Table of Contents
LM1875t amplifier circuit LM1875 30W, Circuit of audio power amplifier 30W. The lm1875 is a monolithic audio amplifier that offers a very low distortion and a performance of high quality for projects of audio amplifiers. The lm1875 supplies 20 watts in loads of 4 Ohms or 8 Ohms.
The LM1875 delivers 20 watts into a 4Ωor 8Ωload on±25Vsupplies. Using an 8 Ω load and±30V supplies, over 30 watts of power may be delivered. The amplifier is designed to operate with a minimum of external components. Device overload protection consists of both internal current limit and thermal shutdown. The LM1875 design takes advantage of advanced circuit techniques and processing to achieve extremely low distortion levels even at high output power levels. Other outstanding features include high gain, fast slew rate and a wide power bandwidth, large output voltage swing, high current capability, and a very wide supply range. The amplifier is internally compensated and stable for gains of 10 or greater.
The LM1875 is a monolithic power amplifier offering very low distortion and high-quality performance for consumer audio applications.
The LM1875 delivers 20 watts into a 4 or 8 load on ±25V supplies. Using an 8 load and ±30V supplies, over 30 watts of power may be delivered. The amplifier is designate to operate with a minimum of external components. Device overload protection consists of both internal current limit and thermal shutdown.
The LM1875 designate takes advantage of advanced circuit techniques and processing to achieve extremely low distortion levels even at high output power levels. Other outstanding features include high gain, fast slew rate and a wide power bandwidth, large output voltage swing, high current capability, and an expansive supply range. The amplifier is internally compensated and stable for gains of 10 or greater.
LM1875T Features
- Up to 30 watts output power
- AVO typically 90 dB
- Low distortion: 0.015%, 1 kHz, 20 W
- Wide power bandwidth: 70 kHz
- Protection for AC and DC short circuits to ground
- Thermal protection with parole circuit
- High current capability: 4A
- Wide supply range, 16V-60V
- Internal output protection diodes
- 94 dB ripple rejection
- Plastic power package TO-220
Schematic Lm1875 amp
PCB layout for Lm1875
BOM for circuit
| Component | Valor |
| Resistors 1/4 Watts 5% | |
| R1, R6 | 1,5k — Brown, Red, Gold |
| R2, R3, R4 | 22k — Red, Red, Orange, Gold |
| R5 | 220K — Red, Red, Orange, Gold |
| R7 1 Watt 5% | 1R — Brown, Black, Gold |
| R8 | 1M — Brown, Black, Green, Gold |
| Capacitors | |
| C1 | 100nF — Ceramic Capacitor – 104, 100n, 0.1 |
| C2,C3 | 3300µF/35V — Polarized Electrolytic Capacitor |
| C4, C5 | 2.2µF/25V — Polarized Electrolytic Capacitor |
| C6 | 220nF/63V — Polarized Electrolytic Capacitor — 220n, 224, 0.22 |
| C7 | 100µF/25V — Polarized Electrolytic Capacitor |
| C8 | 2200µF/35V — Polarized Electrolytic Capacitor |
| Semiconductors | |
| D1, D2, D3, D4 | RL207 — 2A diode |
| LED | LED 5MM – Led any color |
| IC1 | LM1875T Audio amplifier integrated circuit |
| Connectors | |
| CN1 (IN) | Audio Input Connector |
| CN2 (AC) | Power connector, connect the transformer. |
| CN3 (OUT) | Audio Out Connector |
| Miscellaneous: Solder, box for assembly, 2 Amp 20 Volt transformer, wires, etc. | |
The electrolytic capacitors were considered for a transformer power supply up to 20V. For a trafo of up to 28V, use capacitors with a working voltage of 50V.
Last Update: 04/08/2021 13:40
For more information, see the lm1875T datasheet.
Download files to assemble the amplifier – Includes printed circuit board in PDF, PNG and Gerber
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Download PDF datasheet LM1875
TINA-TI Reference Design (Rev. A)
There is an error in the PCB. R5 must connect to pin 2 and pin 4 of IC1 and R6 only to pin 2. There must be no connection between R5, R6 on C5. Only R6 connects to C5.
After the change it works very nicely.
Greetings Andrzej.
Hello Andrzej,
Thanks, corrected layout.
Is the LM1875 is the same as the TDA2030A and how do you power this amp, and does it have a potentiometer and what size well thank you.
i think TDA 2030A it like same as type LM1875 brothers,,using TDA 2050 making power more aggressive sound