CS4525(2008) 查看數據表（PDF） - Cirrus Logic
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CS4525 Datasheet PDF : 98 Pages
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6.1.7
CS4525
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 Table 8 below. The configurations
support stereo full-bridge, stereo half-bridge with full-bridge sub, and mono parallel full-bridge output.
OutputCfg[1:0]
00
01
10
Power Configuration
2 Ch. Full-Bridge
2 Ch. Half-Bridge
+
1 Ch. Full-Bridge
1 Ch. Parallel Full-Bridge
Output Signal
Channel 1 +
Channel 1 -
Channel 2 +
Channel 2 -
Channel 1 +
Channel 2 +
Sub Channel +
Sub Channel -
Channel 1 +
Channel 1 -
Table 8. PWM Power Output Configurations
Output Pin(s)
OUT1
OUT2
OUT3
OUT4
OUT1
OUT2
OUT3
OUT4
OUT1, OUT2
OUT3, OUT4
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
Digital Sound Processing section and Figure 14 on page 29.
Referenced Control
Register Location
OutputCfg[1:0]..................... “Output Configuration (OutputCfg[1:0])” on page 73
PDnAll ................................. “Power Down (PDnAll)” on page 89
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.
The PWM Popguard feature 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 PD-
nAll bits. This gradual voltage ramp minimizes output transients while the DC blocking capacitor is
DS726PP3
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