AT90PWM3B Atmel Corporation, AT90PWM3B Datasheet - Page 140

• Manufacturer Part Number: AT90PWM3B
• Manufacturer: Atmel Corporation

Specifications of AT90PWM3B

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 27
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 125
• Analog Comparators: 3
• Resistive Touch Screen: No
• Dac Channels: 1
• Dac Resolution (bits): 10
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 105
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 5
• Output Compare Channels: 16
• Input Capture Channels: 1
• Pwm Channels: 12
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

140
AT90PWM2/3/2B/3B
fractional divider number. The resulting output frequency is the average of the frequencies in the
frame. The fractional divider (d) is given by OCRnRB[15:12].
The PSC output period is directly equal to the PSCOUTn0 On Time + Dead Time (OT0+DT0)
and PSCOUTn1 On Time + DeadTime (OT1+DT1) values. These values are 12 bits numbers.
The frequency adjustment can only be done in steps like the dedicated counters. The step width
is defined as the frequency difference between two neighboring PSC frequencies:
with k is the number of CLK
with f
Exemple, in normal mode, with maximum operating frequency 160 kHz and f
equals 400. The resulting resolution is Delta F equals 64MHz / 400 / 401 = 400 Hz.
In enhanced mode, the output frequency is the average of the frame formed by the 16 consecu-
tive cycles.
f
Then the frequency resolution is divided by 16. In the example above, the resolution equals 25
Hz.
b1
and f
OP
b2
is the output operating frequency.
are two neightboring base frequencies.
Δf
PSC
=
f
period in a PSC cycle and is given by the following formula:
AVERAGE
f1 f2
f
AVERAGE
–
=
=
=
f
--------- -
16 d
-------------- -
PLL
k
n
16 d
-------------- -
16
–
16
=
–
–
f
----------
----------- -
k
×
f
f
PSC
PLL
OP
+
×
f
--------- -
PLL
1
n
f
b1
=
+
+
----- -
16
f
----- -
16
d
PSC
d
×
×
×
----------- -
n
f
f
b2
PLL
------------------- -
k k
+
(
1
1
+
1
)
PLL
4317J–AVR–08/10
= 64 Mhz, k