acquisitionZONE Products for the week of March 24, 2003
Building upon the company's industry-leading expertise in converter
technology, Analog Devices has introduced two digital temperature sensors
with single-wire, pulse-width-modulation (PWM) outputs that offer the industry's
most powerful combination of performance, low power consumption and small
package size.
About the TMP05 and TMP06
The output of the TMP05 and TMP06 is a square wave; its duty cycle is proportional to the absolute temperature. Both devices offer accuracy to +/-1 degrees C max from 0 degrees C to +70 degrees C, an operating temperature range from -55 degrees C to +150 degrees C, and a supply voltage range of +2.7 V to +5.5 V. They are available in space-saving 5-lead SC-70 and SOT-23 packages.
Both devices offer three modes of operation: daisy chain (allowing designers to connect any number of TMP05/06 sensors to the same microcontroller), continuously converting, and one-shot mode, which reduces the power consumption to 8.25 microW.
The TMP05 has a push-pull output (CMOS/TTL*), while the TMP06 has an
open-drain output. Their combination of accuracy, low power and small package
size make them ideal for battery and portable applications found in the
industrial process control, consumer, instrumentation, and medical industries.
analogZONE Says . . .
The preliminary data sheet of these parts is a little abundant in "TBD" numbers but they look they have the possibility of becoming important players in the temperature sensor market. The typical quiescent of 230 µA (at 3-V supply) suggests that the self-heating effects of the part itself are going to be very low, but of the alternative packages available the size of the SC-70 may be more attractive but the thermal characteristics of the SOT-23 will transfer heat out much better. There will also be heating effects associated with the loading but the designer has some control over that in the design implementation using one-shot modes when possible.
The other modes available are continuously converting and daisy-chained.
In these parts an onboard sensor generates a voltage linearly proportional to temperature. This is compared to an on-chip reference and fed to a first-order delta-sigma modulator and digital filtered to the output. The modulator consists of an input sampler, a summing network where the fed-back 1-bit DAC is added, an integrator and a comparator. The output from both parts is a square-wave with a nominal 120 ms period. The high output is a constant while the low output varies with the measured temperature with these values can easily be monitored by a microprocessor. The TMP05 provides a totem-pole CMOS output (CMOS/TTL compatible) which is rail-to-rail, a preferred mode for most microprocessors. The TMP06 provides an open-drain output which is more flexible for other applications. Accuracy is within 1 degree C up to 70 degrees, and within 4 degrees C from -55 to +150 degrees.
These parts are priced right, and the specifications look like they are going to be very attractive to designs in process control, environmental systems and computer monitoring.
Both the TMP05 and TMP06 are sampling in SC-70-5 and SOT-23-5 and are priced at $0.95 in 1000-piece lots.