16-channel constant-current sink with I²C control
The PCA9955BTWJ is a linear LED driver from NXP, integrating 16 constant-current sink outputs rated at 65 mA per channel. Each output is independently programmable via the I²C-bus interface, allowing per-channel PWM dimming without external shift registers or discrete current-setting resistors. The 16 outputs suit backlight arrays in automotive infotainment displays, industrial keypads, or appliance indicator panels where each LED string needs individual brightness control.
Package thermal path and board integration
Housed in a 28-lead HTSSOP with an exposed pad (4.40 mm body width), the package relies on the pad soldered to a copper land on the PCB to pull heat from the die. At 65 mA per channel on all 16 outputs, the total dissipation is just over 1 W — the exposed pad keeps the junction below the 85 °C ambient limit without forced airflow, provided the PCB copper plane under the pad has adequate area. The I²C address is set via two hardware pins, allowing up to four devices on the same bus for 64 total channels.
It is ROHS3 compliant, covering the full substance restriction without exemption-based carve-outs.