AN3223

Operation modes

Doc ID 17553 Rev 2

13/29

5.5

Torch mode

This mode is intended to be used for low light intensities. The LED current in Torch mode

can be adjusted in a range from 15 mA up to 320 mA.

Torch mode is activated by writing the following data to the COMMAND register.

The TORCH DIMMING register value (TDIM) must also be set, unless it has already been

set during a previous operation. If the TDIM register is not set, then the default output

current value is at the minimum.

It is also possible to set the safety timeout for Torch mode through the TTRCH1 and

TTRCH0 bits.

If Torch mode was terminated by entering Ready or Flash mode, it can be restarted again by

writing the corresponding data to the COMMAND register only, because entering any of the

Ready and Flash modes does not influence the TDIM value. If the Torch mode was

terminated by entering Shutdown mode, then the TDIM value must be set again during

restart of Torch mode, because entering Shutdown mode clears the TDIM and TTRCH

values.

As soon as Torch mode is activated, the NTC feature is automatically activated too in order

to protect the LED against overheating. The NTC feature is activated even if the NTC_ON bit

in the COMMAND register is set to zero.

5.6

Flash mode

This mode is intended to be used for high light intensities. The LED current in Flash mode

can be adjusted up to 12 A with the input voltage ranging from 2.7 V up to 5.5 V with

recommended external components.

Table 8.

NTC feature possibilities

Operation mode

Way of activation

Voltage on the Rx-NTC divider

NTC_W, NTC_H bits

Shutdown

Manual

Available

Not set

Monitoring

Manual

Available

Not set

Idle

Manual

Available

Set

Charging

Manual

Available

Set

Flash

Automatic

Available

Set

Torch

Automatic

Available

Set

Aux LED

Manual

Available

Set

Table 9.

COMMAND register data for entering Torch mode

CMD_REG

PWR_ON FLASH_ON

TCH_ON

NTC_ON

TCHV_H

CHRG

MONTR

N/A

1

0

1

xxxx

0

MSB

LSB