ATA-120
20W Class D Single Channel Audio Amplifier
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FEATURES
HIGH OUTPUT POWER CAPABILITY
SINGLE SUPPLY (+7.5V to +24V)
THD+N < 0.05% @ 1W, 8Ω
HIGH EFFICIENCY, > 90% @ 4Ω, 20W
LOW QUIESCENT CURRENT, 13mA
LOW NOISE (190µV typ.)
POP ELIMINATION AT STARTUP AND
SHUTDOWN
BUILT-IN THERMAL PROTECTION
INTEGRATED SHORT CIRCUIT PROTECTION
180mΩ MOSFET SWITCHES
MUTE / STANDBY MODE
SMALL SMD PACKAGE IS
BOTH LEAD-FREE (Pb) AND GREEN
1.0 GENERAL DESCRIPTION
The ATA-120 Class-D Audio Amplifier is a fully
integrated monolithic audio amplifier that can
provide audio power up to 20 watts @ 10% THD into
a 4Ω speaker.
The ATA-120 incorporates a single ended output
structure
with
built-in
short
circuit
and
overtemperature protection. This low noise, high
performance device delivers the excellent audio
quality of a class A/B amplifier while still achieving
class-D efficiency greater than 90%.
ORDERING INFORMATION:
Part Number *
ATA-120
EB-120
Package
Temperature
SOIC8
-40°C to + 85°C
Evaluation Board for the ATA-120
APPLICATIONS
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TELEVISIONS
HOME AUDIO MINI-SYSTEMS
FLAT PANEL MONITORS
MULTIMEDIA SPEAKERS
SURROUND SOUND DVD SYSTEMS
IN_P
-
BOOST
VDD
IN_N
+
FET
DRIVE
REGULATOR,
CONTROL &
PROTECTION
FET
DRIVE
ENABLE
POUT
AGND
PGND
Figure 1 - Block Diagram
This is preliminary information on a new product. Specifications are subject to change without notice.
129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com
CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc
DRN: PRELIMINARY
Page 1 of 13
ATA-120
Absolute Maximum Ratings [Note 1]
SYMBOL
PARAMETER
V
DD
V
BOOST
V
ENABLE
V
OUT
V
IN_P
V
IN_N
-
Supply Voltage
Bootstrap Voltage
Enable Voltage
Output Switch
Positive Input
Negative Input
Analog GND to Power GND
Junction Temperature
Lead Temperature
Storage Temperature
MIN
V
OUT
-0.3
-0.3
-1
-1
-1
-0.3
TYP
MAX
26
V
OUT
+6.5
6.0
V
DD
+1
V
DD
+1
V
DD
+1
0.3
UNIT
V
V
V
V
V
V
V
T
j
T
LEADS
T
S
-65
150
260
150
°C
°C
°C
Note 1 – Operation above maximum ratings may damage the device.
1.1
V
DD
T
A
Recommended Operating Conditions [Note 2]
PARAMETER
Supply Voltage
Operating Temperature
SYMBOL
MIN
7.5
-40
TYP
MAX
24
85
UNIT
V
°C
Note 2 - Performance not guaranteed beyond recommended operating conditions.
1.2
θ
J-A
θ
J-C
Thermal Characteristics
PARAMETER
Thermal Resistance, Junction to Ambient
Thermal Resistance, Junction to Case [Note 3]
SYMBOL
MIN
TYP
105
50
MAX
UNIT
°C/W
°C/W
Note 3 – Solder pins directly to large copper surface areas to improve device cooling.
