Texas Instruments TLC555CPE4

Overview

TLC555CPE4 from Texas Instruments is a CMOS monolithic timer IC functionally interchangeable with the NE555 and featuring identical 8-pin PDIP pinout. It delivers rail-to-rail CMOS output swing, 100mA sink/10mA source capability, and operates from 2V to 15V supply. Its low 350µA typical supply current at 5V enables precision timing in battery-powered pulse generation and sequential control circuits.

For engineers reviewing the TLC555CPE4 datasheet, TLC555CPE4 pinout, TLC555CPE4 application, or TLC555CPE4 equivalent, this page provides verified functional identity, confirmed 8-pin PDIP package mapping, validated timing parameters (f_max = 2.1MHz, t_r/t_f ≤ 75ns), real-world astable/monostable behavior, and two technically documented alternative parts for design flexibility.

Technical Context

The TLC555CPE4 implements a dual-comparator architecture with an SR latch and high-current output stage, where THRES and TRIG inputs reference internal resistive divider nodes at ≈2/3 VDD and ≈1/3 VDD respectively. The CONT pin directly accesses the upper node, enabling external threshold adjustment and bypass capacitor connection.

Its discharge switch is open-collector with <1.7V on-state voltage at 100mA (VDD = 15V), while the OUT pin provides push-pull drive with VOL ≤ 0.4V at 8mA and VOH ≥ 4.8V at –1mA (VDD = 5V). Reset is active-low and overrides all other inputs, forcing both OUT low and DISCH to ground.

Key Specifications

Pinout & Package

Package: 8-pin Plastic Dual In-line Package (PDIP), 9.81mm × 9.43mm body size, through-hole mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar timer IC applications.

Compared with NE555P and LM555CN, the TLC555CPE4 offers 3.5× lower supply current than LM555CN and 10× higher sink current than NE555P, making it optimal for space-constrained, low-power, and high-drive timing functions without redesigning PCB layout.

Availability

TLC555CPE4 is available at Aetrix Electronics and suitable for precision timing, pulse generation, and time delay generation requiring stable component supply across industrial control, test equipment, and consumer electronics programs.

Supply support for TLC555CPE4 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 leader delivering analog and embedded processing solutions with emphasis on reliability, precision, and energy efficiency.

The TLC555 product line was designed as a CMOS upgrade to legacy bipolar 555 timers, targeting low-power, high-accuracy timing applications across industrial, automotive, and portable electronics.

FAQ

What is the maximum operating frequency of the TLC555CPE4 in astable mode?

The TLC555CPE4 achieves a maximum oscillation frequency of 2.1MHz in astable configuration under specified test conditions (RA = 470Ω, RB = 200Ω, CT = 200pF, VDD = 5V, TA = 25°C). This limit arises from internal propagation delays and discharge switch on-resistance. For reliable design, TI recommends staying below 1MHz for stable duty cycle control and reduced timing error.

Can the TLC555CPE4 replace a NE555 in an existing circuit without modifications?

Yes, the TLC555CPE4 is functionally interchangeable with the NE555 and uses the identical 8-pin PDIP pinout. However, due to its CMOS input structure and rail-to-rail output, minor adjustments may be needed: reduce timing resistor values if input leakage affects accuracy, and verify load compatibility since TLC555CPE4 sinks 100mA versus NE555's 200mA but sources 10mA versus NE555's 100mA.

What is the recommended decoupling for the CONT pin on the TLC555CPE4?

A 10nF ceramic capacitor from CONT (pin 5) to GND is recommended to suppress noise coupling into the internal voltage divider. This improves timing stability, especially in noisy environments or when using high-impedance external control voltage sources. TI's datasheet Figure 6-5 explicitly shows this decoupling capacitor in the astable application circuit.

Does the TLC555CPE4 support operation below 2V supply voltage?

No - the absolute minimum recommended supply voltage for the TLC555CPE4 is 2V, per Section 5.3 of the official datasheet. Operation below this violates recommended conditions and results in undefined behavior, including failure to trigger, incorrect threshold levels, or excessive supply current. For sub-2V applications, consider dedicated ultra-low-voltage timers like the TPL5010.

How does the discharge switch (DISCH) behave during monostable operation of the TLC555CPE4?

During monostable operation, the DISCH pin is an open-collector NMOS output that goes low (≈0.2V at 1mA) when the internal latch is reset - i.e., when THRES exceeds CONT voltage. It remains high-impedance while the timing capacitor charges through RA. This controlled discharge path enables precise timing intervals and allows external components (e.g., diodes, transistors) to be driven directly from DISCH.