MIC2874 Datasheet, PDF (15/22 Pages) Micrel Semiconductor – 1.2A High-Brightness Flash LED Driver with Single-Wire Serial Interface

Micrel, Inc.
Table 4. Torch Current Register Mapping into Internal TEN
and TCUR Registers, and Relationship between Torch
Current and the TCUR Register Setting
Dec.
TEN/TCUR[4:0] Value
Binary TEN[4] TCUR[3:0]
I_TORCH (mA)
0
00000
0
0000
300.0
1
00001
0
0001
287.5
2
00010
0
0010
275.0
3
00011
0
0011
262.5
4
00100
0
0100
250.0
5
00101
0
0101
237.5
6
00110
0
0110
225.0
7
00111
0
0111
212.5
8
01000
0
1000
200.0
9
01001
0
1001
187.5
10 01010
0
1010
175.0
11 01011
0
1011
162.5
12 01100
0
1100
150.0
13 01101
0
1101
137.5
14 01110
0
1110
100.0
15 01111
0
1111
62.5
16 10000
1
0000
300.0
17 10001
1
0001
287.5
18 10010
1
0010
275.0
19 10011
1
0011
262.5
20 10100
1
0100
250.0
21 10101
1
0101
237.5
22 10110
1
0110
225.0
23 10111
1
0111
212.5
24 11000
1
1000
200.0
25 11001
1
1001
187.5
26 11010
1
1010
175.0
27 11011
1
1011
162.5
28 11100
1
1100
150.0
29 11101
1
1101
137.5
30 11110
1
1110
100.0
31 11111
1
1111
62.5
MIC2874
Safety Timer Duration Register (STDUR: default 7)
The safety timer duration register sets the duration of the
flash and torch mode when the LED current exceeds the
programmed threshold current. Valid values are 0 for the
minimum timer duration to 7 for the maximum duration.
Table 5. Safety Timer Duration Register Setting and Safety
Timer Duration
Value
Dec. Binary
STDUR[2:0]
(binary)
Timeout (ms)
0
000
000
156.25
1
001
001
312.5
2
010
010
468.75
3
011
011
625
4
100
100
781.25
5
101
101
937.5
6
110
110
1093.75
7
111
111
1250
Low-Battery Threshold Register (LB_TH: default 1)
The LB_TH register sets the supply threshold voltage
below which the internal low battery flag is asserted and
the LED current driver is disabled. Table 6 shows the
threshold values that correspond to the register settings.
Setting 0 is reserved for disabling the function, and
settings between 1 and 9 inclusively enable and set the
LB_TH value between 3.0V and 3.8V with 100mV
resolution.
Table 6. Low-Battery Threshold Register Setting and Supply
Threshold Voltage
Value
Dec. Binary
LB_TH[3:0]
V_BAT Threshold (V)
0
0000
0000
Disabled
1
0001
0001
3.0
2
0010
0010
3.1
3
0011
0011
3.2
4
0100
0100
3.3
5
0101
0101
3.4
6
0110
0110
3.5
7
0111
0111
3.6
8
1000
1000
3.7
9
1001
1001
3.8
August 26, 2014
15
Revision 1.0