max9788 Maxim Integrated Products, Inc., max9788 Datasheet - Page 7

• Manufacturer Part Number: max9788
• Description: Max9788 14vp-p, Class G Ceramic Speaker Driver
• Manufacturer: Maxim Integrated Products, Inc.

The MAX9788 Class G power amplifier with inverting
charge pump is the latest in linear amplifier technology.
The Class G output stage offers improved performance
over a Class AB amplifier while increasing efficiency to
extend battery life. The integrated inverting charge
pump generates a negative supply capable of deliver-
ing greater than 700mA.
The Class G output stage and the inverting charge
pump allow the MAX9788 to deliver a 14V
swing, up to two times greater than a traditional single-
supply linear amplifier.
The MAX9788 Class G amplifier is a linear amplifier that
operates within a low (V
SV
from the low to high supply range. For small signals,
the device operates within the lower (V
ply range. In this range, the operation of the device
is identical to a traditional single-supply Class AB
amplifier where:
Figure 1. Class G Supply Transition
ON
SS
) supply range. Figure 1 illustrates the transition
P
LOW SUPPLY RANGE OPERATION
I
P
I
P
SV
V
Z
= I
CC
_______________________________________________________________________________________
L
SS
14V
N1
I
Detailed Description
LOAD
CC
I
N1
= I
to GND) and high (V
P-P
N1
N2
N1
Class G Operation
ON
OFF
, Class G Ceramic Speaker Driver
CC
ON
to GND) sup-
P-P
P
BTL CLASS G SUPPLY TRANSITION
voltage
CC
I
P
SUPPLY TRANSITION
to
I
P
= I
SV
V
N1
Z
CC
L
SS
+ I
As the output signal increases so a wider supply is need-
ed, the device begins its transition to the higher supply
range (V
seamless transition between the low and high supply
ranges, both of the lower transistors are on so that:
As the output signal continues to increase, the transi-
tion to the high supply is complete. The device then
operates in the higher supply range, where the opera-
tion of the device is identical to a traditional dual-sup-
ply Class AB amplifier where:
During operation, the output common-mode voltage of
the MAX9788 adjusts dynamically as the device transi-
tions between supply ranges.
Utilizing a Class G output stage with an inverting
charge pump allows the MAX9788 to realize a 20V
output swing with a 5V supply.
N2
I
I
N1
N2
N1
N2
CC
to SV
ON
ON
SS
ON
I
LOAD
) for the large signals. To ensure a
I
LOAD
P
HIGH SUPPLY RANGE OPERATION
= I
I
P
N1
= I
N2
+ I
I
P
N2
SV
V
Z
= I
CC
L
SS
N2
I
N2
N1
N2
OFF
ON
P-P
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