LMZ31710: External clock synchronization to Multiple Module

Hirotsugu Kobayashi

Mastermind 8755 points

Part Number: LMZ31710

Hi, team.

When using LMZ31710 by external clock, how many can be connected?

I'd like to drive 6 of LMZ31710 in 450khz.

Best Regards,

over 6 years ago

0 Jimmy Hua over 6 years ago

TI__Guru 50120 points

Hi Hirotsugu Kobayashi,

Up to six LMZ31710 can be used in parallel to achieve increased output current. Section 8.3.9 "Parallel Operation" in the datasheet depicts a typical example of how the parallel topology works. The LMZ31710s will be synchronized to a fixed external clock that must be present before input power is applied to the device.

For more information please take a look at the LMZ31710 Parallel Operation application note.

Regards,

Jimmy

0 Hirotsugu Kobayashi over 6 years ago in reply to Jimmy Hua

Mastermind 8755 points

Hi, Jimmy,

LMZ31710's are not used in parallel, they are used as shown in the attachment figure.

I'd like to make total 6 devices synchronous by external clock.

External clock is supplied from a load, so after standing up by a RT mode first, a device shifts to a CLK mode.

Is such use method possible?

When connecting one between the RT terminal, how should Rt value be calculated?

Best Regards,

0 J Arrigo over 6 years ago in reply to Hirotsugu Kobayashi

TI__Mastermind 28020 points

The synchronization method shown above is typical for many applications. The LMZ31710 device also has a SYNC_OUT feature which allows sychronization at the same frequency, but 180 degress out of phase. This will improve input ripple and current draw.

Select the RT resistor to set the switching frequency close to the synchronization frequency.

For more discussion, you can contact me directly at jarrigo@ti.com .

Thanks, Jason

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LMZ31710: External clock synchronization to Multiple Module