LTC3421_15 Datasheet, PDF (5/16 Pages) Linear Technology – 3A, 3MHz Micropower Synchronous Boost Converter with Output Disconnect

LTC3421
TYPICAL PERFOR A CE CHARACTERISTICS (T_A = 25°C, unless otherwise specified)
Burst Mode Threshold vs R_BURST
180
160
140
120
100
80
60
OUT OF BURST
40
20
0
20
INTO BURST
70
R_BURST (kΩ)
120
3421 G10
Burst Mode Quiescent Current
20
15
10
5
0
–45 –30 –15 0 15 30 45 60 75 90
TEMPERATURE (°C)
3421 G13
FB Voltage
1.24
1.23
1.22
1.21
1.20
–45 –30 –15 0 15 30 45 60 75 90
TEMPERATURE (°C)
3421 G11
Current Limit Accuracy
1.70
R_LIM = 105k
1.65
1.60
1.55
1.50
1.45
1.40
1.35
1.30
1.25
1.20
–45 –30 –15 0 15 30 45 60 75 90
TEMPERATURE (°C)
3421 G14
Frequency Accuracy
1.03
1.01
0.99
0.97
0.95
–45 –30 –15 0 15 30 45 60 75 90
TEMPERATURE (°C)
3421 G12
R_DS(ON)
0.20
0.18
0.16
PMOS
0.14
0.12
NMOS
0.10
0.08
0.06
0.04
0.02
0
–45 –30 –15 0 15 30 45 60 75 90
TEMPERATURE (°C)
3421 G15
PI FU CTIO S
FB (Pin 1): Feedback Pin. Connect resistor divider tap
here. The output voltage can be adjusted from 2.4V to
5.25V. The feedback reference voltage is typically 1.220V.
SHDN (Pin 2): Shutdown Pin. Less than 0.25V on this pin
shuts down the IC. The IC is enabled when the SHDN
voltage is greater than 1V. Once V_OUT is above 2.2V,
hysteresis is applied to the pin (–500nA out of the pin)
allowing it to operate at a logic high while the battery can
drop to 0.5V.
V_REF (Pin 3): Buffered 1.22V Reference Output. This pin
can source up to 100µA and sink up to 8µA. This pin must
be decoupled with a 0.1µF capacitor for stability.
ENB (Pin 4): Reference Output (V_REF) and Low-Battery
Comparator Enable. When ENB = Low, the V_REF output and
low-battery comparator are disabled, which lowers the
quiescent current by 5µA. When ENB = High, the V_REF
output and the low-battery comparator are enabled. Dur-
ing shutdown, if the ENB = High and the output voltage is
pulled up to greater than 2.5V from a secondary source
such as a coin cell through a Schottky diode, the V_REF
output and low-battery comparator becomes powered
from the output voltage and enabled.
3421f
5