AW3643

Jan 2018 V1.4

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Copyright © 2016 SHANGHAI AWINIC TECHNOLOGY CO., LTD

This fault flag 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.

NTC THERMISTOR INPUT (TORCH/TEMP)

The TORCH/TEMP pin, when set to TEMP mode, serves as a threshold detector and bias source for negative

temperature coefficient (NTC) thermistors. When the voltage at TEMP goes below the programmed threshold,

bit[0] is set to a

‘1’, and the AW3643 is placed into standby mode. The NTC threshold voltage is adjustable

from 200 mV to 900 mV in 100-mV steps. The NTC bias current is set to 50µA. The NTC detection circuitry

can be enabled or disabled via the Enable Register. If enabled, the NTC block turns on and off during the start

and stop of a Flash/Torch event.

Additionally, the NTC input looks for an open NTC connection and a shorted NTC connection. If the NTC input

falls below 100 mV, the NTC short flag is set(bit[4] in the Flags2 Register), and the AW3643 is forced into

standby mode. If the NTC input rises above 2.3 V, the NTC Open flag is set(bit[3] in the Flags2 Register), and

the AW3643 is forced into standby mode. These fault detections can be individually disabled/enabled via the

NTC Open Fault Enable bit and the NTC Short Fault Enable bit in Temp register(0x09)

Control

Logic

VIN

TORCH/

TEMP

Fig 51

Temp Detection Diagram

The AW3643 is not available for operation until Flags2 register is cleared. The three NTC fault flags can be

reset to '0' by reading back the Flags2 Register (0x0B), or by setting HWEN to '0', or by setting the SW

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

UNDERVOLTAGE LOCKOUT (UVLO)

The AW3643 has an internal comparator that monitors the voltage at IN and forces the AW3643 into standby

if the input voltage drops to 2.5 V. If the UVLO monitor threshold is tripped, the UVLO flag bit is set in the

Flags1 Register (0x0A). If the input voltage rises above 2.5 V, the AW3643 is not available for operation until

operation can resume if the input voltage is greater than 2.5 V.

VOUT SHORT FAULT

The Output Short Fault flag reads back a '1' if the device is active in Flash or Torch mode and the boost output

experiences a short condition. VOUT short condition occurs if the voltage at OUT goes below 2.3V (typ.) while

the device is in Torch or Flash mode. There is a deglitch time of 2.048ms before the VOUT Short flag is valid.

The mode bits are cleared upon an the VOUT short fault. The AW3643 is not available for operation until

VOUT Fault flags is cleared. The VOUT 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.