HC230 ALTERA [Altera Corporation], HC230 Datasheet - Page 89

• Manufacturer Part Number: HC230
• Description: HardCopy II Device Family
• Manufacturer: ALTERA [Altera Corporation]

Altera Corporation
September 2008
Figure 4–3
which will be used to explain ESD protection.
Figure 4–3. Transistor-Level Diagram of HardCopy II Device I/O Buffers
The CMOS output drivers in the I/O pins intrinsically provide
electrostatic discharge protection. There are two cases to consider for ESD
voltage strikes: positive voltage zap and negative voltage zap.
A positive ESD voltage zap occurs when a positive voltage is present on
an I/O pin due to an ESD charge event. This can cause the N+
(Drain)/PSubstrate junction of the N-channel drain to break down and
the N+ (Drain)/P-Substrate/N+ (Source) intrinsic bipolar transistor turns
on to discharge ESD current from I/O pin to GND.
shows a typical HardCopy II CMOS I/O buffer structure
Electrostatic Discharge
4–47