DS726PP2
45
CS4525
6.1.7
Powered PWM Outputs
The CS4525’s 3 internal modulators can be used to generate multiple powered PWM output configura-
tions to enable a wide variety of system implementations. The CS4525 also implements PWM Popguard
to minimize output transients in half-bridge configurations.
6.1.7.1
Output Channel Configurations
Three PWM power output configurations are supported as shown in
below. The configurations
support stereo full-bridge, stereo half-bridge with full-bridge sub, and mono parallel full-bridge output.
The configurations are selected by the OutputCfg[1:0] bits in the Output Cfg register and must only be
changed when the device is in power-down mode (the PDnAll bit is set). Any attempt to write the Out-
putCfg[1:0] bits while the device is powered-up will be ignored.
It should be noted that signals on channels 1, 2 and the sub channel are dependent upon the digital sound
processing blocks being used. For instance, if the 2-way crossover is enabled, channel 1 and 2 contain
the 2-way crossover channel A high- and low-pass outputs respectively. For more information, see the
section and
6.1.7.2
PWM Popguard Transient Control
The CS4525 uses Popguard technology to minimize the effects of power-up and power-down output tran-
sients commonly produced by half-bridge, single supply amplifiers implemented with external DC-block-
ing capacitors connected in series with the audio outputs.
PWM Popguard operates by linearly ramping the PWM power outputs up to and down from their bias point
of VP/2 when a channel is powered up and down respectively using the PDnOutX or PDnAll bits. This
OutputCfg[1:0]
Power Configuration
Output Signal
Output Pin(s)
00
2 Ch. Full-Bridge
Channel 1 +
Channel 1 -
Channel 2 +
Channel 2 -
OUT1
OUT2
OUT3
OUT4
01
2 Ch. Half-Bridge
+
1 Ch. Full-Bridge
Channel 1 +
Channel 2 +
Sub C
Sub Channel -
OUT1
OUT2
OUT3
OUT4
10
1 Ch. Parallel Full-Bridge
Channel 1 +
Channel 1 -
OUT1, OUT2
OUT3, OUT4
Table 8. PWM Power Output Configurations
Referenced Control
Register Location
OutputCfg[1:0].....................
“Output Configuration (OutputCfg[1:0])” on page 73
PDnAll .................................