Datasheet

DocID030538 Rev 3 107/226
STM32H743xI Electrical characteristics
196
I/O system current consumption
The current consumption of the I/O system has two components: static and dynamic.
I/O static current consumption
All the I/Os used as inputs with pull-up generate a current consumption when the pin is
ex
ternally held low. The value of this current consumption can be simply computed by using
the pull-up/pull-down resistors values given in Ta ble 58: I/O static characteristics.
For the output pins, any external pull-down or ext
ernal load must also be considered to
estimate the current consumption.
An additional I/O current consumption is due to I/Os
configured as inputs if an intermediate
voltage level is externally applied. This current consumption is caused by the input Schmitt
trigger circuits used to discriminate the input value. Unless this specific configuration is
required by the application, this supply current consumption can be avoided by configuring
these I/Os in analog mode. This is notably the case of ADC input pins which should be
configured as analog inputs.
Caution: An
y floating input pin can also settle to an intermediate voltage level or switch inadvertently,
as a result of external electromagnetic noise. To avoid a current consumption related to
floating pins, they must either be configured in analog mode, or forced internally to a definite
digital value. This can be done either by using pull-up/down resistors or by configuring the
pins in output mode.
I/O dynamic current consumption
In addition to the internal peripheral current consumption (see Table 38: Peripheral current
consumption in Run mode), the I/Os used by an application also contribute to the current
consumption. When an I/O pin switches, it uses the cur
rent from the MCU supply voltage to
supply the I/O pin circuitry and to charge/discharge the capacitive load (internal or external)
connected to the pin:
where
I
SW
is the current sunk by a switching I/O to charge/discharge the capacitive load
V
DDx
is the MCU supply voltage
f
SW
is the I/O switching frequency
C
L
is the total capacitance seen by the I/O pin: C = C
INT
+ C
EXT
Table 37. Typical and maximum current consumption in VBAT mode
Symbol Parameter
Conditions Typ Max (3 V)
(1)
Unit
Backup
SRAM
RTC &
LSE
1.2 V 2 V 3 V 3.4 V
T
J
=
25°C
T
J
=
85°C
T
J
=
105°C
T
J
=
125°C
IDD
(VBAT)
Supply
current in
standby
mode
OFF OFF 0.024 0.035 0.062 0.096 0.074 1.5 4.1 11
µA
ON OFF 1.4 1.6 1.8 1.8 3.2 19 42 74
OFF ON 0.225 0.23 0.25 0.31 - - - -
ON ON 1.95 2.15 2.2 2.35 - - - -
1. Guaranteed by characterization results.
I
SW
V
DDx
f
SW
C
L
××=
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