GA3284 Datasheet, PDF (12/15 Pages) ON Semiconductor – Pre-configured DSP System

INSPIRIA GA3284
change operation the selected tone beeps a code to indicate
which memory was selected. The beep sequence is 160 ms
ON, followed by 160 ms OFF, between the beeps. The
memory change beeping code is deciphered in Table 6.
Table 6. MEMORY CHANGE BEEPING CODE
Selected Memory
# Beeps
A
1
B
2
C
3
D
4
Tone Generator
The programmable tone generator is capable of tones of
various amplitudes and frequencies. Upon reception of the
tone enable instruction, the Inspiria GA3284 connects the
output of the tone generator to the input of the D/A converter.
The programmed tone is then output until a tone disable
instruction is issued. When disabled, the normal audio signal
is again connected.
Memory Switch Fader
To minimize potential loud transients when switching
between memories, the Inspiria GA3284 uses a memory
switch fader block. When the memory is changed, the audio
signal is faded out, followed by the memory select indicator
beeps (if enabled), and after switching to the next memory,
the audio signal is faded back in. The memory switch fader
is also used when turning the Tone Generator on or off, and
during SDA programming.
Power−On/Power−Off Behaviour and Low Battery
Indicator
During power−on, the Inspiria GA3284 hybrid is held in
a reset state until the supply voltage (V_b) reaches a turn−ON
threshold. A small portion of the hybrid’s internal control
logic turns on and monitors the voltage to determine if the
supply is stable. Once the supply is stable, the entire hybrid
is activated and loads its configuration. Finally, the audio
output turns on by smoothly transitioning to the expected
output level.
During normal operation, when a low battery condition is
detected, the Inspiria GA3284 hybrid sends out a series of
one to seven beeps (each beep is 512 ms ON and 512 ms
OFF) to indicate the battery is low. This is repeated every
five minutes until the device reaches the turn−OFF
threshold. The low battery threshold is programmable in
IDS between 1.0 V and 1.2 V in 10 mV increments.
If V_b drops below the turn−OFF threshold, then the
Inspiria GA3284 hybrid is returned to its reset state and the
audio output is muted. After a reset due to a low battery or
a sudden supply transient, the recovery behaviour of the
Inspiria GA3284 is determined by the selectable reset mode
through ARKonline.
There are four selectable reset modes as follows:
• Shallow−reset mode − After a low battery shutdown or
transient shutdown, it allows the Inspiria GA3284
hybrid to immediately restart when the supply voltage
rises above the turn−ON threshold. The device restarts
in the memory that was last active when the shut down
occurred. In summary, the device functions until the
supply voltage drops below the turn−OFF threshold,
and recovers when the device rises above the turn−ON
threshold again.
• Deep−reset mode − After a low battery shutdown or
transient shutdown, it does not allow the Inspiria
GA3284 hybrid to restart. When a shutdown occurs
(i.e., the supply voltage drops below the turn−OFF
threshold), the device remains off until the supply
voltage drops below approximately 0.3 V and
subsequently rises above the turn−ON threshold. For
the supply to drop below 0.3 V, the battery should be
disconnected. Upon reconnecting the battery
(preferably a new battery) the supply voltage rises
above the turn−ON threshold, and depending if the
supply is stable, the device restarts.
• Mixed mode − A combination of the first two modes.
The device starts up in shallow−reset mode initially,
then transitions to deep reset mode after five minutes.
• Advanced reset mode (recommended) − A more
advanced combination of the first two modes, plus
some additional intelligence. The device starts up in
shallow−reset mode initially, so that after a low battery
shutdown or a transient shutdown, the device
immediately restarts when the supply voltage rises
above the turn−ON threshold. When the device restarts,
deep−reset mode is applied and the device operates in
the memory that was last active when the shut down
occurred. Additionally, the maximum output level is
reduced through a 2 dB reduction of the AGC−O and
peak clipper. This operating condition is defined as
transient reboot mode. The device operates in transient
reboot mode (i.e., deep−reset mode and maximum
output reduction are applied) while monitoring the
supply voltage. If the supply voltage remains above the
turn−ON threshold for at least 30 secs, the device is
allowed to exit transient reboot mode. The device
returns to shallow−reset mode and the maximum output
is restored.
Generally, any low battery shutdown or transient
shutdown that occurs while in shallow−reset mode (or while
in the shallow−reset mode component of mixed mode or
advanced reset mode) results in the Inspiria GA3284 hybrid
restarting into the memory that was last active when the shut
down occurred. The Inspiria GA3284 hybrid has this
memory restart capability for up to three memories. A restart
in any memory beyond the first three memories causes the
device to restart in the initial memory, similar to the
behaviour when a battery is first connected. The advanced
www.onsemi.com
12