Texas Instruments SN74145NSRE4

Overview

SN74145NSRE4 from Texas Instruments is a bipolar BCD-to-decimal decoder/driver IC in 16-pin SOP (NS) package, operating from 4.75 V to 5.25 V, with TTL-compatible inputs, open-collector outputs capable of sinking ≥40 mA per channel, and rated for 0°C to 70°C industrial temperature range. It drives common-anode LED displays and relay loads in legacy instrumentation interfaces.

For engineers reviewing the SN74145NSRE4 datasheet, SN74145NSRE4 pinout, SN74145NSRE4 application, or SN74145NSRE4 equivalent, this page delivers verified package mapping, confirmed output drive capability, validated BCD decoding logic, and direct alternatives for through-hole and surface-mount migration paths.

Technical Context

The SN74145NSRE4 implements a 4-bit binary-coded decimal (BCD) input decoder with active-low decoded decimal outputs (Y₀–Y₉), using standard TTL transistor-transistor logic architecture. Each output is an open-collector NPN transistor with base drive internally configured for direct interface to common-anode LEDs or electromechanical relays.

No internal pull-ups are provided; external pull-up resistors are required on all outputs. Input thresholds match standard TTL levels (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), and propagation delay is specified at 35 ns typical (V_CC = 5 V, T_A = 25°C).

Key Specifications

Pinout & Package

SN74145NSRE4 uses a 16-pin SOP (Small Outline Package) with NS drawing code, 1.27 mm pitch, 8.1 mm body width, and 2.00 mm max height. Pin 1 is marked by a beveled corner or notch orientation in the top-left quadrant of the tape.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar BCD-to-decimal decoder/driver applications.

Compared with SN74145NSRE4, SN74LS145NSR offers measurable power and speed improvements within the same SOP-16 footprint, while SN74145N preserves full functional equivalence at the cost of larger board area and manual assembly requirements.

Availability

SN74145NSRE4 is available at Aetrix Electronics and suitable for industrial panel meters, legacy test equipment displays, and electromechanical control panels requiring stable component supply across long-lifecycle production programs.

Supply support for SN74145NSRE4 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.

The SN74xx and SN74LSxx families were designed for robust, low-cost digital logic implementation in commercial and industrial systems - emphasizing interoperability, noise margin, and ease of use in discrete logic-based architectures.

FAQ

What is the maximum sink current per output of the SN74145NSRE4?

The SN74145NSRE4 guarantees a minimum sink current of 40 mA per output at V_OL ≤ 0.5 V with V_CC = 5 V and T_A = 25°C. This rating holds across the full 0°C to 70°C operating range, enabling reliable driving of common-anode LED segments and small signal relays without external buffering. Exceeding 40 mA risks thermal overstress and parametric shift in the SN74145NSRE4 output transistors.

Does the SN74145NSRE4 support 3.3 V logic inputs?

No, the SN74145NSRE4 does not reliably accept 3.3 V logic inputs. Its TTL input thresholds require V_IH ≥ 2.0 V minimum and V_IL ≤ 0.8 V maximum - while 3.3 V CMOS outputs may meet V_IH, their V_OL (often <0.4 V) satisfies V_IL, but noise margin degrades significantly. For guaranteed operation, SN74145NSRE4 must be driven by true TTL or 5 V CMOS sources; level translation is recommended for 3.3 V microcontrollers.

Can the SN74145NSRE4 drive a 12 V LED display directly?

Yes, the SN74145NSRE4 can drive a 12 V common-anode LED display directly via its open-collector outputs. Connect each output to the cathode of its corresponding LED segment, and tie the anode to +12 V through a current-limiting resistor. The SN74145NSRE4 output transistors safely sink up to 40 mA per channel at V_CE = 12 V, provided power dissipation remains within 500 mW total device limit and ambient temperature stays ≤70°C.

Is the SN74145NSRE4 pin-compatible with the SN74LS145NSR?

Yes, the SN74145NSRE4 and SN74LS145NSR are fully pin-compatible and functionally interchangeable in SOP-16 (NS) packages. Both share identical pinout, BCD decoding behavior, open-collector output structure, and 0°C to 70°C temperature rating. The primary differences are propagation delay (35 ns vs. 25 ns) and supply current (55 mW vs. 38 mW), making SN74LS145NSR a drop-in performance upgrade for the SN74145NSRE4 where lower power or faster response is needed.

What is the marking on the top of the SN74145NSRE4 package?

The SN74145NSRE4 is laser-marked "74145" on the top surface of the SOP-16 package, consistent with TI's standard marking convention for 74xx-series logic devices in NS packaging. No date code, lot trace, or RoHS symbol appears in the primary marking field; those identifiers are placed separately on the tape carrier or tube label per TI's packaging documentation.