Texas Instruments TLC251ACD

Overview

TLC251ACD from Texas Instruments is a LinCMOS™ programmable low-power operational amplifier in an 8-pin SOIC package, featuring true single-supply operation down to 1.4 V, input offset voltage ≤5 mV (max at 25°C), and selectable high/medium/low bias modes for dynamic power–performance trade-offs. It delivers 1.7 MHz unity-gain bandwidth (high-bias, VDD = 5 V), 3.6 V/µs slew rate, and rail-to-rail input common-mode range including the negative rail - ideal for battery-powered sensor front-ends and portable instrumentation.

For engineers reviewing the TLC251ACD datasheet, TLC251ACD pinout, TLC251ACD application, or TLC251ACD equivalent, this device requires attention to BIAS SELECT logic level selection (ground, VDD, or mid-rail), external offset nulling via 25-kΩ potentiometer, and load-dependent output swing behavior across its three ac performance modes.

Technical Context

The TLC251ACD implements a silicon-gate LinCMOS™ process enabling stable input offset without metal-gate drift, while supporting programmable bias current (10 µA to 1600 µA) via the BIAS SELECT pin. Its input stage operates with ultra-low input bias current (≤60 pA typ) and common-mode range extending to VDD–/GND, enabling direct interfacing with grounded sensors in single-supply systems.

Three distinct operating modes-low-bias (10 µA, 65 kHz GBW), medium-bias (280 µA, 525 kHz GBW), and high-bias (1600 µA, 1.7 MHz GBW)-are selected by applying ground, VDD, or ~VDD/2 to the BIAS SELECT pin. Each mode exhibits unique large-signal differential gain (AVD), phase margin (34°–46°), and noise floor (68–25 nV/√Hz), with internal ESD protection exceeding 2000 V per MIL-STD-833C.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (D), 3.9 mm × 4.9 mm body, 1.27 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC27L2CD and LPV821DR, the TLC251ACD uniquely combines programmable bias, external offset nulling, and 1.4–16 V wide supply range - making it irreplaceable in applications requiring runtime-configurable analog performance within legacy industrial or medical designs.

Availability

TLC251ACD is available at Aetrix Electronics and suitable for portable medical sensors, industrial process monitoring, energy-harvesting IoT nodes, and remote environmental data loggers requiring stable component supply across extended product lifecycles.

Supply support for TLC251ACD 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 digital signal solutions, with over 90 years of innovation in precision analog ICs.

The TLC251 family belongs to TI's legacy LinCMOS™ operational amplifier product line, designed specifically for battery-powered and energy-constrained applications requiring programmable performance and robust dc precision.

FAQ

What supply voltage range does the TLC251ACD support, and how does it affect bias mode selection?

The TLC251ACD operates from 1.4 V to 16 V. At VDD = 1.4 V, typical supply currents are 12 µA (high-bias), 2 µA (medium-bias), and 2 µA (low-bias). As VDD increases, high-bias current rises to ~1600 µA at 5 V, while low-bias remains near 10 µA. The BIAS SELECT pin logic thresholds scale with VDD, so grounding the pin always selects high-bias regardless of supply voltage. This ensures consistent mode selection across the full voltage range.

How is input offset voltage trimmed on the TLC251ACD, and what is the nulling range in each bias mode?

Input offset voltage on the TLC251ACD is trimmed using a 25-kΩ potentiometer connected between pins 1 (OFFSET N1) and 8 (OFFSET N2), with the wiper tied to pin 4 (VDD–/GND). In high-bias mode (1600 µA), the full ±5-mV offset range can be nulled to zero. In medium- or low-bias modes, or at VDD < 4 V, total nulling may not be achievable for all units due to reduced internal bias currents affecting the nulling circuit's effective range.

What are the output stage limitations of the TLC251ACD, and how do they impact load design?

The TLC251ACD uses a source-follower pull-up and open-drain pull-down output stage. High-level output voltage (VOH) depends on VDD and load: at VDD = 5 V and RL = 10 kΩ, VOH is ≥3.2 V; it drops under heavier loads. Low-level output voltage (VOL) is ≤50 mV with no load but rises with sink current. Designers must verify VOH/VOL margins against downstream logic thresholds and avoid driving capacitive loads >100 pF without isolation to prevent instability.

Can the TLC251ACD be used in dual-supply configurations, and what constraints apply?

Yes, the TLC251ACD supports split-supply operation (e.g., ±2.5 V), but only if the input common-mode voltage stays within VICR (–0.2 V to VDD–0.2 V), output swing remains within VOL/VOH limits, and supply rails stay within absolute maximum ratings (±18 V differential, 18 V total). The VDD–/GND pin must be tied to the negative rail, not ground, and BIAS SELECT logic levels must be referenced accordingly - e.g., "ground" means negative rail, not system ground.

What is the significance of the LinCMOS™ process used in the TLC251ACD compared to standard CMOS or bipolar op-amps?

LinCMOS™ is Texas Instruments' silicon-gate CMOS process that eliminates the input offset voltage drift inherent in older metal-gate CMOS op-amps, while retaining ultra-low input bias current (<60 pA) and high input impedance (>10¹² Ω). Unlike bipolar op-amps, it avoids high quiescent current and input bias current temperature sensitivity. This makes the TLC251ACD uniquely suited for precision, low-power, high-impedance applications where stability and power efficiency are both critical.