SBOS891B October 2018 – April 2021 TMP144
The TMP144 is a digital output temperature sensor in a wafer chip-scale package (WCSP) that is designed for thermal management and thermal profiling. The TMP144 includes a SMAART Wire™ / UART interface that can communicate in a daisy-chain loop with up to 16 devices on a single bus. The interface requires two pins from the host: the first device in the daisy-chain receives data from the host and the last device in the daisy-chain returns data to the host, closing the loop. In addition, the TMP144 can do multiple device access (MDA) commands that allow multiple TMP144 devices to respond to a single global bus command. MDA commands reduce communication time and power in a bus that contains multiple TMP144 devices. The operation of TMP144, is specified over a temperature range of –40 °C to 125 °C.
The TMP144 can also configure the bus in a transparent mode, where the input from the host is sent directly to the next device in the chain without delay. Additionally, the TMP144 can disconnect the chain and create a serial communication controlled by each TMP144 on the bus, thereby allowing each device to have configurable addressing and interrupt capabilities. The input pin, RX, is a high-impedance node. The output pin, TX, has an internal push-pull output stage that can drive the host to GND or V+.
After an initialization sequence, each device on the bus is programmed with its own unique interface address based upon its position in the chain, that allows it to respond to its own address. The devices can also respond to general commands that permit the user to read or write to all devices on the bus without the need to send individual addresses and commands to each device.
The temperature sensor in the TMP144 is the chip itself. Thermal paths run through the package bumps as well as the package. The lower thermal resistance of metal and the low height of the devices, causes the bumps and the topside to provide the dominant thermal paths to the sensing element on the device. To maintain accuracy in applications that require air or surface temperature measurement, care should be taken to isolate the package from ambient air temperature. A thermally-conductive adhesive can help to achieve accurate surface temperature measurement.