ST72521 STMICROELECTRONICS [STMicroelectronics], ST72521 Datasheet - Page 182

• Manufacturer Part Number: ST72521
• Description: 8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, FIVE TIMERS, SPI, SCI, I2C, CAN INTERFACE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST72521
EMC CHARACTERISTICS (Cont’d)
True Open Drain Pin Protection
The centralized protection (4) is not involved in the
discharge of the ESD stresses applied to true
open drain pads due to the fact that a P-Buffer and
diode to V
local protection between the pad and V
5b) is implemented to completely absorb the posi-
tive ESD discharge.
Figure 97. Positive Stress on a True Open Drain Pad vs. V
Figure 98. Negative Stress on a True Open Drain Pad vs. V
Figure 99. Multisupply Configuration
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Main path
Path to avoid
Main path
V
V
DD
DD
SS
are not implemented. An additional
V
V
V
V
SS
SS
DD
DD
V
AREF
V
SSA
(5a)
(3b)
(3b)
(3b)
SS
(5a &
OUT
OUT
BACK TO BACK DIODE
BETWEEN GROUNDS
Multisupply Configuration
When several types of ground (V
power supply (V
any reason (better noise immunity...), the structure
shown in
device against ESD.
(4)
(4)
SS
DD
Figure 99
IN
IN
(2b)
DD
, V
is implemented to protect the
AREF
(2b)
(1)
(1)
, ...) are available for
SS
(3b)
V
V
(5b)
, V
SSA
AREF
SSA
, ...) and
V
V
V
V
SS
SS
DD
DD