Datasheet

Functional overview STM8L15xx8, STM8L15xR6
16/134 DocID17943 Rev 6
3.3 Reset and supply management
3.3.1 Power supply scheme
The device requires a 1.65 V to 3.6 V operating supply voltage (V
DD
). The external power
supply pins must be connected as follows:
• V
SS1
, V
DD1
, V
SS2
, V
DD2
, V
SS3
, V
DD3
, V
SS4
, V
DD4
= 1.65 to 3.6 V: external power supply
for I/Os and for the internal regulator. Provided externally through V
DD
pins, the
corresponding ground pin is V
SS
. V
SS1
/V
SS2
/V
SS3
/V
SS4
and V
DD1
/V
DD2
/V
DD3
/V
DD4
must not be left unconnected.
• V
SSA
, V
DDA
= 1.65 to 3.6 V: external power supplies for analog peripherals (minimum
voltage to be applied to V
DDA
is 1.8 V when the ADC1 is used). V
DDA
and V
SSA
must
be connected to V
DD
and V
SS
, respectively.
• V
REF+
, V
REF-
(for ADC1): external reference voltage for ADC1. Must be provided
externally through V
REF+
and V
REF-
pin.
• V
REF+
(for DAC1/2): external voltage reference for DAC1 and DAC2 must be provided
externally through V
REF+
.
3.3.2 Power supply supervisor
The device has an integrated ZEROPOWER power-on reset (POR)/power-down reset
(PDR). For the device sales types without the “D” option (see Section 11: Ordering
information scheme), it is coupled with a brownout reset (BOR) circuitry. It that case the
device operates between 1.8 and 3.6 V, BOR is always active and ensures proper operation
starting from 1.8 V. After the 1.8 V BOR threshold is reached, the option byte loading
process starts, either to confirm or modify default thresholds, or to disable BOR permanently
(in which case, the V
DD
min. value at power-down is 1.65 V).
Five BOR thresholds are available through option bytes, starting from 1.8 V to 3 V. To
reduce the power consumption in Halt mode, it is possible to automatically switch off the
internal reference voltage (and consequently the BOR) in Halt mode. The device remains in
reset state when V
DD
is below a specified threshold, V
POR/PDR
or V
BOR
, without the need for
any external reset circuit.
Note: For device sales types with the “D” option (see Section 11: Ordering information scheme)
BOR is permanently disabled and the device operates between 1.65 and 3.6 V. In this case
it is not possible to enable BOR through the option bytes.
The device features an embedded programmable voltage detector (PVD) that monitors the
V
DD
/V
DDA
power supply and compares it to the V
PVD
threshold. This PVD offers 7 different
levels between 1.85 V and 3.05 V, chosen by software, with a step around 200 mV. An
interrupt can be generated when V
DD
/V
DDA
drops below the V
PVD
threshold and/or when
V
DD
/V
DDA
is higher than the V
PVD
threshold. The interrupt service routine can then generate
a warning message and/or put the MCU into a safe state. The PVD is enabled by software.