Hardware -- The frontend's INA321 inamp

A project log for Heartbeat Logger

A portable device that logs a snippet of your heart at the push of a button.

Ole Andreas UtstumoOle Andreas Utstumo 01/26/2016 at 19:030 Comments

Image taken from the datasheet of Texas Instruments INA321.

Some of the in amps selling points are:

The INA321 was chosen for this project mainly for its rail-to-rail output swing and low supply
voltage. Rail-to-rail means that the in amps output signal can be from GND to Vcc, which for a
3.3V system would be critical. The AD620 in amp, for example, has a output swing from GND +1.1V to Vcc - 1.5V, allowing for a 3.3V system just 3.3V - (1.1 + 1.5)V = 0.7V of signal swing at the