Single Power Supply, low standby current, 8-bit CMOS data acquisition devices.. PCF8591 has 4 analog inputs, one analog output and a serial I2C bus interface. Operating voltage range: 2.5V-6V, analog voltage range from VSS to VDD. Control and data signals are through the two-wire bi-directional I2C bus to serial transfrom. Allowing access to eight PCF8591 devices on the same I2C bus without additional hardware. Specification: Material: Module Size: Approx. 36x23x9mm / 1.42x0.91x0.35inch Package Includes: 1 Piece PCF8591 AD/DA Converter Module(7 Pack) Note: A module chip PCF8951 2 module four external voltage input acquisition (voltage input range 0-5v) 3 modules integrated photoresistor, you can collect the ambient light intensity AD exact numeric 4 modules integrated thermistor, you can collect the ambient temperature exact numeric AD 5 module integrates a road 0-5V voltage input acquisition (via the blue potentiometer to adjust the input voltage) 6 modules with power indicator (on the module power indicator will light) 7 modules with DA output indicator, when the module DA output interface voltage reaches a certain value, it will light up the board DA output indicator, the greater the voltage, the LED brightness is more obvious; 8 standard dual panel, thickness 1.6mm, nice layout, surrounded by a through-hole, pore size: 3mm, convenient fixed