st72324bk STMicroelectronics, st72324bk Datasheet - Page 144

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

Electrical characteristics
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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 87. 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
0.1 µF and optionally, if needed 10 pF capacitors as close as possible to the ST7 power
supply pins and a 1 to 10 µF 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 10 µF
is used as a reference voltage by the A/D converter and any
ST7
digital noise
filtering
External
noise
filtering
0.1 µF
0.1 µF
V
V
V
V
SS
DD
AREF
SSA
ST72XXX
ST72323 ST72323L
Figure
87).