
162
8048C–AVR–02/12
ATtiny43U
20.7
Boost Converter Characteristics
Note:
2. Minimum shutdown voltage is not guaranteed. At very low battery voltages the logic may cease to operate before issuing a
stop signal. Application firmware can use the ADC to monitor battery voltage at regular intervals and issue a firmware stop
when required.
Table 20-7.
Characteristics of Boost Converter. T = -20
°C to +85°C, unless otherwise noted
Symbol
Parameter
Min
Typ
Max
Unit
VBAT
Input Voltage
0.7
1.8
V
START
Start Voltage
1.0
1.2
1.35
V
VSTOP
Shutdown Voltage
0.5
0.8
V
VBOOST
1.0
V
VCC
Output Voltage
Active Mode, I
LOAD > 1mA
2.7
3.0
3.3
V
Low Current Mode
2.0
3.6
V
ILOAD
Load Current
VBAT = 0.7V
0
10
mA
V
BAT = 1.0V
0
30
mA
VRPP
Output Voltage Ripple
VBAT = 1.0V, ILOAD = 30 mA, CLOAD = 22 F
40
mV
tSTART
Start-up Time
VBAT = Step Change from 0V to 1.2V
2
ms
IIN
Current consumption of entire
device
V
BAT = 0.4V, Converter in Stop Mode
MCU not powered
1A
VBAT = 1.0V, Converter in Stop Mode
MCU not powered
2A
VBAT = 1.2V, Active Low Current Mode
MCU in Power Down, WD disabled
5A
V
BAT = 1.2V, Active Regulated Mode
MCU active, 4 MHz
5mA
f
SW
Switching frequency
75
100
125
kHz
T
SW
Switching period
T
S = 1 / fSW
8
10
13.3
s
DSW
Duty Cycle
370
%
VBATOL
Lowest V
BAT voltage where device
recovers from overload
Output overload or short circuit removed
0.9
V
Load Regulation:
T = 25
°C, V
BAT = 1.2V
Boost converter in Active Mode
2.7
%
Line Regulation:
T = 25
°C, I
LOAD = 1mA
Boost converter in Active Mode
1.0
%
Temperature Regulation:
VBAT = 1.2V, ILOAD = 1mA
Boost converter in Active Mode
2.3
%
V
CC
LOADMIN
V
CC
LOADMAX
–
V
CC
LOADMAX
-----------------------------------------------------------------------------
V
CC
VBATMAX
V
CC
VBATMIN
–
V
CC
VBATNOM
---------------------------------------------------------------------------
V
CC
TEMPMAX
V
CC
TEMPMIN
–
V
CC
TEMPNOM
-----------------------------------------------------------------------------