16-bit I²C GPIO expander with POR and interrupt
The Maxim Integrated MAX7318AUG+ is a 16-bit I²C- and SMBus-compatible GPIO expander in a 24-TSSOP package. It provides 16 push-pull I/O lines, a power-on reset (POR) circuit that initializes all outputs to a known state, and an interrupt output that signals the host when an input changes. The wide supply range from 2V to 5.5V lets it bridge 3.3V and 5V microcontroller domains without level shifters on the I/O side.
The 2V to 5.5V supply means a single 3.3V or 5V rail powers the expander directly, and the I/O pins tolerate 5V logic even when VCC is 3.3V — a common requirement when interfacing legacy 5V sensors or microcontrollers.
Output drive: 31 mA source, 43 mA sink
Each I/O can source 31 mA or sink 43 mA, enough to drive small LEDs, optocoupler inputs, or low-power relays directly. For higher loads, the push-pull outputs can be configured as open-drain by software, allowing wired-AND connections or level translation. The total package dissipation limits how many outputs can run at full drive simultaneously — a quick thermal check is worthwhile if driving all 16 outputs near the maximum.