Texas Instruments LM1875T/NOPB Audio Amplifiers:A Comprehensive Guide

Texas Instruments LM1875T/NOPB +BOM

Texas Instruments LM1875T/NOPB's Features

1. High-Performance Audio Amplification

• High Output Power:
  • Delivers 20W continuous output power to 4Ω or 8Ω loads under ±25V power supply.
  • Exceeds 30W output power with an 8Ω load and ±30V power supply.
• Low Distortion:
  • Typical total harmonic distortion (THD) of 0.015% (1kHz, 20W output, 8Ω load) ensures high-quality audio reproduction.
• Wide Power Bandwidth:
  • Power bandwidth of 70kHz, suitable for high-fidelity audio systems and wide-band applications.

2. Robust Protection Mechanisms

• Short-Circuit Protection:
  • Supports AC and DC short-circuit-to-ground protection to prevent damage from accidental output shorts.
• Thermal Protection:
  • Integrated thermal shutdown circuit (Parole circuit) automatically turns off the chip when the junction temperature reaches ~170°C and restores operation below 145°C, avoiding long-term overheating stress.
• Current Limiting:
  • Maximum output current limited to 4A, combined with dynamic current limiting to reduce current thresholds at high voltages, expanding the safe operating area (SOA).
• Internal Protection Diodes:
  • Integrated output protection diodes prevent transient surges from reverse voltage and inductive loads.

3. Wide Operating Range and Stability

• Broad Power Supply Range:
  • Supports dual power supply inputs from ±16V to ±60V, or equivalent single-supply configurations (with external biasing), adapting to various power designs.
• High Ripple Rejection:
  • Power supply rejection ratio (PSRR) of 94dB effectively reduces power supply noise interference with audio signals.
• Stable Closed-Loop Gain:
  • Internally compensated design ensures stability with closed-loop gain ≥10, eliminating the need for additional compensation components and simplifying circuit design.

4. Electrical and Physical Characteristics

• High Current Capability:
  • Peak output current of 4A supports driving low-impedance loads (e.g., 4Ω speakers).
• Low Input Bias Current:
  • Input bias current varies minimally with supply voltage, typically <200μA at 25°C, suitable for high-impedance signal sources.
• TO-220 Plastic Package:
  • Standard TO-220 package (5 pins) facilitates heat sink installation, allowing direct mounting to grounded heat sinks for optimized thermal performance (no insulation required).
• RoHS Compliance:
  • The LM1875T/NOPB model is marked "RoHS: Yes," meeting environmental standards with a lead finish (SN).

5. Application Flexibility

• Diverse Applications:
  • Suitable for high-performance audio systems, bridge amplifiers, stereo phono systems, servo amplifiers, and instrumentation.
• Simple Peripheral Circuitry:
  • Requires only minimal external components (e.g., input capacitors, power filter capacitors), reducing design complexity.

Summary

Texas Instruments LM1875T/NOPB's Applications

1. High-Performance Audio Systems

• Home stereo systems, bookshelf speakers, high-end headphone amplifiers, professional monitoring equipment, etc.

2. Bridge Amplifiers (BTL Configuration)

• Scenarios requiring higher output power (e.g., car audio, public address systems) and low-impedance load driving (e.g., 2Ω speakers).

3. Stereo Phonographs

• Power amplification stages for vinyl record players, retro audio equipment upgrades.

4. Servo Amplifiers

• Motor driving (e.g., precision servo motors, stepper motors), position/speed control in industrial systems.

5. Instrument Systems & Industrial Equipment

• Signal generators, power signal amplification, testing equipment, medical instruments (e.g., ultrasonic probe driving).

6. Additional Extended Applications

• Uses single-supply power (e.g., 32V~120V) with biasing circuits for battery-powered devices or car audio systems, simplifying power supply design.

• Standard TO-220 package and mature peripheral circuit schematics (refer to datasheet typical applications) make it ideal for hobbyists building amplifier modules.

Application Design Considerations

• Must use a heat sink (recommended thermal resistance ≤2.2°C/W) to avoid thermal protection activation during high-power or long-term operation.

• Isolate input/feedback loops from power/output paths to reduce EMI, following grounding and decoupling guidelines in the datasheet.

