TDC1 Time to Digital Converter

The TDC1 is a combined moderate-speed counter and timestamping/timetagging device for processing electrical pulses in four independent inputs. It can accept a wide range of standardized signal standards including (NIM and TTL) and is completely powered from a USB2 connection. The internal clock source can be disciplined by an external 10 MHz timing reference for precise absolute timing.

In counting mode, the device has 4 independent counters registering events on each of the four inputs, and 4 counting coincidence events between 4 pairs of inputs that register counts for a selectable integration time from 1ms to 65s.

In timetag mode, the device registers the absolute time of the leading edge every signal event (pulse) at any of the input lines with a resolution of 2ns together with the logical state of all four input lines. This allows to identify complex detector patterns with a single device.

The TDC1 is bundled with open source scripts in Python and C to perform data collection and visualize real time counts and coincidences.

Physical Parameters:

Size approx 85mm x 46mm x 22mm
Weight 150g
Power consumption

<0.5W (100mA from USB bus)


Signal Inputs:

Impedance 50Ohm (default) and 1kOhm (selectable by jumpers)
Input standards TTL, NIM, custom (positive or negative pulses with a trigger
level between -3.3V and +3.3V)
Minimal pulse width 2ns
Minimal pulse separation 2ns
Connector LEMO00 size coaxial connector (optional: SMA)


Clock reference:

External reference frequency 10MHz nominal (accepts 9...11MHz)
External reference amplitude 100mVpp min, 2.3Vpp max
Clock selection
automatic or forced manual
Internal clock accuracy
<50ppm, temperature drift TBD


Counter mode parameters:

Maximal count rate 250MHz in each channel
Integration time 1ms to 65535ms in steps of 1ms


Timestamp mode parameters:

Timing resolution 2ns
Timing jitter <200ps (nominal)
Maximal counting rate >10Mevents/s average, >250 Mevents/s in bursts of <512
events (see detail specification)
Dead time between events None



Host connection USB CDC ACM class / virtual com port (no device driver necessary)
Data format
Text or binary



Windows, Mac, Linux Labview .vi and Python scripts hosted at Github (MIT Licence)