LP8552 datasheet(20/49 Pages) TI2

20 / 49 page

LP8552

SNVS693E – SEPTEMBER 2011 – REVISED SEPTEMBER 2014

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When undervoltage is detected the LED outputs and boost will shutdown, FAULT pin is pulled down and

corresponding fault bit is set in fault register. LEDs and boost will start again when the voltage has increased

above the threshold level. Hysteresis is implemented to threshold level to avoid continuous triggering of fault

when threshold is reached.

Fault is cleared by setting EN pin low or by reading the fault register.

8.3.4.3 Overcurrent Protection

The device has detection for too-high loading on the boost converter. When overcurrent fault is detected, the

LP8552 will shut down.

Fault is cleared by setting EN pin low or by reading the fault register.

8.3.4.4 Device Thermal Regulation

The LP8552 has an internal temperature sensor which can be used to measure the junction temperature of the

device and protect the device from overheating. During thermal regulation, LED PWM is reduced by 2% of full

scale per °C whenever the temperature threshold is reached. Temperature regulation is enabled automatically

when chip is enabled. 11-bit temperature value can be read from Temp MSB and Temp LSB registers; MSB

should be read first. Temperature limit can be programmed in EEPROM as shown in Table 4.

Thermal regulation function does not generate fault signal.

Table 4. Temperature Limits Programmable in EEPROM

TEMP_LIM[1:0]

OVER-TEMP LIMIT (°C)

OFF

110

120

130

8.3.4.5 Thermal Shutdown

If the LP8552 reaches thermal shutdown temperature (150°C) the LED outputs and boost will shut down to

protect it from damage. Also, the fault pin will be pulled down to indicate the fault state. Device will activate again

when temperature drops below 130°C degrees.

Fault is cleared by setting EN pin low or by reading the fault register.

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LP8552 Datasheet(PDF) 20 Page - Texas Instruments