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LM1875T/LB05

Texas Instruments

Texas Instruments LM1875T/LB05, Class AB audio amplifier IC, 1-Channel (Mono), 25W x 1 @ 8Ohm, 16V ~ 60V or ±8V ~ 30V supply, Through Hole, TO-220-5 Formed Leads, 0°C ~ 70°C.

Texas Instruments LM1875T/LB05
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[IN STOCK] In Stock: 4 pcs
$9.86/ pc

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Technical specifications

LM1875T/LB05 specifications
Parameter / AttributeSpecification / Value
TypeClass AB
Output type1-Channel (Mono)
MountingThrough Hole
Supply voltage16V ~ 60V, ±8V ~ 30V
Max output power x channels @ load25W x 1 @ 8Ohm
Operating temperature0°C ~ 70°C (TA)
PackageTube
FeaturesShort-Circuit and Thermal Protection
CaseTO-220-5 Formed Leads
100% Footprint Match · Solder-Ready (No PCB Redesign Needed)

Need Stock or a Drop-in Second-Source for LM1875T/LB05?

Package: Pentawatt (TO-220-5) · Pin-compatible replacements with immediate Shenzhen spot stock

Footprint Match 98%
Supply Chain & Allocation Reality:

This is the chip-amp family of computer speakers, guitar practice amps and a hundred thousand DIY boards: five pins, tab at the negative rail, and a pinout so standard that TDA2030A, TDA2040, TDA2050 and LM1875 boards are routinely published as one PCB. The differences live in three numbers - supply ceiling, output power and peak current - and in one market reality: the TDA2050 is discontinued at ST and the open market is full of parts that are visibly TDA2030 dies under a 2050 laser. Substitution here is easy and the fake screening is mandatory; the 4-ohm corner is where an otherwise correct swap trips protection and sounds broken.

Verified Pin-Compatible Replacements (3 verified alternatives)

TDA2050 STMicroelectronics (discontinued) Pentawatt (TO-220-5)
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

The 32W Peak of the Family - Verify Every Lot

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The highest-current member of the classic four: about 32W into 8 ohms at +/-22V and the strongest 4-ohm drive of the group, same five-pin socket as the rest.

Rails to +/-22V - between the TDA2030 (+/-18V class) and the LM1875 (+/-30V class).

Compatibility & Drop-In Notes: The market warning: original ST TDA2050 is discontinued, and marketplace stock is frequently a TDA2030 die relabeled - it works in single-chip amps at lower power and fails the moment the design asks for 2050-class output. Buy verified lots with photographed markings, and expect the screening conversation.
Package & Solder Footprint: Identical five-pin Pentawatt footprint across the family; the tab sits at the negative rail - insulate against grounded heatsinks.
Shenzhen Warehouse Stock & MOQ: Stocked with lot verification; treat every 2050 claim as unverified until the markings are photographed.
Request Volume Quote for TDA2050 Compare LM1875T/LB05 vs TDA2050 Spec Matrix
LM1875 Texas Instruments Pentawatt (TO-220-5)
Functional Equivalent
Availability & Target Pricing:

The Still-In-Production Quality Choice

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The TI member: about 20W into 8 ohms at +/-25V with the family lowest distortion and a +/-30V supply ceiling - still in production where the TDA2050 line is not.

Rails to +/-30V (absolute class): the largest margin in the socket.

Compatibility & Drop-In Notes: The swap rules of the family: the replacement supply ceiling must exceed the amplifier rail, and its minimum load must be at or below the original. LM1875 into a 4-ohm TDA2050 board is electrically legal but dynamically challenged - check the speaker impedance before promising it.
Package & Solder Footprint: Same five-pin socket; same tab-at-negative-rail isolation requirement.
Shenzhen Warehouse Stock & MOQ: Active TI production; the safe genuine buy in this family.
Request Volume Quote for LM1875 Compare LM1875T/LB05 vs LM1875 Spec Matrix
TDA2030A STMicroelectronics / multiple Pentawatt (TO-220-5)
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

The 18W Baseline Everybody Has

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The 18W-class original of the socket: +/-18V class rails, 12W guaranteed into 4 ohms, and the family reference point every board and module was laid out around.

The lowest ceiling of the three (-18V class; some vendor datasheets allow a step more) - which is exactly why it substitutes freely into higher-rated boards at reduced volume, and never the reverse.

Compatibility & Drop-In Notes: The classic fake direction: a genuine 2030 that is honest about being a 2030 is fine; the problem part is the 2030 die sold as 2050 or LM1875. Read markings, distrust smooth relabels, and check the die behavior under the original rail voltage.
Package & Solder Footprint: Same socket as the family; verify the protection-diode network on 2030-era designs.
Shenzhen Warehouse Stock & MOQ: Ubiquitous genuine and clone stock; the family workhorse for repair.
Request Volume Quote for TDA2030A Compare LM1875T/LB05 vs TDA2030A Spec Matrix
Buyer & Quality Checklist for Sourcing Alternatives
  • Substitution arithmetic for the family: the replacement supply ceiling must exceed the actual rail, and its minimum stable load must be at or below the original. Downward moves are safe at reduced power; upward moves risk overvoltage.
  • The TDA2050 market warning: original production ended at ST; marketplace 2050s are frequently relabeled TDA2030 dies. Verify lots and behavior, not markings alone.
  • The 4-ohm corner: the LM1875 protects earlier than the TDA2050 at high 4-ohm output - a swap that passes the bench at low volume can distort at party level.
  • Keep the era-correct protection network: TDA2006/2030 designs carry external clamp diodes the later members internalize; deleting them while "simplifying" a repair reintroduces the failure mode.
  • Zobel network values differ slightly across the family (the 2050 datasheet shows its own RC): if the board was rebuilt around a substituted chip, use the network of the chip actually fitted.
  • Gain below about 24dB invites instability in this whole family - when a repaired board oscillates or hisses, check the feedback divider against the fitted chip before the chip itself.
  • The tab is at the negative rail, not ground: insulator kits are part of the design, not optional in shared-heatsink builds.
Frequently Asked Technical Questions

Q: Can I replace TDA2030 with TDA2050 or LM1875?

A: Same five-pin socket, and upward substitutions work at the same volume: both replacements tolerate the 2030 rails easily. The reverse (2050 replaced by 2030) runs at reduced supply headroom and power - fine for a bench, a downgrade for the product.

Q: Why do TDA2050 parts from the market sound weaker than expected?

A: Because the TDA2050 line is discontinued and many open-market parts are TDA2030 dies with a 2050 laser: they work at reduced power and clip early. Buy verified lots; treat every 2050 marking as a claim until the lot is photographed and behavior-checked.

Q: Why does the LM1875 go into distortion into 4-ohm speakers?

A: Its protection engages earlier than the TDA2050 at high 4-ohm output. The swap is electrically valid but the dynamic headroom differs - check speaker impedance against the fitted chip, or move to a higher-current member.

Technical details

25W mono Class AB amplifier in a TO-220-5

The LM1875T/LB05 is a Class AB audio power amplifier IC from Texas Instruments, delivering 25W continuous into an 8Ω load from a single-ended or split supply. Typical applications include active speakers, powered subwoofers, home-theater amplifiers, and general-purpose audio line drivers where a single-chip solution with modest heatsinking is preferred over discrete designs.

The supply range of 16V to 60V (or ±8V to ±30V) covers most common audio rails. The 25W output at 8Ω is the headline figure.

LM1875T/LB05
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