16 I/O lines over a two-wire bus
The TCA9535DBT is a 16-bit I²C/SMBus I/O expander from Texas Instruments, giving a microcontroller 16 extra GPIO pins using just the SDA and SCL lines — no extra address pins needed beyond the three hardware-selectable ones on the bus. The I²C clock stretches to 400 kHz, fast enough for polling a bank of switches, LEDs, or relay drivers in a control loop under 100 µs.
Interrupt-driven I/O and output drive
An interrupt output (INT) goes low when any input pin changes state — the host MCU does not need to poll the expander continuously, which saves bus bandwidth and firmware cycles in event-driven systems. Each I/O can source 10 mA or sink 25 mA, enough to drive a standard LED directly or switch a small-signal relay through a transistor. The POR (power-on reset) feature ensures all I/Os come up as inputs after a supply brown-out, avoiding unintended output glitches during power sequencing.
Active and RoHS3 compliant
RoHS3 compliant, with no restricted substances above the threshold — no separate exemption paperwork needed for EU-market shipments.