What LDO (Low Voltage Regulator) do you have?

I am new to LDO (Low Voltage Regulator) world.
I'm curious what you people had buy and have in your personal stock at home.
(also what packages, TO-220 SOT-223)

From the good old Ebay I spot a couple and also open their respective dataSheets:

LM317T (LM117,LM217) Input Voltage : 2-40V
OUTPUT CURRENT Maximum Load Current 2.2A
OUTPUT VOLTAGES adjustable over a 1.2 to 37V range.

L7800 SERIES
Input Voltage : 2-35V (5-18); 20-40V (20-24)
OUTPUT CURRENT 1.5A
OUTPUT VOLTAGES 5; 5.2; 6; 8; 8.5; 9; 10; 12; 15; 18; 24V

AMS1117 - 1.2V 1.5V, 1.8V, 2.5V, 2.85V, 3.3V and 5.0V (Advanced Monolithic Systems)
Input Voltage : 2-18or30V Output Current of 800mA
OUTPUT VOLTAGES 1.5V, 1.8V, 2.5V, 2.85V, 3.3V and 5.0V

HT73xx-7 Input Voltage :
2-30V output current : 250mA
OUTPUT VOLTAGES: 2.1, 2.3, 2.5, 2.7, 3.0, 3.3, 3.6, 4.0, 4.4, 5.0

HT75xx-1
Input Voltage : 24V
output current : 100mA
OUTPUT VOLTAGES: 2.1, 2.3, 2.5, 2.7, 3.0, 3.3, 3.6, 4.0, 4.4, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 12.0

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There’s no one LDO that works for everything. The reason they make so many kinds is there are many different requirements.

And LDO (Low DROPOUT Regulator) refers to a specific variety of voltage regulator that will work with a small difference between input and output voltage, the ones you mentioned are not LDO.

Brian.

You have mixed the Term LDO with LowVoltage Regulators.
LM317 ,L7800 etc are not LDO type regulators.

At least the AMS1117 is advertised as LDO :grin:, but there are LDOs which can be operated with a much lower dropout voltage e.g. the listed HT73xx-7.

Something you should keep in mind, the dorpout voltage has a direct impact on the power dissipated by your voltage regulator, thus a low dropout voltage is favourable.
Further, the required dropout voltage increases with an increase of the required/sourced output current e.g. for the HT73xx-7: 6 mV @ 1 mA and 120 mA @ 30 mA.

stenzer said:

At least the AMS1117 is advertised as LDO :grin:, but there are LDOs which can be operated with a much lower dropout voltage e.g. the listed HT73xx-7.

Something you should keep in mind, the dorpout voltage has a direct impact on the power dissipated by your voltage regulator, thus a low dropout voltage is favourable.
Further, the required dropout voltage increases with an increase of the required/sourced output current e.g. for the HT73xx-7: 6 mV @ 1 mA and 120 mA @ 30 mA.

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The dropout voltage has nothing to do with power dissipation. The Input/output voltage differential determines the power. The dropout voltage is simply the MINIMUM differential the device will operate at.

Most of the sellers at ebay know nothing about electronics and do not know what LDO means. instead look at the electronic parts distributor Digikey.

Most of my projects have CMOS IC's because they work on a wide supply range.

Low dropout and low power go well with a shunt regulator. I keep assorted zener diodes. Narrow adjustment can be made by adding a diode or resistor. I have TL431 which is handy as an adjustable zener.

I guess low dropout can be achieved by combining a shunt and series regulator. The shunt is only needed when a small voltage needs to be dropped. (However I'm not sure how to detach the shunt from overmuch current as supply voltage rises.)

I like this simple series voltage regulator made from an NPN. I once used this design to replace a blown 5W power zener in an intercom power supply. (It isn't a low drop type.)



7400 family IC's need regulated 5V. Then power is wasted if I start with 9V (say from a battery) since it must drop to 5V. As for me I like the idea of practicing conservationism.
However I have series regulators if needed: 7805, 7808, 7812, 317, 723.

barry said:

The dropout voltage has nothing to do with power dissipation. The Input/output voltage differential determines the power. The dropout voltage is simply the MINIMUM differential the device will operate at.

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Yes of course, but I meant if someone uses a LDO which requires a "high" MINIMUM differential voltage it dissipates more power compared to an LDO which requires a lower MINIMUM differential voltage. E.g. the listed AMS1117 requies a voltage difference of 1.1 V (typical) if a current of 0.8 A is sourced, on the other hand the LT3022 requiers only a voltage difference of 0.285V (maximum) to source 1 A. For this reason, the LT3022 would dissipate less power when sourcing 0.8 A.

Hi,

Only true if one really lowers down it's input voltage. Often this is not possible.
Like a battery as source, or a non adjustable main supply.

And if one can not reduce the input voltage: it does not matter which voltage regulator one uses..power dissipation is the same.
(just focussed on dropout voltage)

Klaus

Of course, I totally agree with that!

My new favourites are the Holtek HT75xx-1 series. Compared to the popular AMS1117, the HT75xx-1 has twice the maximum input voltage rating, and their quiescent current of 2.5µA is negligible compared to the AMS1117's 5-10mA. Besides, the AMS1117 has a minimum load requirement of 5-10mA. And they are cheap, being available at aliexpress.com for a few US cents in small quantities.

I bought a batch last year and they work well, but I haven't got around to testing them for things ripple rejection, dropout at different currents, etc. Here are some of the features -

Vin max = 30V (old versions 26V)
Imax = 100mA
Iq = 2.5uA
Output range 2.1 to 12V (previously 3.3-5V)
Tolerance 3%
Vdo = 25/30mV at 1mA (old versions 100mV)
Package - various

Datasheet: https://www.holtek.com/documents/10179/116711/HT75xx-1v250.pdf