stcf03i STMicroelectronics, stcf03i Datasheet - Page 21

• Manufacturer Part Number: stcf03i
• Description: High Power White Led Driver With I2ctm Interface
• Manufacturer: STMicroelectronics

8.5
Table 11. Dimming register
8.6
8.7
Figure 12. Flash and Torch current vs. dimming value
Note:
21/33
SHUTDOWN MODE
SUB ADD=01
RESET Value
(write mode)
Power ON,
DIM_REG
FTIM_0~3
This 4-bits register defines the maximum Flash duration. It is intended to limit the energy
dissipated by the LED to a maximum safe value or to leave to the STCF03I the control of the
Flash duration during normal operation. Values from 0~15 correspond to 0~1.5 s (100 ms
steps). The timing accuracy is related to the internal oscillator frequency that clocks the
Flash Time Counter (+/-20%, TBD). Entering Flash mode (either by soft or hard triggering)
activates the Flash Time Counter, which begins counting down from the value loaded in the
F_TIM register. When the counter reaches zero, Flash mode is stopped by resetting
TRIG_EN bit, and simultaneously the ATN pin is set to true (LOW) to alert the µP that the
maximum time has been reached. FTIM value remains unaltered at the end of the count.
TDIM_0~3
These 4 bits define the LED current in Torch mode with 16 values fitting an exponential law.
Max Torch current value is 25% of max Flash current.
FDIM_0~3
These 4 bits define the LED current in Flash mode with 16 values fitting an exponential law.
The Max value of the current is set by the external resistors R
LED current values refer to R
TDIM_3
MSB
0
TDIM_2
0
FL
=0.27 Ω , R
TDIM_1
0
TDIM_0
TR
=1.8 Ω
0
Current Step Coefficient - 1.19
FDIM_3
(Figure
0
FL
12)
FDIM_2
and R
0
TR
FDIM_1
.
(Figure
0
12)
FDIM_0
LSB
0