PSoC
®
Thermal Management Expansion Board Kit Guide, Doc. No. 001-89649 Rev. **
13
Figure 2-3. VDDIO Selection on KIT-036 Using Jumper J3
2.3 Temperature Sensors
2.3.1 I
2
C Temperature Sensor
The CY8CKIT-036 EBK demonstrates I
2
C temperature-sensing capability using a two-wire I
2
C-compatible digital
temperature sensor, the TMP175. I
2
C digital temperature sensors are common for thermal management and are used in a
variety of communication, computer, consumer, environmental, industrial, and instrumentation applications due to the
popularity of the I
2
C bus.
The sensor is powered by the VDDIO power supply, and the value of the VDDIO power supply is controlled by jumper J3
(3.3 V or 5 V), as shown in
Figure 2-3
. The VDDIO selection should be the same as the VDD operating voltage of the PSoC
chip. For details, refer to the temperature sensor datasheet, which is available on the manufacturer
’s website or on the
kit
webpage
.
2.3.2 PWM Output Digital Temperature Sensors
The CY8CKIT-036 EBK has two TMP05 PWM-based temperature sensors onboard. The TMP05 is a monolithic
temperature sensor that generates a modulated serial digital output (PWM) signal. The duty cycle of this PWM signal is
proportional to the ambient temperature measured by the device. The TMP05 sensor has a two-pin interface. The CONV/IN
input pin, when pulsed by PSoC, initiates a new temperature measurement. The output (OUT) pin provides a PWM signal;
and the logic-high duration, logic-low duration of the PWM signal is used to determine the ambient temperature.
The TMP05 sensors support a daisy-chain mode of operation, in which the OUT signal of the first sensor can be connected
directly to the CONV/IN input of the subsequent sensor. The OUT signal of the second sensor carries the PWM signals
from both sensors. Many sensors can be daisy-chained in this fashion, with the final OUT signal carrying the PWM
temperature encoding from all sensors in the daisy chain. Jumper J2 on the CY8CKIT-036 EBK, as shown in
Figure 2-4
, is
used to select between the single PWM temperature sensor (PWM_TMP1) or the daisy-chain mode of operation
(PWM_TMP1 followed by PWM_TMP2). This sensor generally is operated either in one-shot mode or in continuous mode.
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