RT9104 RICHTEK [Richtek Technology Corporation], RT9104 Datasheet - Page 9

• Manufacturer Part Number: RT9104
• Description: 3W Stereo Class-D Audio Power Amplifier with DC Volume Control
• Manufacturer: RICHTEK [Richtek Technology Corporation]

Short Circuit Protection
The RT9104 has short circuit protection circuitry on the
outputs which prevents damage to the device during
unexpected applications. When a short circuit is detected,
the outputs are disabled immediately .However, once the
short is removed, the device will re-activate again.
Low Supply Voltage Detection
The RT9104 incorporates circuitry designed to detect low
supply voltage level. When the supply voltage falls to 4V
or below, the RT9104 goes into a state of shutdown and
the current consumption drops from milliamperes to
microamperes. The device will resume normal function
again once V
Thermal Protection
Thermal protection on the RT9104 automatically disables
the outputs when the junction temperature exceeds 150°C
in order to prevent damage to the device. There is a ±20
degree tolerance on this trip point from device to device.
Once the temperature cools below 130°C, the device will
auto-resume normal operations.
How to Reduce EMI
Most applications require a ferrite bead filter as shown in
Figure 2. The ferrite filter reduces EMI of around 1MHz
and higher. When selecting a ferrite bead, choose one
with high impedance at high frequencies and low
impedance at low frequencies.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
DS9104-01 April 2011
Figure 2. Typical Ferrite Chip Bead Filter
DD
OUT+
OUT-
> 4.2V.
Ferrite Bead
Ferrite Bead
1nF
1nF
P
where T
the ambient temperature, and θ
thermal resistance.
For recommended operating condition specifications of
the RT9104, the maximum junction temperature is 125°C
and T
thermal resistance, θ
WQFN-16L 3x3 packages, the thermal resistance, θ
68°C/W on a standard JEDEC 51-7 four-layer thermal test
board. For SOP-16 packages, the thermal resistance, θ
is 85° C/W on a standard JEDEC 51-7 four-layer thermal
test board. For DIP-16 packages, the thermal resistance,
θ
thermal test board.The maximum power dissipation at
T
P
WQFN-16L 3x3 package
P
SOP-16 package
P
DIP-16 package
The maximum power dissipation depends on the operating
ambient temperature for fixed T
resistance, θ
curves in Figure 3 allow the designer to see the effect of
rising ambient temperature on the maximum power
dissipation.
JA
A
D(MAX)
D(MAX)
D(MAX)
D(MAX)
, is 75°C/W on a standard JEDEC 51-7 four-layer
= 25°C can be calculated by the following formula :
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Figure 3. Derating Curves for RT9104 Package
A
is the ambient temperature. The junction to ambient
= (T
J(MAX)
= (125°C − 25°C) / (68°C/W) = 1.471W for
= (125°C − 25°C) / (75°C/W) = 1.333W for
0
= (125°C− 25°C) / (85°C/W) = 1.176W for
J(MAX)
JA
is the maximum junction temperature, T
. For the RT9104 packages, the derating
25
− T
SOP-16
Ambient Temperature (°C)
A
) / θ
JA
JA
50
, is layout dependent. For
JA
is the junction to ambient
DIP-16
WQFN-16L 3x3
75
J(MAX)
Four-Layer PCB
RT9104
www.richtek.com
and thermal
100
JA
125
A
, is
JA
is
9
,