Texas Instruments LM285H-1.2

Overview

LM285H-1.2 from Texas Instruments is a micropower 2-terminal band-gap voltage reference diode delivering a precise 1.235 V output with ±1% initial tolerance, 1 Ω dynamic impedance, and operation across 10 μA–20 mA current range. It serves as a stable low-voltage reference in battery-powered instrumentation, portable meters, and micropower regulators where long shelf-life battery operation is critical.

For engineers reviewing the LM285H-1.2 datasheet, LM285H-1.2 pinout, LM285H-1.2 application, or LM285H-1.2 equivalent, key selection considerations include its −40°C to +85°C industrial temperature range, TO-92 package compatibility, low 30 ppm/°C temperature coefficient (X-suffix), and suitability for 1.5 V–9 V supply-referenced circuits requiring <100 μA quiescent current.

Technical Context

The LM285H-1.2 implements a band-gap reference architecture using on-chip trimmed transistors and resistors to achieve low noise (60 μV_rms, 10 Hz–10 kHz) and excellent long-term stability (20 ppm/1000 hr). Its 2-terminal configuration simplifies layout and eliminates external bias components.

Designed for capacitive loading tolerance, it maintains regulation stability without output capacitance restrictions-enabling direct use in ADC reference inputs, precision current sources, and thermocouple cold-junction compensators. The device's wide operating current range allows flexible sourcing from high-impedance nodes or low-current batteries.

Key Specifications

Pinout & Package

LM285H-1.2 is supplied in a 3-pin TO-92 molded plastic package (package drawing LP), with leads formed for through-hole mounting. Pin 1 is anode, Pin 2 is cathode, and Pin 3 is internally connected to the die attach pad and may be left floating or tied to Pin 2 per TI design guidance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM385Z-1.2/NOPB, LM285H-1.2 offers broader industrial temperature support and tighter long-term drift; versus REF3012AIDBZR, it trades absolute accuracy for zero-bias simplicity, lower noise, and proven robustness in high-capacitance sensor interfaces.

Availability

LM285H-1.2 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensor nodes, and industrial temperature monitoring systems requiring stable component supply with guaranteed long-term continuity.

Supply support for LM285H-1.2 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 connectivity technologies with over 50 years of analog design heritage.

The LM285 series belongs to TI's precision voltage reference product line, engineered specifically for micropower, low-drift, 2-terminal shunt reference applications in portable, battery-constrained, and industrial measurement systems.

FAQ

What is the maximum reverse current rating for LM285H-1.2?

The absolute maximum reverse current for LM285H-1.2 is 30 mA, as specified in the Absolute Maximum Ratings table. Exceeding this limit risks permanent damage. For reliable operation, TI recommends staying within the 10 μA–20 mA functional range defined in Electrical Characteristics-where the device maintains 1.235 V regulation and 1 Ω dynamic impedance. LM285H-1.2 must be operated in reverse-bias mode with current flowing into the anode (Pin 1).

Does LM285H-1.2 require an external capacitor for stability?

No, LM285H-1.2 does not require an external capacitor for stability. Its internal design provides exceptional tolerance to capacitive loading-TI explicitly states it is "exceptionally tolerant of capacitive loading, making it easy to use in almost any reference application." This allows direct connection to ADC reference inputs, op-amp feedback nodes, or high-C bus lines without series resistance or phase-compensation networks. LM285H-1.2 remains stable with output capacitance values from 0 pF up to several microfarads.

What is the temperature coefficient of LM285H-1.2, and how is it denoted in the part number?

LM285H-1.2 has a temperature coefficient of 30 ppm/°C, corresponding to the 'X' suffix in its full orderable designation (e.g., LM285BXZ-1.2/NOPB). This value represents the average deviation of output voltage over the full −40°C to +85°C operating range, limiting total drift to ±2.55 mV. The 'Y' suffix denotes 50 ppm/°C, while unspecified variants default to 150 ppm/°C. LM285H-1.2's X-suffix performance is validated per TI's production testing protocol.

Can LM285H-1.2 be used with a 1.5 V battery supply?

Yes, LM285H-1.2 can operate directly from a 1.5 V battery, as demonstrated in Figure 16 of the official datasheet (SNVS742E). With a minimum operating current of 10 μA and forward voltage drop near 1.235 V, it functions reliably at supply voltages as low as ~1.3 V-well within the 1.5 V nominal range of alkaline or lithium primary cells. LM285H-1.2 draws only ~30 μA total in such configurations, enabling multi-year operation from common coin cells.

What is the difference between LM285H-1.2 and LM285Z-1.2?

LM285H-1.2 and LM285Z-1.2 share identical electrical specifications, TO-92 packaging, and pinout-but differ in temperature grade and marking. LM285H-1.2 is the industrial-grade variant rated for −40°C to +85°C operation, while LM285Z-1.2 is the commercial-grade version rated 0°C to 70°C. Both are available in NOPB (RoHS-compliant) versions. LM285H-1.2 is the appropriate choice for automotive under-hood, factory-floor, or outdoor-deployed equipment where extended temperature reliability is required.