Open-drain hot-swap fail-safe

Home - Features - Open-drain hot-swap fail-safe

Open-drain / Hot-swap / Over voltage tolerant / fail-safe

For a number of interfaces the conventional ESD protection (2 diodes) is not possible. Specifically the diode from I/O to Vdd causes a lot of issues. Fortunately other ESD concepts are available.

Examples

When the diode from I/O to Vdd causes problems Sofics proposes a local clamp approach

This can happen when the signal voltage on the I/O can go above the voltage on the reference Vdd domain.

Another typical reason is when designers need to use ‘open-drain’ communication lines like the I²C bus.

More recently it is also relevant when sub-domains on a SoC are powered down while the signals can still be applied.

Also in Space applications designers sometimes have a cold-spare chip that is not powered but still receives the I/O signals.

Mature CMOS (0.5um to 180nm)

Process Pad ESD robustness Leakage
TSMC 180nm 5V I/O > 8 kV HBM < 5 nA
TSMC 180nm 7V I/O > 2 kV HBM < 50 nA

Mainstream CMOS (130nm to 65nm)

Process pad ESD robustness Leakage
TSMC 130nm 5V I/O > 3 kV HBM < 1 nA
TSMC 130nm 7V I/O > 4 kV HBM < 1 nA
TSMC 65nm 5V I/O > 4 kV HBM < 1 nA
TSMC 65nm 5V I/O > 4 kV HBM < 100 nA

Advanced CMOS (40nm to 22nm)

Process Pad ESD robustness Leakage
TSMC 40nm 5V I/O > 2 kV HBM < 10 nA
TSMC 28nm 3.9V I/O > 2 kV HBM < 50 pA
TSMC 28nm 5.5V I/O > 2 kV HBM < 400 pA
TSMC 28nm 6.5V I/O > 2 kV HBM < 400 pA
TSMC 28nm 12V I/O > 2 kV HBM < 40 nA
UMC 28nm 8.6V I/O > 500V HBM < 1 uA

FinFET technology

Process Pad ESD robustness Leakage
TSMC 16nm 5V I/O > 1 kV HBM < 30 nA
TSMC 12nm 5V I/O > 4 kV HBM < 3 uA

SOI technology

Process Pad ESD robustness Leakage
GF 22FDX 3.3V I/O > 2 kV HBM < 500 pA

BiCMOS technology

Process Pad ESD robustness Parasitic capacitance
TSMC 130nm 1.2V I/O > 4 kV HBM < 100 fF
TSMC 130nm 1.2V I/O OVT > 2 kV HBM < 50 fF
UMC 130nm 1.2V I/O > 2 kV HBM < 150 fF
TSMC 90nm 3.3V I/O > 2kV HBM < 100 fF
TSMC 65nm 1.8V I/O > 4 kV HBM < 100 fF
TSMC 65nm 1.0V I/O > 3 kV HBM < 70 fF
GF 65nm 1.2V I/O > 2 kV HBM < 50 fF
GF 65nm 3.3V I/O > 2 kV HBM < 50 fF

Customer quotes

Further reading