HX711 24-Bit Analog-to-Digital Converter (ADC) for Weigh Scales DESCRIPTION FEATURES Two selectable differential input channels Based on Avia Semiconductors patented technology, HX711 is a precision 24-bit analog- On-chip active low noise PGA with selectable gain to-digital converter (ADC) designed for weigh of 32, 64 and 128 scales and industrial control applications to On-chip power supply regulator for load-cell and interface directly with a bridge sensor. ADC analog power supply On-chip oscillator requiring no external The input multiplexer selects either Channel A component with optional external crystal or B differential input to the low-noise On-chip power-on-reset programmable gain amplifier (PGA). Channel A Simple digital control and serial interface: can be programmed with a gain of 128 or 64, corresponding to a full-scale differential input pin-driven controls, no programming needed voltage of 20mV or 40mV respectively, when Selectable 10SPS or 80SPS output data rate a 5V supply is connected to AVDD analog power Simultaneous 50 and 60Hz supply rejection supply pin. Channel B has a fixed gain of 32. On- Current consumption including on-chip analog chip power supply regulator eliminates the need power supply regulator: for an external supply regulator to provide analog normal operation < 1.5mA, power down < 1uA power for the ADC and the sensor. Clock input is Operation supply voltage range: 2.6 ~ 5.5V flexible. It can be from an external clock source, a Operation temperature range: -40 ~ +85 crystal, or the on-chip oscillator that does not require any external component. On-chip power- 16 pin SOP-16 package on-reset circuitry simplifies digital interface initialization. APPLICATIONS There is no programming needed for the internal registers. All controls to the HX711 are Weigh Scales through the pins. Industrial Process Control V V AVDD SUP S8550 2.7~5.5V R R 2 1 10uF VFB BASE VSUP DVDD Load cell AVDD INA+ Analog Supply Regulator DOUT INA- To/From Digital PD SCK MCU Input Interface 24-bit MUX INB+ ADC PGA RATE INB- Gain = 32, 64, 128 VBG Internal HX711 Bandgap Reference Oscillator 0.1uF AGND XI XO Fig. 1 Typical weigh scale application block diagram TEL: (592) 252-9530 (P. R. China) AVIA SEMICONDUCTOR EMAIL: market aviaic.com HX711 Pin Description DVDD Digital Power Regulator Power VSUP 1 16 Regulator Control Output BASE RATE Output Data Rate Control Input 2 15 Analog Power AVDD 3 14 XI Crystal I/O and External Clock Input XO Crystal I/O Regulator Control Input VFB 4 13 12 DOUT Serial Data Output Analog Ground AGND 5 Reference Bypass VBG 6 11 PD SCK Power Down and Serial Clock Input 10 INPB INNA 7 Ch. B Positive Input Ch. A Negative Input 8 9 INNB Ch. A Positive Input INPA Ch. B Negative Input SOP-16L Package Pin Name Function Description 1 VSUP Power Regulator supply: 2.7 ~ 5.5V 2 BASE Analog Output Regulator control outputNC when not used 3 AVDD Power Analog supply: 2.6 ~ 5.5V 4 VFB Analog Input Regulator control inputconnect to AGND when not used 5 AGND Ground Analog Ground 6 VBG Analog Output Reference bypass output 7 INA- Analog Input Channel A negative input 8 INA+ Analog Input Channel A positive input 9 INB- Analog Input Channel B negative input 10 INB+ Analog Input Channel B positive input 11 PD SCK Digital Input Power down control (high active) and serial clock input 12 DOUT Digital Output Serial data output 13 XO Digital I/O Crystal I/O (NC when not used 14 XI Digital Input Crystal I/O or external clock input, 0: use on-chip oscillator 15 RATE Digital Input Output data rate control, 0: 10Hz 1: 80Hz 16 DVDD Power Digital supply: 2.6 ~ 5.5V Table 1 Pin Description AVIA SEMICONDUCTOR 2