TS4631 Light-to-Digital Converter

Triad Semiconductor’s TS4631 enables cost-effective deployment of Valve Corporation’s SteamVR tracking system and is compatible with GEN1 and GEN2 SteamVR base stations. The TS4631 provides pulse detection circuitry for use in room-scale tracking/positioning for virtual reality gaming which requires millimeter position accuracy. Working with an IR photodiode, the TS4631 converts infrared light pulses from a SteamVR Lighthouse base station into position, indicating digital envelope signals. The device also includes a digital output data pin that is a representation of the optical carrier waveform applied to the photodiode.

The TS4631 includes circuits for photodiode biasing and provides high gain, noise filtering, and envelope detection of pulsed IR base station light sources. The envelope output of the TS4631 is a digital signal that tracks the envelope of the infrared light that is incident on the photodiode. The data output is a digital signal that tracks the modulated light input. The TS4631 is configured by a two-wire bus that shares the envelope and data digital pins of the device. The signal path is driven from an external photodiode which is connected directly to the package inputs then AC coupled to the inputs of a differential TIA. Internal bias blocks provide the necessary biasing for the photodiode. The output of the differential TIA is followed by filtering and gain blocks to limit noise before the signal drives an envelope detector and data slicer to generate the envelope and data output signals. The TS4631 is available in a 9-bump WLCSP package with dimensions of 1.2 mm x 1.2 mm and a bump pitch of 0.4 mm to achieve a minimal footprint size for use in space-constrained assemblies.