LTC3421

5

3421f

FB Voltage

Frequency Accuracy

Burst Mode Quiescent Current

Current Limit Accuracy

20

0

20

60

80

100

INTO BURST

OUT OF BURST

120

180

3421 G10

40

70

120

140

160

TEMPERATURE (

°C)

–45

1.20

1.21

1.22

1.23

1.24

–30 –15

0

15

3421 G11

30

45

60

75

90

TEMPERATURE (

°C)

–45

0.95

0.97

0.99

1.01

1.03

–30 –15

0

15

3421 G12

30

45

60

75

90

TEMPERATURE (

°C)

–45

0

5

10

15

20

–30 –15

0

15

3421 G13

30

45

60

75

90

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

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.

can source up to 100

µA and sink up to 8µA. This pin must

be decoupled with a 0.1

µF capacitor for stability.

PI FU CTIO S

low-battery comparator are disabled, which lowers the

quiescent current by 5

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

output and low-battery comparator becomes powered

from the output voltage and enabled.

TEMPERATURE (

°C)

–45

1.20

1.25

1.35

1.40

1.45

1.70

1.55

–15

15

30

90

3421 G14

1.30

1.60

1.65

1.50

–30

0

45

60

75

TEMPERATURE (

°C)

–45

0

0.02

0.06

0.08

0.10

0.20

0.14

–15

15

30

90

3421 G15

0.04

0.16

0.18

0.12

–30

0

45

60

75

PMOS

NMOS