Datasheet

DS9773 Rev 4 13/93
STM32F030x4/x6/x8/xC Functional overview
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3.4 Cyclic redundancy check calculation unit (CRC)
The CRC (cyclic redundancy check) calculation unit is used to get a CRC code using a
configurable generator polynomial value and size.
Among other applications, CRC-based techniques are used to verify data transmission or
storage integrity. In the scope of the EN/IEC 60335-1 standard, they offer a means of
verifying the Flash memory integrity. The CRC calculation unit helps compute a signature of
the software during runtime, to be compared with a reference signature generated at link-
time and stored at a given memory location.
3.5 Power management
3.5.1 Power supply schemes
• V
DD
= 2.4 to 3.6 V: external power supply for I/Os and the internal regulator. Provided
externally through VDD pins.
• V
DDA
= from V
DD
to 3.6 V: external analog power supply for ADC, Reset blocks, RCs
and PLL. The V
DDA
voltage level must be always greater or equal to the V
DD
voltage
level and must be provided first.
For more details on how to connect power pins, refer to Figure 13: Power supply scheme.
3.5.2 Power supply supervisors
The device has integrated power-on reset (POR) and power-down reset (PDR) circuits.
They are always active, and ensure proper operation above a threshold of 2 V. The device
remains in reset mode when the monitored supply voltage is below a specified threshold,
V
POR/PDR
, without the need for an external reset circuit.
• The POR monitors only the V
DD
supply voltage. During the startup phase it is required
that V
DDA
should arrive first and be greater than or equal to V
DD
.
• The PDR monitors both the V
DD
and V
DDA
supply voltages, however the V
DDA
power
supply supervisor can be disabled (by programming a dedicated Option bit) to reduce
the power consumption if the application design ensures that V
DDA
is higher than or
equal to V
DD
.
3.5.3 Voltage regulator
The regulator has two operating modes and it is always enabled after reset.
• Main (MR) is used in normal operating mode (Run).
• Low power (LPR) can be used in Stop mode where the power demand is reduced.
In Standby mode, it is put in power down mode. In this mode, the regulator output is in high
impedance and the kernel circuitry is powered down, inducing zero consumption (but the
contents of the registers and SRAM are lost).