STCF01 STMicroelectronics, STCF01 Datasheet - Page 8

• Manufacturer Part Number: STCF01
• Description: Step-up Converter For Cell Phone Camera Flash Leds
• Manufacturer: STMicroelectronics

Detailed description
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Detailed description
The STCF01 white Led boost converter drives from two up to four white LEDs with a constant
current. It needs few external components: two ceramic capacitors (C
inductor L=10µH and one schottky diode. The device works with a minimum V
an Over Voltage Protection on the output guaranteed at minimum value equal to 17V. This
value ensures proper operation with a maximum of four White LEDs in series. In the worst case
of V
V
maximum IO current is limited by inductor peak current internally set at Typ 1.2A. This feature
allows for a longer battery life as it reduces intensive use of the flash. The SEL pin allows
selection of high and low current values flowing on the White LEDs.
The two current values are set through external resistors R
following formula:
I
I
A High logic level on SHDN pin puts the device in shutdown mode; if it is held at LOW the flash
or torch mode is activated. When the SHDN pin is LOW the device provides the requested
current in less than 200µs (see TURN ON TIME plot). This fast turn-on time makes the device
suitable for single shoot and multiple shoot operation modes.
LED(FLASH)
LED(TORCH)
OVP
I
=2.6V at V
=11V (typical value of three LEDs) it is possible obtain I
= 2100 * (V
= 2400 * (V
OVP
=8V (typical value of two LEDs) it is possible to obtain I
I
I
- V
- V
HC
LC
) / R
) / R
HC
LC
HC
O
=180mA (
and R
LC
I
=2.2µF C
according to the
Figure 4
O
=270mA, while at
I
=2.6V, and it has
O
). The
=4.7µF), one
STCF01