STMicroelectronics STCF03, Руководство пользователя

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Description of internal registers STCF03
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8.5 FTIM_0~3
This 4bit 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 STCF03 the control of the
Flash duration during normal operation. Values from 0~15 correspond to 0~1.5s (100ms
steps). The timing accuracy is related to the internal oscillator frequency that clocks the
Flash Time Counter (+/-20%). 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.
8.6 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. (
Figure 12 )
8.7 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
FL
and R
TR
. ( Figure 12 )
Note: LED current values refer to R
FL
=0.27
Ω
, R
TR
=1.8
Ω
Table 11. Dimming register
DIM_REG
(write mode)
MSB LSB
SUB ADD=01 TDIM_3 TDIM_2 TDIM_1 TDIM_0 FDIM_3 FDIM_2 FDIM_1 FDIM_0
Power ON, SHUTDOWN
MODE
RESET Value
0 0 0 0 0 0 0 0
Figure 12. Flash and Torch current vs. dimming value
Current Step Coefficient - 1.19