LP5523: internal clock use with two devices and TRIG for synchronous operation

David Mckinney

Part Number: LP5523

Can you confirm that we can use two LP5523 with the TRIG pins configured as shown in page 50 of the datasheet in Figure 26 as the Typical Application Schematic with both devices running from their internal oscillators? (no external oscillator connected)

We want to verify that we can use the TRIG pins to maintain synchronization to drive 5 RGB LEDs with two LP5523s.

The patterns will be simple, but we will need hand-off between devices and want to make sure the patterns do not drift or lose synchronization.

Can you confirm the devices can run autonomously and maintain sync? Note: The INT is not planned to be used in this configuration. Is this also allowed?

over 4 years ago

0 Charles-Chen over 4 years ago

TI__Genius 11836 points

Hi David,

Proper engineer has been assigned to look at this and will reply to you soon.

0 Hardy Wu over 4 years ago

TI__Genius 12915 points

Hi David,

If you use internal oscillator and TRIG pins, two device cannot absolutely synchronized work. They may vary one or two clock which is internal 32kHz. The difference of LEDs cannot be captured by human eyes.

0 David Mckinney over 4 years ago in reply to Hardy Wu

TI__Expert 6410 points

Hi Hardy;

It would be acceptable for the variation to be a few clock cycles, as long as the two parts work together and do not loose relative timing to each other, or stop.

So with proper use of the TRIG pins, the two devices can work together like they were aligned, but will vary by a few clock cycles. Is this correct?

0 Hardy Wu over 4 years ago in reply to David Mckinney

TI__Genius 12915 points

Hi David,

Yes your understanding is right.

0 David Mckinney over 4 years ago in reply to Hardy Wu

TI__Expert 6410 points

Thank you for the response. One last question: In this application, is the INT pin required or can it be left unconnected?

0 Hardy Wu over 4 years ago in reply to David Mckinney

TI__Genius 12915 points

Hi David,

It is suggested to left unconnected of INT pin. I think it is also OK to connect to GND since it is a open drain output pin

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LP5523: internal clock use with two devices and TRIG for synchronous operation