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Electrical characteristics
ST7LITEUS2, ST7LITEUS5
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12.8
I/O port pin characteristics
12.8.1 General
characteristics
Subject to general operating conditions for V
DD
, f
OSC
, and T
A
unless otherwise specified.
Figure 48.
Two typical applications with unused I/O pin
1.
Caution
: During normal operation the ICCCLK pin must be pulled- up, internally or externally (external pull-
up of 10k mandatory in noisy environment). This is to avoid entering I
2
C mode unexpectedly during a reset.
2.
I/O can be left unconnected if it is configured as output (0 or 1) by the software. This has the advantage of
greater EMC robustness and lower cost.
Table 63.
General characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
V
IL
Input low level voltage
-40°C to 125°C
0.3V
DD
V
V
IH
Input high level voltage
0.7V
DD
V
hys
Schmitt trigger voltage
hysteresis
(1)
1.
Data based on characterization results, not tested in production.
400
mV
I
L
Input leakage current
V
SS
≤
V
IN
≤
V
DD
±1
μ
A
I
S
Static current
consumption induced by
each floating input pin
(2)
2.
Configuration not recommended, all unused pins must be kept at a fixed voltage: using the output mode of
the I/O for example or an external pull-up or pull-down resistor (see
). Static peak current value
taken at a fixed V
IN
value, based on design simulation and technology characteristics, not tested in
production. This value depends on V
DD
and temperature values.
Floating input mode
400
R
PU
Weak pull-up equivalent
resistor
(3)
(4)
3.
The R
PU
pull-up equivalent resistor is based on a resistive transistor (corresponding I
PU
current
4.
R
PU
not applicable on PA3 because it is multiplexed on RESET pin
V
IN
=
V
S
S
V
DD
=5 V
80
120
170
k
Ω
V
DD
=3 V 200
C
IO
I/O pin capacitance
5
pF
t
f(IO)out
Output high to low level
fall time
1)
C
L
=50 pF
Between 10% and 90%
25
ns
t
r(IO)out
Output low to high level
rise time
1)
25
t
w(IT)in
External interrupt pulse
time
(5)
5.
To generate an external interrupt, a minimum pulse width has to be applied on an I/O port pin configured
as an external interrupt source.
1
t
CPU
10k
Ω
UNUSED I/O PORT
ST7XXX
10k
Ω
UNUSED I/O PORT
ST7XXX
V
DD
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