MIC2873 Datasheet, PDF (16/24 Pages) Micrel Semiconductor – 1.2A High-Brightness Flash LED Driver with Single-Wire Serial Interface

Micrel, Inc.
MIC2873
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
FDUR[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
Safety Timer Threshold Current Register
(ST_TH: default 4)
Safety timer threshold current determines the amount of
LED current flowing through the external LED before the
internal LED safety timer is activated. Setting ST_TH to 0
disables the safety timer function, and setting the register
to values 1 to 5 set the safety time threshold current
100mA to 300mA in 50mA steps.
Table 7. Safety Timer Threshold Current Register Setting
and Safety Timer Threshold Current
Value
Dec. Binary
ST_TH[2:0]
Safety Timer Threshold
Current (mA)
0
000
000
Disabled
1
001
001
100
2
010
010
150
3
011
011
200
4
100
100
250
5
101
101
300
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
flash functions are inhibited. 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]
VBAT 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
July 17, 2014
16
Revision 1.0