5

LM3554

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SNVS549C – JUNE 2009 – REVISED FEBRUARY 2016

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Copyright © 2009–2016, Texas Instruments Incorporated

(1)

All voltages are with respect to the potential at the GND pin.

(2)

Minimum (MIN) and maximum (MAX) limits are ensured by design, test, or statistical analysis. Typical (TYP) numbers are not ensured,

(3)

The typical curve for overvoltage protection (OVP) is measured in closed loop using the Typical Application Circuit. The OVP value is

Characteristics is found in an open-loop configuration by ramping the voltage at OUT until the OVP comparator trips. The closed loop

data can appear higher due to the stored energy in the inductor being dumped into the output capacitor after the OVP comparator trips.

At worst case is an open circuit condition where the output voltage can continue to rise after the OVP comparator trips by approximately

(4)

inductor current stops increasing. The value given in Electrical Characteristics 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

6.5 Electrical Characteristics

ambient temperature range (–30°C

(1) (2)

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

CURRENT SOURCE SPECIFICATIONS

Current source

accuracy

600-mA flash LED setting,

1128

1200

1284

mA

541

600

657

17-mA torch current setting

30.4

33.8

37.2

Current source

regulation voltage

300

mV

LED Current

Matching

0.35%

STEP-UP DC-DC CONVERTER

Output voltage

accuracy

2.7 V

4.8

5

5.2

V

Output overvoltage

protection trip

On threshold, 2.7 V

5.4

5.6

5.7

V

Off threshold

5.3

PMOS switch on-

resistance

150

m

Ω

NMOS switch on-

resistance

150

m

Ω

Switch current

CL bits = 00

0.711

1.05

1.373

A

CL bits = 01

1.295

1.51

1.8

CL bits = 10

1.783

1.99

2.263

CL bits = 11

2.243

2.45

2.828

Output short-circuit

current limit

550

mA

Indicator current

LEDI/NTC bit = 0

IND1, IND0 bits = 00

2.3

mA

IND1, IND0 bits = 01

4.6

IND1, IND0 bits = 10

6.9

IND1, IND0 bits = 11

8.2

Comparator trip

threshold

LEDI/NTC bit = 1, 2.7 V

0.947

1.052

1.157

V

Switching frequency

2.7 V

1.75

2

2.23

MHz

Quiescent supply

current

Device not switching

630

µA

Shutdown supply

current

2.7 V

3.5

6.6

µA

Flash-to-torch LED

current settling time

20

µs