Texas Instruments LM3916N-1/NOPB

Overview

LM3916N-1/NOPB from Texas Instruments is a monolithic logarithmic dot/bar display driver IC that senses analog input voltage and drives ten open-collector NPN outputs for LEDs, LCDs, or vacuum fluorescent displays. It operates from 3V to 25V single supply, features ±35V input tolerance, 0.2 dB typical accuracy, and user-selectable bar/dot mode via pin 9 - used in audio VU meters, power level indicators, and signal monitoring systems.

For engineers reviewing the LM3916N-1/NOPB datasheet, LM3916N-1/NOPB pinout, LM3916N-1/NOPB application, or LM3916N-1/NOPB equivalent, key selection considerations include its logarithmic 3 dB/step threshold spacing, programmable LED current (1–30 mA), internal 1.25 V reference, floating 10-step divider, and operation down to ground with no input protection required.

Technical Context

The LM3916N-1/NOPB integrates a high-impedance input buffer, precision 10-step logarithmic voltage divider (8–17 kΩ total), and ten matched comparators referenced to the divider. Its input accepts signals from ground to within 1.5 V of V+, with ±35 V fault tolerance on pin 5.

Each output is a current-regulated open-collector NPN transistor; LED current is set by reference load current (≈10× I_REF) and remains stable across 2–17 V LED supply range. Mode selection (bar vs. dot) is controlled by pin 9 voltage relative to V+: ≥(V+ −20 mV) enables bar mode; ≤(V+ −200 mV) or open circuit enables dot mode.

Key Specifications

Pinout & Package

LM3916N-1/NOPB is housed in an 18-lead plastic dual in-line package (PDIP-NFK), with 0.3-inch body width and standard through-hole mounting. Pin 1 is top-left corner when notch faces up.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar logarithmic display driver applications.

Compared with LM3916N-1/NOPB, LM3915N-1/NOPB provides superior low-level accuracy for audio peak detection, while LM3914N-1/NOPB delivers predictable linear scaling for instrumentation - all share identical PDIP-18 packaging and reference programming, enabling drop-in layout reuse across measurement types.

Availability

LM3916N-1/NOPB is available at Aetrix Electronics and suitable for audio instrumentation, power monitoring systems, and industrial signal integrity panels requiring stable component supply and long-term production continuity.

Supply support for LM3916N-1/NOPB 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 innovation in precision analog ICs.

The LM3916N-1/NOPB belongs to TI's legacy analog display driver family designed specifically for replacing mechanical meters with solid-state LED/LCD/VFD visual indicators in audio, test, and industrial equipment.

FAQ

What is the primary function of the LM3916N-1/NOPB in a circuit?

The LM3916N-1/NOPB functions as a dedicated logarithmic dot/bar display driver IC that converts an analog input voltage into a 10-segment visual output. It internally generates a precision 10-step logarithmic voltage divider, compares the input against each threshold, and drives corresponding open-collector outputs to illuminate LEDs or other displays. Its core purpose is to replace analog panel meters with faster, more rugged, and highly visible digital-style indicators - especially in audio level monitoring where human-perceived loudness follows a logarithmic scale. The LM3916N-1/NOPB achieves this without external op-amps or DACs, using only passive components for full-scale adjustment and brightness control.

How does the LM3916N-1/NOPB achieve logarithmic scaling, and what is its step resolution?

The LM3916N-1/NOPB achieves logarithmic scaling through a factory-trimmed internal 10-step resistor ladder configured to produce thresholds spaced at precisely 3 dB intervals - meaning each successive LED activates at approximately twice the input voltage (or power) of the prior one. This corresponds to a 3 dB/step resolution across its full dynamic range. Accuracy is typically better than 0.2 dB near mid-scale and holds within ±1 dB at −20 dB full-scale. The logarithmic behavior is fixed in silicon and does not require external configuration; it is intrinsic to the LM3916N-1/NOPB's comparator reference structure and is distinct from the linear LM3914 or the alternate logarithmic LM3915 (which shares the same 3 dB/step but differs in internal offset calibration).

Can the LM3916N-1/NOPB drive LEDs directly without current-limiting resistors?

Yes, the LM3916N-1/NOPB can drive LEDs directly without external current-limiting resistors because each of its ten output pins is a current-regulated open-collector NPN transistor. LED current is programmed by the load current drawn from the REF OUT (pin 7): I_LED ≈ 10 × I_REF. By selecting appropriate resistor values for the reference voltage divider (R1 and R2), users set I_REF and thereby fix I_LED across all active outputs - typically between 1 mA and 30 mA. This regulation remains stable over temperature and LED supply voltage (2–17 V), eliminating part-to-part LED brightness variation and simplifying BOM. However, VLED must remain below 7 V unless a series dropping resistor is added to limit IC power dissipation.

What is the role of pin 9 (MODE) on the LM3916N-1/NOPB, and how is it configured for bar vs. dot mode?

Pin 9 (MODE) on the LM3916N-1/NOPB selects between bar graph and moving dot display modes. In bar mode, pin 9 must be connected directly to V+ (pin 3); the internal comparator interprets this as ≥(V+ −20 mV) and activates all outputs up to and including the highest-threshold LED that exceeds the input. In dot mode, pin 9 is left open-circuit (or pulled ≥200 mV below V+), causing only one LED - the one whose threshold is closest to the input - to illuminate. This pin also enables cascading: in multi-device dot-mode configurations, pin 9 of a lower-range device connects to pin 1 of the next higher-range device to coordinate carry logic and prevent ambiguous overlapping illumination. No external logic or timing circuitry is required for either mode.

Is the LM3916N-1/NOPB compatible with modern PCB assembly processes, and what is its package type?

Yes, the LM3916N-1/NOPB is compatible with standard through-hole PCB assembly processes. It is supplied in an 18-lead plastic dual in-line package (PDIP-NFK) with 0.3-inch body width and 0.1-inch lead pitch - a legacy but widely supported through-hole format. While not surface-mount, its PDIP package allows reliable hand-soldering, wave soldering, and automated insertion in legacy and mixed-technology boards. The "NOPB" suffix indicates lead-free (Pb-free) finish per JEDEC J-STD-609, compliant with RoHS directives. Note that the LM3916N-1/NOPB is not offered in SOIC or TSSOP variants; for SMT alternatives, engineers should evaluate functional equivalents like the LM3916NS/NOPB (SOIC-16, not pin-compatible) or redesign around newer display drivers - but the LM3916N-1/NOPB remains actively stocked for repair, replacement, and legacy production.