STCF04 datasheet(24/43 Pages) STMICROELECTRONICS

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Description of the internal registers

STCF04

24/43

Doc ID 022927 Rev 3

9.1.4

NTC_ON

This bit activates the comparators that monitor the LED temperature. NTC-related blocks

are always active regardless of this bit in Torch mode and Flash mode.

9.1.5

TCHV_H

Torch voltage HIGH: when set to 1, the SuperCap voltage is maintained to the value set by

the feature register (VDC_0~1) during Torch mode. If this bit is set to 0, voltage on the

SuperCap is regulated to maintain the desired torch current and optimize the efficiency in

Torch mode.

9.1.6

CHRG

This bit enables the charging of the SuperCap, when set to 1, the device starts to charge the

SuperCap by the limited current from the PVBAT. During this operation the active balancing

circuit is enabled.

9.1.7

MONTR

When this bit is set and the VDC voltage in the feature register is set to a non-zero value at

the same time, the device enters Monitoring mode.

9.2

Flash register (FL_REG) 01(hex)

FDIM_0~2: these 3 bits define the LED current in Flash mode with 8 values.

FTIM_0~4: these 5 bits define the flash duration timer value in Flash mode with 32 values.

Note:

RFL is the external sensing resistor, external MOS transistor connected, see Figure 3.

Table 11.

Flash register

CL_REG

(Write mode)

MSB

LSB

SUB ADD=01

FTIM_4

FTIM_3

FTIM_2

FTIM_1

FTIM_0

FDIM_2

FDIM_1

FDIM_0

Power-ON, Shutdown

mode RESET value

0000000

Table 12.

Flash mode dimming registers settings (EXT_REG = 0)

F_DIM (hex)

234

DRIVE voltage

[mV]**

108

120

LED current [A]*

0.012 V /

RFL

0.048 V /

RFL

0.060 V /

RFL

0.072 V /

RFL

0.084 V /

RFL

0.096 V /

RFL

0.108 V /

RFL

0.120 V /

RFL

Example LED

current (A) for

RFL = 10 mΩ

1.2

4.8

7.2

8.4

9.6

10.8

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