SPI GPIO expansion at 26 MHz
The MAX7301ATL+ is a 28-bit I/O expander controlled over an SPI interface running up to 26 MHz. That clock rate means the host MCU can update all 28 outputs in roughly 1 µs — fast enough for LED multiplexing, latch-based status readback, or driving a parallel bus through the expander without stalling the main loop. Each I/O is individually configurable as a push-pull output or a logic input with interrupt generation. The interrupt output lets the host respond to edge transitions without polling the SPI bus, saving CPU cycles in a low-latency control system.
Supply and temperature envelope
Output drive is rated 4.5 mA source and 10 mA sink per I/O. That sink current is enough to drive a standard LED (20 mA total with two I/Os paralleled) or a small-signal relay coil with a flyback diode. For higher loads, the push-pull outputs can be used as gate-drive signals for external MOSFETs.