Are ESD protection devices for signal lines and transient voltage suppression diodes for power lines same? For ex, if I have a data line that is 5V logic level and a power input of 5V to the board can I use the same type of devices for both?
I have a regulated 5V DC coming in to the board via 2-3 mtr cable. Can I use the ESD protection diodes specified for 5V data lines here instead of transient voltage suppression devices specified especially as for data lines?
I understand low capacitance required for high speed data lines. Is low capacitance of esd devices specified for data lines an issue for power lines?
Do I need unidirectional or bi-directional for 5V DC power line?
diodes for power lines same? For ex, if I have a data line that is 5V logic level and a power input of 5V to the board can I use the same type of devices for both?
There're the same, but different. Both are Zener-like devices but on different scales and tuned for different purposes.
the ESD protection diodes specified for 5V data lines here instead of transient voltage suppression devices specified especially as for data lines?
Possible, but probably not. There are many strategies for dealing with ESD. Some use a series impedance with a capacitor, or clamp. The series impedance limits the energy from an ESD strike so a smaller device can be used. There is a tradeoff that has to be made to select the appropriate device. The chances are that your diodes specified for 5V data lines won't be robust enough to protect a power input, where you may or may not be able to add sufficient impedance to limit the energy.
They make hundreds of different devices for a reason.
capacitance of esd devices specified for data lines an issue for power lines?
Low capacitance generally means low energy capability. Power lines generally require higher energy capability.
Usually, unidirectional devices are used for DC inputs. You only want the Zener action in the direction of the applied voltage. In the reverse direction the TVS diode is a diode, so will protect against excursions below ground, which will also destroy devices. There isn't any reason to limit the negative excursion to the positive supply voltage. The reverse diode will also help protect against supply reversal (assuming you have a protection device to limit current).
Bidirectional TVS diodes are most often used for differential data lines, where there is no reference to ground. The TVS diodes are selected using the maximum common mode voltage.
Diodes are more rugged when forward biased than reverse biased, so I wouldn't go bidirectional if you don't need that feature.
The machine model only has a 200pF cap, but nearly no resistance. The human body model is 100pF with a 1500 ohm resistor. For power supply lines, the capacitance on the line itself should be enough to limit the voltage. Just think of it as a charge transfer design problem, i.e. conserve charge and you can predict the final voltage.
Generally the machine model is the one that gets you.