MIC2874 Datasheet, PDF (14/22 Pages) Micrel Semiconductor – 1.2A High-Brightness Flash LED Driver with Single-Wire Serial Interface

Micrel, Inc.
MIC2874
MIC2874 Registers
The MIC2874 supports five writeable registers for
controlling the torch and the flash modes of operation as
shown in Table 2. Note that register addressing starts at 1.
Writing any value above the maximum value shown for
each registers will cause an invalid data error and the
frame will be discarded.
Table 2. Five Writable Registers of MIC2874
Address
Name
Max.
Value
Description
1
FEN/FCUR 31
Flash Enable/Current
2
TEN/TCUR 31
Torch Enable/Current
3
STDUR
7
Safety Timer Duration
4
LB_TH
9
Low Battery Voltage
Detection Threshold
5
ST_TH
5
Safety Timer Threshold
Flash Current Register (FEN/FCUR: default 4)
The flash current register enables and sets the flash mode
current level. Valid values are 0 to 31; values 0-15 will set
the flash current without enabling the flash (such that it can
be triggered externally), values 16-31 will set the flash
current and enable the flash. The flash current register
maps into the internal FEN and FCUR registers as shown
in the table below. Table 3 describes the relationship
between the flash current and the FCUR register setting.
Table 3. Flash Current Register Mapping into Internal FEN
and FCUR Registers, and Relationship between Flash
Current and the FCUR Register Setting
Dec.
FEN/FCUR[4:0] Value
Binary FEN[4] FCUR[3:0]
I_FLASH (A)
0
00000
0
0000
1.200
1
00001
0
0001
1.150
2
00010
0
0010
1.100
3
00011
0
0011
1.050
4
00100
0
0100
1.000
5
00101
0
0101
0.950
6
00110
0
0110
0.900
7
00111
0
0111
0.850
8
01000
0
1000
0.800
9
01001
0
1001
0.750
10
01010
0
1010
0.700
11
01011
0
1011
0.650
12
01100
0
1100
0.600
13
01101
0
1101
0.550
14
01110
0
1110
0.400
Dec.
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
FEN/FCUR[4:0] Value
Binary FEN[4] FCUR[3:0]
01111
0
1111
10000
1
0000
10001
1
0001
10010
1
0010
10011
1
0011
10100
1
0100
10101
1
0101
10110
1
0110
10111
1
0111
11000
1
1000
11001
1
1001
11010
1
1010
11011
1
1011
11100
1
1100
11101
1
1101
11110
1
1110
11111
1
1111
I_FLASH (A)
0.250
1.200
1.150
1.100
1.050
1.000
0.950
0.900
0.850
0.800
0.750
0.700
0.650
0.600
0.550
0.400
0.250
Torch Current Register (TEN/TCUR: default 4)
The torch current register enables and sets the torch mode
current level. Valid values are 0 to 31; values 0 − 15 will
set the torch current without enabling the torch (such that it
can be triggered by setting the internal TEN register value
to 1), values 16 − 31 will set the torch current and enable
the torch. A value of 0 at the internal TEN register will
disable the torch. The torch current register maps into the
internal TEN and TCUR registers as shown in Table 4.
The table also describes the relationship between the
torch current and the TCUR register setting.
August 26, 2014
14
Revision 1.0