LP8545 datasheet(22/44 Pages) TI1

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LP8545

SNVS635D – APRIL 2010 – REVISED DECEMBER 2013

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Under-Voltage Detection

LP8545 has detection for too-low VIN voltage. Threshold level for the voltage is set with EEPROM register bits

as seen in the following table:

UVLO[1:0]

Threshold (V)

OFF

2.7V

5.7V

8.7V

When under voltage 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.

Over-Current Protection

LP8545 has detection for too-high loading on the boost converter. When over-current fault is detected, the

LP8545 will shut down.

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

Device Thermal Regulation

LP8545 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 the following table.

Thermal regulation function does not generate fault signal.

TEMP_LIM[1:0]

Over-Temp Limit (°C)

OFF

110

120

130

Thermal Shutdown

If the LP8545 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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