Audio Switching Amplifier
AD1994
GENERAL DESCRIPTION
Integrated stereo modulator and power stage
<0.005% THD + N
105 dB dynamic range (A-weighted)
2 × 25 W output power (6 Ω, 10% THD + N)
1 × 50 W output power (3 Ω, 10% THD + N)
RDS-ON < 0.3 Ω (per transistor)
PSRR > 65 dB
On-off-mute pop noise suppression
EMI optimized modulator
Short-circuit protection
Overtemperature protection
Low cost DMOS process
The AD1994 is a 2-channel, bridge tied load (BTL), switching
audio power amplifier with integrated Σ-Δ modulator. The
modulator accepts a single-ended, analog input signal and
converts it to a switching waveform to drive speakers directly.
One of the two modulators can control both output stages
providing twice the current and almost twice the efficiency for
single-channel applications. Both modulators can also control
external power devices for arbitrarily high output power. A
digital, microprocessor-compatible interface provides control of
reset, mute, and PGA gain, as well as feedback signals for thermal
and overcurrent error conditions. The output stage can operate
over a power supply voltages range of 8 V to 20 V. The analog
modulator and digital logic operate from a 5 V supply.
TE
FEATURES
LE
APPLICATIONS
Advanced televisions
Compact multimedia systems
Minicomponents
NFL–
PGA0
B
SO
PGA1
NFL+
FUNCTIONAL BLOCK DIAGRAM
AVDD
DVDD
FEEDBACK
NETWORK
PVDD
AD1994
AINL
MOD_FILT
ORDER
REDUCER
O
AINR
CLKO
OSCILLATOR
REF_FILT
OUTL+
A2
B1
LEVEL
SHIFTER
AND
DEAD TIME
CONTROL
Σ-Δ
MODULATOR
PGA
CLKI
A1
Σ-Δ
MODULATOR
PGA
OUTL–
B2
H-BRIDGE
C1
OUTR+
C2
MODE CONTROL
LOGIC AND
POP/CLICK
SUPPRESSION
VOLTAGE
REFERENCE
D1
PGND
FEEDBACK
NETWORK
05775-001
DCTRL0
DCTRL1
DCTRL2
NFR–
NFR+
ERR0
ERR1
ERR2
MUTE
RESET
AGND
OUTR–
D2
Figure 1.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
