
ond delay before the charge pump supplies the lower rail voltages to the amplifiers. This hysteresis en-
sures that the charge pump doesn't toggle between the two rail voltages as signals approach the clip
threshold. It also prevents clipping in the instance of repetitive high level transients in the input signal. The
timing diagram for this transitional behavior is detailed in Figure 16.
Output Level
-10 dB
1 second
Time
Amplifier Rail
Voltage
VCP
VCP
2
- VCP
2
- VCP
Time
Figure 16. VHPFILT Hysteresis
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