Texas Instruments SN74HCS137DR

Overview

SN74HCS137DR from Texas Instruments is a 3-to-8 line decoder/demultiplexer with latched address inputs, Schmitt-trigger inputs, and dual strobe control (G0, G1). It operates from 2 V to 6 V, delivers ±7.8-mA output drive at 6 V, supports –40°C to +125°C ambient temperature, and features typical ICC of 100 nA. It enables memory device selection on shared data buses in industrial microcontroller systems.

For engineers reviewing the SN74HCS137DR datasheet, SN74HCS137DR pinout, SN74HCS137DR application, or SN74HCS137DR equivalent, key selection criteria include latch-enable timing (LE setup/hold), Schmitt-trigger hysteresis (ΔVT = 0.6–1.6 V), output drive strength under load, and dual-strobe gating behavior for cascaded demultiplexing.

Technical Context

The SN74HCS137DR implements a CMOS-based 3:8 decoder with transparent address latching controlled by active-low LE. When LE is low, A2–A0 directly determine Y0–Y7 output state; when LE is high, outputs retain prior decoded state regardless of address changes. Strobe inputs G0 (active-high) and G1 (active-low) provide independent output enable/disable logic - either active strobe forces all outputs high.

Its Schmitt-trigger inputs provide hysteresis (ΔVT ≥ 0.6 V at 6 V), enabling robust operation with slow-rising signals or noisy environments. Output structure uses balanced CMOS push-pull drivers capable of sourcing/sinking up to 7.8 mA at 6 V while maintaining VOL ≤ 0.33 V and VOH ≥ 5.4 V.

Key Specifications

Pinout & Package

SN74HCS137DR is supplied in SOIC-16 (D) package, body size 9.90 mm × 3.90 mm, with standard 1.27-mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder with latch applications.

Compared with SN74HCS137DR, SN74HCS237DR removes latching capability but adds dedicated OE control - trading state retention for simplified enable logic; CD74HC237M96 offers identical performance with alternate manufacturing traceability, supporting long-term production continuity.

Availability

SN74HCS137DR is available at Aetrix Electronics and suitable for industrial control systems, automotive electronics, battery-powered IoT nodes, and memory subsystems requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SN74HCS137DR 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 consumer markets.

The SN74HCS137DR belongs to TI's HCS logic family - designed specifically for low-power, high-noise-immunity digital interfacing in harsh environments where reliability and extended temperature operation are critical.

FAQ

What is the latch enable (LE) polarity for SN74HCS137DR?

The latch enable (LE) input on the SN74HCS137DR is active low. When LE is low, the device performs real-time 3-to-8 decoding based on A2–A0 inputs. When LE is high, the internal address latches retain their previous state, freezing the output selection regardless of subsequent changes to A2–A0. This behavior is confirmed in the device functional modes table and timing diagrams of the official datasheet SCLS831A.

Does SN74HCS137DR support 3.3-V operation?

Yes, SN74HCS137DR fully supports 3.3-V operation within its recommended supply range of 2 V to 6 V. At 3.3 V, it maintains guaranteed output drive (±6 mA), Schmitt-trigger hysteresis (ΔVT ≥ 0.4 V), and propagation delay ≤ 14 ns. Input thresholds scale with VCC, ensuring compatibility with standard 3.3-V CMOS logic levels without level shifters.

How do the G0 and G1 strobe inputs interact on SN74HCS137DR?

On SN74HCS137DR, G0 is active-high and G1 is active-low. Either strobe being asserted forces all eight outputs (Y0–Y7) into the high state, effectively disabling the decoder. Both must be inactive (G0 low, G1 high) for normal decoded output behavior. This dual-strobe architecture simplifies cascading - for example, G1 of a downstream device can be driven by Y0 of an upstream SN74HCS137DR.

Can SN74HCS137DR drive LEDs directly?

Yes, SN74HCS137DR can drive low-current LEDs directly when configured in active-low mode (Yx = LOW activates LED). At 6 V supply, it sinks up to 7.8 mA per output - sufficient for indicator LEDs with series resistors ≥ 680 Ω. For higher-current or multi-LED loads, external buffering is recommended. Always verify VOL remains ≤ 0.33 V under actual load conditions per the Electrical Characteristics table.

What is the maximum capacitive load SN74HCS137DR can drive while meeting timing specs?

The SN74HCS137DR is characterized for CL = 50 pF in its switching and timing specifications. Driving loads exceeding 50 pF will increase propagation delay and transition time - for example, tpd rises from 6 ns (typ) to >12 ns at 100 pF. For reliable timing compliance in high-speed designs, keep total output capacitance (trace + load) ≤ 50 pF, or add series termination to dampen ringing if larger loads are unavoidable.