User's Manual

USER MANUAL 1.34

STM 300 / STM 300C / STM 300U

3.3.1 GPIO supply voltage

For digital communication with other circuitry (peripherals) the digital I/O configured pins

of the mixed signal sensor interface (ADIO0 to ADIO7) and the pins of the programming

interface (SCSEDIO0, SCLKDIO1, WSDADIO2, RSDADIO3) may be operated from supply

voltages different from DVDD. Therefore an interface supply voltage pin IOVDD is available

which can be connected either to DVDD or to an external supply within the tolerated volt-

age range of IOVDD. Please note that the wristwatch XTAL I/Os WXIDIO and WXODIO are

always supplied from UVDD.

If DVDD=0 V (e.g. in any sleep mode or if VDD<VOFF) and IOVDD is supplied,

there may be unpredictable and varying current from IOVDD caused by internal

floating nodes. It must be taken care that the current into IOVDD does not exceed

10 mA while DVDD=0 V.

If DVDD=0 V and IOVDD is not supplied, do not apply voltage to any above men-

tioned pin. This may lead to unpredictable malfunction of the device.

For I/O pins configured as analog pins the IOVDD voltage level is not relevant!

However it is important to connect IOVDD to a supply voltage as specified in 3.5.

IOVDD

ADIO0

ADIO1

ADIO2

ADIO3

ADIO4

ADIO5

ADIO6

ADIO7

SCSEDIO0

SCLKDIO1

WSDADIO2

RSDADIO3

If configured as digital I/O