Maxim Adds Two Analog Temperature Sensor IC’s to its Essential Analog PortfolioSeptember 21, 2020 by Gary Elinoff
The new ICs reduce design complexity while delivering the high measurement accuracy for systems charged with the protection of cold-chain assets.
The MAX31825 is designed to operate with up to 64 units on a single bus. Because the bus employed is the simple and inexpensive 1-Wire bus, it only takes one wire to both power the string of devices and to read their outputs. MAX31889 digital temperature sensor is targeted at replacing resistance temperature detectors (RTDs) for cost savings and for increasing reliability.
The MAX31889 can read and report temperatures to within ±0.25 ℃ over a temperature range of
-20 to +105°C and with ± 0.65°C accuracy from -40°C to +125°C. It works with supply voltages ranging from 1.7 to 3.6 volts. It will draw 68µA while making measurements and requires 0.55µA while in standby.
Basic Block Diagram of the MAX31889. Image courtesy of Maxim
- Monitoring pharmaceutical cold chains
- Industrial automation including IoT sensors
- Medical monitoring
- Replacing RTDs
- Precision temperature monitoring
The MAX31889 works over an I2C Digital Interface. It comes in a 6-pin 2 x 2 x 0.8 mm µDFN package.
Because the Max31825 works with the 1-Wire bus, up to 64 of the units can operate on one string, as opposed to what Maxim maintains is the more standard limitation of eight. They can coexist on one wire because each device is set apart from its peers by a unique identification code. This alone allows systems based on the MAX31825 to enjoy an 8x reduction in necessary wiring.
In addition, the same “one wire” that serves to report the observed temperature can also serve to power the devices, further reducing cost, weight and complexity.
Application circuit employing the MAX31825 illustrating the 1-Wire Bus. Image courtesy of Maxim
An important feature of the device is that it can work with what Maxim describes as "parasite power"; power it obtains from the data line. This eliminates the need for a power supply, as well as any separate wiring needed to connect it to a string of MAX31825’s. It can, however, work with an external 1.6 to 3.6 volt power supply. It requires a standby current of 2.5µA.
In such a manner, the MAX31825 enables temperature measurement to within ±1℃ accuracy from 0 to +70°C and ±1.75°C accuracy from -45 to +145°C.
- Industrial equipment
- Data Center devices
- Communications equipment
- Consumer devices
The MAX31825 is available in a 6-bump WLP package.
Maxim’s “Essential Analog” Products
Maxim’s essential analog ICs include a wide range of devices including sensors, data converters, signal chain amplifiers and power ICs targeted at low-power analog circuitry. They include wireless devices designed to work in difficult, electrically noisy environments.
As described by Colin Barnden, principal analyst, Semicast Research, “These Essential Analog products by Maxim Integrated enable manufacturers to make their operations and supply chains more reliable, helping to ensure quality to their customers and savings to their bottom line.”
Getting to Market Faster
The MAX31889EVS Evaluation System is for the MAX31889. This EV system includes both a microcontroller board and an EV kit board.
The MAX31889EVS Board. Image courtesy of Maxim
The MAX31825EVS Evaluation System is aimed at aiding designers in their evaluation of the MAX31825 1-Wire temperature sensor. It includes a Maxim DS2481 I2C to 1-Wire converter and windows-based software development tools.