Phone

    00852-6915 1330

TS974 in Practice: Low-Noise Audio Performance vs. Input Voltage Pitfalls

  • Contents

Quick-Reference Card: TS974 at a Glance

Attribute Detail
Component Type Quad Operational Amplifier
Manufacturer STMicroelectronics
Key Spec 4 nV/√Hz Input Noise Voltage
Supply Voltage 2.7V to 10V (Single or Dual)
Package Options DIP-14 (Standard through-hole)
Lifecycle Status Active
Best For High-fidelity audio pre-amplification and battery-powered sensing

1. What Is the TS974? (Definition + Architecture)

The TS974 is a quad operational amplifier from STMicroelectronics that combines high-speed 12 MHz performance with an ultra-low noise floor of 4 nV/√Hz and rail-to-rail output capabilities. Unlike generic op-amps that prioritize low power consumption at the cost of signal integrity, the TS974 is engineered specifically for AC performance in space-constrained, low-voltage environments.

1.1 Core Architecture & Design Philosophy

Internally, the TS974 utilizes a bipolar transistor architecture designed to minimize Total Harmonic Distortion (THD) to a staggering 0.003%. While many modern op-amps use CMOS stages for high input impedance, ST’s choice of bipolar inputs in the TS974 ensures the low voltage noise density required for professional audio applications. The output stage is designed for "Rail-to-Rail" swing, allowing the signal to reach within millivolts of the supply rails, maximizing dynamic range in 3.3V or 5V systems.

1.2 Where It Fits in the Signal Chain

The TS974 typically serves as the first or second stage in a signal chain. It is positioned downstream from low-output sensors (like MEMS microphones or strain gauges) and upstream from Analog-to-Digital Converters (ADCs) or power amplifiers. Its role is to provide clean gain without adding significant "hiss" or harmonic artifacts.


2. Electrical Characteristics: The Numbers That Matter

2.1 Power Supply & Consumption Profile

The TS974 operates from 2.7V to 10V. This makes it versatile for both lithium-ion battery-powered gadgets (3.7V nominal) and standard 5V/9V industrial rails. However, designers should note that while it is low-noise, it is not "ultra-low power"; ensure your thermal budget can handle the quiescent current when all four channels are active.

2.2 Performance Specs (Speed, Accuracy, or Efficiency)

  • Gain Bandwidth Product (12 MHz): Allows for high-gain configurations at audio frequencies (20Hz–20kHz) without losing phase margin.
  • Slew Rate (4 V/μs): Fast enough to prevent transient intermodulation distortion, ensuring crisp reproduction of high-frequency square waves or percussion hits.
  • Input Offset Voltage (1 mV): Respectable precision for a high-speed part, though not "zero-drift" grade.

2.3 Absolute Maximum Ratings — What Will Kill It

  • Supply Voltage: Do not exceed 12V. Even momentary spikes from an unregulated wall adapter can cause permanent junction breakdown.
  • Input Voltage: Must remain within the supply rails.
  • Electrostatic Discharge (ESD): Rated for 2kV (HBM). Standard handling precautions apply, but it is more robust than many sensitive CMOS alternatives.

3. Pinout & Package Guide

3.1 Pin-by-Pin Functional Groups

The TS974 follows the industry-standard quad op-amp pinout, making it a candidate for drop-in replacement in many existing PCB layouts.

Pin Group Pins Function
Power 4 (VCC+), 11 (VCC-) Positive and Negative/Ground supply rails
Channel 1 1, 2, 3 Output, Inverting Input, Non-inverting Input
Channel 2 7, 6, 5 Output, Inverting Input, Non-inverting Input
Channel 3 8, 9, 10 Output, Inverting Input, Non-inverting Input
Channel 4 14, 13, 12 Output, Inverting Input, Non-inverting Input

3.2 Package Variants & Soldering Notes

Package Pitch Thermal Pad? Soldering Method
DIP-14 2.54mm No Wave or Hand Solder

Note: The DIP-14 package is ideal for prototyping on breadboards or for through-hole manufacturing where mechanical robustness is required.

3.3 Part Number Decoder

A typical order code might look like TS974IPT or TS974ID: * TS974: Base part number. * I: Industrial temperature range (-40°C to +125°C). * D/N/P: Package designator (D=SO-14, N=DIP-14, P=TSSOP-14).


4. Known Issues, Errata & Real-World Pain Points

4.1 Input Common-Mode Voltage Range Limitation

Problem: Many engineers assume "Rail-to-Rail Output" means "Rail-to-Rail Input." It does not. The TS974 requires at least 1.15V of headroom from the negative rail for the input stage to stay linear. Root Cause: The bipolar input stage saturation characteristics. Recommended Fix: In single-supply 5V designs, ensure your input bias point is centered (e.g., 2.5V). If the input signal swings too close to ground, the output may "latch up" or saturate unexpectedly.

