These devices consist of two independent, high-gain, frequency-compensated operational amplifiers designed to operate from a single supply over a wide range of voltages. Operation from split supplies also is possible if the difference between the two supplies is 3 V to 32 V, and VCC is at least 1.5 V more positive than the input common-mode voltage. The low supply-current drain is independent of the magnitude of the supply voltage.

• Wide supply voltage ranges
• Low supply-current drain independent of supply voltage
• Common-mode input voltage range includes ground, allowing direct sensing near ground
• Low input bias and offset parameters
• Internal frequency compensation

The AD8244BRMZ is a low power FET input quad Unity-gain Buffer designed to isolate very large source impedances from the rest of the signal chain. The 2pA maximum bias current, near zero current noise and 10 TΩ input impedance introduce almost no error, even with source impedance well into the megaohms. Many traditional operational amplifier pinouts have a supply pin that is next to the non-inverting input. A guard trace must be routed between these pins to avoid leakage currents much larger than the bias current of a FET input op amp. The AD8244 solves this problem with unique pinout that physically separates the high impedance inputs from the low impedance supplies and outputs of the other buffers. The AD8244 design is focused on solving problems specific to buffers. This includes close channel-to-channel matching which allows channels of the AD8244 to be used in differential signal chains with minimal error.

• Extremely high input impedance
• Low noise
• High DC precision – 3μV/°C maximum offset drift (B grade)
• No leakage from inputs to supply pins
• Provides guarding capability
• Rail-to-rail output
• Single-supply operation – Input range extends to ground
• 250μA Maximum supply current per amplifier
• 2pA Maximum input bias current at 25°C