Application Note 1834
3
AN1834.0
May 9, 2013
Figure 6 shows the Measurement Display screen. From this
screen, the user can stop and start data collection, adjust the
minimum and maximum X & Y axis and go back to the set-up
screen by clicking on the Show Main button. A calibrate button is
provided to zero out the voltage reading when the board is not
under strain. This helps to give an accurate reading from time
zero, and is required because the board does not always return to
the same deflection point after a strain is applied to the board.
Design Considerations
ISL28134
The ISL28134 is an ideal choice for the input amplifier for a
strain gauge design. The ISL28134 uses auto-correction circuitry
to provide ultra low offset voltage (2.5ƫV), and low offset
temperature drift (15nV/°C). The very low 1/f noise corner
<0.1Hz and low input noise voltage (8nV/¥Hz @ 100Hz) of the
amplifier makes it ideal for low frequency precision applications
requiring very high gain and low noise. Other attributes of the
ISL28134 are the wide gain bandwidth and rail-to-rail
input/output swing.
ISL26102 24-bit ADC
The ISL26102 is a complete analog front-end with dual
differential multiplexed inputs for high resolution
measurements. ISL26102 features a third order modulator
providing up to 21.4-bit noise-free performance (10Sps). The
24-bit delta-sigma analog-to-digital converter includes a very
low-noise amplifier with programmable gain. Although this
application demo uses an input buffer amplifier (ISL28134), the
high input impedance of the ISL26102 allows direct connection
of sensors, such as load cell bridges to ensure the specified
measurement accuracy without a buffer amplifier.
In order to initiate a correct power-up reset, diode D1, resistor R3
and capacitor C8 implement a simple RC delay to ensure the
PDWN
transitions from low to high after both power supplies
have settled to specified levels.
ISL21010 (4.096V)
The ISL21010CFH341 is a precision 4.096V, low dropout
micropower bandgap voltage reference. It provides a ±0.2%
accurate reference. The ISL21010 provides up to 25mA output
current sourcing with low 150mV dropout voltage. The low supply
current and low dropout voltage combined with high accuracy
make the ISL21010 ideal for precision low powered applications.
ISL22316 DCP
The ISL22316 is a low noise, low power I
2
C™ bus, 128 tap DCP.
The DCP can be used as a three-terminal potentiometer or as a
two-terminal variable resistor in a wide variety of applications
including control, parameter adjustments, and signal processing.
ISL43741 Diff 4 to 1 Multiplexer
The ISL43741 is a precision, bidirectional, differential 4-channel
multiplexer/demultiplexer. The mux is designed to operate from
a single +2V to +12V supply or from ±2V to ±6V supplies. The
ISL43741 has low charge injection with 1pC (Max) at V
S
= ±5V.
Reference Documents
• Intersil ISL28134 Data Sheet “5V Ultra Low Noise, Zero Drift
Rail-to-Rail Precision Op Amp,” FN6957
• Intersil ISL21010 Data Sheet “Micropower Voltage Reference,”
FN7896
• Intersil ISL26102 Data Sheet “Low-Noise 24-bit Delta Sigma
ADC,” FN7608
• Intersil ISL43741 Data Sheet “Low-Voltage, Single and Dual
Supply, 8 to 1 Multiplexer and Differential 4 to 1 Multiplexer,”
FN6053
• Intersil ISL22316 Data Sheet “Low Noise, Low Power I
2
C®
Bus, 128 Taps,” FN6186
• Renesas R5F10JBC Data Sheet
FIGURE 6. GUI MEASUREMENT SCREEN
