TS925 STMicroelectronics, TS925 Datasheet - Page 11

• Manufacturer Part Number: TS925
• Description: Excellent audio performance / low distortion (0.005%)
• Manufacturer: STMicroelectronics

Specifications of TS925

• Low Noise: 9 nV/√Hz
• High Output Current: 80 mA (able to drive 32 Ω loads)
• High-speed: 4 MHz, 1.3 V/μs
• Low Input Offset Voltage: 900 μV max. (TS925A)
• Esd Internal Protection: 2 kV

TS925
3.1
3.2
Preamplifier configuration
The operators A1 and A4 are wired with a non-inverting gain of respectively:
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With the following values:
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The gain of the preamplifier chain is therefore equal to 58 dB.
Alternatively, the gain of A1 can be adjusted by choosing a JFET transistor Q1 instead of
R17. This JFET voltage controlled resistor arrangement forms an automatic level control
(ALC) circuit, useful in many microphone preamplifier applications. The mean rectified peak
level of the output signal envelope is used to control the preamplifier gain.
Headphone amplifier
The operators A2 and A3 are organized in a push-pull configuration with a gain of 5. The
stereo inputs can be connected to a CD player and the TS925 can directly drive the head-
phone speakers. This configuration shows the ability of the circuit to drive a 32 Ω load with a
maximum output swing and high fidelity suitable for sound and music.
Figure 19
competitor parts are employed in the same circuit for comparison (note the much-reduced
clipping level and crossover distortion).
A1# (R4/(R3+R17))
A4# R6/R5
R4 = 22 kΩ - R3 = 50 Ω - R17 = 1.2 kΩ
R6 = 47 kΩ - R5 = 1.2 kΩ ,
shows the available signal swing at the headset outputs: two other rail-to-rail
Doc ID 4949 Rev 4
Using the TS925 as a preamplifier and speaker driver
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