FAB2210 Datasheet, PDF (12/35 Pages) Fairchild Semiconductor – Audio Subsystem with Class-G Headphone and 3.3W Mono Class-D Speaker with Dynamic Range Compression

Detailed Description
Shutdown Modes
Standby
When the SRST bit is set to 1, the FAB2210 enters a
low-power Standby Mode.
While SRST=1, I²C communications are available and
I²C values are reset to default values. Any values written
to the I²C registers (except SRST) while in Standby
Mode are ignored and default values is preserved.
To achieve low supply current during Standby Mode, all
inputs must be DC. Audio inputs must be AC grounded.
V_SVDD and V_DVDD must be within recommended
operating conditions. I²C pins must be grounded or
pulled HIGH with no toggling. If AC is presented to the
inputs during Standby Mode, standby current may
increase slightly, but there are no other negative effects.
Thermal Shutdown Protection (TSP)
If the junction temperature of the device exceeds the
thermal shutdown threshold of 150°C (see the Electrical
Characteristics table), the device protects itself by
turning off the amplifiers. The I²C port remains functional
and the OTP_ERR bit is set to 1. Other bits retain their
values and are not reset. See the Electrical
Characteristics table for output impedances. The
amplifiers remain off until the junction temperature falls
below the thermal shutdown recovery point and SRST is
cycled or power is cycled.
Over-Current Protection (OCP)
If the speaker amplifier’s output current limit of 1.3A_PEAK
is exceeded (see the Electrical Characteristics table),
the amplifier turns off. During current-limit shutdown, the
I²C port remains functional and the OCP_ERR bit is set
to 1. Other bits retain their values and are not reset. The
speaker amplifier remains off and the OCP_ERR
remains HIGH until SRST is cycled or power is cycled.
DC Output Protection
If the magnitude of the speaker amplifier output voltage
across SOUT+ and SOUT- exceeds the DC detect
voltage of 1.5V_pk for more than t_DCERR (see the Electrical
Characteristics table), the speaker amplifier turns off.
This protects the loudspeaker from damage due to DC
signals. Low-frequency audio input signals may trigger
unintentional DC output shutdown. Set the input DC
coupling capacitor value small enough to avoid a DC
output shutdown caused by a low-frequency audio
signal. For the default t_DCERR setting of 2ms, the input
DC-coupling capacitor value must be 0.1F or lower.
During DC output shutdown, the I²C port remains
functional and the DC_ERR bit is set to 1. Other bits
retain their values and are not reset. The speaker
amplifier remains off and the DC_ERR bit remains HIGH
until SRST is cycled or power is cycled.
Signal Path
Audio signals pass from the input pins through a
preamplifier, a mixer, a volume control, and finally
through an amplifier. The preamplifiers can be set to
-3dB to 18dB of gain. The headphone and speaker
paths have volume controls that range from -64dB to
0dB. The headphone amplifier has gain settings of 0dB,
1.5dB, 3dB, and 6dB. The speaker amplifier has gain
settings of 16dB, 20dB, and 24dB.
A variety of combinations of the input signals can be
routed from the preamplifiers to the headphone and
speaker volume blocks. Routing is controlled by the
HP_AMIX, HP_BMIX, SP_AMIX, SP_BMIX, DIFA,
DIFB, and MONO bits.
For example, to connect the left headphone amplifier
channel to INA1 and the right headphone amplifier
channel to INA2, set HP_AMIX to 1. HP_BMIX, DIFA,
and MONO should be set to 0.
To configure INB1 and INB2 as a differential input and
route the signal to the speaker amplifier, set DIFB and
SP_BMIX to 1. SP_AMIX should be set to 0.
When HP_AMIX and HP_BMIX are both 0, the
headphone amplifier is off. When SP_AMIX and
SP_BMIX are both 0, the speaker amplifier is off.
Unused audio input pins must be grounded either
directly or through a DC-blocking capacitor.
To prevent internal clipping in the headphone amplifier
path, internal signal amplitudes from the preamplifier
outputs to the headphone amplifier input should not
exceed a peak-to-peak voltage equivalent to V_DVDD -
0.2V. If HP_MONO = 1, the peak-to-peak voltage can
be as high as (V_DVDD * 2) - 0.2V. Extra caution should be
taken if mixing signals together.
To prevent internal clipping in the speaker amplifier
path, internal signal amplitudes from the preamplifier
outputs to the speaker amplifier input should not exceed
a peak-to-peak voltage equivalent to V_DVDD - 0.2V. Extra
caution should be taken if mixing signals together.
© 2011 Fairchild Semiconductor Corporation
FAB2210 • Rev. 1.1.1
12
www.fairchildsemi.com