STA304 STMicroelectronics, STA304 Datasheet - Page 10
STA304
Manufacturer Part Number
STA304
Description
Audio DSPs Digital Audio Proc
Manufacturer
STMicroelectronics
Datasheet
1.STA304.pdf
(31 pages)
Specifications of STA304
Mounting Style
SMD/SMT
Package / Case
TQFP-44
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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STA304
5.0 DDX OUTPUT SWITCHING
The 5 DDX output (L,R,SL,SR,LFE) are ternary modulated PWM, designed to drive directly STA50X power
bridge ICs or any custom discrete power. The PWM output frame is delayed from channel to channel in order
to reduce the crosstalk at the stereo STA50X device at low audio dynamics. The PWM order in the STA304 is:
with 32 ticks (of master clock) or ~640ns between the beginning of each PWM frame (frame period is ~2.6usec).
The LFE PWM signal is independently generated (synchronous with LS PWM output), because it is intended to
be used alone on a mono-configured STA50x IC (no crosstalk issues).
In this way the low-modulated level PWM signal of different channels switches when the others are at zero level,
so when the output power is in dump state (both terminals of the speaker loads are connected to ground), caus-
ing no noise cross-injection.
Best performances are obtained when only front channels (L/R) or rear channels (SL/SR) are fed to a single
STA50X device, because the PWM frames of L an R have the maximum distance of ~1.3usec (same for SL and
SR).
Of course crosstalk is anyway removed with a good power supply design/layout for STA50x ICs (low impedance
stage and low inductance loop between powerVDD and GND). See application notes for more details
10/31
– L
– LS
– R
– RS