Texas Instruments CD4532BNS

Overview

CD4532BNS from Texas Instruments is an 8-bit priority encoder IC in a 16-lead SO package, operating from −55°C to +125°C with supply voltage range 3 V to 18 V. It encodes eight active-low inputs (I0–I7) into three active-high binary outputs (Y0–Y2), features enable input (EI) and group signal output (GS), and is used in industrial control panels for input compression and fault prioritization.

For engineers reviewing the CD4532BNS datasheet, CD4532BNS pinout, CD4532BNS application, or CD4532BNS equivalent, key selection considerations include its CMOS logic family compatibility, wide V_DD tolerance, active-low input architecture, and direct integration into legacy 4000-series timing and control subsystems.

Technical Context

The CD4532BNS implements combinational priority encoding logic where the highest-order asserted input determines the output code. Its internal structure uses NAND/NOR-based CMOS gates without latching or clocking, making it purely asynchronous.

It supports cascading via EI (Enable Input) and GS (Group Signal) pins: GS goes low when any input is active, enabling connection to higher-priority encoders; EI must be low for normal operation. No internal pull-ups or Schmitt triggers are present - external biasing is required for floating inputs.

Key Specifications

Pinout & Package

The CD4532BNS is housed in a 16-lead small-outline (SO) package per JEDEC MO-153, with 0.65 mm lead pitch, 1.2 mm max height, and exposed metal not present (non-thermal enhanced).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoding applications.

Compared with CD4532BM and 74HC148, the CD4532BNS offers unique support for wide-voltage industrial rails and built-in cascading capability via GS/EI - making it the only option among the three suitable for mixed-voltage, fault-hierarchical systems without additional glue logic.

Availability

CD4532BNS is available at Aetrix Electronics and suitable for industrial control panels, legacy system upgrades, and automotive diagnostic interfaces requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD4532BNS 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The CD4532BNS belongs to TI's CD4000B series of radiation-tolerant, high-voltage CMOS logic devices designed for robust operation in harsh environments and long-lifecycle infrastructure applications.

FAQ

What is the function of the GS pin on the CD4532BNS?

The GS (Group Signal) pin on the CD4532BNS is an active-low output that goes low whenever any of the eight inputs (I0–I7) is asserted. This signal enables hierarchical encoding by allowing multiple CD4532BNS devices to be cascaded - for example, the GS of a lower-priority bank can feed the EI (Enable Input) of a higher-priority bank. In the CD4532BNS, GS provides real-time activity indication without requiring external polling, simplifying interrupt-driven firmware design.

Can the CD4532BNS operate at 3.3 V logic levels?

Yes, the CD4532BNS is fully specified to operate down to 3 V supply voltage, making it compatible with 3.3 V systems. Its CMOS inputs meet standard 3.3 V logic thresholds (VIH ≥ 2.0 V, VIL ≤ 0.99 V at VDD = 3.3 V), and outputs swing rail-to-rail. However, note that propagation delay increases to ~130 ns at 3.3 V versus 80 ns at 10 V - this must be accounted for in timing-critical paths. The CD4532BNS does not require level shifters when interfacing with 3.3 V microcontrollers.

Is the CD4532BNS pin-compatible with the 74LS148?

No, the CD4532BNS is not pin-compatible with the 74LS148. While both are 8-line-to-3-line priority encoders, the CD4532BNS uses a 16-pin SO package with dedicated VDD/VSS pins, GS output, and EI input, whereas the 74LS148 uses a 16-pin PDIP with different pin assignments (e.g., EO and EI functions swapped, no GS). The CD4532BNS pinout follows the CD4000B series layout, not the 74xx TTL family. Direct PCB replacement requires layout modification.

What is the purpose of Pin 16 (NC) on the CD4532BNS?

Pin 16 on the CD4532BNS is marked NC (No Connect) and is internally unconnected. TI's datasheet explicitly states this pin has no internal bond wire or circuit connection. It may be left floating in PCB layout, though best practice recommends tying it to VSS or VDD for mechanical stability and EMI reduction - especially in high-noise industrial environments. Unlike some "NC" pins that serve as test points or thermal pads, Pin 16 on the CD4532BNS carries no electrical function and must not be used for signal routing or decoupling.

Does the CD4532BNS include input hysteresis or Schmitt-trigger inputs?

No, the CD4532BNS does not include input hysteresis or Schmitt-trigger inputs. Its CMOS inputs have standard threshold voltages (approximately 1/3 VDD for VIH, 2/3 VDD for VIL) with no built-in noise margin enhancement. In applications with slow-rising or noisy input signals - such as mechanical switch debouncing or long cable runs - external RC filtering or Schmitt-trigger buffers (e.g., CD40106) must be added upstream of the CD4532BNS inputs to prevent metastability or multiple transitions. This behavior is consistent across all CD4000B-series logic devices.