ZHCSSI3 February 2024 ADS1288
PRODUCTION DATA
The ADC provides a buffer option, bypassing the PGA. The PGA is powered-down in buffer mode. Use the buffer for ±2.5VPP input signals when operating AVDD1 at 3.3V. Buffer operation is enabled by setting the GAIN[2:0] bits = 111b of the CONFIG1 register.
Figure 7-7 shows the buffer voltage headroom with AVDD1 = 3.3V, VCM = 1.65V, and the input signal = ±2.5VPP. The buffer has sufficient voltage headroom for ±2.5VPP input signals when operating with AVDD1 = 3.3V.
Regardless of PGA or buffer operation, connect two 47nF, C0G-dielectric capacitors from each buffer output to AVSS (CAPBP and CAPBN). The voltage charge pump increases the buffer input operating headroom. Connect an external 4.7nF capacitor between CAPC and AGND for the charge pump operation.