Toshiba Thermoflagger™: PTC ICs for Temperature Monitoring

September 14, 2023 — Toshiba Electronic Components and Storage Device Corporation ("Toshiba") has announced a significant expansion of its ThermoflaggerTM over-temperature detection IC product line with the introduction of the new "TCTH0xxxE series." These innovative ICs are specifically designed for use in simple electronic circuits featuring Positive Temperature Coefficient (PTC) thermistors. Their primary function is to monitor temperature increases within electronic devices. These six new products are now readily available for bulk orders, with shipments commencing immediately.

Maintaining electronic devices' proper functionality necessitates strict adherence to their design parameters. Of these parameters, internal temperature is of paramount importance. When temperatures surpass the predetermined thresholds during the design process, it can give rise to serious safety and reliability concerns. To address this, an over-temperature monitoring solution becomes indispensable to promptly identify and respond to any temperature deviations.

When integrated into a basic circuit that incorporates PTC thermistors (devices whose resistance changes with temperature fluctuations), the ThermoflaggerTM over-temperature detection ICs offer dual functionality. They not only detect temperature increases but also monitor changes in the resistance of PTC thermistors located near heat sources. Consequently, they trigger FLAG signals when temperatures exceed prescribed safety levels. For instance, when ThermoflaggerTM detects anomalous heating and transmits a FLAG signal to the Microcontroller Unit (MCU), the MCU can take action, such as shutting down the device or modifying the operation mode of the heating element or semiconductor. By connecting PTC thermistors in series, simultaneous over-temperature detection at multiple points becomes achievable.

The new additions to the product line consist of the following models: TCTH011AE, TCTH012AE, TCTH021AE, TCTH022AE, TCTH011BE, and TCTH012BE. These, along with the previously launched TCTH021BE and TCTH022BE, extend the TCTH0xxxE series to encompass a total of eight distinct products. These new offerings support two types of PTCO output currents, offering users the flexibility to select the most suitable PTC thermistor for their applications. Users can choose between push-pull or open-drain FLAG signal output types and have the option to enable or disable the FLAG signal latch function. This wide range of product options facilitates versatile circuit design while ensuring minimal power consumption.

The new products come in compact, industry-standard SOT-553 packages (referred to as ESV by Toshiba), making it straightforward to incorporate them into over-temperature detection systems for complete electronic devices. This contributes to a dual improvement in size and power efficiency.

In addition to the previously released reference design for the ThermoflaggerTM over-temperature detection IC (TCTH021BE, open-drain type), Toshiba has unveiled a new version on its official website: "ThermoflaggerTM Application Circuit for Over-Temperature Detection IC" (TCTH021AE, push-pull type).

Toshiba leveraged pertinent technical insights on PTC thermistors from Murata Manufacturing Co., Ltd. ("Murata") to develop this comprehensive over-temperature detection solution. Murata highly recommends pairing ThermoflaggerTM with PTC thermistors for optimal performance.

· Applications:

- Mobile Devices (e.g., laptops)

- Home Appliances

- Industrial Equipment, and more.

· Key Features:

· Streamlined configuration, compatible with PTC thermistors.

· Simultaneous over-temperature monitoring at multiple points via serially connected PTC thermistors.

· Minimal power consumption:

- IDD = 1.8μA (typical value) (TCTH011AE, TCTH012AE, TCTH011BE, TCTH012BE).

- IDD = 11.3μA (typical value) (TCTH021AE, TCTH022AE).

· Compact standard package: SOT-553 (ESV).

· Expands PTC thermistor options with two types of PTCO output currents:

- IPTCO = 1.00μA (typical value) (TCTH011AE, TCTH012AE, TCTH011BE, TCTH012BE).

- IPTCO = 10.0μA (typical value) (TCTH021AE, TCTH022AE).

· High PTCO output current accuracy: ±8%.

· Selectable FLAG signal output (PTCGOOD) in push-pull and open-drain configurations.

· Optional FLAG signal latch function for added flexibility.