Cirrus Logic CS44800 - Manual (Page 54)

54 DS632F1
CS44800
7.5.4 De-Emphasis Control (DEM[1:0])
Default = 00
00 - no de-emphasis
01 - 32 kHz de-emphasis filter
10 - 44.1 kHz de-emphasis filter
11 - 48 kHz de-emphasis filter
Function:
Enables the appropriate digital filter to maintain the standard 15 ms/50 ms digital de-emphasis filter re-
sponse.
7.6 Ramp Configuration (address 05h)
7.6.1 Ramp-Up/Down Setting (RAMP[1:0])
Default = 00
00 - Ramp-up and ramp-down are disabled
01 - Ramp-up is disabled. Ramp-down is enabled.
10 - Reserved
11 - Ramp-up and ramp-down are enabled. Note that after a ramp-up sequence has completed, audio will
not play until RAMP[1:0] is set to 01.
Function:
When ramping is enabled, the duty cycle of the output PWM signal is increased (ramp-up) or decreased
(ramp-down) at a rate determined by the Ramp Speed variable (RAMP_SPDx). This function is used in
single-ended applications to reduce pops in the output caused by the DC-blocking capacitor. When the
ramp-up/down function is disabled in single-ended applications, there will be an abrupt change in the out-
put signal. Refer to Section 5.1.1
.
If ramp-up or down is not needed, as in a full-bridge application, these bits should be set to 00. If ramp-
up or down is needed, as in a single-ended half-bridge application, these bits must be used in the proper
sequence as outlined in
“Recommended Power-Up Sequence” on page 43 and “Recommended Power-
Down Sequence” on page 45 .
7.6.2 Ramp Speed (RAMP_SPD[1:0])
Default = 01
00 - Ramp speed = approximately 0.1 seconds
01 - Ramp speed = approximately 0.2 seconds
10 - Ramp speed = approximately 0.3 seconds
11 - Ramp speed = approximately 0.65 seconds
Function:
This feature is used in single-ended applications to reduce pops in the output caused by the DC-blocking
capacitor. The Ramp Speed sets the time for the PWM signal to linearly ramp-up and down from the bias
point (50% PWM duty cycle). Refer to Section 5.1.1
7 6 5 4 3 2 1 0
RESERVED RESERVED RESERVED RAMP1 RAMP0 RESERVED RAMP_SPD1 RAMP_SPD0