Texas Instruments LT1009CD

Overview

LT1009CD from Texas Instruments is a precision 2.5-V shunt voltage reference IC in SOIC-8 package, featuring ±10 mV initial tolerance (±0.4%), 15 ppm/°C max average temperature coefficient over 0°C to 70°C, 0.6 Ω max dynamic impedance at 1 mA, and adjustable ±5% output via ADJ pin. It serves as a stable reference for 8-bit ADCs, DACs, and power-supply monitors in industrial instrumentation.

For engineers reviewing the LT1009CD datasheet, LT1009CD pinout, LT1009CD application, or LT1009CD equivalent, key selection considerations include its fixed 2.5-V nominal output with trim capability, SOIC-8 thermal performance (θ_JA = 97°C/W), compatibility with LM136-2.5 layouts, and operation across 0°C to 70°C ambient range without external compensation.

Technical Context

The LT1009CD implements a bandgap-derived shunt reference architecture with on-chip laser trimming to achieve tight initial voltage accuracy and minimized α_VZ. Its three-terminal configuration (ANODE, CATHODE, ADJ) enables system-level error correction while maintaining inherent stability without external components.

It operates as a two-quadrant device: sinking current from a higher-voltage source into its cathode while regulating voltage between anode and cathode. The ADJ pin connects internally to a resistive divider network, allowing ±5% output adjustment by injecting current-enabling calibration without altering temperature coefficient behavior.

Key Specifications

Pinout & Package

LT1009CD uses an 8-pin SOIC (D) package with 1.75 mm maximum height, JEDEC MS-012 compliant footprint, and NIPDAU lead finish. Pin 1 is located in quadrant Q1 per tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt reference applications.

Compared with LM136-2.5 and TL431ACDR, the LT1009CD delivers superior initial accuracy and lower impedance in a pin-compatible SOIC-8 package, making it optimal for applications demanding sub-0.5% reference stability without external components.

Availability

LT1009CD is available at Aetrix Electronics and suitable for industrial process monitoring, 8-bit data acquisition systems, and power supply supervision circuits requiring stable component supply with guaranteed long-term parametric consistency.

Supply support for LT1009CD 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 logic technologies, with decades of heritage in precision analog design.

The LT1009 series was developed specifically for high-stability, low-drift voltage referencing in industrial instrumentation and test equipment, emphasizing factory-trimmed accuracy and minimal system-level calibration overhead.

FAQ

What is the maximum operating junction temperature for the LT1009CD?

The LT1009CD has a maximum operating virtual junction temperature (T_J) of 150°C. This rating applies across its specified ambient range of 0°C to 70°C. Thermal design must account for its SOIC-8 package thermal impedance of 97°C/W to ensure T_J remains within limit under worst-case power dissipation. Exceeding 150°C may degrade long-term reliability and voltage stability of the LT1009CD.

Can the LT1009CD replace the LM136-2.5 without PCB modifications?

Yes, the LT1009CD is explicitly designed as a terminal-for-terminal replacement for the LM136-2.5 in SOIC-8 packages. Both share identical pinout, footprint, and electrical interface. However, the LT1009CD offers tighter initial tolerance (±0.4% vs. ±1%) and built-in ADJ functionality-so while no PCB changes are needed, system-level calibration routines may require update to leverage the improved accuracy of the LT1009CD.

What is the purpose of the ADJ pin on the LT1009CD?

The ADJ pin on the LT1009CD provides ±5% output voltage adjustment by injecting or sinking current, enabling system-level calibration to correct for PCB trace resistance, sensor offset, or gain errors. Unlike trimming resistors, this method preserves the device's low temperature coefficient and does not require external components-making it ideal for field-adjustable instrumentation where the LT1009CD serves as the primary reference.

Does the LT1009CD require an external capacitor for stability?

No, the LT1009CD is internally compensated and operates stably without any external capacitor. Its design eliminates the need for output bypass capacitors commonly required by other shunt references, simplifying layout and reducing component count-especially valuable in compact, high-density applications like portable test equipment where the LT1009CD functions as the core reference.

How does the LT1009CD's dynamic impedance affect ADC reference performance?

The LT1009CD's dynamic impedance of 0.6 Ω max at 1 mA ensures minimal voltage droop during transient current demands from successive-approximation ADCs. This low impedance suppresses noise coupling and maintains reference integrity during sampling events, directly supporting accurate 8-bit conversions where even 1 mV deviation causes ≥1 LSB error-critical for consistent performance in systems relying on the LT1009CD as the reference source.