STCF04 datasheet(25/43 Pages) STMICROELECTRONICS

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STCF04

Description of the internal registers

Doc ID 022927 Rev 3

25/43

FTIM_0~4: these 5 bits define the maximum flash duration. It is intended to limit the energy

dissipated by the LED to a maximum safe value or to leave the control of the flash duration

to the STCF04 during normal operation. Values from 0~31 correspond to 0~410 ms

(according to

Table 13). 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 the TRIG_EN bit, and simultaneously, the ATN pin is set to true (LOW) to alert the

microprocessor that the maximum time has been reached. The FTIM value remains

unaltered at the end of the count.

9.3

AUX LED (AUX_REG) 02(hex)

AUXI_0~3: this 4-bit register defines the AUX LED current from 0 to 100 mA. See

Table 15

AUX LED dimming for reference. Loading any value between 1 and 11 also starts the AUX

LED current source timer, if enabled. The AUX LED current source is active only in Idle

mode, and is deactivated in any other mode.

AUXT_0~3: this 4-bit register controls the timer that defines the ON-time of the AUX LED

current source. ON-time starts when the AUXI register is loaded with any value other than

zero, and stops after the time defined in the AUXT register. Values from 0 to 14 of the AUXT

steps. The value 15 puts the AUX LED into the continuous light mode. The

activation/deactivation of the AUX LED current source is controlled using only the AUXI

Table 13.

Flash time dimming register settings

FTIM_DIM(hex)

23456789

Flash length[ms]

FTIM_DIM(hex)

12131415

16171819

Flash length[ms]

110 130 150

170

190

210

230

250

270

290

310

330

350

370

390

410

Table 14.

AUX LED register

AUX_REG

(Write mode)

MSB

LSB

SUB ADD = 02

AUXI_3

AUXI_2

AUXI_1

AUXI_0

AUXT_3

AUXT_2

AUXT_1

AUXT_0

Power-ON,

Shutdown mode

RESET value

000

Table 15.

Auxiliary LED dimming table

AUXI (hex)

123456

789

AUX LED current

[mA]

100

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