LM3560 Datasheet, PDF(20/42 Page) Texas Instruments – LM3560 Synchronous Boost Flash Driver w/ Dual 1A High-Side Current Sources (2A Total Flash Current)

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LM3560 Datasheet, PDF (20/42 Pages) Texas Instruments – LM3560 Synchronous Boost Flash Driver w/ Dual 1A High-Side Current Sources (2A Total Flash Current)

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To avoid noise from falsely triggering the NTC Comparator,

this mode incorporates a 250 Âµs de-glitch timer. With NTC

mode active, VLEDI/NTC must go below the trip point (VTRIP) and

remain below it for 250 Âµs before the LEDs are forced into

Torch mode (or shutdown) and the NTC Flag is written.

ALTERNATE EXTERNAL TORCH (AET MODE)

With Configuration Register 2 bit [2] set to '1', the LM3560 is

configured for AET mode, and the operation of TX1/TORCH

becomes dependent on its occurrence relative to the

STROBE input. In this mode, if TX1/TORCH goes high first,

then STROBE goes high, the LEDs are forced into Torch

mode with no timeout. In this mode, if TX1/TORCH goes high

after STROBE has gone high, then the TX1/TORCH pin op-

erates as a normal LED current interrupt (TX1), and the LEDs

will turn off at the end of the timeout duration (see Figure

11).

FIGURE 11. AET Mode Timing

30113810

INPUT VOLTAGE MONITOR

The LM3560 has an internal comparator at IN which monitors

the input voltage and can force the LED current into Torch

mode or into shutdown if VIN falls below the programmable

VIN Monitor Threshold. Bit 0 in the VIN Monitor Register en-

ables or disables this feature. When enabled, Bits [2:1] pro-

gram the 4 adjustable thresholds of 2.9V, 3.0V, 3.1V, and

3.2V. Bit 3 in Configuration Register 2 selects whether a VIN

Monitor event forces Torch mode or forces LED1 and/or LED2

into shutdown. See Table 11 for additional information. When

the input voltage monitor is active, and VIN falls below the

programmed VIN Monitor threshold, the LEDs will either turn

off or be forced into the Torch current setting. To reset the

LED current to its previous level, two things must occur. First,

VIN must go above the VIN Monitor threshold, and the Flags

Timing Waveform.

To avoid noise from falsely triggering the VIN Monitor, this

mode incorporates a 250 Âµs de-glitch timer. With the VIN

Monitor active, VIN must go below the VIN Monitor Threshold

(VIN_TH), and remain below it, for 250 Âµs before the LEDs are

forced into Torch mode (or shutdown) and the VIN Monitor

Flag is written.

FIGURE 12. VIN Monitor Waveform

30113809

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