AD8532AR Analog Devices Inc, AD8532AR Datasheet - Page 15

• Manufacturer Part Number: AD8532AR
• Description: Amplifier IC
• Manufacturer: Analog Devices Inc

Specifications of AD8532AR

• No. Of Amplifiers: 2
• Bandwidth: 3MHz
• Slew Rate: 5V/µs
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC
• Rohs Status: RoHS non-compliant
• Amplifier Type: General Purpose
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Gain Bandwidth Product: 3MHz
• Current - Input Bias: 5pA
• Voltage - Input Offset: 25000µV
• Current - Supply: 750µA
• Current - Output / Channel: 250mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 6 V, ±1.35 V ~ 3 V
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

SINGLE-SUPPLY HEADPHONE AMPLIFIER
Because of its speed and large output drive, the AD8531/
AD8532/AD8534 make an excellent headphone driver, as
illustrated in Figure 44. Its low supply operation and rail-to-rail
inputs and outputs give a maximum signal swing on a single
5 V supply. To ensure maximum signal swing available to drive
the headphone, the amplifier inputs are biased to V+/2, which
in this case is 2.5 V. The 100 kΩ resistor to the positive supply
is equally split into two 50 kΩ resistors, with their common
point bypassed by 10 μF to prevent power supply noise from
contaminating the audio signal.
The audio signal is then ac-coupled to each input through a
10 μF capacitor. A large value is needed to ensure that the 20 Hz
audio information is not blocked. If the input already has the
proper dc bias, the ac coupling and biasing resistors are not
required. A 270 μF capacitor is used at the output to couple the
amplifier to the headphone. This value is much larger than that
used for the input because of the low impedance of the head-
phones, which can range from 32 Ω to 600 Ω. An additional 16 Ω
resistor is used in series with the output capacitor to protect the
output stage of the op amp by limiting the capacitor discharge
current. When driving a 48 Ω load, the circuit exhibits less
than 0.3% THD+N at output drive levels of 4 V p-p.
RIGHT
SINGLE-SUPPLY, 2-WAY LOUDSPEAKER
CROSSOVER NETWORK
Active filters are useful in loudspeaker crossover networks
because of small size, relative freedom from parasitic effects, the
ease of controlling low/high channel drive, and the controlled
driver damping provided by a dedicated amplifier. Both Sallen-
Key (SK) and multiple-feedback (MFB) filter architectures are
useful in implementing active crossover networks. The circuit
shown in Figure 45 is a single-supply, 2-way active crossover
that combines the advantages of both filter topologies.
INPUT
INPUT
LEFT
10µF
10µF
50kΩ
50kΩ
50kΩ
50kΩ
Figure 44. Single-Supply, Stereo Headphone Driver
V 5V
V
100kΩ
100kΩ
10µF
10µF
AD8532
AD8532
1/2
1/2
V 5V
1µF/0.1µF
16Ω
16Ω
270µF
270µF
50kΩ
50kΩ
LEFT
HEADPHONE
RIGHT
HEADPHONE
Rev. F | Page 15 of 20
This active crossover exhibits less than 0.4% THD+N at output
levels of 1.4 V rms using general-purpose, unity-gain HP/LP stages.
In this 2-way example, the LO signal is a dc-to-500 Hz LP woofer
output, and the HI signal is the HP (>500 Hz) tweeter output.
U1B forms an LP section at 500 Hz, while U1A provides an HP
section, covering frequencies ≥500 Hz.
The crossover example frequency of 500 Hz can be shifted
lower or higher by frequency scaling of either resistors or
capacitors. In configuring the circuit for other frequencies,
complementary LP/HP action must be maintained between
sections, and component values within the sections must be in
the same ratio. Table 6 provides a design aid to adaptation, with
suggested standard component values for other frequencies.
For additional information on the active filters and active crossover
networks, refer to the data sheet for the OP279, a dual rail-to-
rail, high output current, operational amplifier.
Table 6. RC Component Selection for Various Crossover
Frequencies
Crossover Frequency (Hz)
100
200
319
500
1 k
2 k
5 k
10 k
1
2
3
TO U1
V
Applicable for Filter A = 2.
For Sallen-Key stage U1A: R1 = R2, and C1 = C2, and so on.
For multiple feedback stage U1B: R6 = R5, R7 = R5/2, and C4 = 2C3.
IN
100kΩ
V
S
R
IN
10µF
0.1µF
C
Figure 45. A Single-Supply, 2-Way Active Crossover
IN
100kΩ
100kΩ
1
0.01µF
31.6kΩ
31.6kΩ
C1
100µF/25V
V
R5
S
R2
C2
0.01µF
10µF
AD8531/AD8532/AD8534
C4
0.02µF
15.8kΩ
COM
5V
31.6kΩ
31.6kΩ
R7
R1
R6
3
2
6
5
R1/C1 (U1A)
160 kΩ/0.01 μF
80.6 kΩ/0.01 μF
49.9 kΩ/0.01 μF
31.6 kΩ/0.01 μF
16 kΩ/0.01 μF
8.06 kΩ/0.01 μF
3.16 kΩ/0.01 μF
1.6 kΩ/0.01 μF
V
S
4
U1A
AD8532
0.01µF
U1B
AD8532
C3
1
7
49.9Ω 270µF
49.9Ω
2
R3
, R5/C3 (U1B)
R4
270µF
+
+
100kΩ
100kΩ
AND UP
500Hz
DC –
500Hz
LO
3
HI