• Series 1Ω~10Ω resistors to prevent oscillation when driving capacitive loads (e.g., long cables); rely on internal protection diodes for inductive load transient absorption.

Conclusion

Texas Instruments LM1875T/NOPB's  Attributes

Texas Instruments LM1875T/NOPB's Datasheet

Texas Instruments LM1875T/NOPB's Symbol, Footprint and 3D Model

The Texas Instruments LM1875T/NOPB is a high-performance audio power amplifier in a TO-220-5 formed leads package, featuring 5 pins with the following configuration and functions:

Pinout Diagram & Functionality

Key Operational Notes

1. Power Supply Requirements:
   • Dual-Supply Mode: Vcc = +16V~+60V, Vee = -16V~-60V.
   • Single-Supply Mode: Vcc = 32V~120V, with Vee tied to GND. A coupling capacitor is required at the output to block DC offset 68.
   • Voltage Handling: Ensure proper decoupling capacitors (e.g., 100μF) near Vcc/Vee to stabilize power and reduce noise.
2. Gain Configuration:
   • The amplifier’s voltage gain (A_v) is set by external resistors:Av​=1+Rg​Rf​​
     where Rf​ is the feedback resistor (between -IN and OUT) and Rg​ is the input resistor (between +IN and GND). A typical gain of 20~50 is recommended to avoid instability 89.
3. Thermal Management:
   • Pin 4 (OUT) and the metal tab of the TO-220 package are thermally connected. A heat sink with thermal resistance ≤2.2°C/W is mandatory for high-power operation to prevent thermal shutdown 16.
4. Protection Features:
   • Short-Circuit Protection: Automatically limits output current during faults.
   • Thermal Shutdown: Activates when junction temperature exceeds ~150°C, turning off the output until the device cools down 29.

Texas Instruments LM1875T/NOPB's Category-Audio Amplifiers

Audio amplifiers are essential electronic devices that bridge the gap between weak audio signals and powerful sound reproduction, serving as the backbone of any sound system, from compact headphones to grand concert setups. Their primary role is to increase the amplitude of audio signals—derived from sources like smartphones, turntables, or microphones—enough to drive speakers and produce audible sound with clarity and power. Amplifiers come in various classes, each balancing trade-offs between efficiency, sound quality, and design complexity. Class A amplifiers, known for their warm, distortion-free sound, operate with constant current flow, delivering superior fidelity but at the cost of low energy efficiency and high heat generation. Class B amplifiers improve efficiency by using two transistors to handle positive and negative signal halves, though they may introduce crossover distortion. Class AB amplifiers, a hybrid of A and B, mitigate distortion while maintaining reasonable efficiency, making them popular in high-fidelity (Hi-Fi) applications. Modern Class D amplifiers, leveraging digital switching technology, achieve ultra-high efficiency, ideal for portable devices, though they require careful design to avoid noise and maintain audio purity. Key performance metrics for audio amplifiers include output power (determining loudness and speaker compatibility), total harmonic distortion (THD) (a measure of signal accuracy, with lower values indicating purer sound), and power supply range (flexibility in adapting to different voltage sources). Stability, thermal management, and protection against overloads or short circuits are also critical for reliability.
 

Among the standout solutions in the Class AB category, the LM1875T/NOPB from Texas Instruments (TI) embodies the perfect blend of performance and practicality. Designed for high-fidelity audio systems, this amplifier delivers up to 30W of continuous power into 8Ω loads with a minuscule THD of just 0.015%, ensuring faithful reproduction of even the most nuanced musical details. Its wide power supply range (±16V to ±60V) accommodates both dual-supply Hi-Fi setups and single-supply industrial applications, while built-in protections—including thermal shutdown and short-circuit current limiting—guard against real-world faults.
 

LM1875T/NOPB's manufacturer-Texas Instruments

Texas Instruments (TI) has established itself as a global leader in audio amplifier technology, driving innovation across consumer, automotive, and industrial sectors through relentless advancements in performance, efficiency, and integration.

