ATmega406 Atmel Corporation, ATmega406 Datasheet - Page 24

• Manufacturer Part Number: ATmega406
• Manufacturer: Atmel Corporation

Specifications of ATmega406

• Flash (kbytes): 40 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 1 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 18
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -30 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Pwm Channels: 2
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

24
ATmega406
3. Voltage Reference Spike
Figure 8-6.
The Voltage Reference, VREF, will spike each time a temperature measurement is started
with the Voltage-ADC.
Problem Fix/Workaround
An accurate temperature measurement could be obtained by doing 10 temperature conver-
sions immediately after each other. The first 9 results would be inaccurate, but the 10th
conversion will be correct.
Figure 9-6
versions in a row (external decoupling capacitor of 1μF).
VADMUX3:0
If the CC-ADC is doing current accumulation while the V-ADC is doing temperature mea-
surement, both the Instantaneous and the Accumulated conversion results will be affected.
The spike on VREF will be visible on 1 Accumulated Current (CADAC3…0) and 2 Instanta-
neous Current (CADIC1…0) conversion results.
VADSC
1.1 V
Voltage
XXX
Voltage Reference Spike
illustrates the spike on the Voltage Reference when doing 10 temperature con-
V~50mV
(10 VTEMP conversion in a row)
VTEMP
t ~< 5ms
VREF
time
2548ES–AVR–07/06