ST72521R9-Auto STMicroelectronics, ST72521R9-Auto Datasheet - Page 251

• Manufacturer Part Number: ST72521R9-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST72521R9-Auto

• Hdflash Endurance: 100 cycles, data retention 20 years
• Clock Sources: crystal/ceramic resonator oscillators, internal RC oscillator and bypass for external clock
• 4 Power Saving Modes: Halt, Active Halt, Wait and Slow

ST72521xx-Auto
20.12.2
General PCB design guidelines
To obtain best results, some general design and layout rules should be followed when
designing the application PCB to shield the noise-sensitive, analog physical interface from
noise-generating CMOS logic signals.
●
●
●
●
Figure 115. Power supply filtering
Use separate digital and analog planes. The analog ground plane should be connected
to the digital ground plane via a single point on the PCB.
Filter power to the analog power planes. It is recommended to connect capacitors, with
good high frequency characteristics, between the power and ground lines, placing
0.1µF and optionally, if needed 10pF capacitors as close as possible to the ST7 power
supply pins and a 1 to 10µF capacitor close to the power source (see
The analog and digital power supplies should be connected in a star network. Do not
use a resistor, as V
resistance would cause a voltage drop and a loss of accuracy.
Properly place components and route the signal traces on the PCB to shield the analog
inputs. Analog signals paths should run over the analog ground plane and be as short
as possible. Isolate analog signals from digital signals that may switch while the analog
inputs are being sampled by the A/D converter. Do not toggle digital outputs on the
same I/O port as the A/D input being converted.
POWER
SUPPLY
SOURCE
V
DD
AREF
1 to 10µF
is used as a reference voltage by the A/D converter and any
Doc ID 17660 Rev 1
+
ST7
DIGITAL NOISE
FILTERING
EXTERNAL
NOISE
FILTERING
0.1µF
0.1µF
V
V
V
V
SS
DD
AREF
SSA
Electrical characteristics
ST72XXX
Figure
115).
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