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Hardware Description
Thermistor
Extra power and ground header
Figure 1. AFE4110 Thermometer Demonstration Board Front (Bottom Layer) and Back (Top Layer)
As the AFE4110 lacks any nonvolatile memory to store code or data (unless is burnt permanently into its
ROM), the board actually uses the AFE4110 RAM-based (15 KB) emulation version and loads, at boot
time, the thermometer application code (~3 KB long) from an external 128k-bit SPI EEPROM. Notice that
in the final application, the EEPROM is not needed if the code is burnt into the ROM version of the
AFE4110. Furthermore, the device displays the temperature, in Celsius, with 0.1°C resolution, using a
5-digit LCD display. The solution also includes a piezo-based buzzer, along with a JTAG interface for
programming or debugging
Finally, the kit comes with a 1.5-V button-cell battery (SR60 standard) with a typical capacity of 20 mAh,
under standard operating conditions.
Component
Thermistor
EEPROM
Piezo-Buzzer
Power-Supply/Ground
Header
LCD
Push-Button Switch
JTAG Header
Battery Holder
2
AFE4110 Thermometer Demonstration Board
Battery
Holder
Piezo
AFE4110
buzzer
(Table 1
presents a list of key components).
Table 1. Description of Main Board Components
Description
Murata NCP15WB473J03RC. NTC thermistor, 47 kΩ ± 5% and a B-constant tolerance of ± 1%. This
implementation demonstrates a cost-effective solution by complementing the use of a relaxed tolerance
thermistor with a 2-point calibration.
128k-bit SPI EEPROM. When a battery is inserted into the holder, the code is loaded from the
EEPROM into the AFE4110 internal RAM, and the AFE4110 proceeds to measure the resistance of the
thermistor. Notice that in the final application, the EEPROM is not needed if the code is burnt into the
ROM version of the AFE4110.
The buzzer is used to indicate the end of the temperature display. Following this, the AFE4110 goes
into LPM5 (sleep) mode.
Onboard connectors for 1.5-V external power supply and ground. Can be used instead of battery.
The AFE4110 has an internal charge pump to provide constant 3.3-V supply operation to the LCD, for
constant contrast even when battery voltage drops.
This switch is used to bring the AFE4110 out of the LPM5 mode. See
events.
Provided for programming/debugging purposes.
1.5-V button cell holder.
Copyright © 2011, Texas Instruments Incorporated
Push button switch
LCD
EEPROM
www.ti.com
JTAG header
Section 2
for the sequence of
SLAU417 – December 2011
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