ECG front end in a 20-LFCSP — what to know before you reflow
The AD8232ACPZ-RL is an ECG front end from Analog Devices, purpose-built for heart rate monitoring. It handles the analog signal chain from electrode to ADC-ready output — filtering, gain, and lead-off detection are integrated. The 20-LFCSP (4x4) package is a QFN derivative with an exposed pad; that pad needs a good thermal via pattern under it, or the part will cook before the solder wets.
20-LFCSP with a 4x4 mm body — that's a small thermal mass, which is good for hand rework under hot air.