LM3556

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SNVS796C – AUGUST 2011 – REVISED APRIL 2013

REGISTER DESCRIPTIONS

Register Name

Internal Hex Address

Power On/RESET Value

Silicon Revision and Filter Time Register

0x00

0x04

IVFM Mode Register

0x01

0x80

NTC Settings Register

0x02

0x12

Indicator Ramp Time Register

0x03

0x00

Indicator Blinking Register

0x04

0x00

Indicator Period Count Register

0x05

0x00

Torch Ramp Time Register

0x06

0x00

Configuration Register

0x07

0x78

Flash Features Register

0x08

0xD2

Current Control Register

0x09

0x0F

Enable Register

0x0A

0x00

Flags Register

0x0B

0x00

Silicon Revision and Filter Time Register (0x00)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

RFU

RFU

RFU

IVFM Filter Times

Bits available for Silicon Revision

'00' = 1/2 of the Current Step Time

Current Value = '100'

'01' = 256 µs

'10' =512 µs

'11' = 1024 µs

Input Voltage Flash Monitor (IVFM) Mode Register (0x01)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

1 = UVLO EN

Hysteresis Level

IVM-D (Down) Threshold

IVFM Adjust Mode

(default)

00 = 50 mV (default)

000 = 2.9V (default)

00 = Report Mode (default)

01 = 100 mV

001 = 3.0V

01 = Stop and Hold Mode

10 = 150 mV

010 = 3.1V

10 = Down Mode

11 = Hysteresis Disabled

011 = 3.2V

11 = Up and Down Mode

100 = 3.3V

101 = 3.4V

110 = 3.5V

111 = 3.6V

00 = Report Mode Sets IVFM Flag in Flags Register upon crossing IVM-D Line Only. Does not adjust current.

Line. Sets IVFM Flag in Flags Register upon crossing IVM-D Line.

the IVM-D line + the IVFM hystersis setting. The LM3556 will decrease the current throughout the flash

pulse anytime the input voltage falls below the IVM-D line, and not just once. The flash current will not

increase again until the next flash. Sets IVFM Flag in Flags Register upon crossing IVM-D Line.

above the IVM-D line + the IVFM hystersis setting. In this mode, the current will continually adjust with the

rising and falling of the input voltage throughout the entire flash pulse. Sets IVFM Flag in Flags Register

upon crossing IVM-D Line.

UVLO EN If enabled and VIN drops below 2.8V, the LM3556 will enter standby and set the UVLO flag in the

Flags Register. Enabled = ‘1’, Disabled = ‘0’

IVM-U = IVM-D + IVFM Hysteresis

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