STROBE

ILED

TIME-OUT

Start

TIME-OUT

Reached

VOUT goes low,

LED turn off

STROBE

ILED

10

LM36011

SNVSAN5 – JULY 2017

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7.3 Feature Description

7.3.1 Flash Mode

In flash mode, the LED current source provides 128 target current levels from 11 mA to 1.5 A, set by the LED

Flash Brightness Register (0x03 bits [6:0]). Flash mode is activated by the Enable Register (0x01), setting mode

M1, M0 (bits [1:0]) to 11. Once the flash sequence is activated, the LED current source ramps up to the

programmed flash current by stepping through all current steps until the programmed current is reached.

When flash mode is enabled using the mode M1, M0 (bits [1:0]) of the Enable Register (0x01), the mode bits in

the Enable Register are cleared after a flash time-out event.

7.3.2 Torch Mode

In torch mode, the LED current source provides 128 target current levels from 2.4 mA to 376 mA, set by the LED

Torch Brightness Register (0x04 bits [6:0]). Torch mode is activated by the Enable Register (0x01), setting mode

M1, M0 (bits [1:0]) to 10. Once the TORCH sequence is activated, the LED current source ramps up to the

programmed torch current by stepping through all current steps until the programmed current is reached. The

rate at which the current ramps is determined by the value chosen in the Torch Ramp bit [0] in Timing Register

(0x02).

7.3.3 IR Mode

In IR mode, the target LED current is equal to the value stored in the LED Flash Brightness Register (0x03 bits

[7:0]). IR mode is enabled by the Enable Register (0x01) setting mode M1, M0 (bits [1:0]) to 01. In IR mode,

toggling the STROBE pin enables and disables the LED current source. The STROBE pin can only be set to be

Level sensitive, as all timing of the IR pulse is externally controlled. In IR mode, the current source does not

control the ramp rate of the LED output. The current transitions immediately from off to on and then on to off.

Figure 17. IR Mode

(1)

When the flash timer elapses, the device goes into stand-by regardless of strobe state

Figure 18. IR Mode Time-out