AT90CAN32 Automotive Atmel Corporation, AT90CAN32 Automotive Datasheet - Page 364

• Manufacturer Part Number: AT90CAN32 Automotive
• Manufacturer: Atmel Corporation

Specifications of AT90CAN32 Automotive

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• Can: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 125
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

26. Decoupling Capacitors
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AT90CAN32/64/128
The operating frequency (i.e. system clock) of the processor determines in 95% of cases the
value needed for microcontroller decoupling capacitors.
The hypotheses used as first evaluation for decoupling capacitors are:
Figure 26-1. Capacitor description
According to the operating frequency of the product, the decoupling capacitances are chosen
considering the frequencies to filter,
The relation between frequencies to cut and decoupling characteristics are defined by:
where:
Then, in normalized value range, the decoupling capacitors become:
Table 26-1.
These decoupling capacitors must to be implemented as close as possible to each pair of power
supply pins:
Nevertheless, a bulk capacitor of 10-47 µF is also needed on the power distribution network of
the PCB, near the power source.
For further information, please refer to Application Notes AVR040 “EMC Design Considerations“
and AVR042 “Hardware Design Considerations“ on the Atmel web site.
• The operating frequency (
• An SMC capacitor connected to 2 micro-vias on a PCB has the following characteristics:
peaks are located at
– 1.5 nH from the connection of the capacitor to the PCB,
– 1.5 nH from the capacitor intrinsic inductance.
– L: the inductance equivalent to the global inductance on the Vcc/Gnd lines.
– C
– 21-22 and 52-53 for logic sub-system,
– 64-63 for analogical sub-system.
1
f
op
& C
, operating frequency
2
Decoupling Capacitors vs. Frequency
: decoupling capacitors (C
16 MHz
12 MHz
10 MHz
8 MHz
6 MHz
4 MHz
f
op
and 2 •
f
op
) supplies itself the maximum peak levels of noise. The main
f
op
f
op
f
op
=
.
and 2 •
0.75 nH
---------------------- -
2Π LC
1
1
= 4 • C
1
f
op
.
2
).
Capacitor
120 nF
220 nF
560 nF
33 nF
56 nF
82 nF
1.5 nH
C
and
1
2
•
0.75 nH
f
op
=
PCB
---------------------- -
2Π LC
1
120 nF
10 nF
15 nF
22 nF
33 nF
56 nF
7682C–AUTO–04/08
C
2
2