Datasheet
Sliders
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3.1 Address and Data Pulldown Menus
The top 2 pull-down menus show the chip address (0x53) and select the internal register addresses. The
Data field to the right of the Address pull-down menu is for the hexadecimal register data. The two buttons
directly below the Address pull-down menu allow for the Writing or Reading of data from the specified
register in the Address pull-down menu.
3.1.1 Flash, Torch, Voltage Mode, and Indicator Enable Buttons
Strobe L/E Button:—This sets the STR bit (bit 7) in the Flash Brightness Register to a '1' (pushed in) or
a '0' not pushed.
ENVM Button:—This programs the VM bit (bit 2) of the Flash Brightness Register and the Torch
Brightness Register with a ‘1’ (button pushed) or a ‘0’ button not pushed. The resulting code in the
Flash Brightness Register and the Torch Brightness Register is shown in the field to the right.
EN1 Button:—This programs the EN1 bit (bit 1) of the Flash Brightness Register and the Torch
Brightness Register with a ‘1’ (button pushed) or a ‘0’ button not pushed. The resulting code in the
Flash Brightness Register and the Torch Brightness Register is shown in the field to the right.
EN0 Button:—This programs the EN0 (bit 0) of the Flash Brightness Register and the Torch Brightness
Register with a ‘1’ (button pushed) or a ‘0’ button not pushed. The resulting code in the Flash
Brightness Register and the Torch Brightness Register is shown in the field to the right.
Flash Button:—This causes a Flash event. This is the same as pushing EN1 and EN0 button.
Torch Button:—This places the LM3554 in torch mode. This is the same as pushing the EN1 button with
the EN0 button not pushed.
Indicator Button:—This turns on the indicator current source. This is the same as pushing the EN0
button with the EN1 button not pushed.
OFF Button:—This turns off the ENVM, EN1, and EN0 buttons and programs bits [2:0] of the Flash
Brightness Register and the Torch Brightness Register with 0.
4 Sliders
4.1 Torch Slider
This slider bar selects the Torch Current Level and writes the corresponding Torch Current setting shown
in Table 1 to the Torch Current Select Bits (bits [5:3] of the Torch Brightness Register). The field to the
right of the Torch slider is updated with the current Hexadecimal equivalent of the Torch Current Select
bits.
Table 1. Torch Current Levels
Torch Current Setting I
LED1
or I
LED2
(mA) I
LED1
+I
LED2
(mA)
0 18.75 37.5
1 37.5 75
2 56.25 (Default) 112.5 (Default)
3 75 150
4 93.75 187.5
5 112.5 225
6 131.25 262.5
7 150 300
4
AN-1742 LM3554 Evaluation Board SNVA646B–January 2009–Revised July 2013
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