STCF05 STMicroelectronics, STCF05 Datasheet - Page 13

• Manufacturer Part Number: STCF05
• Description: HIGH POWER WHITE LED DRIVER WITH I2C INTERFACE
• Manufacturer: STMicroelectronics

Specifications of STCF05

• Flash Mode: up to 400 mA
• Torch Mode: up to 120 mA

STCF05
7
7.1
7.2
7.3
7.3.1
7.3.2
7.3.3
Detailed description
Introduction
The STCF05 is a synchronous boost converter, dedicated to power and control the current
of power white LEDs in a camera cell phones. The device operates at a typical constant
switching frequency of 1.8 MHz. It steps an input voltage ranging from 2.5 V to 5.5 V up to
10.2 V. I²C bus controls device operation and diagnostic. Torch current is adjustable from 15
mA to 120 mA; flash current is adjustable up to 400 mA; aux LED current can be adjusted
from 0 to 20 mA. The device uses an external NTC to sense the temperature of the white
LEDs. These NTC functions may not be needed in all applications, and in those cases the
relevant external components can be omitted.
Boost converter
The STCF05 contains the 3-loop system of the PWM controller regulation and soft-start
function. When the output voltage is lower than input voltage, the STCF05 is charging output
by the internal current source with 120 mA typ. When the output voltage is higher than
battery, the STCF05 automatically enable the boost converter with 3-loop regulation system.
First loop is controlling the output current according the setting of the dimming register,
second loop is regulating the output voltage to the stable value and third loop is regulating
the voltage drop on the LED current source to reach high efficiency of the operation. (see
Figure 1: Block
Logic pin description
SCL, SDA pins
These are the standard clock and data pins as defined in the I²C bus specification. External
pull-up is required according to I²C bus specifications.
TRIG pin
This input pin is internally and-ed with the TRIG_EN bit to generate the internal signal that
activates the flash operation. This gives to the user the possibility to accurately control the
flash duration using a dedicated pin, avoiding the I²C bus latencies (hard-triggering). No
internal pull-up nor pull-down is provided.
ATN pin
This output pin (open-drain, active LOW) is provided to better manage the information
transfer from the STCF05 to the microprocessor. Because of the limitations of a single
master I²C bus configuration, the microprocessor should regularly poll the STCF05 to verify
if certain operations have been completed, or to check diagnostic information. Alternatively,
the microprocessor can use the ATN pin to be advised that new data are available in the
STAT_REG, thus avoiding continuous polling. The information can be read in the
STAT_REG by a read operation via I²C that, besides, automatically resets the ATN pin. The
STAT_REG bits affecting the ATN pin status are mapped in
provided.
diagram).
Doc ID 15257 Rev 4
Table
15. No internal pull-up is
Detailed description
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