Gpio Current Consumption; Voltage Output And Current Drive - ST STM32 Application Note

GPIO electrical characteristics and definitions
The maximum V
maximum voltage is the minimum value among V
augmented of 3.6 V with a maximum V
Note: There is no injected current while -0.3 V < V
The total injected current is limited, typically to 25 mA per device. Refer to the device
datasheet for the value of the exact limitation. This restricts the number of pins on which
current can be injected.
5.1.3

GPIO current consumption

There are two types of I/O pin current consumption in STM32 devices:
1. The static current consumption which is mainly due to pull-up resistors when I/O pin is
used as input and held low or when I/O pin is used as output with external pull-down or
external load.
2. The dynamic current consumption which is the current from the I/O supply voltage used
by the I/O pin circuitry and capacitive load when the I/O pin switches.
The dynamic current consumption is given by
Equation 1
–
–
–
–
Note: The GPIO speed has no impact on the dynamic current consumption.
5.1.4

Voltage output and current drive

All STM32 GPIOs are CMOS and TTL compliant and are able to source or sink current from
external pin.
sourced current when GPIO output is in High state. I
in Low state. The maximum output current which can be sunk or sourced by one GPIO or
from the power supplies is limited to preserve the GPIO from as well as that the sum of the
current sourced or sunk by all GPIO and cannot exceed the AMR values fixed inside the
product datasheet. Following the current drive limitations, the number of GPIO which can
drive current has to be limited consequently.
For more details, see the values of I
allowed into the AMR current characteristics table available in the datasheet.
14/31
voltage is equal to V
IN
I = C x V
SW L
I is the current sunk by a switching I/O to charge / discharge the capacitive load
SW
C is the total load capacitance seen by the I/O pin
L
C is the sum of internal, external, PCB, and package capacitances
L
V is the I/O supply voltage
DD
F is the I/O switching frequency
SW
Figure 3 shows the current flow according to the output level selected. I
+ 0.3 V for TT GPIO. For FT GPIO, the V
DD
, V
DD
value limited to 5.5 V.
IN
< V
IN INmax
Equation
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