External component selection

STCF07

20/26

Doc ID 16757 Rev 3

11

External component selection

11.1

Input and output capacitor selection

For input and output capacitors it is recommended to use ceramic capacitors with low ESR.

For good device stability when supplied by a low input voltage of 2.7 V at maximum ratings,

it is recommended to use 10 µF / 6.3 V as a minimum value for the input capacitor, and 4.7

µF / 6.3 V as a minimum value for the output capacitor.

Note:

See recommended components in Table 5 on page 7.

11.2

Inductor selection

A thick, shielded inductor with low DC series wiring resistance is recommended for this

application. For good efficiency, it is recommended to use an inductor with a series DC

For nominal operation, the peak inductor current can be calculated using the formula:

where:

η = efficiency of the STCF07

L = inductance value of the inductor

F = switching frequency

Note:

See recommended components in Table 5 on page 7.

11.3

LED selection

All LEDs with forward voltages from 2.7 V to 5 V are suitable for use with STCF07 device.

The LED forward voltage must include the voltage spread of this value. It is possible to set

the LED current in the two different operating modes (high current mode and low current

mode) through two external sensing resistors.

Note:

See recommended components in Table 5 on page 7.

11.4

use a 1206 package size thin metal film resistor with 1% or 5% maximum tolerance. The

maximum high LED current for the STCF07 device is 800 mA with a battery voltage range

2.7 V to 5.5 V.