With an external voltage regulator, the TL431 chip external voltage (2.5V) is used as the excitation source of the external pressure sensor, and the voltage is more stable.

Description:

CS1238 is a high-precision, low-power analog-to-digital converter chip with two differential input channels, built-in temperature sensor and High precision oscillator.
PGA of CS1238 is optional: 1, 2, 64, 128, and the default is 128.
The ADC data output rate of CS1238 is optional: 10Hz, 40Hz, 640Hz, 1.28kHz, and the default is 10Hz;
MCU can communicate with CS1238 through 2-wire SPI interface SCLK, DRDY/DOUT
Line configuration, such as channel selection, PGA selection, output rate selection, etc.

Characteristics: 

• Built-in crystal oscillator
• Integrated temperature sensor With power down function
  
• 2-wire SPI interface, the fastest rate is 1.1MHz
• 24-bit lossless code
• PGA magnification options: 1, 2, 64, 128
• Integrated 2-channel 24-bit lossless differential input, ENOB is 20.7 bits (working at 5V)  20.2 when PGA=128
• Bit (working at 3.3V)
• P-P noise: PGA=128, 10Hz: 150nV;
• INL is less than 0.0015%
• Output rate options: 10Hz, 40Hz, 640Hz, 1.28kHz
• In-band short function