TO-8 SPAD has internal cooling for low dark count

Hamamatsu Photonics has launched a TO-8 canned SPAD (single photon avalanche photodiode) with an in-built thermoelectric cooler.

Hamamatsu_s16835-050 spad single photon diode

Called S16835, there are two models, which differ in the width* of their sensors: 54µm or 100µm.

In standard operating conditions (25°C ambient, -20°C SPAD) typical dark currents are 15 or 60 count/s respectively (50 or 200 count/s max).


Terminal capacitance and gain are 2.8pF and 6×106, or 3.2pF and 1.5×107, again respectively.


Photo detection efficiency including after-pulses is 67% in both cases and the sensitive spectrum is 400 to 1,000nm (visible and near-infrared) peaking at 610nm.

“These features make them ideal for a variety of applications such as low-light-level measurement, particle diameter measurement, fluorescence measurement, and analytical instruments,” according to the company.

The packages are 14mm diameter TO-8 metal cans with a borosilicate glass window, and inside is the SPAD, a two-stage thermoelectric cooler and a thermistor.

SPAD breakdown voltage is 40V±5V, and recommended drive is at 7V over the breakdown voltage – at which the temperature coefficient is typically 45mV/°C.

Maximums for the cooler drive are 1A and 900mV – the current-voltage characteristic is near-linear up to these values.

Typically is will take ~430mA to get the SPAD to -20°C with +25°C ambient and a 3°C/W heatsink, at which thermistor resistance is typically 60kΩ – max allowable thermistor dissipation is 200μW.

Find the 100μm S16835 SPAD on this web page

*Hamamatsu literature frequently describes these dimensions as ‘area’, but the company has confirmed to Electronics Weekly that it is the measurement across the sensor.

Steve Bush

Steve Bush is the long-standing technology editor for Electronics Weekly, covering electronics developments for more than 25 years. He has a particular interest in the Power and Embedded areas of the industry. He also writes for the Engineer In Wonderland blog, covering 3D printing, CNC machines and miscellaneous other engineering matters.

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