4.2 Short-Circuit Vulnerability

Problem: The TS974 can drive significant current to the output, but it lacks sophisticated thermal shutdown. Root Cause: Excessive power dissipation during a direct short to a rail. Recommended Fix: Use series resistors (10–100Ω) on the output if the device is driving external connectors where shorts are likely.


5. Application Circuits & Integration Examples

5.1 Typical Application: High-Fidelity Audio Pre-Amplifier

In this scenario, the TS974 is used to amplify a low-level signal from a microphone. Because of the 4 nV/√Hz noise floor, the "hiss" remains below the audible threshold even at high gain.

5.2 Interface Example: Connecting to a Microcontroller

When using the TS974 to buffer a signal for an STM32 or Arduino ADC: 1. Voltage Scaling: Ensure the op-amp supply matches the MCU's VCC (usually 3.3V) to prevent overvoltage on the ADC pin. 2. Anti-Aliasing: Add a simple RC filter (e.g., 1kΩ and 10nF) between the TS974 output and the MCU input.

// No digital initialization required for this analog component.
// Ensure the ADC reference voltage is stable for accurate readings.
raw_value = analogRead(A0);
voltage = (raw_value * 3.3) / 1024.0;

6. Alternatives, Replacements & Cross-Reference

6.1 Pin-Compatible Drop-In Replacements

Part Number Manufacturer Key Difference Compatible?
LM833 TI / Onsemi Higher noise (4.5 nV), lower GBW (16MHz) ? Yes
MC33079 Onsemi Very similar specs, slightly higher current ? Yes
TL074 Various JFET inputs, much higher noise, higher voltage ?? Pin-compatible but worse noise

6.2 Upgrade Path (Better Performance)

For ultra-critical audio paths, the Texas Instruments OPA4134 offers even lower distortion and FET inputs, though at a significantly higher price point.

6.3 Cost-Down Alternatives

The LM224 is the industry standard "cheap" quad op-amp. It is pin-compatible but is NOT suitable for high-quality audio due to high noise and crossover distortion.


7. Procurement & Supply Chain Intelligence

  • Lifecycle Status: Active. STMicroelectronics continues to support this part for industrial and automotive customers.
  • Typical MOQ & Lead Time: Available in tubes (25-50 pcs) or tape-and-reel (2500 pcs). Lead times are generally stable (8–12 weeks).
  • BOM Risk Factors: Low risk. This is a multi-sourced footprint, and several manufacturers produce functionally similar (though perhaps noisier) alternatives.
  • Authorized Distributors: Digi-Key, Mouser, Arrow, and Avnet.

8. Frequently Asked Questions

Q: What is the TS974 used for? A: It is primarily used in professional audio circuits, portable communication devices (cell phones/pagers), and high-accuracy instrumentation where low noise is critical.

Q: What are the best alternatives to the TS974? A: The Onsemi MC33079 is the closest performance match. For lower-cost applications where noise is less critical, the TL074 is a common alternative.

Q: Is the TS974 still in production? A: Yes, it is currently in "Active" status and widely available from major global distributors.

Q: Can the TS974 work with 3.3V logic? A: Yes, it operates down to 2.7V. However, remember that the input signal cannot go all the way to ground (0V) without distortion.


9. Resources & Tools

  • Official Datasheet: [STMicroelectronics TS974 Product Page]
  • Evaluation Board: STEVAL-IPE020V1 (Check for availability)
  • Reference Designs: See ST Application Note AN442 for audio design tips.
  • SPICE Model: Available on the ST website for simulation in LTspice or PSpice.

TS974IN Documents & Media

Download datasheets and manufacturer documentation for STMicroelectronics TS974IN.
Datasheets
datasheet

TS974IN PCB Symbol, Footprint & 3D Model

STMicroelectronics TS974IN

STMicroelectronics

IC OPAMP GP 4 CIRCUIT 14DIP

Get a quote

Quantity:

Click To Quote

Kynix

Kynix was founded in 2008, specializing in the electronic components distribution business. We adhere to honesty and ethics as our business philosophy and have gradually established an excellent reputation and credibility in our international business. With the accurate quotation, excellent credit, reasonable price, reliable quality, fast delivery, and authentic service, we have won the praise of the majority of customers.

Join our mailing list!

Be the first to know about new products, special offers, and more.

Leave a Reply

We'd love to hear from you! Feel free to share your thoughts and comments below. Rest assured, your email address will remain private.

Name *
Email *
Captcha *
Rating:

Kynix

  • How to purchase

  • Order
  • Search & Inquiry
  • Shipping & Tracking
  • Payment Methods
  • Contact Us

  • Tel: 00852-6915 1330
  • Email: info@kynix.com
  • Follow Us

authentication

Kynix

© 2008-2026 kynix.com all rights reserved.