ATmega406 Atmel Corporation, ATmega406 Datasheet - Page 114

• 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

19. Voltage Regulator
19.1
19.2
114
Features
Operation
ATmega406
•
•
•
ATmega406 is supplied by the VFET terminal. Operating voltage range at the VFET terminal is
4.0 - 25V. The Internal Voltage Regulator regulates this voltage down to 3.3V, which is a suitable
supply voltage for the internal logic, I/O lines, and analog circuitry.
An external decoupling capacitor of 1 µF or larger is required for stable operation of the Voltage
Regulator. A larger capacitor will allow larger load currents and increase start-up time.
The block diagram of the Voltage Regulator is shown in
Figure 19-1. Voltage Regulator Block Diagram
The Regulator will operate in all sleep modes, including Power-off. In this mode the regulator will
automatically reduce the ATmega406's power consumption by turning off supply for all periph-
eral modules, allowing only the Charger Detect module and the Voltage Regulator itself to
operate.
The Regulator will automatically ensure that it has stable work conditions before allowing itself to
start regulating the VFET terminal. If the voltage at the VFET pin is below the Regulator-on
Threshold voltage, V
Powering-up the regulator is either done from the battery side when the smart battery controller
is assembled with the battery pack and there is no charger present, or from the charger side
when a deep discharge has occurred (0V charging).
When powering- up with a charger present, the voltage between the VFET and the PVT pin must
be above a Charge-Threshold voltage, V
Linear Regulation.
Operating Voltage Range 4.0 - 25V.
Fixed Output Voltage at 3.3V.
Rsense
RN
RP
PVT
PV1
ROT
, the LDO will be switched off.
Regulator
Control
CHT
POWER_OFF
LDO_ON
.
Voltage Regulator
Supply
Digital
Figure
Distributor
Regulator
Power
LDO
VFET
19-1.
Analog
Supply
VREG
2548E–AVR–07/06
Creg > 1 uF