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CD74HC191E
Texas Instruments
IC BINARY COUNTER 4-BIT 16DIP
2061 Pcs New Original In Stock
Counter IC Binary Counter 1 Element 4 Bit Positive Edge 16-PDIP
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5.0 / 5.0
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CD74HC191E
Product Overview
1257717
DiGi Electronics Part Number
CD74HC191E-DGManufacturer
Texas Instruments
CD74HC191E
Description
IC BINARY COUNTER 4-BIT 16DIPInventory
2061 Pcs New Original In Stock
Counter IC Binary Counter 1 Element 4 Bit Positive Edge 16-PDIP
CAD Models - PCB Symbols & Footprints
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Minimum 1
Minimum 1
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CD74HC191E Technical Specifications
Category
Logic, Counters, Dividers
Packaging
Tube
Series
74HC
Product Status
Active
Logic Type
Binary Counter
Direction
Up, Down
Number of Elements
1
Number of Bits per Element
4
Reset
Asynchronous
Timing
Synchronous
Count Rate
35 MHz
Trigger Type
Positive Edge
Voltage - Supply
2 V ~ 6 V
Operating Temperature
-55°C ~ 125°C
Mounting Type
Through Hole
Package / Case
16-DIP (0.300", 7.62mm)
Supplier Device Package
16-PDIP
Base Product Number
74HC191
Datasheet & Documents
HTML Datasheet
CD74HC191E-DG
Environmental & Export Classification
RoHS Status
ROHS3 Compliant
Moisture Sensitivity Level (MSL)
Not Applicable
REACH Status
REACH Unaffected
ECCN
EAR99
HTSUS
8542.39.0001
Additional Information
Other Names
CD74HC191E-DG
2166-CD74HC191E-296
296-49590
Standard Package
25
Reviews
5.0/5.0-(Show up to 5 Ratings)
Dec 02, 2025
La logistique était impeccable, livraison sans souci et bien assurée.
Dec 02, 2025
The combination of excellent support and well-stocked inventory sets them apart.
Dec 02, 2025
Product durability exceeded my expectations, even after frequent use.
Dec 02, 2025
Reliability is a hallmark of DiGi Electronics' products; I highly recommend them.
Dec 02, 2025
I highly recommend DiGi Electronics for anyone seeking excellence in quality and support.
Dec 02, 2025
The durability of the packaging kept my purchase safe during transit, even through harsh weather conditions.
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Frequently Asked Questions (FAQ)
Can the CD74HC191E be safely used as a drop-in replacement for the older CD40191BE in a 5V industrial control system, and what timing or loading issues should I watch for during the transition?
While the CD74HC191E and CD40191BE are functionally similar 4-bit binary counters, they are not direct drop-in replacements due to fundamental logic family differences. The CD74HC191E is a high-speed CMOS (HC) device with TTL-compatible inputs and a 2–6V supply range, whereas the CD40191BE is a standard CMOS part requiring stricter voltage thresholds and typically operating at 3–18V. At 5V, the CD74HC191E will generally work, but you must verify input signal levels—especially from TTL sources—and ensure fan-out compatibility, as the HC family has lower output drive than some 4000-series parts. Additionally, the CD74HC191E’s faster propagation delay (~13 ns vs ~60 ns at 5V) may expose race conditions or glitches in asynchronous reset or clocking schemes that were previously masked. Always validate timing margins and consider adding Schmitt-trigger buffering if driving long traces or capacitive loads.
What are the key reliability risks when operating the CD74HC191E near its maximum count rate of 35 MHz in a high-temperature environment close to 125°C?
Operating the CD74HC191E at or near its 35 MHz maximum count rate while approaching the upper limit of its -55°C to 125°C range significantly increases the risk of timing failures due to propagation delay degradation. At elevated temperatures, internal gate delays increase, potentially violating setup/hold times in synchronous systems or causing metastability in asynchronous resets. Although the datasheet specifies 35 MHz at 25°C, derating is essential—TI typically recommends reducing max frequency by 20–30% at 125°C. Thermal cycling can also accelerate electromigration in the DIP package’s bond wires under continuous high-speed switching. To mitigate risk, implement conservative timing margins, avoid simultaneous high-frequency counting and asynchronous reset assertions, and consider active cooling or selecting an automotive-grade variant if long-term reliability under stress is critical.
How does the asynchronous reset behavior of the CD74HC191E impact system design in motor control applications where glitch-free startup is required?
The CD74HC191E features an asynchronous active-low reset (MR pin), which immediately clears the counter regardless of the clock state. While useful for emergency shutdowns, this poses a risk in motor control systems where unintended resets—triggered by power-up transients, noise, or ground bounce—can cause erratic behavior or unsafe startup sequences. Unlike synchronous reset counters, the asynchronous nature means the output can change at any time, potentially generating short pulses (glitches) on decoded outputs used for phase control or enable signals. To ensure glitch-free operation, add a power-on reset (POR) circuit with a clean, delayed release after VCC stabilizes, and use RC filtering or a Schmitt trigger on the MR line. For safety-critical designs, consider gating the clock instead of relying solely on reset, or evaluate alternatives like the SN74LV8154 (dual 4-bit counter with synchronous reset) if deterministic startup is non-negotiable.
Can I parallel multiple CD74HC191E devices to create an 8-bit counter, and what synchronization challenges might arise compared to using a dedicated 8-bit counter like the CD74HC4040E?
Yes, you can cascade two CD74HC191E ICs to form an 8-bit up/down counter by connecting the ripple clock output (RCO) of the first stage to the clock input of the second. However, this introduces cumulative propagation delay that limits maximum operating frequency and risks synchronization errors, especially in down-counting modes or when mixing up/down directions. Unlike the CD74HC4040E—a dedicated 12-bit ripple counter with optimized internal delays—the cascaded CD74HC191E approach suffers from variable RCO timing dependent on count direction and load conditions. In time-critical applications (e.g., encoder interfaces or PWM generation), this can lead to missed counts or phase misalignment. For robust 8-bit counting, prefer monolithic solutions like the CD74HC590E (8-bit binary counter with output register) or ensure your system tolerates the added jitter by using lower clock frequencies and validating worst-case timing across temperature and voltage corners.
Is the through-hole 16-DIP package of the CD74HC191E suitable for high-vibration automotive environments, and how does its mechanical reliability compare to surface-mount alternatives like the CD74HC191M?
The CD74HC191E’s 16-DIP (through-hole) package offers superior mechanical robustness in high-vibration environments compared to surface-mount SOIC variants like the CD74HC191M, making it a better choice for under-hood or chassis-mounted automotive applications where solder joint fatigue is a concern. The leads provide inherent strain relief and better resistance to thermal cycling-induced cracking. However, DIP packages are more susceptible to moisture ingress and require careful conformal coating in humid conditions. While both parts share identical electrical specs and are RoHS3 compliant, the CD74HC191E lacks an MSL rating because through-hole devices are generally not moisture-sensitive. If board space allows, the DIP version is preferable for vibration-heavy use cases—but ensure proper PCB mounting (e.g., standoffs or potting) to prevent flexing. For compact designs, consider the CD74HC191M in a TSSOP package with underfill epoxy to enhance mechanical stability.
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DiGi ensures the quality and authenticity of every electronic component through professional inspections and batch sampling, guaranteeing reliable sourcing, stable performance, and compliance with technical specifications, helping customers reduce supply chain risks and confidently use components in production.
CD74HC191E CAD Models
Texas Instruments CD74HC191E PCB symbols & footprints
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