Analog Devices Inc. ADPD4000 and ADPD4001 Multimodal Sensor Front End can stimulate up to eight LEDs and measure the return signal on up to eight separate current inputs. Twelve available time slots can enable 12 separate measurements per sampling period. The data output and functional configuration utilise an I2C interface on the ADPD4001 or a serial port interface (SPI) on the ADPD4000. The control circuitry includes flexible LED signalling and synchronous detection. The devices use a 1.8V analogue core and 1.8V/3.3V compatible digital input/output (I/O).