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
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