Detailed operating description

STCF02

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6.7

Soft start

To avoid spikes the battery during start-up sequence, a soft start function has been implemented. This

soft start is achieved by progressively increasing the feedback voltage reference. In the worst case

Figure 13. Start up - LED current rise time

6.8

LED Failure Protection

The device is self protected when the LED fails as a result of a short or open circuit. Such performances

are tested using a standard mobile phone Lithium battery with internal resistance 170m

Ω typ.

6.9

Overvoltage protection

The device includes a power switch protection that stops the operation of the PWM controller when the

6.10

Thermal shutdown protection

Internal thermal shutdown protection will switch off the device when the junction temperature exceeds

140°C typical. The hysteresis comparator allows for the automatic restart of the PWM controller, when the

temperature is reduced by 20°C.

6.11

Sensing of LED temperature by NTC resistor

The device is able to switch off the power circuit, if high temperature on the LED is detected (see

Figure 14).