Camera Power Distribution
Grablink Quickpack CFA PCIe is a PoCL SafePower frame grabber. It is compatible with both conventional and PoCL cameras.
Note. This feature is not available on Grablink Quickpack CFA (PCI).
The power must be delivered to the PoCL camera through a PoCL-compliant Camera Link cable. A conventional camera may operate with both PoCL and non-PoCL compliant cables.
PoCL camera current rating
Grablink Quickpack CFA PCIe is capable of delivering a sustained supply current up to 400 mA to PoCL-compliant cameras attached on the Camera Link connector.
PoCL camera current rating
Parameter |
Max |
Units |
PoCL camera current rating |
400 |
mA |
PoCL cameras up to 4W can operate normally at the minimal camera supply voltage of 10 V.
Source supply voltage requirement
The power is delivered to the camera from an an external power source attached to the Camera Power connector. The power source must be a regulated 12 V DC power supply capable of sustaining the current required by the camera and satisfying the voltage requirements of a PoCL frame grabber.
Source supply voltage requirement
Parameter |
Min |
Typ. |
Max |
Units |
Source supply voltage requirement |
11 |
12 |
13 |
V |
The voltage loss across the protection circuits is negligible. The current required by the on-board circuits is also negligible.
The voltage delivered by the external power supply on Camera Power connector is monitored by the PoCL control logic. The board class parameter POCL_PowerInput reports a value ON if the voltage is greater than 11 V, else reports a value OFF.
PoCL over-current protection circuit
The PoCL over-current protection circuit of Grablink Quickpack CFA PCIe is an electronic device that controls the current delivered to the PoCL using:
- a dV/dt limiter
- a short circuit current limiter
- an overload current limiter
- a thermal protection.
The dV/dt limiter controls the output voltage rising slope. This limits the current during the charging of the load capacitor.
The short circuit current limiter is effective when a short circuit event occur. It is also effective during the charging of the load capacitor since during that phase, the load is equivalent to a short circuit.
The overload current limiter is effective when during normal operation, the load current increases excessively; when the overload level is reached, the overload current limiter will automatically reduce the current to the short circuit level.
The thermal protection limits the temperature of the electronic device by opening the circuit until the device temperature reduces sufficiently.
PoCL OCP characteristics
PoCL OCP characteristics |
Min |
Typ. |
Max |
Units |
Output voltage slew rate |
|
0.15 |
|
V/ms |
Short circuit current limit |
0.6 |
1 |
1.8 |
A |
Overload current limit |
3.1 |
3.2 |
3.5 |
A |
PoCL over-voltage protection circuit
The PoCL over-voltage protection circuit of Grablink Quickpack CFA PCIe clamps the output voltage in case of a defective external power supply.
PoCL OVP characteristics
PoCL OVP characteristics |
Min |
Typ. |
Max |
Units |
Output clamping voltage |
13 |
15 |
17 |
V |
The parameter PoCL_Mode controls the operation mode of the PoCL controller. When set to AUTO, the default mode, the PoCL controller identifies the type of camera attached on the Camera Link connector and configures the camera power distribution accordingly. When set to OFF, the PoCL controller inhibits the PoCL camera detection and, if power is already applied, it will turn off the power.
PoCL device detector
The PoCL device detector measures the impedance of the PoCL camera at the off state. Therefore, a calibrated sensing current is injected and voltage developed across the camera impedance. Following table summarizes the characteristics of the PoCL device detection circuit.
PoCL device detector characteristics
PoCL device detector characteristics |
Min |
Typ. |
Max |
Units |
Sense current on 10K impedance load |
30 |
52 |
75 |
μA |
Detector thresholds |
0.3 |
0.52 |
1.2 |
V |
The sensing current is injected during a period of 1 second. The voltage developed on the camera input impedance is measured. If the voltage is between the thresholds, and external power is present and greater than 11 V, the power is applied.
The power is maintained while the camera is present. The PoCL control logic checks permanently the camera presence by monitoring the clock delivered by the camera. Any clock loss for an interval exceeding 100 milliseconds is interpreted as a cable connection, and the power is immediately turned off. The presence check is disabled during the first three seconds after establishing power to allow camera boot-up time.
PoCL status report
The parameter PoCL_Status reports the state of the PoCL controller.
PoCL status report
Meaning |
|
POCL_CAMERA |
The camera connected is a PoCL capable camera, and it is powered by the frame grabber. |
CONVENTIONAL_CAMERA |
The camera connected is either a conventional camera, or is connected through a non-PoCL cable. |
NO_CAMERA |
There is no camera connected. |