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STM32F20xxx Electrical characteristics
177
Static latch-up
Two complementary static tests are required on six parts to assess the latch-up
performance:
• A supply overvoltage is applied to each power supply pin
• A current injection is applied to each input, output and configurable I/O pin
These tests are compliant with EIA/JESD 78A IC latch-up standard.
6.3.15 I/O current injection characteristics
As a general rule, current injection to the I/O pins, due to external voltage below V
SS
or
above V
DD
(for standard, 3 V-capable I/O pins) should be avoided during normal product
operation. However, in order to give an indication of the robustness of the microcontroller in
cases when abnormal injection accidentally happens, susceptibility tests are performed on a
sample basis during device characterization.
Functional susceptibilty to I/O current injection
While a simple application is executed on the device, the device is stressed by injecting
current into the I/O pins programmed in floating input mode. While current is injected into
the I/O pin, one at a time, the device is checked for functional failures.
The failure is indicated by an out of range parameter: ADC error above a certain limit (>5
LSB TUE), out of spec current injection on adjacent pins or other functional failure (for
example reset, oscillator frequency deviation).
The test results are given in Table 45.
Table 44. Electrical sensitivities
Symbol Parameter Conditions Class
LU Static latch-up class T
A
= +105 °C conforming to JESD78A II level A
Table 45. I/O current injection susceptibility
Symbol Description
Functional susceptibility
Unit
Negative
injection
Positive
injection
I
INJ
Injected current on all FT pins –5 +0
mA
Injected current on any other pin –5 +5