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GA3284 Datasheet, PDF (10/15 Pages) ON Semiconductor – Pre-configured DSP System | |||
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INSPIRIA GA3284
refer to the Biquad Filters In PARAGON Digital Hybrid
information note.
Volume Control
The Volume Control (VC) can be either external or
programmable. If VC is programmed for external operation,
a variable resistor should be connected to the 9 bit A/D
converter.
The external VC can be configured to work with either a
twoâterminal 200 kW variable resistor or a threeâterminal
0.1 MW â1 MW variable resistor. In twoâterminal
configuration, the VC is connected between GND and the
VC input. In threeâterminal configuration, it is connected
between GND, Vreg and the VC input.
If using a twoâterminal VC, it must be calibrated before
use. Calibration is not necessary with a threeâterminal
connection. Hysteresis is built into the VC circuitry to
prevent unintentional volume level toggling. A log taper
potentiometer is recommended so that gain in dB would be
linear with potentiometer rotation. The range of VC is
adjustable and can be set between 1 dB (min) and 42 dB
(max).
AGCâO and Peak Clipper
The output compressionâlimiting block (AGCâO) is an
output limiting circuit whose compression ratio is fixed at
â:1. The threshold level is programmable. The AGCâO
module has programmable attack and release time
constants.
The AGCâO on the Inspiria GA3284 has optional
adaptive release functionality. When this function is
enabled, the release time varies depending on the
environment. In general terms, the release time becomes
faster in environments where the average level is well below
the threshold and only brief intermittent transients exceed
the threshold.
Conversely, in environments where the average level is
close to the AGCâO threshold, the release time applied to
portions of the signal exceeding the threshold is longer. The
result is an effective low distortion output limiter that clamps
down very quickly on momentary transients but reacts more
smoothly in loud environments to minimize compression
pumping artifacts. The programmed release time is the
longest release time applied, while the fastest release time is
16 times faster. For example, if a release time of 128 ms is
selected, the fastest release time applied by the AGCâO
block is 8 ms.
The Inspiria GA3284 also includes the Peak Clipper block
for added flexibility.
Memory Select Switches
One or two, twoâpole Memory Select (MS) switches can
be used with the Inspiria GA3284. This enables users
tremendous flexibility in switching between configurations.
These switches may be either momentary or static and are
configurable to be either pullâup or pullâdown through the
settings tab in IDS.
Up to four memories can be configured on the Inspiria
GA3284. Memory A must always be valid. All memory
select options are selectable via the settings tab in IDS.
Momentary Switch on MS
This mode uses a single momentary switch on MS (Pin4)
to change memories. Using this mode causes the part to start
in memory A, and whenever the button is pressed, the next
valid memory is loaded. When the user is in the last valid
memory, a button press causes memory A to be loaded.
This mode is set by programming the âMSSModeâ
parameter to âMomentaryâ and âDonlyâ to âdisabledâ.
Example:
If 4 valid memories: ABCDABCDAâ¦
If 3 valid memories: ABCABCAâ¦
If 2 valid memories: ABABAâ¦
If 1 valid memories: AAAâ¦
Momentary Switch on MS, Static Switch on MS2 (Jump
to Last Memory)
This mode uses a static switch on MS2 (Pin5) and a
momentary switch on MS (Pin4) to change memories. If the
static switch is OPEN, the part starts in memory A and
behaves like momentary, with the exception that memory D
is not used. If the static switch on MS2 is set to HIGH, the
part automatically jumps to memory D (occurs on startâup
or during normal operation). In this setup, the momentary
switchâs state is ignored, preventing memory select beeps
from occurring. When MS2 is set to OPEN, the part loads in
the last select memory.
This mode is set by programming the âMSSModeâ
parameter to âMomentaryâ and âDonlyâ to âenabledâ.
www.onsemi.com
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