LM3554

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SNVS549A – JUNE 2009 – REVISED APRIL 2011

Electrical Characteristics (continued)

range (-30°C

(1) (2)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

CL bits = 00

0.711

1.05

1.373

CL bits = 01

1.295

1.51

1.8

Switch Current

A

CL bits = 10

1.783

1.99

2.263

CL bits = 11

2.243

2.45

2.828

Output Short

Circuit Current

550

mA

Limit

IND1, IND0 bits

2.3

= 00

IND1, IND0 bits

4.6

= 01

Indicator

LEDI/NTC bit =

mA

Current

0

IND1, IND0 bits

6.9

= 10

IND1, IND0 bits

8.2

= 11

Comparator

LEDI/NTC bit = 1, 2.7V

0.947

1.052

1.157

V

Trip Threshold

5.5V

Switching

2.7V

1.75

2

2.23

MHz

Frequency

Quiescent

Device Not Switching

630

µA

Supply Current

Shutdown

2.7V

3.5

6.6

µA

Supply Current

Flash-to-Torch

LED Current

20

µs

1.2A to 180mA

Settling Time

VIN Monitor

2.95

3.09

3.23

V

Trip Threshold

3.1V)

TX1/TORCH/GPIO1, STROBE, HWEN, ENVM/TX2/GPIO2 Voltage Specifications

Input Logic Low 2.7V

0

0.4

V

Input Logic

2.7V

1.2

V

High

Output Logic

400

mV

Low

Internal Pull-

down

300

k

Ω

Resistance at

TX1/TORCH

Internal Pull-

Down

300

k

Ω

Resistance at

STROBE

Input Logic Low 2.7V

0

0.4

V

Input Logic

2.7V

1.22

V

High

Output Logic

400

mV

Low (SCL)

(4)

inductor current stops increasing. The value given in the Electrical Table is measured open loop and is found by forcing current into SW

until the current limit comparator threshold is reached. Closed loop data appears higher due to the delay between the comparator trip

point and the NFET turning off. This delay allows the closed loop inductor current to ramp higher after the trip point by approximately

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