Pioneering Advanced Amplification Technologies

LM1875T/NOPB alternative parts: LM1875T, LM1875T/LB03

Hide Shared Attributes
Part Number	LM1875T/NOPB  +BOM	LM1875T  +BOM	LM1875T/LB03 +BOM
Manufacturer:	Texas Instruments	Texas Instruments	Texas Instruments
Description:	IC AMP CLASS AB MONO 25W TO220-5	IC AMP CLASS AB MONO 25W TO220-5	IC AMP CLASS AB MONO 25W TO220-5
Lifecycle Status:	ACTIVE (Last Updated: 5 days ago)	ACTIVE (Last Updated: 3 days ago)	ACTIVE (Last Updated: 2 days ago)
Factory Lead Time:	6 Weeks	6 Weeks	6 Weeks
Mounting Type:	Through Hole	Through Hole	Through Hole
Package / Case:	TO-220-5 Formed Leads	TO-220-5 Formed Leads	TO-220-5 Formed Leads
Surface Mount:	NO	NO	-
Number of Pins:	5	5	5
Weight:	9.071847g	-	-
Operating Temperature:	0°C~70°C TA	0°C~70°C TA	0°C~70°C TA
Packaging:	Tube	Tube	Tube
JESD-609 Code:	e3	e0	e0
Pbfree Code:	yes	-	-
Part Status:	Active	Active	Active
Moisture Sensitivity Level (MSL):	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Termination:	Through Hole	-	-
ECCN Code:	EAR99	EAR99	-
Type:	Class AB	Class AB	Class AB
Terminal Finish:	Matte Tin (Sn)	Tin/Lead (Sn/Pb)	Tin/Lead (Sn/Pb)
Voltage - Supply:	16V~60V ±8V~30V	16V~60V ±8V~30V	16V~60V ±8V~30V
Terminal Position:	ZIG-ZAG	ZIG-ZAG	ZIG-ZAG
Number of Functions:	1	1	1
Base Part Number:	LM1875	LM1875	LM1875
Output Type:	1-Channel (Mono)	1-Channel (Mono)	1-Channel (Mono)
Operating Supply Voltage:	28V	28V	28V
Number of Channels:	2	1	1
Nominal Supply Current:	100mA	100mA	100mA
Max Supply Current:	100mA	100mA	100mA
Quiescent Current:	70mA	-	-
Output Power:	25W	25W	25W
Slew Rate:	8 V/μs	8 V/μs	-
Supply Type:	Dual, Single	Dual, Single	Dual, Single
Input Offset Voltage (Vos):	15mV	15mV	15mV
Gain Bandwidth Product:	5.5MHz	5.5MHz	5.5MHz
Voltage Gain:	90dB	90dB	90dB
Power Supply Rejection Ratio (PSRR):	95dB	95dB	95dB
Gain:	90 dB	-	-
Max Dual Supply Voltage:	30V	30V	30V
Max Output Power:	30W	30W	25W
Min Dual Supply Voltage:	8V	8V	8V
Dual Supply Voltage:	18V	28V	18V
Input Bias Current:	2μA	2μA	2μA
Max Output Power x Channels @ Load:	25W x 1 @ 8 Ω	25W x 1 @ 8 Ω	25W x 1 @ 8 Ω
Harmonic Distortion:	1%	1%	1%
Number of Amplifiers:	1	1	-
Load Impedance:	8Ohm	8Ohm	-
Features:	Short-Circuit and Thermal Protection	Short-Circuit and Thermal Protection	Short-Circuit and Thermal Protection
Height:	4.7mm	4.7mm	4.7mm
Length:	14.986mm	14.986mm	14.986mm
Width:	10.16mm	10.16mm	10.16mm
Thickness:	4.572mm	4.572mm	4.572mm
REACH SVHC:	No SVHC	No SVHC	-
Radiation Hardening:	No	No	No
RoHS Status:	ROHS3 Compliant	Non-RoHS Compliant	Non-RoHS Compliant
Lead Free:	Lead Free	Contains Lead	Contains Lead
Pin Count:	-	3	-
Operating Supply Current:	-	70mA	70mA
Bandwidth:	-	5.5MHz	70 kHz
Mount:	-	-	Through Hole
Number of Terminations:	-	-	5
Peak Reflow Temperature (Cel):	-	-	260
Terminal Pitch:	-	-	1.7mm
Time@Peak Reflow Temperature-Max (s):	-	-	40