Texas Instruments TPA2014D1 Evaluation Module (EVM) TPA2014D1EVM TPA2014D1EVM Datenbogen
Produktcode
TPA2014D1EVM
2.2
Boost Settings
2.2.1
Boost Terms
2.2.2
Changing the Boost Voltage
V
CC
+
ǒ
0.5
ǒ
R
1
)
R
2
Ǔ
Ǔ
R
1
(1)
2.2.3
Changing the Boost Inductor
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Operation
jumpers back between headers 2 and 3 to tie the shutdown pins to V
DD
to enable Class-D amplifier.
Remove J10 and J12 to achieve the minimum Class-D shutdown current.
Note:
The boost converter provides power to the Class-D amplifier. When the boost converter is
shut down, no voltage is supplied to the Class-D amplifier causing the Class-D amplifier to
power off.
shut down, no voltage is supplied to the Class-D amplifier causing the Class-D amplifier to
power off.
The default voltage for the boost converter is 5 V
The following is a list of terms and definitions:
C
MIN
Minimum boost capacitance required for a given ripple voltage on V
CC
.
f
boost
Switching frequency of the boost converter.
I
CC
Current pulled by the Class-D amplifier from the boost converter.
I
L
Current through the boost inductor.
R1 and R2
Resistors used to set the boost voltage.
R
ESR
ESR of the boost capacitor.
V
CC
Boost voltage. Generated by the boost converter. Voltage supply for the Class-D
amplifier.
amplifier.
V
DD
Supply voltage to the integrated circuit.
ΔI
L
Ripple current through the inductor.
ΔV
Ripple voltage on V
CC
due to capacitance.
ΔV
ESR
Ripple voltage on V
CC
due to the ESR of the boost capacitor.
1. If a different boost voltage is desired, use
to determine the new values of R1 and R2.
2. The recommended value of R2 is 453 k
Ω
.
Working inductance decreases as inductor current increases. If the drop in working inductance is severe
enough, it can cause the boost converter to become unstable, or cause the TPA2014D1 to reach its
current limit at a lower output power than expected. Inductor vendors specify currents at which inductor
values decrease by a specific percentage. This can vary by 10% to 35%. Inductance is also affected by dc
current and temperature.
enough, it can cause the boost converter to become unstable, or cause the TPA2014D1 to reach its
current limit at a lower output power than expected. Inductor vendors specify currents at which inductor
values decrease by a specific percentage. This can vary by 10% to 35%. Inductance is also affected by dc
current and temperature.
The requirements of the load determine the inductor current rating. The two factors that determine
inductance are the minimum value required for stability and the maximum ripple current permitted in the
application.
inductance are the minimum value required for stability and the maximum ripple current permitted in the
application.
Use
to determine the required current rating. This equation shows the approximate relationship
between the average inductor current, I
L
, to the load current, load voltage, and input voltage (I
CC
, V
CC
, and
V
DD
, respectively.) Insert I
CC
, V
CC
, and V
DD
into
to solve for I
L
. The inductor must maintain at
least 90% of its initial inductance value at this current.
SLOU211 – May 2008
TPA2014D1EVM
3