MAX98400BETG+ Maxim Integrated Products, MAX98400BETG+ Datasheet - Page 17

• Manufacturer Part Number: MAX98400BETG+
• Description: Audio Amplifiers Stereo, High Power, r, Class D Amplifier
• Manufacturer: Maxim Integrated Products

Specifications of MAX98400BETG+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

There are three modes for the limiter, defined by V
the voltage applied to the LIM_TH pin (Table 1).
In Mode1, the limiter is disabled. The output clips when
output peak voltage reaches the voltage on PVDD, V
In Mode2, the limiter threshold (V
voltage, V
approximately V
In Mode3, the limiter threshold, V
mable. V
the desired output threshold. The limiter threshold can
be set down to 0.5 x V
V
Threshold settings below V
speakers; the peak output voltage is limited to a value of
V
Threshold settings above V
output distortion; the peak output voltage is limited to a
value of V
tor takes into account the voltage drop across the power
FET that occurs when the amplifier is clipped. Choose
R
the LIM_TH pin. For best accuracy, the parallel combina-
tion R
Example:
If the speaker in the application can handle only
12V peak, but V
(V
The voltage that needs to be applied to V
defined as:
Table 1. Limiter Control Modes
Note: V
THRESH
THRESH
LIM1
Mode1
Mode2
Mode3
MODE
THRESH
LIM1
and R
V
THRESH
LIM_TH
LIM_TH
cannot exceed 22V.
= V
) should be set to 12V:
THRESH
||R
PVDD
PVDD tracking
Programmable
LIM2
LIM2
LIM_TH
Disable
NAME
is the output peak limiting voltage (limiter threshold voltage).
= V
. The peak output voltage is limited to
THRESH
can be set to a voltage proportional to
PVDD
(Figure 3) to set the desired voltage at
should be approximately 100kI.
= V
Limiter Threshold Control (LIM_TH)
THRESH
V
x 6.4.
Stereo, High-Power, Class D Amplifiers
THRESH
LIM_TH
is higher, the threshold voltage
= V
PVDD
The limiter is disabled when connecting LIM_TH to V
than 3.9V.
The output peak voltage is limited to just below the supply voltage,
V
a voltage below 0.3V.
The output peak voltage, V
voltage applied on the LIM_TH so that V
When V
limited to 10%.
/6.4 = 12V/6.4 = 1.88V
PVDD
PVDD
PVDD
PVDD
x 6.4 x 0.95. The 0.95 fac-
= 12V
and up to 1.6 x V
. V
can be used to limit the
can be used to protect
THRESH
THRESH
x 0.95.
THRESH
THRESH
is set 20% higher than V
) tracks supply
LIM_TH
= V
, is program-
PVDD
LIM_TH
is then
PVDD
PVDD
x 0.95 when LIM_TH is connected to ground or
THRESH
FUNCTION
,
.
.
, is limited to the threshold set by the
Figure 3. Limiter Control, Mode3 Configuration (Table 1)
For a 5V supply, a resistor-divider of R
R
and the desired output resistance of approximately
100kI.
If only distortion limiting is desired, set V
20% higher than V
levels to approximately 10% THD.
The attack time for the limiter is fixed, typically < 200Fs.
The release time for the limiter is set by an external
capacitor at RELEASE (C
Release Time [s] x 1FF. The C
THRESH
PVDD
LIM2
R
LIM2
, the output THD distortion is
= 270kI gives both an unloaded voltage of 1.82V
= V
LIM_TH
S
1.0 µ F
or a voltage greater
C2
x 6.4.
PVDD
V
S
Release Time Control (RELEASE)
LIM_TH
R
LIM1
. This limits the output clipping
REL
REGULATOR
MAX98400A
MAX98400B
CONTROL
LIMITER
) to GND. Choose C
V
S
REL
RELEASE
0.6V P V
limit is 2.2FF.
C
1.0 µ F
3.9V < V
LIM_Th VOLTAGE
REL
V
GND
PVDD
PVDD
PVDD
RANGE
LIM1
P V
0.15V
LIM_TH
THRESH
LIM_TH
LIM_TH
= 165kI/
C1
1.0 µ F
18V
P 3.8V
P V
REL
to be
<
S
17
=