A time-of-flight ranging system disclosed herein includes a receiver asserting a photon received signal in response to detection of light that has reflected off a target and returned to the time-of-flight ranging system. A first latch circuit has first and second data inputs receiving a first pair of differential timing references, the first latch circuit latching data values at its first and second data inputs to first and second data outputs based upon assertion of the photon received signal. A first counter counts latching events of the first latch circuit during which the first data output is asserted, and a second counter counts latching events of the first latch circuit during which the second data output is asserted. Processing circuitry determines distance to the target based upon counted latching events output from the first and second counters.