RE: Exploring the LT4320 Ideal Diode Bridge Controller

akaad — Fri, 06 Aug 2021 09:26:44 GMT

The LT4320 ideal bridge is great.

Energy saving.

Headache saving.

But I cannot find the part on the Farnell.NL component search - i.e. they do not stock it.

How can that be proposed?

From the innovation a few years back, now several boards have been develooped for these components. That implies the demand should increase.

RE: Exploring the LT4320 Ideal Diode Bridge Controller

jw0752 — Thu, 09 Feb 2017 05:53:25 GMT

I wasn't very happy with the breadboard of the LT4320 Ideal Bridge circuit. The jumper wires that I used added a resistance variable that did not allow me to get a good comparison with the regular diode bridge. Therefore I decided to put together a prototype circuit on perf board and solder the connections and jumpers. After three attempts to lay out the components I settled on this layout:

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/5165.contentimage_5F00_183555.jpg:620:465]

The graph paper represents holes of the perf board. Since this is a top view I took a picture in a mirror to produce a bottom view as this is the side I would have to solder the connections to.

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/4670.contentimage_5F00_183556.jpg:620:465]

Except for a position shift in all the MOSFETs to better use the space and better align with the gate output pins of the IC I proceeded to solder up the board as drawn. I made an attempt to color coordinate the nodes. The green jumper was the only gate output to it corresponding MOSFET that wasn't tied directly to the IC.

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/2526.contentimage_5F00_183557.jpg:620:465]

This board is 3.7 cm by 3.3 cm and here is the other side, all labeled up as is my nature:

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/5658.contentimage_5F00_183558.jpg:620:465]

I hooked up the new board and set up the same experiment as I performed in the original post and here are a picture of the set up and the results:

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/8877.contentimage_5F00_183559.jpg:620:465]

Diode Bridge LT4320 & MOSFETs LT4320 & MOSFETs

(Original Bread Board) (Prototype Board)

Input Voltage 25.75 VAC 60 Hz 25.75 VAC 60 Hz 25.75 VAC 60 Hz

Output Voltage 27.95 V DC 29.4 V DC 30.76 V DC

Ripple 2.68 V PP 2.68 V PP 2.96 V PP

Load Current 390 mA 400 mA 420 mA

Here are the pictures of the Meters and Scope:

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/2110.contentimage_5F00_183560.jpg:620:465]

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-9c3bb042-7206-47c8-bdc9-0e20bb6ea180/0066.contentimage_5F00_183561.jpg:620:465]

The output of the traditional diode bridge was 27.95 Volts and the output of the LT4320 Ideal Diode bridge was 30.76 Volts. This represents a 10% improvement in voltage level for the same VAC input. This combined with the reduction of heat generation may make this choice a better one than I originally thought. After having to draw and wire this circuit several times it was not as confusing as it seemed at first either.

John

RE: Exploring the LT4320 Ideal Diode Bridge Controller

mcb1 — Fri, 03 Feb 2017 06:55:22 GMT

Nice work John.

You're getting very good with this discrete stuff, we might need to get you into microcontrollers ...image what you could achieve.

mark

RE: Exploring the LT4320 Ideal Diode Bridge Controller

DAB — Wed, 01 Feb 2017 20:40:27 GMT

Great job John.

Excellent description of the test and results.

DAB

RE: Exploring the LT4320 Ideal Diode Bridge Controller

D_Hersey — Wed, 01 Feb 2017 16:41:06 GMT

IIRC I was trying to hint to you about synchronous rectifiers some months ago, cool report, John! This chip sure makes it seem easy to implement one