1.3
I
STBY
I
Q
Electrical Characteristics [Note 4]
PARAMETER
Standby Current
Quiescent Current
Output MOSFET on Resistance
Short Circuit Current
IN_P, IN_N Input
Common Mode Voltage Range
IN_P, IN_N Input Current
Enable Threshold Voltage
Enable Input Current
Thermal Shutdown Trip Point
Thermal Shutdown Hysteresis
Rising signal voltage
Falling signal voltage
V
ENABLE
= 5V
T
J
Rising
SYMBOL
Supply Current
CONDITION
V
ENABLE
= 0
MIN
TYP
130
13
0.18
5
VDD
2
1
1.4
1.2
1
150
30
MAX
UNIT
µA
mA
Ω
A
Output Drivers
R
DS-ON
I
SC
Sourcing and Sinking
Sourcing and Sinking
3
0
Inputs
V
IN
I
IN
V
ENABLE
I
ENABLE
T
SD
T
SD-HYS
VDD-1.5
5
2.0
V
µA
V
µA
°C
°C
0.4
Thermal Shutdown
Note 4 – Performance based on circuit in Figure 3, V
DD
= 24V, V
ENABLE
= 5V, T
A
= 25°C
This is preliminary information on a new product. Specifications are subject to change without notice.
129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com
CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc
DRN: PRELIMINARY
Page 2 of 13
ATA-120
1.4
P
OUT
THD+N
η
BW
DNR
SNR
PSR
Typical Operating Characteristics [Note 5]
PARAMETER
Power Output
Total Harmonic Distortion
Plus Noise
Efficiency
Maximum Power Bandwidth
Dynamic Range
Signal to Noise Ratio
Noise Floor
Power Supply Rejection
SYMBOL
CONDITION
THD+N = 10%
, 4Ω Load
THD+N = 10%
, 8Ω Load
P
OUT
= 1 W
, 4Ω Load
P
OUT
= 1 W
, 8Ω Load
P
OUT
= 20 W,
4Ω Load
P
OUT
= 10 W, 8
Ω
Load
A-Weighted
A-Weighted, relative to 15W
A-Weighted
MIN
TYP
20
10
0.1
0.05
90
93
20
91
92
190
47
MAX
UNIT
W
W
%
%
%
%
KHz
dB
dB
µV
dB
Note 5 – Performance based on circuit of Figure 3, V
DD
= 24V, V
ENABLE
= 5V, f = 1 KHz, T
A
= 25°C
2.0 PIN DESCRIPTION
Pin No.
1
2
3
4
5
Pin Name
IN_P
IN_N
AGND
ENABLE
BOOST
Pin Function
Amplifier Positive Input.
IN_P is the positive side of the differential input to the
amplifier. Use a resistive voltage divider to set the voltage at IN_P to V
DD
/2. See
Figure 3
.
Amplifier Negative Input.
IN_N is the negative side of the differential input to the
amplifier. Drive the input signal and close the feedback loop at IN_N. See
Figure 3
.
Analog Ground.
Signal input ground. Connect AGND to PGND at one single point.
Enable Input.
Set ENABLE high to turn-on the amplifier; set it low to turn it off.
High-Side MOSFET Bootstrap Input.
A capacitor from BOOST to POUT supplies
the gate drive current to the high-side of the MOSFET. Connect a 0.47µF capacitor
from POUT to BOOST. Place a 6.2V zener diode from BOOST to POUT to prevent
overstressing the internal circuitry.
Power Supply Input.
VDD is the drain of the high-side MOSFET switch and supplies
the power to both the output stage and the ATA-120 internal control circuitry. In
addition to the main bulk capacitor, bypass VDD to PGND with a 1µF X7R capacitor
placed close to the IC’s V
DD
(pin 6) and P
GND
(pin 8).
Switched Power Output.
POUT is the output of the ATA-120. Connect the L-C filter
between POUT and the output blocking capacitor. See
Figure 3
.
Power Ground.
Power stage ground. Connect PGND to AGND at one single point.
6
VDD
7
8
POUT
PGND
This is preliminary information on a new product. Specifications are subject to change without notice.
129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com
CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc
DRN: PRELIMINARY
Page 3 of 13
ATA-120
3.0 Functional Description
The ATA-120 is a single-ended Class-D audio amplifier that converts analog audio input signals into PWM pulses.
The pulses drive an internal high current output stage and, when filtered through an external L-C filter, reproduce
the input signal across the load. Because of the switching Class-D output stage, power dissipation in the amplifier
is drastically reduced compared to Class A, Class B or Class A/B amplifiers while maintaining high fidelity and low
distortion.
