STLED25

Detailed description

Doc ID 022323 Rev 3

19/30

6.5

Undervoltage lockout

The undervoltage lockout function prevents improper operation of the STLED25 when the

input voltage is not high enough. When the input voltage is below the UVLO threshold, the

device is in shutdown mode. The hysteresis of 100 mV prevents unstable operation when

the input voltage is close to the UVLO threshold.

6.6

Overtemperature protection

An internal temperature sensor continuously monitors the IC junction temperature. If the IC

temperature exceeds 150 °C (typical), the device stops operating. As soon as the

temperature falls below 135 °C (typical), normal operation is restored.

6.7

Open LED protection

The device is able to detect an “Open LED” failure in each LED channel independently.

When this failure appears, the DC-DC increases the output voltage to maintain the current

source headroom voltage until the OVP threshold is reached; the device detects which LED

channel is the root cause and switches off this LED channel. This state is maintained until

the STLED25 goes into shutdown mode.

6.8

Overvoltage protection

components against the high voltage coming from the DC-DC, in case of a disconnected

load. When the output voltage level reaches the OVP threshold (9.3 V typical), the DC-DC is

turned off until the output voltage level goes below the OVP threshold. The hysteresis of the

OVP threshold is approximately 250 mV.

6.9

Short LED protection

The device is able to detect a shorted LED in each LED channel independently; when the

protection detects a failure on any of the LED channels, it switches off this channel until the

STLED25 enters shutdown mode.