Texas Instruments CD74ACT157PWR

Overview

CD74ACT157PWR from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer in TSSOP-16 package, operating at 4.5V–5.5V V_CC, with ±24mA output drive, balanced propagation delays (t_PLH/t_PHL ≤ 8.6ns at –40°C to 85°C), and TTL-voltage-compatible inputs. It routes four independent 2:1 data paths under shared A/B address and active-low strobe (G) control, used in digital bus switching and logic-level multiplexing.

For engineers reviewing the CD74ACT157PWR datasheet, CD74ACT157PWR pinout, CD74ACT157PWR application, or CD74ACT157PWR equivalent, key selection criteria include its 16-pin TSSOP package, guaranteed operation across –55°C to 125°C, CMOS push-pull output structure, SCR-latchup resistance, and ESD rating of ±2kV per MIL-STD-883 Method 3015.

Technical Context

The CD74ACT157PWR implements four independent 2:1 multiplexers sharing one address input (A/B) and one active-low output enable (G). Each Y output reflects the selected input (A or B) when G is high; all outputs force low when G is low. Its asynchronous operation requires no clock, and all channels respond identically to the same control signals.

It uses a silicon-gate CMOS process with TTL-compatible input thresholds (V_IL = 0.8V, V_VIH = 2.0V), balanced push-pull outputs capable of sourcing/sinking ±24mA, and internal clamp diodes for ESD protection. Input transition rate must be ≤10 ns/V to prevent oscillation and excessive power draw.

Key Specifications

Pinout & Package

TSSOP-16 package (PW): 5.00mm × 6.4mm body size, 0.65mm lead pitch, thermally enhanced layout with exposed pad (not electrically connected unless tied to GND).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 2:1 multiplexer applications.

Compared with SN74ACT157PW, CD74ACT157PWR offers identical functionality and drop-in replacement capability; versus 74LCX157MTCX, it delivers 5V operation, TTL compatibility, and tighter timing-critical for mixed-voltage or legacy system upgrades.

Availability

CD74ACT157PWR is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, and test instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74ACT157PWR 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 CD74ACT157PWR belongs to TI's Advanced CMOS Logic (ACT) family, engineered for high-speed, low-power 5V digital signal routing in noise-immune, latchup-resistant applications.

FAQ

What is the maximum capacitive load the CD74ACT157PWR can drive while maintaining specified timing?

The CD74ACT157PWR is characterized for a 50pF load in its switching specifications (t_PLH, t_PHL). Driving larger capacitances increases propagation delay and may cause signal integrity issues like ringing or overshoot. While operation beyond 50pF is possible, timing margins degrade progressively - TI recommends limiting total load capacitance to ≤50pF for guaranteed compliance with datasheet timing limits across temperature and voltage.

Does the CD74ACT157PWR require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of the CD74ACT157PWR must be terminated to either V_CC or GND to prevent floating nodes, which can cause excessive power consumption, oscillation, or logic malfunction. A 10kΩ resistor is recommended for pull-up/pull-down if the input may be driven intermittently; direct connection is acceptable for permanently unused inputs. This requirement applies to A/B, G, and any unconnected data inputs (1A–4B).

Can the CD74ACT157PWR operate reliably at 3.3V supply voltage?

No - the CD74ACT157PWR is specified only for 4.5V to 5.5V V_CC. Operation below 4.5V violates the Recommended Operating Conditions and risks incorrect logic levels, increased propagation delay, and potential functional failure. For 3.3V systems, consider TI's 74LVC157 or similar LVCMOS-family alternatives explicitly rated for that voltage range.

Is the thermal pad on the CD74ACT157PWR package electrically connected internally?

No - the exposed thermal pad on the CD74ACT157PWR (TSSOP-16) is not electrically connected to any internal node. TI documentation states it may be left floating or connected to GND for improved thermal performance, but it must never be connected to V_CC or any signal net. Soldering the pad to a GND plane enhances heat dissipation and improves long-term reliability under sustained load conditions.

How does the strobe (G) input affect output behavior in the CD74ACT157PWR?

The G input is an active-low output enable: when G = LOW, all four Y outputs (1Y–4Y) are forced LOW regardless of the states of A/B or data inputs. When G = HIGH, outputs reflect the selected A or B input per the A/B address. This allows global disabling of all multiplexer outputs - useful for bus arbitration, power sequencing, or fault-safe shutdown without altering address or data lines.