G1432 Datasheet, PDF (12/15 Pages) Global Mixed-mode Technology Inc – 2W Stereo Audio Amplifier

Global Mixed-mode Technology Inc.
G1432
Application Information
(TSSOP-24/QFN4X4-24 Pin No.)
Input MUX Operation
There are two input signal paths – IN1 & IN2. With the
prompt setting, the G1432 allows the setting of differ-
ent gains for different input sources. If setting the
IN1 /IN2 pin low, the IN1 input source is selected.
When setting the IN1 /IN2 pin high, the IN2 input
source is chosen.
Bridged-Tied Load Mode Operation
The G1432 has two linear amplifiers to drive both ends
of the speaker load in Bridged-Tied Load (BTL) mode
operation. Figure A shows the BTL configuration. The
differential driving to the speaker load means that
when one side is slewing up, the other side is slewing
down, and vice versa. This configuration in effect will
double the voltage swing on the load as compared to a
ground reference load. In BTL mode, the peak-to-peak
voltage V_O(PP) on the load will be two times than a
ground reference configuration. The voltage on the
load is doubled, this will also yield 4 times output
power on the load at the same power supply rail and
loading. Another benefit of using differential driving
configuration is that BTL operation cancels the dc off-
sets, which eliminates the dc coupling capacitor that is
needed to cancelled dc offsets in the ground reference
configuration. Low-frequency performance is then lim-
ited only by the input network and speaker responses.
Cost and PCB space can be minimized by eliminating
the dc coupling capacitors.
VDD
Vo(PP)
MUTE and SHUTDOWN Mode Operations
The G1432 implements the mute and shutdown
mode operations to reduce supply current, I_DD, to
the absolute minimum level during nonuse periods
for battery-power conservation. When the shutdown
pin (pin 8/5) is pulled high, all linear amplifiers will
be deactivated to mute the amplifier outputs. And
the G1432 enters an extra low current consumption
state, I_DD is smaller than 5µA. If pulling the mute pin
(pin 14/11) high, it will force the activated linear
amplifier to supply the VDD/2 dc voltage on the
output & shutdown the second linear amplifiers to
mute the AC performance. In the mute mode opera-
tion, the current consumption will be a smaller than
BTL modes. Shutdown and Mute pins should never
be left unconnected, this floating condition will
cause the amplifier operations unpredictable.
Maximum Power Clampping Function
The G1432 supports the maximum output power
clamping function to avoid damaging the speaker
when the amplifier output a power beyond the speaker
tolerance. The Vol pin (pin 23/20) is weakly pull-low
internally. If inputting a non-zero voltage (low bound-
ary voltage) to the Vol pin, the G1432 will generate a
high boundary voltage which the difference between
the VDD/2 and the high boundary voltage is the same
as the difference between the VDD/2 and the low
boundary voltage. ( i.e. V_OH – VDD/2 = VDD/2 – V_OL )
Then the outputs of linear amplifiers will be effectively
limited between the high/low boundary voltage, the
maximum output power is clamped. By setting the
voltage of Vol, the maximum output power can be well
controlled. When the maximum power clamping func-
tion is not used, the Vol pin should be floated or tied to
GND.
RL
VDD
2xVo(PP)
-Vo(PP)
Figure A
Ver: 1.1
Jun 21, 2006
TEL: [phone]
http://www.gmt.com.tw
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