Texas Instruments LM759CH

Overview

LM759CH from National Semiconductor is a high-output-current power operational amplifier in an 8-lead TO-99 metal can package, delivering ≥325 mA peak output current, ±15 V supply operation, input common-mode range extending to the negative rail, and internal thermal shutdown/safe-area protection. It serves as a robust output stage in linear voltage regulators and audio power drivers requiring high quiescent current tolerance and ruggedized thermal handling.

For engineers reviewing the LM759CH datasheet, LM759CH pinout, LM759CH application, or LM759CH equivalent, key selection criteria include its metal-can thermal performance (θ_JC = 30°C/W), case-connected negative supply terminal, 1 MHz unity-gain bandwidth, 0.6 V/µs slew rate, and guaranteed 325 mA minimum short-circuit current under specified conditions.

Technical Context

The LM759CH implements a bipolar input stage with complementary NPN/PNP output transistors, featuring internal safe-area compensation to prevent second breakdown during transient overloads. Its input stage supports rail-to-negative-rail common-mode operation and exhibits 80–100 dB CMRR and PSRR across the commercial temperature range.

Designed for single- or dual-supply use up to ±18 V, the device integrates short-circuit current limiting, thermal shutdown, and junction temperature monitoring via thermal resistance parameters (θ_JA = 120°C/W unheatsinked). The metal-can package requires mechanical mounting to a heatsink with electrical isolation when the case is tied to the negative supply.

Key Specifications

Pinout & Package

LM759CH uses an 8-lead TO-99 metal can package (National Semiconductor package code H08C), with the case internally bonded to pin 4 and serving as the negative supply connection. Mounting requires electrical isolation if chassis-grounded.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power operational amplifier applications.

Compared with LM759CP and LM77000, the LM759CH offers superior thermal conduction and highest guaranteed output current, making it the only option among the three qualified for chassis-mounted, high-dissipation linear regulator and industrial servo applications requiring sustained >300 mA drive.

Availability

LM759CH is available at Aetrix Electronics and suitable for voltage regulators, audio power drivers, and servo amplifiers requiring stable component supply, long-term obsolescence management, and traceable sourcing of legacy National Semiconductor analog products.

Supply support for LM759CH includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

National Semiconductor was a U.S.-based analog semiconductor company acquired by Texas Instruments in 2011, known for high-reliability op amps, data converters, and power management ICs.

The LM759 product line was engineered for high-current linear applications including precision regulators, audio amplification, and industrial motion control-prioritizing ruggedness, thermal survivability, and fault tolerance over ultra-low noise or speed.

FAQ

What is the maximum supply voltage rating for the LM759CH?

The LM759CH is rated for a maximum supply voltage of ±18 V (36 V total across V₊ and V₋). Exceeding this risks permanent damage to internal transistors. Operation at ±15 V is typical for most applications, and the absolute maximum differential input voltage is 30 V. The LM759CH datasheet specifies that for supplies below 30 V, the input voltage must remain within the supply rails - a critical constraint when designing input protection networks for the LM759CH.

How is the case of the LM759CH electrically connected, and why does it matter?

The metal case of the LM759CH is internally connected to pin 4, which serves as the negative supply terminal (V₋). This means the case is not isolated and must be electrically insulated from the chassis if the system ground references the negative rail. Failure to isolate may cause short circuits or ground loops. When heatsinking the LM759CH, insulating washers or mica pads are mandatory unless the chassis itself functions as the negative supply return path - a design decision directly impacting safety and signal integrity in the LM759CH implementation.

Does the LM759CH require external compensation for stability?

The LM759CH is internally compensated for unity-gain stability and does not require external compensation capacitors in standard configurations. Its 1 MHz bandwidth and 0.6 V/µs slew rate reflect this fixed compensation. However, when driving capacitive loads >100 pF or operating in high-gain configurations (>AV = 10), phase margin may degrade - in such cases, a small series resistor (10–100 Ω) between the LM759CH output and the load is recommended to maintain stability without altering the LM759CH's internal compensation network.

What thermal management is required for continuous operation of the LM759CH?

The LM759CH has a junction-to-case thermal resistance (θ_JC) of 30°C/W and a junction-to-ambient (θ_JA) of 120°C/W without heatsinking. To sustain continuous operation at 25°C ambient, power dissipation must stay below ~540 mW to avoid exceeding the 125°C max junction temperature. For higher loads, a stud-mounted heatsink with insulating hardware is required - the LM759CH's metal-can package demands mechanical clamping and thermal interface material to achieve effective heat transfer, unlike surface-mount alternatives.

Can the LM759CH replace the LM759CP in an existing design?

The LM759CH and LM759CP share identical electrical specifications and pinout, but differ critically in package construction and thermal behavior. The LM759CH's metal-can package requires stud mounting and electrical isolation, while the LM759CP uses a plastic DIP-8 with tab-heatsinking. Swapping them requires verifying mechanical fit, thermal path integrity, and grounding scheme compatibility - the LM759CH cannot be drop-in substituted without redesigning the LM759CH heatsink interface and isolation strategy.