Texas Instruments THS3122CDDARG3

Overview

THS3122CDDARG3 from Texas Instruments is a dual-channel, bipolar-input current feedback amplifier optimized for high-output-current, low-distortion video and instrumentation signal conditioning. It delivers 450 mA output drive, 128-MHz –3-dB bandwidth (RL = 50 Ω, RF = 470 Ω), 1550-V/µs slew rate (G = 2), 2.2-nV/√Hz voltage noise, and ±15-V dual-supply operation - enabling robust driving of four serially-terminated 75-Ω video lines with <0.01% differential gain error.

For engineers reviewing the THS3122CDDARG3 datasheet, THS3122CDDARG3 pinout, THS3122CDDARG3 application, or THS3122CDDARG3 equivalent, key selection criteria include its SOIC-8 PowerPAD™ package thermal performance, dual-channel current-feedback architecture, 2.9-pA/√Hz noninverting input current noise, shutdown-incompatible design (no SHUTDOWN/REF pins), and suitability for wide-swing line driver and piezo actuator interfaces requiring >26-VPP output into 50 Ω.

Technical Context

The THS3122CDDARG3 implements a current feedback topology with high-impedance noninverting inputs and low-impedance inverting inputs, enabling stable gain-setting via feedback resistor networks independent of closed-loop gain. Its transimpedance open-loop gain exceeds 1 MΩ, supporting fast settling (64 ns to 0.1%) and wide full-power bandwidth (64 MHz at ±15 V, 20 VPP).

Designed for bipolar supply operation (±5 V to ±15 V), it features rail-to-rail output swing capability (13.3 VPP into 50 Ω at ±15 V), low input offset voltage (±25 mV max), and excellent common-mode rejection (67 dB typ at ±15 V), making it suitable for precision DC-coupled signal paths where dynamic range and harmonic integrity are critical.

Key Specifications

Pinout & Package

THS3122CDDARG3 is housed in an 8-pin SOIC PowerPAD™ (DDA) package with exposed thermal pad on underside, requiring PCB copper pour connection for thermal management. Package dimensions: 4.89 mm × 3.90 mm × 1.75 mm (height), JEDEC MS-012AC compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel current feedback amplifier applications.

Compared with THS3122CD and THS3202DR, THS3122CDDARG3 uniquely balances high output current (450 mA), low voltage noise (2.2 nV/√Hz), and thermally robust PowerPAD™ packaging - making it the only option among the three capable of sustained 26-VPP output into 50 Ω at +70°C ambient without derating.

Availability

THS3122CDDARG3 is available at Aetrix Electronics and suitable for video distribution systems, precision instrumentation signal chains, and high-speed line driver designs requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for THS3122CDDARG3 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 and embedded processing technologies, with decades of expertise in high-speed amplifier design and manufacturing.

The THS312x product line was engineered specifically for demanding video, instrumentation, and high-current line driver applications where low noise, wide bandwidth, and robust output drive must coexist - addressing limitations of traditional voltage-feedback op-amps in heavy-load scenarios.

FAQ

What is the maximum safe continuous output current for THS3122CDDARG3?

The THS3122CDDARG3 is rated for 450 mA continuous output current per channel under recommended operating conditions (TA ≤ +70°C, proper thermal pad connection). Absolute maximum rating is 550 mA, but sustained operation above 450 mA risks thermal overload unless board-level heatsinking exceeds 67°C/W θJA. The THS3122CDDARG3 datasheet specifies 440 mA typical drive into 25 Ω at ±15 V, confirming its capability to deliver full-rated current without clipping.

Does THS3122CDDARG3 support single-supply operation?

No, THS3122CDDARG3 is designed exclusively for dual-supply operation from ±5 V to ±15 V. It lacks rail-to-rail input common-mode range below the negative rail and does not specify performance for single-supply configurations. Attempting single-supply use (e.g., 0 V and +15 V) violates the absolute maximum rating for input voltage (–VCC to +VCC) and risks latch-up or degraded distortion performance. For single-supply applications, consider TI's THS3491 or OPA695 alternatives.

What is the purpose of the exposed thermal pad on the THS3122CDDARG3 DDA package?

The exposed thermal pad on the THS3122CDDARG3 DDA package serves as the primary thermal conduction path from the die to the PCB, reducing junction-to-ambient thermal resistance (θJA) from 95°C/W (standard SOIC) to 67°C/W. It must be soldered to a solid copper pour connected to internal ground or power planes; failure to do so causes junction temperature to exceed 150°C under 450-mA load, triggering permanent damage. TI Technical Brief SLMA002 provides layout guidelines for optimal thermal pad implementation.

Can THS3122CDDARG3 replace THS3125 in existing designs?

No, THS3122CDDARG3 cannot directly replace THS3125 because it lacks SHUTDOWN and REF pins - the THS3125 uses a 14-pin HTSSOP package with power-down functionality, while THS3122CDDARG3 is an 8-pin SOIC PowerPAD™ device with fixed-on operation. Pin count, pinout, and feature set are incompatible. Board redesign is required to substitute THS3122CDDARG3 for THS3125, and vice versa; they belong to the same family but serve distinct functional roles.

What feedback resistor value is recommended for G = 2 configuration with THS3122CDDARG3?

For a noninverting gain of 2, TI recommends RF = 470 Ω with RL = 50 Ω in the THS3122CDDARG3 datasheet (SLOS382E, Section 7.4). This combination achieves 128-MHz –3-dB bandwidth and –80 dBc THD at 1 MHz. Using RF = 470 Ω also balances stability margin and noise gain; lower values risk instability, while higher values degrade bandwidth and increase thermal noise. Layout must minimize parasitic capacitance at the inverting input (Pin 2) to preserve specified performance.