<commit_before># BoostBuckConverterModule

Quick test of an LM2577S/LM2596S Boost/Buck Converter Module

## Notes

I got an [LM2577S/LM2596S Boost/Buck Converter Module](http://www.aliexpress.com/item/New-Arrive-LM2577S-LM2596S-DC-DC-Step-Up-Down-Boost-Buck-Voltage-Power-Converter-Module/32358637220.html)
to see if it might be any good as a current-limited power supply for prototyping,
and also to investigate the buck/boost circuit it uses in more detail.

It has a handy output voltage range of 1.25-25V and constant current limiting between 0-2A.

Since the voltage/current/charging indicator controls are trimmers on the PCB, and because there is no integrated display of voltage or current,
it probably makes the module more suitable for applications where the voltage/current settings need only a one-time adjustment.

Here's the module annotated with connections, controls and indictors:

![module_annotated](./assets/module_annotated.jpg?raw=true)

### Constant Voltage Control

With an input voltage of 12V, I measure that actual output voltage range as from 1.24V to 26.6V (no load).
The selected output voltage range appears to remain very stable under load.

### Constant Current Control (with WARNING)

At first, I thought the constant current control was not working. But after a bit of experimentation,
I discovered I was being mislead by a pretty important design flaw to note:

> the constant current control *only* takes effect if the load is connected after the unit is powered up

i.e. if you have a circuit connected (or an ammeter for short-circuit current test) when you turn on the input power,
the current will not be limited according the the constant current setting.
But if you turn on the unit first, then connect the laod, the preset constant current setting will take effect.

For battery charging applications, this may not be a big deal.
But for powering a fixed installation (like a LED array as suggested in the application notes),
this would appear to make the power supply pretty useless, and a good way to fry some LEDs if not careful.
My advice would be to design the circuit without relying on the current-limiting feature of the power supply.
But then why use a power supply with a "constant current" feature? Good question.

#### A 5V 150mA Power Supply<commit_msg>[BoostBuckConverterModule] fix typos<commit_after># BoostBuckConverterModule

Quick test of an LM2577S/LM2596S Boost/Buck Converter Module

## Notes

I got an [LM2577S/LM2596S Boost/Buck Converter Module](http://www.aliexpress.com/item/New-Arrive-LM2577S-LM2596S-DC-DC-Step-Up-Down-Boost-Buck-Voltage-Power-Converter-Module/32358637220.html)
to see if it might be any good as a current-limited power supply for prototyping,
and also to investigate the buck/boost circuit it uses in more detail.

It has a handy output voltage range of 1.25-25V and constant current limiting between 0-2A.

Since the voltage/current/charging indicator controls are trimmers on the PCB, and because there is no integrated display of voltage or current,
it probably makes the module more suitable for applications where the voltage/current settings need only a one-time adjustment.

Here's the module annotated with connections, controls and indictors:

![module_annotated](./assets/module_annotated.jpg?raw=true)

### Constant Voltage Control

With an input voltage of 12V, I measure that actual output voltage range as from 1.24V to 26.6V (no load).
The selected output voltage range appears to remain very stable under load.

### Constant Current Control (with WARNING)

At first, I thought the constant current control was not working. But after a bit of experimentation,
I discovered I was being mislead by what appears to be a pretty important design flaw:

> the constant current control *only* takes effect if the load is connected after the unit is powered up

i.e. if you have a circuit connected (or an ammeter for short-circuit current test) when you turn on the input power,
the current will not be limited according the the constant current setting.
But if you turn on the unit first, then connect the load, the preset constant current setting will take effect.

For battery charging applications, this may not be a big deal.
But for powering a fixed installation (like a LED array as suggested in the application notes),
this would appear to make the power supply pretty useless, and a good way to fry some LEDs if not careful.
My advice would be to design the circuit without relying on the current-limiting feature of the power supply.
But then why use a power supply with a "constant current" feature? Good question.

#### A 5V 150mA Power Supply
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