ATmega16HVB Atmel Corporation, ATmega16HVB Datasheet - Page 123

• Manufacturer Part Number: ATmega16HVB
• Manufacturer: Atmel Corporation

Specifications of ATmega16HVB

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 17
• Ext Interrupts: 15
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 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: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

21.4
21.5
8042D–AVR–10/11
Bandgap calibration
Bandgap buffer settling time
By default the Bandgap Buffer will be enabled as the buffered reference voltage is used as refer-
ence for the Battery Protection, the internal Cell Balancing, the V-ADC and the CC-ADC. If any
of these modules are enabled the Bandgap Buffer must be enabled, otherwise it is recom-
mended to disable the buffer by writing to the BGD bit in BGCSR to save power. Note that the
Bandgap Buffer needs settling time before the voltage is stable. For details on settling time, see
“Bandgap buffer settling time”
To ensure that the battery protection has safe operation condition, the Voltage Reference
includes a Short-circuit Detector. The Bandgap Short Detector continuously monitors the internal
1.100V reference voltage against the VREF pin voltage to detect potentially external short condi-
tions to VCC or GND. If an external short condition is detected, the Bandgap Short Circuit
Detection is capable of interrupting and waking up the CPU from any sleep mode. If a Bandgap
Short-circuit condition occurs software should immediately disable the C-FET and D-FET. If no
external protection is provided to detect such a condition it is recommended to always enable
this feature, by setting the BGSCDE bit in the Bandgap Control and Status Register.
The Temperature Sensor generates a voltage Proportional-To-Absolute-Temperature, VPTAT.
This voltage is connected to the multiplexer at the V-ADC input and it can be used for runtime
compensation of temperature drift in both the voltage reference and the On-chip Oscillator. To
get the absolute temperature in degrees Kelvin, the measured VPTAT voltage must be scaled
with the VPTAT factory calibration value stored in the signature row. See
row from software” on page 195
details on temperature accuracy.
To guarantee ultra low temperature drift the Voltage Reference includes two calibration registers
that should be initialized by software after reset. See
details. Changing values to the BGCCR IO register will change the nominal value of the Band-
gap Reference Voltage, while changing values to the BGCRR IO register trims the temperature
gradient of the bandgap reference.
When the calibration registers are changed it will affect both the Voltage Regulator output and
BOD-level. The BOD will react quickly to new detection levels, while the regulator will adjust the
voltage more slowly, depending on the size of the external decoupling capacitor. To avoid that a
BOD-reset is issued when calibration is done, it is recommended to change the values of the
BGCC and BGCR bits stepwise, with a step size of one, and with a hold-off time between each
step. See
Changing VREF will influence the conversion results for the V-ADC and CC-ADC. It is therefore
not recommended to do V-ADC and CC-ADC conversions while calibrating the bandgap.
After the Voltage Reference have been enabled it needs a settling time before the voltage is sta-
ble. The settling time depends on the size of the external decoupling capacitor. With 1µF
external capacitor a minimum settling time of 2ms should be used. Until settling is done it is not
recommended to enable the NFET driver (OC/OD or enter DUVR operation), Battery Protection,
V-ADC or CC-ADC.
Settling time is needed when the Buffer is enabled by software, or after a reset condition.
”Electrical characteristics” on page 225
.
for details. See
for details on hold-off time.
”Electrical characteristics” on page 225
ATmega16HVB/32HVB
”Register description” on page 124
”Reading the signature
123
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