STCF03ITBR Datasheet STCF03ITBR | P22-P24

Description of internal registers STCF03I

22/33

8.8 AUXI_0~3

This 4 bits register defines the AUX LED current from 0 to 20 mA. See AUX LED dimming

table for reference. Loading any value between 1 and 15 also starts the AUX LED current

source timer, if enabled. The AUX LED current source is active only in ready mode, and is

deactivated in any other mode.

8.9 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 1 to 14 of the AUXT register

correspond to an ON-time of the AUX LED ranging from 100 to 1400 ms in 100 ms steps.

The value 15 puts the AUX LED to the continuous light mode. The activation/deactivation of

the AUX LED current source is controlled using only the AUXI register.

Note: LED current values refer to R

=0.27 Ω, R

=1.8 Ω.

Table 12. Auxiliary 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

00 000 000

Table 13. Auxiliary LED dimming table

(1)

AUXI (hex) 0123456789ABCDEF

AUX LED

current [mA]

0.0 1.3 2.6 4.0 5.3 6.6 8.0 9.3 10.6 12.0 13.3 14.6 16.0 17.3 18.6 20.0

1. 20 mA output current is achievable only if the supply voltage is higher than 3.3 V.

Table 14. Torch mode and Flash mode dimming registers settings

T_DIM

(hex)

0 1 2 3 4 5 6 7 8 9 A B C D E F

F_DIM

(hex)

0 1 2 3 4 5 6 7 8 9 A B C D E F

LED

current

[mA]

16 19 23 27 32 39 46 55 65 77 92 109 124 147 175 209 248 296 352 418 498 592 705 840

Internal

step

123456789101112131415161718192021222324

REF1

[mV]

33 40 47 56 67 80 95 113 134 160 190 227 33 40 47 56 67 79 95 113 134 160 190 227

Sense

Resist.

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Description of internal registers STCF03I

23/33

8.10 F_RUN

This bit is kept HIGH by the STCF03I during flash mode. By checking this bit, the µP can

verify if the flash mode is running or has been terminated by the time counter.

8.11 LED_F

This bit is set by the STCF03I when the voltage seen on the LED pin is V

REF2

> 5.3 V during

a torch or flash operation. This condition can be caused by an open LED, indicating a LED

failure. The device automatically goes into Ready mode to avoid damage. Internal high

frequency filtering avoids false detections. This bit is reset by the STCF03I following a read

operation of the STAT_REG.

8.12 NTC_W

This bit is set HIGH by the STCF03I and the ATN pin is pulled down, when the voltage seen

on the pin Rx exceeds V

REF4

= 0.56 V. This threshold corresponds to a warning temperature

value at the LED measured by the NTC. The device is still operating, but a warning is sent to

the µP. This bit is reset by the STCF03I following a read operation of the STAT_REG.

8.13 NTC_H

This bit is set HIGH by the STCF03I and the ATN pin is pulled down, when the voltage seen

on the pin Rx exceeds V

REF5

. This threshold (1.2 V) corresponds to an excess temperature

value at the LED measured by the NTC. The device is put in ready mode to avoid damaging

the LED. This bit is reset by the STCF03I following a read operation of the STAT_REG.

8.14 OT_F

This bit is set HIGH by the STCF03I and the ATN pin is pulled down, when the chip over-

temperature protection (~140°C) has put the device in ready mode. This bit is reset by the

STCF03I following a read operation of the STAT_REG.

Table 15. Status register

STAT_REG

(read mode)

MSB LSB

SUB ADD=03 N/A F_RUN LED_F NTC_W NTC_H OT_F N/A VOUTOK_N

Power ON,

SHUTDOWN MODE

RESET Value

0000000 0

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Description of internal registers STCF03I

24/33

8.15 VOUTOK_N

This bit is set by the STCF03I. It is used to protect the device, if the output is shorted. The

VOUTOK_N bit is set to HIGH at the start-up. Then a current generator of 20 mA charges

the output capacitor for 360 µs typ. and it detects when the output capacitor reaches 100

mV. If this threshold is reached the bit is set to LOW. If the output is shorted to ground or the

LED is shorted, this threshold is never reached: the bit stays HIGH, ATN pin is pulled down

and the device will not start. This bit is reset following a read operation of the STAT_REG

Figure 14. VOUTOK_N behavior

Table 16. Status register details

Bit Name

F_RUN

(STAT_REG)

LED_F

(STAT_REG)

NTC_W

(STAT_REG)

NTC_H

(STAT_REG)

OT_F

(STAT_REG)

VOUTOK_N

(STAT_REG)

Default value 00 0 0 0 0

Latched

(1)

NO YES YES YES YES YES

Forces

Ready mode

when set

NO YES NO YES YES YES

Sets ATN

LOW when

set

NO YES YES YES YES YES

1. YES means that the bit is set by internal signals and is reset to default by an I²C read operation of STAT_REG NO means

that the bit is set and reset by internal signals in real-time.

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STCF03ITBR

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IC LED DRIVER RGLTR DIM 25TFBGA

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