Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

IND1

Bit 7

Bit 6

MSB

LSB

Torch Brightness Register

Register Address 0xA0

IND0

TC2

TC1

TC0

VM

EN1

EN0

R/W

Bit 0

1

Bit 1

1

Bit 2

0

Bit 3

0

Bit 4

1

Bit 5

1

Bit 7

0

Bit 6

MSB

LSB

I

2

C Slave Address (chip address)

23

LM3554

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SNVS549C – JUNE 2009 – REVISED FEBRUARY 2016

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Programming (continued)

Figure 40. Device Address

7.5.1.3 Transferring Data

Every byte on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each byte

of data must be followed by an acknowledge bit (ACK). The acknowledge related clock pulse (9th clock pulse) is

generated by the master. The master releases SDA (HIGH) during the 9th clock pulse (write mode). The LM3554

pulls down SDA during the 9th clock pulse, signifying an acknowledge. An acknowledge is generated after each

byte has been received.

7.6 Register Maps

7.6.1 Register Descriptions

Table 1. LM3554 Internal Registers

REGISTER NAME

INTERNAL HEX ADDRESS

POWER ON OR RESET VALUE

Torch Brightness

0xA0

0x50

Flash Brightness

0xB0

0x68

Flash Duration

0xC0

0x4F

Flag Register

0xD0

0x40

Configuration Register 1

0xE0

0x42

Configuration Register 2

0xF0

0xF0

GPIO Register

0x20

0x80

VIN Monitor Register

0x80

0xF0

7.6.1.1 Torch Brightness Register

Bits [2:0] of the Torch Brightness Register, or bits [2:0] of the Flash Brightness Register place the device in

shutdown or control the on/off state of Torch, Flash, the Indicator LED and the voltage-output mode (see

Table 2). Writing to Torch Brightness Register bits [2:0] automatically updates the Flash Brightness Register bits

[2:0]; writing to bits [2:0] of the Flash Brightness Register automatically updates bits [2:0] of the Torch Brightness

Register. Bits [5:3] set the current level in Torch mode (see Table 2). Bits [7:6] set the LED Indicator current level

(see Table 2).

Torch Brightness Register Description