CS43L43 datasheet(10/36 Pages) CIRRUS

10 / 36 page

CS43L43

DS479PP3

3.6.1 Power-up

When the device is initially powered-up, the audio outputs, HP_A and HP_B, are clamped to GND.

Following a delay of approximately 1000 sample periods, each output begins to ramp toward the qui-

escent voltage. Approximately 10,000 LRCK cycles later, the outputs reach VQ and audio output be-

gins. This gradual voltage ramping allows time for the external DC-blocking capacitors to charge to

the quiescent voltage, minimizing the power-up transient.

3.6.2 Power-down

To prevent transients at power-down, the device must first enter its power-down state by setting the

RST pin low. When this occurs, audio output ceases and the internal output buffers are disconnected

from HP_A and HP_B. In their place, a soft-start current sink is substituted which allows the

DC-blocking capacitors to slowly discharge. Once this charge is dissipated, the power to the device

may be turned off and the system is ready for the next power-on.

3.6.3 Discharge Time

To prevent an audio transient at the next power-on, the DC-blocking capacitors must fully discharge

before turning on the power or exiting the power-down state. If full discharge does not occur, a tran-

sient will occur when the audio outputs are initially clamped to GND. The time that the device must

remain in the power-down state is related to the value of the DC-blocking capacitance and the output

load. For example, with a 220 µF capacitor and a 16

Ω load, the minimum power-down time will be

approximately 0.4 seconds.

CS43L43 Datenblatt(PDF) 10 Page - Cirrus Logic