AW3643

Jan 2018 V1.4

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Copyright © 2016 SHANGHAI AWINIC TECHNOLOGY CO., LTD

LED SHORT FAULT

The LED Short Fault flags read back a '1' if the device is active in Flash or Torch mode and either active LED

output experiences a short condition. An LED short condition is determined if the voltage at LED1 or LED2

goes below 500mV (typ.) while the device is in Torch or Flash mode. There is a

deglitch time of 256μs before

the LED Short Fault flag is valid. The mode bits are cleared upon an LED short fault. The AW3643 is not

available for operation until the LED Short Fault flags is cleared. The LED Short Faults can be reset to '0' by

reading back the Flags1 Register (0x0A), or by setting HWEN to '0', or by setting the SW RESET bit to a '1', or

by removing power to the AW3643.

OVERVOLTAGE PROTECTION (OVP)

The output voltage is limited to typically 5 V. In situations such as an open LED, the AW3643 raises the output

voltage in order to try and keep the LED current at its target value. When VOUT reaches 5 V (typ.) the

overvoltage comparator trips and turns off the internal NMOS. When VOUT falls below the

Threshold

”, the AW3643 begins switching again. The mode bits are cleared, and the OVP Fault flag is set,

when an OVP condition is present for three rising OVP edges. This prevents momentary OVP events from

forcing the device to shut down. The AW3643 is not available for operation until the OVP Fault flag is cleared.

The OVP Fault can be reset to '0' by reading back the Flags2 Register (0x0A), or by setting HWEN to '0', or by

setting the SW RESET bit to a '1', or by removing power to the AW3643.

THERMAL SHUTDOWN (TSD)

When the AW3643 die temperature reaches 155°C, the thermal shutdown detection circuit trips, forcing the

AW3643 into standby and writing a '1' to the Thermal Shutdown Fault flag of the Flags1 Register (0x0A) . The

AW3643 is only allowed to restart after the Thermal Shutdown Fault flag is cleared. The Thermal Shutdown

Faults can be reset to '0' by reading back the Flags1 Register (0x0A), or by setting HWEN to '0', or by setting

the SW RESET bit to a '1', or by removing power to the AW3643. Upon restart, if the die temperature is still

above 155°C, the AW3643 resets the Fault flag and re-enters standby.