PSoC
®
Thermal Management Expansion Board Kit Guide, Doc. No. 001-89649 Rev. **
14
Figure 2-4. TMP05 Sensors with Daisy-Chain Mode or Single-Sensor Mode Selection Using Jumper J2
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
Figure 2-3
shows. The VDDIO selection should be the same as the VDD operating voltage of the PSoC
chip.
For details, refer to the TMP05 device datasheet, which is available on the manufacturer’s website or on the
kit
webpage
.
2.3.3 One-Wire Digital Temperature Sensor
The CY8CKIT-036 EBK has a Maxim DS18S20 one-wire, high-precision digital temperature sensor installed. The DS18S20
digital thermometer provides 9-bit resolution Celsius temperature measurements and has an alarm function with nonvolatile
user-programmable upper and lower trigger points. The DS18S20 communicates over a proprietary one-wire bus that by
definition requires only one data line (and ground) to communicate with a host microprocessor. It has an operating
temperature range of
–55° C to +125° C.
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
Figure 2-3
shows. The VDDIO selection should be the same as the operating voltage of the PSoC chip.
For details, refer to the datasheet, which is available on the manufacturer’s website or on the
kit webpage
.
2.3.4 Diode Analog Temperature Sensors
The CY8CKIT-036 EBK has two onboard MMBT3904 transistors for temperature measurement. MMBT3904 is a bipolar
junction transistor (BJT) designed as a general-purpose amplifier and switch. The useful dynamic range extends to 100 mA
as a switch and to 100 MHz as an amplifier. For measuring the temperature, the transistor is connected in the diode
configuration by shorting the collector and base terminals of the transistor. The temperature measurement is based on the
principle of diode forward voltage drop dependence on temperature.
For details on the transistor characteri
stics, refer to the datasheet, which is available on the manufacturer’s website or on
the
kit webpage
.
2.4 Communication Interface
The CY8CKIT-036 EBK has an I
2
C/SMBus/PMBus Port J1 that can be used by an external I
2
C/SMBus/PMBus host to
communicate with the PSoC chip. PSoC will act as the I
2
C/PMBus/SMBus slave, and the host can send commands to the
PSoC device and receive status information about the thermal management zone (fan speed, sensor temperature).
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