ZHCSH81 December 2017 PGA302
PRODUCTION DATA.
Table 66 shows the recommended component values for the design shown in Figure 116.
DESIGNATOR | VALUE | COMMENT |
---|---|---|
VINPP resistor (R1) VINPN resistor (R2) | 0 Ω | These resistors are in place to determine the cutoff frequency of the lowpass filter created by R1/R2 and C1/C2. When using a resistive bridge these resistors should be 0 Ω (not used) and C1/C2 are calculated based on the bridge resistance. |
VINPP capacitor (C1) | 0.15 μF | Place as close to the VINPP pin as possible. |
VINPN capacitor (C2) | 0.15 μF | Place as close to the VINPN pin as possible. |
VDD capacitor (C4) | 0.1 μF | Place as close to the VDD pin as possible. |
DVDD capacitor (C3) | 0.1 μF | Place as close to the DVDD pin as possible. |
To make use of the full range of the internal ADC it is important to carefully select the sensor to be paired with the PGA302. While the input pins can handle between 0.2 V and 4.2 V, it is good practice to make sure that the common-mode voltage of the sensor remains in middle of this range for differential signals. Note that the P Gain amplifier can be configured to measure half-bridge output, where the half bridge is connected to either VINPP or VINPN, and the remaining pin is internally connected to a voltage of VBRG/2.
To achieve the best performance, take the differential voltage range of the sensor into account. Using proper calibration with a digital compensation algorithm, any voltage range can be mapped to the full range of ADC output values, but the final measurement accuracy will be the highest if the analog voltage input matches the ADC’s input range. The gain of the P Gain amplifier can be selected from 1.33 V/V to 200 V/V to aid in matching the input range of the ADC from –2.5 V to 2.5 V.