ATtiny43U Atmel Corporation, ATtiny43U Datasheet - Page 42

• Manufacturer Part Number: ATtiny43U
• Manufacturer: Atmel Corporation

Specifications of ATtiny43U

• Flash (kbytes): 4 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 64
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 0.7 to 5.5
• Operating Voltage (vcc): 0.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8.4
8.5
8.5.1
42
Overload Behaviour
Software Control of Boost Converter
ATtiny43U
Stopping the Boost Converter
Figure 8-7.
See section
and off duty cycle control.
The use of Full Duty Cycle mode is recommended only at low load currents.
The output is considered overloaded when the load current, I
in
mum duty cycle and can no longer regulate V
voltage will drop as load current increases. If V
will switch to Start Mode.
In Start Mode the converter has a low load current capability, which means nearly all overload
current will be drained straight from the battery (or other power source) via the inductor and the
diode. The resistance of the inductor is typically very low and, provided the voltage of the power
source remains constant, the output voltage during overload will stabilise to battery voltage,
V
The boost converter is an independent hardware module that requires no interaction by the
microcontroller, although some features can be controlled by firmware. Features that can be
controlled by firmware are described in the following sections.
The device firmware can stop the boost converter on demand. When issued a stop signal, the
boost converter will exit Active Mode and enter Stop Mode, as illustrated in
37. This procedure allows the device to read true battery voltage using the on-board ADC,
assess if the voltage is sufficient for the selected battery chemistry and then control the boost
converter accordingly.
BAT
Table 20-7 on page
, minus the forward voltage drop, V
“Software Control of Boost Converter” on page 42
Typical Output Voltage of Boost Converter at Constant Full Duty Cycle.
V
CC
159. During an overload condition the boost converter operates at maxi-
F
, of the diode used.
CYCLE
CC
DUTY
CC
. If the overload condition prevails the output
drops below its minimum level the converter
LOAD
for instructions on how to turn on
FDC = ON
FDC = OFF
, exceeds the maximum given
Figure 8-3 on page
8048B–AVR–03/09