LM3554TMXSLASHNOPB datasheet(26/47 Pages) TI1

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Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

TX1/

TORCH

Bit 7

Bit 6

MSB

LSB

Configuration Register 1

TX2

Polarity

ENVM/TX2

HYST

Ext Flash

Inhibit

Disable

LEDI/NTC

LM3554

SNVS549C – JUNE 2009 – REVISED FEBRUARY 2016

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Table 5. Flags Register Bit Settings

Bit 7 (VIN

Monitor Fault

Fault)

Bit 6 (Unused)

Bit 5 (LED

Thermal

Fault)

Bit 4 (TX2

Interrupt)

Bit 3 (TX1

Interrupt )

Bit 2 (Led

Fault)

Bit 1 (Thermal

Shutdown)

Bit 0 (Flash

Timeout)

0 = No Fault at

VIN (default)

Not Used

(Reads Back 1

)

0 = LEDI/NTC

pin is above

VTRIP (default)

0 = ENVM/TX2

has not

changed state

(default)

0 = TX1/TORCH

has not changed

state (default)

0 = Proper

LED Operation

(default)

0 = Die

Temperature

below Thermal

Shutdown Limit

(default)

0 = Flash

TimeOut did not

expire (default)

1 = Input

Voltage

Monitor is

enabled and

VIN has fallen

below the

programmed

threshold

1 = LEDI/NTC

has fallen

below

VTRIP(NTC

mode only)

1 = ENVM/TX2

has changed

state (TX2

mode only)

1 = TX1/TORCH

pin has changed

state (TX1 mode

only)

1 = LED Failed

(Open or Short

1 = Die

Temperature

has crossed

the Thermal

Shutdown

Threshold

1 = Flash

TimeOut

Expired

7.6.1.5 Configuration Register 1

Configuration Register 1 holds the light load disable bit, the voltage mode select bit (OV), the external flash

inhibit bit, the control bit for the LEDI/NTC pin, the control bit for ENVM to TX2 mode, the polarity selection bit for

the TX2 input, and the control bit for the TX1/TORCH bit (see and Table 6).

Configuration Register 1 Description

Table 6. Configuration Register 1 Bit Settings

Bit 7

(Hardware

Torch Mode

Enable)

Bit 6 (TX2

Polarity)

Bit 5

(ENVM/TX2)

Bit 4 (N/A)

Bit 3

(LEDI/NTC)

Bit 2 (External

Flash Inhibit)

Bit 1 (OV,

Output

Voltage

Select)

Bit 0

(Disable Light

Load )

0 =

TX1/TORCH is

a TX1 flash

interrupt input

(default)

0 = ENVM/TX2

pin is an active

low Flash

inhibit

0 = ENVM

Mode The

ENVM/TX2 pin

is a logic input

to enable

Voltage Mode.

A high on

ENVM/TX2

forces voltage-

output mode

(default)

Reads Back '0'

0 = LEDI/NTC

pin in Indicator

mode (default)

0 = STROBE

Input Enabled

(default)

0 = Voltage

Mode output

voltage is 4.5 V

0 = Light load

comparator is

enabled. The

LM3554 goes

into PFM mode

at light load

(default).

1 =

TX1/TORCH

pin is a

hardware

TORCH enable

1 = ENVM/TX2

pin is an active

high Flash

inhibit (default)

1 = TX2 Mode

The ENVM/TX2

is a Power

Amplifier

Synchronization

input. A high on

ENVM/TX2

forces the

LM3554 from

flash to torch

mode.

1 = LEDI/NTC

pin in Thermal

Comparator

Mode. Indicator

current is

disabled.

1 = STROBE

Input Disabled

1 = Voltage

Mode output

voltage is 5 V

(default)

1 = Light load

comparator is

disabled. The

LM3554 does

not go into PFM

mode at light

load.

LM3554TMX/NOPB Datasheet(PDF) 26 Page - Texas Instruments

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