A basic connection diagram for the ADS1000-Q1 is shown in Figure 8-1.

The fully differential voltage input of the ADS1000-Q1 is ideal for connection to differential sources with moderately low source impedance, such as bridge sensors and thermistors. Although the ADS1000-Q1 can read bipolar differential signals, the device cannot accept negative voltages on either input. Think of the ADS1000-Q1 positive voltage input as noninverting, and of the negative input as inverting.

When the ADS1000-Q1 is converting, the device draws current in short spikes. The 0.1-μF bypass capacitor supplies the momentary bursts of extra current needed from the supply.

The ADS1000-Q1 interfaces directly to standard mode, fast mode, and high-speed mode I²C controllers. Any microcontroller I²C peripheral, including controller-only and non-multiple-controller I²C peripherals, work with the ADS1000-Q1. The ADS1000-Q1 does not perform clock-stretching (that is, the device never pulls the clock line low), so providing for this function is not necessary unless other devices are on the same I²C bus.

Pullup resistors are necessary on both the SDA and SCL lines because I²C bus drivers are open-drain. The size of these resistors depends on the bus operating speed and capacitance of the bus lines. Higher-value resistors consume less power, but increase the transition times on the bus, limiting the bus speed. Lower-value resistors allow higher speed at the expense of higher power consumption. Long bus lines have higher capacitance and require smaller pullup resistors to compensate. The resistors must not be too small; if they are, the bus drivers can possibly be unable to pull the bus lines low.

Figure 8-1 Typical Connections of the ADS1000-Q1