LM3644: About LED Current Ramp-Up / Down of LM3644 / LM3644TT

user5118965

Part Number: LM3644

About LED Current Ramp-Up / Down of LM3644 / LM3644TT
Please tell me Trise and Tfall for Flash Mode and Torch Mode.
Also, please let me know the prerequisites.

over 6 years ago

0 Sean Zhou over 6 years ago

TI__Mastermind 22745 points

Hi,

For torch mode, the ramp time is set by the regs 0x08;

For flash mode, the Trise is about 35us under Pass mode and 200us under boost mode.

It is better to share us the deial application and requirement. Sicne LM3644 support IR mode which support fast dimming pulse and frequency

Regards

Sean

0 user5118965 over 6 years ago in reply to Sean Zhou

Prodigy 70 points

About torch current ramp time
Timing setting register (0x08)
Bits [6: 4]: 000 = No Ramp ⇒ ILED OFF?
Also, does it mean that there is no Tfall regulation in FALSH MODE and TORCH MODE?

0 Sean Zhou over 6 years ago in reply to user5118965

TI__Mastermind 22745 points

Hi Sir,

When you set the torch ramp time to "No Ramp", that means it has very very short time to output desired torch current, it doesn't mean OFF.

Yes, there is no spec for Tall time.

Regards

Sean

Power management

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LM3644: About LED Current Ramp-Up / Down of LM3644 / LM3644TT