ATtiny43U Atmel Corporation, ATtiny43U Datasheet - Page 41

• 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

8.3.2
8.3.3
8048B–AVR–03/09
Active Low Current Mode
Full Duty Cycle
Figure 8-6.
The boost converter enters Active Low Current Mode from Active Regulated Mode when output
voltage reaches its maximum and duty cycle is at its minimum. In practice, this means that the
load current drops below a threshold. The threshold varies with converter input voltage and tem-
perature but a typical plot is shown in
From
and high load currents (I
Current Mode. Using Full Duty Cycle mode the boost converter can be forced to enter Active
Low Current Mode at input voltages lower than those shown in
“Full Duty Cycle” on page
In Low Current Mode the boost converter stops switching and reduces current consumption to a
minimum, while still remaining active. Provided there are no external loads active the boost con-
verter enters Low Current Mode automatically when the microcontroller goes into Power Down
Mode (see
In this mode of operation the converter periodically reaches its duty cycle low limit. When this
happens the converter stops switching and the output voltage starts dropping. The converter
starts switching again when the output voltage has decreased to the low limit of Active Low Cur-
rent Mode. This results in a periodical pattern as illustrated in
If the output voltage, V
verter goes back to Start Mode. In addition, the firmware can instruct the converter to leave this
mode and enter Stop Mode. See
By default, the boost converter keeps V
ing waveform. It is possible to bypass the duty cycle regulation and lock the duty cycle at its
maximum, resulting in a V
dropping when the boost converter enters Low Current Mode. See
Figure 21-1 on page 165
“Sleep Modes” on page
Typical Output Voltage of Boost Converter in Active Regulated Mode.
V
CC
CC
LOAD
, drops below V
41.
CC
voltage that quickly ramps up to the maximum limit and then starts
typically above 0.6mA) the boost converter will never enter Low
can be seen that at low input voltages (V
“Software Control of Boost Converter” on page
31).
Figure 21-1 on page
CC
BOOST
within limits by controlling the duty cycle of the switch-
(due to an overload or a short circuit) the con-
f
SW
ACTIVE REGULATED MODE
V
RPP
165.
Figure 8-5 on page
Figure 21-1 on page
Figure
BAT
t
8-7, below.
typically below 1.0V)
42.
39.
165. See
41