ATmega8HVA Atmel Corporation, ATmega8HVA Datasheet - Page 125

• Manufacturer Part Number: ATmega8HVA
• Manufacturer: Atmel Corporation

Specifications of ATmega8HVA

• Flash (kbytes): 8 Kbytes
• Pin Count: 28
• Max. Operating Frequency: 4 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 3
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 6
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 6
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 256
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -20 to 85
• I/o Supply Class: 1.8 to 9.0
• Operating Voltage (vcc): 1.8 to 9.0
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

23.3
23.4
23.5
23.6
8024A–AVR–04/08
Short-circuit Protection
Discharge Over-current Protection
Charge Over-current Protection
Discharge High-current Protection
The Current Battery Protection (CBP) monitors the cell current by sampling the shunt resistor
voltage at the PI/NI input pins. A differential operational amplifier amplifies the voltage with a
suitable gain. The output from the operational amplifier is compared to an accurate, programma-
ble On-chip voltage reference by an Analog Comparator. If the shunt resistor voltage is above
the Detection level for a time longer than the corresponding Protection Reaction Time, the chip
activates Current Protection. A sampled system clocked by the internal ULP Oscillator is used
for Short-circuit, Over-current, and High-current Protection. This ensures a reliable clock source,
offset cancellation and low power consumption.
The Short-circuit detection is provided to enable a fast response time to very large discharge
currents. If the voltage at the PI/NI pins is above the Short-circuit Detection Level for a period
longer than Short-circuit Reaction Time, the Short-circuit Protection is activated.
When the Short-circuit Protection is activated, the external D-FET and C-FET are disabled and a
Current Protection Timer is started. This timer ensures that the D-FET and C-FET are disabled
for at least one second. The application software must then set the DFE and CFE bits in the FET
Control and Status Register to re-enable normal operation. If the D-FET is re-enabled before the
cause of the short-circuit condition is removed, the Short-circuit Protection will be activated
again.
If the voltage at the PI/NI pins is above the Discharge Over-current Detection level for a time
longer than Over-current Protection Reaction Time, the chip activates Discharge Over-current
Protection.
When the Discharge Over-current Protection is activated, the external D-FET and C-FET are
disabled and a Current Protection Timer is started. This timer ensures that the FETs are dis-
abled for at least one second. The application software must then set the DFE and CFE bits in
the FET Control and Status Register to re-enable normal operation. If the D-FET is re-enabled
while the loading of the battery still is too large, the Discharge Over-current Protection will be
activated again.
If the voltage at the PI/NI pins is above the Charge Over-current Detection level for a time longer
than Over-current Protection Reaction Time, the chip activates Charge Over-current Protection.
When the Charge Over-current Protection is activated, the external D-FET and C-FET are dis-
abled and a Current Protection Timer is started. This timer ensures that the FETs are disabled
for at least one second. The application software must then set the DFE and CFE bits in the FET
Control and Status Register to re-enable normal operation. If the C-FET is re-enabled and the
charger continues to supply too high currents, the Charge Over-current Protection will be acti-
vated again.
If the voltage at the PI/NI pins is above the Discharge High-current Detection level for a time
longer than High-current Protection Reaction Time, the chip activates Discharge High-current
Protection.
ATmega8HVA/16HVA
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