Hot Socketing and Power-On Reset in MAX II Devices
Figure 4–3. ESD Protection During Positive Voltage Zap
I/O
Source
D
Gate
PMOS
N+
Drain
P-Substrate
G
I/O
Drain
S
Gate
N+
NMOS
Source
GND
GND
When the I/O pin receives a negative ESD zap at the pin that is less than
–0.7 V (0.7 V is the voltage drop across a diode), the intrinsic
P-Substrate/N+ drain diode is forward biased. Therefore, the discharge
ESD current path is from GND to the I/O pin, as shown in Figure 4–4.
Altera Corporation
December 2007
4–5
MAX II Device Handbook, Volume 1