STMicroelectronics TS555CDT

Overview

TS555CDT from STMicroelectronics is a low-power single CMOS timer IC designed for precision timing in battery-powered and space-constrained systems. It delivers 110 µA typical supply current at 5 V, supports 2.7 MHz maximum astable frequency, operates across 2–16 V supply range, and maintains timing accuracy in both monostable and astable modes - used in portable instrumentation, sensor wake-up circuits, and LED flash controllers.

For engineers reviewing the TS555CDT datasheet, TS555CDT pinout, TS555CDT application, or TS555CDT equivalent, key selection considerations include its ultra-low ICC (90 µA @ 3 V), high input impedance (10¹² Ω), reduced supply current spikes during transitions, and SO8 package compatibility with legacy NE555 layouts while enabling smaller decoupling capacitors and minimized timing capacitors.

Technical Context

The TS555CDT implements a CMOS-based bistable multivibrator architecture with dual comparators, SR flip-flop, and open-drain discharge transistor. Its internal voltage divider sets precise 1/3 VCC and 2/3 VCC thresholds, enabling supply-independent timing intervals in both monostable (t = 1.1·R·C) and astable (f = 1.44/(RA + 2RB)·C) configurations.

Unlike bipolar NE555 variants, it eliminates base-current loading on external RC networks via 10¹² Ω input impedance and reduces dynamic supply current transients through optimized output stage switching - directly enabling lower-value bypass capacitors (e.g., 100 nF instead of 1 µF) without instability.

Key Specifications

Pinout & Package

TS555CDT is housed in an SO8 (plastic micropackage) with 1.27 mm pitch, 5.0 mm × 6.2 mm body, and exposed pad not connected internally. Pin numbering follows standard DIP-8 orientation (pin 1 at top-left corner, counterclockwise).

Key Features

Applications

Equivalent & Alternatives

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

Compared with NE555P and TLC555CP, TS555CDT uniquely combines industrial temperature range (–40 °C to +125 °C), lowest ICC among SO8 CMOS timers (90 µA @ 3 V), and highest astable frequency (2.7 MHz), making it optimal for ruggedized portable and embedded timing where longevity and performance coexist.

Availability

TS555CDT is available at Aetrix Electronics and suitable for portable instrumentation, sensor wake-up circuits, and LED flash controllers requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TS555CDT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensing solutions for automotive, industrial, and consumer markets.

The TS555 belongs to ST's precision analog timer product line, engineered specifically for ultra-low-power, high-accuracy timing in resource-constrained embedded systems where battery life and thermal resilience are critical.

FAQ

Can TS555CDT replace NE555 in existing designs without modifications?

Yes - TS555CDT is pin-to-pin functionally compatible with bipolar NE555 and uses the same SO8 footprint. No PCB changes are needed. However, due to its CMOS input structure and lower supply current, decoupling capacitors can be reduced (e.g., 100 nF ceramic instead of 1 µF), and timing capacitors may be downsized thanks to 10¹² Ω input impedance.

What is the minimum supply voltage for reliable operation?

TS555CDT operates reliably down to +2 V per datasheet Table 2. At 2 V, supply current is 65 µA (typ), threshold and trigger voltages scale linearly (e.g., trigger ≈ 0.4 V, threshold ≈ 0.8 V), and timing accuracy remains within ±5% in monostable mode - validated across –40 °C to +125 °C.

Does TS555CDT support variable-frequency operation via control voltage?

Yes - pin 5 (Control Voltage) provides direct access to the internal voltage divider. Applying an external voltage between 0.5 V and VCC–0.5 V modulates the 2/3 VCC threshold, enabling voltage-controlled oscillator (VCO) behavior in astable mode. Full-range frequency tuning (e.g., 10:1 ratio) is achievable with proper op-amp buffering to avoid loading the high-impedance node.

Is TS555CDT qualified for automotive applications?

No - while TS555CDT operates from –40 °C to +125 °C and meets AEC-Q200 stress test recommendations for temperature cycling and HBM ESD (1500 V), it is not officially AEC-Q100 qualified. For automotive ECUs, ST recommends the automotive-grade TS555IDTTR variant, which carries full AEC-Q100 Grade 1 certification and enhanced lot traceability.