The amplifier uses a differential input to the modulator. IN_P is the positive input and IN_N is the negative input.
The common mode voltage of the input is set to half the DC power supply input voltage (V
DD
/2) through the
resistive voltage divider formed by R2 and R5. The input capacitor C3 couples the AC input signal into the
amplifier while blocking the DC component.
The output driver stage uses two 180 mΩ N-channel MOSFETs to deliver the pulses to the L-C output filter which
in turn drives the load. When the output switches low, the bootstrap capacitor, C9, which is located between
POUT and BOOST, is charged from VDD through internal circuitry inside the ATA-120. The gate of the upper
MOSFET is driven from this voltage (higher than VDD but clamped to safe levels by zener diode D2).
3.1
Pop Elimination
The DC-blocking capacitor, C38, allows only AC current to pass to the output load (speaker). To insure that the
amplifier properly passes low frequency signals, the time constant of C38*R
LOAD
needs to be long. Typically the
C11 capacitor charges over a long time period and would normally result in turn-on and/or turn-off “pops”. The
ATA-120, however, includes internal circuitry that eliminates the turn-on and turn-off pops associated with this
charging of the AC coupling capacitor.
3.2
Short Circuit/Overload Protection
The ATA-120 has internal overload and short circuit protection. The currents in both the high-side and low-side
MOSFETs are internally measured and if the current exceeds the 5A (typical) short circuit current limit on either
MOSFET, both MOSFETs are placed in an open condition. After the short circuit condition is removed, the
ATA-120 restarts with the same power up sequence that is used for normal starting to prevent a pop from
occurring.
3.3
Mute/Enable Function
The ENABLE input is an active high enable control. To enable the device, drive ENABLE with a 2.0V or greater
voltage. To disable the amplifier, drive it below 0.4V. While the device is disabled, the VDD operating current is
less than 130µA and the output MOSFETs are turned off. The ATA-120 requires approximately 500ms from the
time that ENABLE is asserted (driven high) to when the amplifier arrives at normal operation.
This is preliminary information on a new product. Specifications are subject to change without notice.
129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com
CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc
DRN: PRELIMINARY
Page 4 of 13
ATA-120
4.0 Power Output
Figure 2 shows the full-scale sine-wave output power as a function of Power Supply Voltage for 2, 3, 4, 6, and 8
Ohm loads. Output power is constrained for higher impedance loads by the maximum voltage limit of the
ATA-120 and by the over-current protection limit for lower impedance loads. The minimum threshold for the over-
current protection circuit is 3.0A (at 25 ºC) but the typical threshold is 5.0A. Solid lines depict typical output power
capability of the ATA-120. Dashed lines depict the output power capability constrained to the minimum current
specification of for the ATA-120. The output power curves assume proper thermal management of the power
device’s internal dissipation. Since The IC’s thermal path is predominantly through the leadframe to the PC Board
copper foil, a sufficient copper area must be connected to each lead in order to facilitate proper cooling.
24
22
20
10% THD Output Power (Watts)
18
16
14
12
10
8
6
4
2
0
7
8
9
10% THD Output Power vs Supply Voltage
3Ω
4Ω
2Ω
6Ω
8Ω
10
11
12
13
14
15
16
17
18
Power Supply Voltage (VDC)
19
20
21
22
23
24
LEGEND
I
OUT
(min) = 3.0A
I
OUT
(typ) = 5.0A
RL=8Ω
RL=6Ω
RL=4Ω
RL=3Ω
RL=8Ω
RL=6Ω
RL=4Ω
RL=3Ω
Figure 2 – 10% THD Power Output vs. Power Supply Voltage
RL=2Ω
RL=2Ω
Note 6 : Sine-wave output power (<1% THD) is approximately 23% Lower.
This is preliminary information on a new product. Specifications are subject to change without notice.
129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com
CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc
DRN: PRELIMINARY
Page 5 of 13
Analogue and Mixed Signal
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