DOGMA Usage

Here we collect some hints how to use a Dogma-System.

Hardware (hints how to setup/use the hardware)

Voltage settings:

The idea behind the power-supply architecture is to enable the user of e.g. the DiRICH5d2 modules to have the minimum needed power dissipation in your setup, by reducing the amount of power lost in the voltage regulators on the module. And linear regulators are used to reduce the noise to the absolute minimum to ensure best time measurement performance.

We mention the “nominal” voltages for the three supplyvoltages we need, where nominal is what the devices on the PCB need.

But the voltage has a ohmic drop on the cable from the supply to the dog and then we use LDOs (low dropout regulators) which keep the output voltage constant for the FPGA and the other devices, which will not work with fluctuating voltages. These LDO again generate a voltage drop of ~100mV.

So, for a safe operation, with “normal” lab cables (1m-2m), you need to increase the input voltage by at least ~200mV.

So, first recommendation:

nominal: 1.1V -> 1.4V (potentially larger drop on the cable as higher current)
nominal: 2.5V -> 2.7V
nominal: 3.3V -> 3.5V

You can check if the voltages are fine:

% DOGMA_IP=192.168.50.102 dog adc 0x0000d060
Input Voltages on DiRICH5d2:
1.1V: 1262mV
2.5V: 2610mV
3.3V: 3474mV

The inputs voltages on the DiRICH5d2 should be at least 100mV above the nominal level. But you can also go higher and you can not break things. The LDOs will just dissipate more power.