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Toshiba expands multi-point over-temperature detection IC family

Posted Date:2023-09-15 13:42:36

Toshiba expands multi-point over-temperature detection IC family

Each of these simple ICs, (branded ‘Thermoflagger’) works with one or more PTC (positive temperature coefficient) thermistors to detect over temperature across a PCB, for example, perhaps sensing the individual temperatures of multiple power mosfets .

“With safety paramount in many applications, the over-temperature detection ICs monitor internal temperatures to ensure that systems are working as intended, thereby ensuring safety,” according to the company. “Typical applications include mobile devices, home appliances and industrial equipment.”

They are not intended to implement precision temperature measurement, instead delegating accuracy to external PTC thermistors that have an intrinsic sharp knee in their temperature-resistance characteristic that sets the detection threshold.

___noise___ 1000

Toshiba expands multi-point over-temperature detection IC familyWhen multiple thermistors are used, they are wired in series 

The result of a recent agreement, Murata has become Toshiba’s preferred thermistor company, and Murata now promotes Thermoflagger ICs for use with its thermistors.

Inside the ICs is a constant current source to drive the thermistor or thermistor string, and a comparator with its own voltage reference to detect when the thermistors have increased past their characteristic knee.

Options across the family were intended to be, and now are: latching or non-latching output, totem pole or open drain output, and 10μA or 1μA thermistor sense current – eight devices are planned to cover all the options.

The first two devices were both 10μA sense, open-drain types: the non-latching TCTH021BE and the latching TCTH022BE.

And now the family is completed with all eight possible combinations:

TCTHxxxxE PTC drive Output Output type
011Ax = xxxx 1μA no latch totem pole
012A 1 latch totem pole
012A 10 no latch totem pole
022A 10 latch totem pole
011B 1 no latch open-drain
012B 1 latch open-drain
021B 10 no latch open-drain
022B 10 latch open-drain

Latching versions have a reset input (RESET) to clear the latch, while in non-latching versions this pad is labelled GND2 and needs to be grounded as the non-latching devices have an un-used reset circuit – or so Toshiba explained to Electronics Weekly after the initial introduction. “When GND2 is open or high level, the device may malfunction, so GND2 need to be on a low level the same as GND1,” it said.

IC operation is over -40 and +125°C and 1.7 to 5.5V, with consumption of a few microamps above the thermistor drive current.

Packaging is 1.6 x 1.6 x 0.55mm SOT-553.

The TCTH0xxxE family web page is here and there is an excellent application note, as well as an evaluation board, which adds the idea of using a light-dependent resistor instead of thermistors.
Find Murata’s PTC thermistors here

View more : IGBT modules | LCD displays | Electronic Components

Source from: https://www.shunlongwei.com/toshiba-expands-multi-point-over-temperature-detection-ic-family/

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