Texas Instruments UC3178QPTR

Overview

UC3178QPTR from Texas Instruments is a full-bridge power amplifier IC designed for precision servo loop control, delivering ±450mA continuous output current with 1.2V typical total saturation voltage at 450mA, programmable over-current protection, and 4:1 transconductance range switching via the RANGE input-used in industrial motion control systems requiring tight current regulation and thermal robustness.

For engineers reviewing the UC3178QPTR datasheet, UC3178QPTR pinout, UC3178QPTR application, or UC3178QPTR equivalent, this device supports demanding closed-loop servo designs where low quiescent current (12–18mA), dual supply operation (3–15V), and integrated current sense amplifier gain selection are critical selection criteria.

Technical Context

The UC3178QPTR integrates two matched high-side/low-side power amplifiers (A and B) with independent inputs and outputs, enabling differential drive to inductive loads. Its internal current sense amplifier features selectable gain (0.5× or 2.0×) via the RANGE pin, directly altering overall transconductance while maintaining stable loop dynamics through COMP ADJ pin compensation tuning.

Protection architecture includes UVLO (2.8V threshold), thermal shutdown (165°C), open-collector O/C IND output, and inhibit-controlled shutdown drawing <1.5mA. The QP package uses seven power-ground pins tied to die substrate, achieving θ_jl = 15°C/W for sustained 450mA operation without external heatsinking.

Key Specifications

Pinout & Package

UC3178QPTR is housed in a 28-pin PLCC "QP" package (drawing FN) with seven dedicated PWR GND pins (pins 12–18) bonded directly to the die substrate for enhanced thermal conduction and low-inductance ground return paths.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar full-bridge power amplifier applications.

Compared with UC3178QPTR, TSC1013IDT provides no power drive capability and LMD18200T lacks on-chip current sensing and gain-range control - making UC3178QPTR uniquely suited for compact, self-contained servo loops needing integrated precision current regulation and thermal resilience.

Availability

UC3178QPTR is available at Aetrix Electronics and suitable for industrial servo actuation, robotic joint control, and precision valve positioning requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant green packaging.

Supply support for UC3178QPTR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in industrial control ICs.

The UC3178QPTR belongs to TI's legacy Unitrode power amplifier product line, engineered specifically for high-accuracy, thermally robust servo and motion control applications where integrated current sensing and programmable transconductance are essential.

FAQ

What is the maximum continuous output current supported by the UC3178QPTR?

The UC3178QPTR supports ±450mA continuous output current per bridge leg under specified thermal conditions. This rating assumes proper PCB copper area and airflow per TI's thermal data (θ_ja = 30–40°C/W). At 450mA, total V_sat is typically 1.2V, resulting in ~540mW dissipation per channel - well within the QP package's thermal limits when mounted per recommended footprint.

How does the RANGE pin affect the UC3178QPTR's current control performance?

The RANGE pin on the UC3178QPTR selects between two current sense amplifier gains: logic-low sets gain = 2.0×, logic-high sets gain = 0.5×. This 4:1 change directly scales the transconductance of the full-bridge, allowing one UC3178QPTR design to handle both coarse positioning (high current, low resolution) and fine-force control (low current, high resolution) without hardware modification.

Can the UC3178QPTR operate from a single 5V supply?

Yes, the UC3178QPTR operates from 3V to 15V on VIN(+) and VC(+), and functions fully at 5V. At 5V supply, total quiescent current is 12–16mA, UVLO triggers at 2.8V, and output saturation remains within specification. However, maximum load voltage swing is reduced versus 12V operation - verify headroom for your motor or actuator's back-EMF and IR drop.

What protection features are built into the UC3178QPTR?

The UC3178QPTR includes UVLO (2.8V threshold with 300mV hysteresis), thermal shutdown (165°C junction), programmable over-current detection (1.0V threshold), and logic-controlled inhibit shutdown (<1.5mA I_Q). All protections are internal and require no external components - the O/C IND open-collector output signals faults to host controllers, and inhibit input disables all power stages and sensing blocks simultaneously.

Is the UC3178QPTR pin-compatible with other Unitrode full-bridge amplifiers?

No, the UC3178QPTR has a unique 28-pin QP package pinout optimized for thermal performance and integrated current sensing. It is not pin-compatible with UC3175, UC3176, or UC3177 - each uses different pin assignments for C/S(+), COMP ADJ, IDIF REF, and auxiliary logic inputs. Board redesign is required when substituting among these variants.