When placed near the USB connectors, the TPD4E001
ESD solution offers little or no signal distortion during normal operation due to
low IO capacitance and ultra-low leakage current specifications. The TPD4E001
ensures that the core circuitry is protected and the system is functioning properly
in the event of an ESD strike. For proper operation, the following layout/ design
guidelines must be followed:
- Place the TPD4E001 solution close to the connectors. This allows the TPD4E001 to
take away the energy associated with ESD strike before it reaches the internal
circuitry of the system board.
- Place a 0.1μF capacitor very close to the VCC pin. This limits any
momentary voltage surge at the IO pin during the ESD strike event.
- Ensure that there is enough metallization for the VCC and GND loop.
During normal operation, the TPD4E001 consumes nA leakage current. But during
the ESD event, VCC and GND may see 15A to 30A of current, depending
on the ESD level. Sufficient current path enables safe discharge of all the
energy associated with the ESD strike.
- Leave the unused IO pins floating. In this example of protecting two USB ports,
none of the IO pins are left unused.
- The VCC pin can be connected in two different ways:
- If the VCC pin is connected to the system power supply, the
TPD4E001 works as a transient suppressor for any signal swing above
VCC + VF. A 0.1μF capacitor on the device
VCC pin is recommended for ESD bypass.
- If the VCC pin is not connected to the system power supply,
the TPD4E001 can tolerate higher signal swing in the range up to 10V.
Please note that a 0.1μF capacitor is still recommended at the
VCC pin for ESD bypass.