NTE1956 LDO Regulator

Thread Starter

tracecom

Joined Apr 16, 2010
3,944
My NTE1956 LDO regulators came in today. The pinout is the same as the LM78xx series, but the datasheet doesn't provide any application notes. Does anyone know if the standard LM78xx circuit will work, or is there a better alternative? Thanks.
 

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Audioguru

Joined Dec 20, 2007
11,248
I don't think that NTE makes anything. They probably just buy some ordinary ICs (LDO regulators here), erase the original part number then stamp them with their own part number. Then they sell them as "replacements" at an extremely high price.

Many semiconductor manufacturers make low dropout regulators. This one is probably one of them.

This one works when its input minus the output (its dropout voltage) is typically only 0.5V but it might need to be as high as 1.0V.
An LM7824 works when its input minus the output is typically 2.0V but it might need to be as high as 3.0V.
 

Thread Starter

tracecom

Joined Apr 16, 2010
3,944
I don't think that NTE makes anything. They probably just buy some ordinary ICs (LDO regulators here), erase the original part number then stamp them with their own part number. Then they sell them as "replacements" at an extremely high price.

Many semiconductor manufacturers make low dropout regulators. This one is probably one of them.

This one works when its input minus the output (its dropout voltage) is typically only 0.5V but it might need to be as high as 1.0V.
An LM7824 works when its input minus the output is typically 2.0V but it might need to be as high as 3.0V.
I didn't find another 24V LDO, regulator, so I bought the NTE1956.

The input that I will be using is 31.8 V with no load, but drops to 24.9 V at 1 A. I may have to limit the current to ensure that the regulator works consistently; at about 700 mA, the voltage is 26.3 V.
 

SgtWookie

Joined Jul 17, 2007
22,230
The absolute maximum input voltage for the NTE1956 is 30v; I suggest that you don't exceed 29v. You say you're planning on feeding it 31.8v. You're going to go through a LOT of those regulators, as you'll be burning them up.

It doesn't look like you'll be able to use a simple linear regulator for your application.
 

Thread Starter

tracecom

Joined Apr 16, 2010
3,944
The absolute maximum input voltage for the NTE1956 is 30v; I suggest that you don't exceed 29v. You say you're planning on feeding it 31.8v. You're going to go through a LOT of those regulators, as you'll be burning them up.

It doesn't look like you'll be able to use a simple linear regulator for your application.
I interpreted Note 1 from the datasheet to mean that the device has built-in protection from a high input voltage.


"Note 1. At the application of VIN = 30V, the overvoltage protection may be operated by the ASO protection circuit, leading to the output shut down."


Is that not what the note means? Thanks.​
 

bountyhunter

Joined Sep 7, 2009
2,512
My NTE1956 LDO regulators came in today. The pinout is the same as the LM78xx series, but the datasheet doesn't provide any application notes. Does anyone know if the standard LM78xx circuit will work, or is there a better alternative? Thanks.
I know it can't work the same as the 78XX series, because the 78 series are not low dropout. They use the NPN darlington pass transistor design. They are both linear voltage regulators, but their behavior and performance is not the same. Hence, app circuits for the 78XX may not work on this one.
 

bountyhunter

Joined Sep 7, 2009
2,512
I interpreted Note 1 from the datasheet to mean that the device has built-in protection from a high input voltage.


"Note 1. At the application of VIN = 30V, the overvoltage protection may be operated by the ASO protection circuit, leading to the output shut down."


Is that not what the note means? Thanks.​
maybe..... but it does say the abs max rating is 30V so it's never smart to exceed that. You MIGHT get away with it for a one off, since the parts have a wide distribution of breakdown voltage and they set the limit at the lowest edge of the distribution. Would not be a good design to go into production with, but you might get lucky on one. The odds are good.
 

Thread Starter

tracecom

Joined Apr 16, 2010
3,944
maybe..... but it does say the abs max rating is 30V so it's never smart to exceed that. You MIGHT get away with it for a one off, since the parts have a wide distribution of breakdown voltage and they set the limit at the lowest edge of the distribution. Would not be a good design to go into production with, but you might get lucky on one. The odds are good.
Thanks. The data from NTE on this device is often contradictory. For example, some places it says the drop out voltage is .5 V and other places it says 1.3 V. Some places it list the minimum input voltage as 21.5 V, which makes no sense to me for a 24 V regulator. Not very good documentation!
 

SgtWookie

Joined Jul 17, 2007
22,230
As Bertus mentions, the LT1185 would be a far better choice.
The LM317 would be a lot cheaper, but it will have a 1.7v dropout voltage @ 500mA - and that will increase with an increase in the output current. However, you might use one of the pass transistor schemes as shown in the application notes in the National Semiconductor version of the datasheet for the LM117/LM317: http://www.ti.com/lit/ds/symlink/lm117.pdf
 

bertus

Joined Apr 5, 2008
22,270
Hello,

From the description on the farnell website:


  • IC, V REG, LDO ADJ, 1185, TO-220-5
  • Primary Input Voltage: 35V
  • Output Voltage Adjustable Range: 2.5V to 25V
  • Dropout Voltage Vdo: 750mV
  • No. of Pins: 5
  • Output Current: 3A
  • Voltage Regulator Case Style: TO-220
  • Operating Temperature Range: 0°C to +125°C
  • SVHC: No SVHC (18-Jun-2012)
  • Adjustable Output Voltage Max: 25V
  • Adjustable Output Voltage Min: 2.5V
  • Base Number: 1185
  • IC Generic Number: 1185
  • Input Voltage Max: 35V
  • Input Voltage Min: 3.25V
  • No. of Outputs: 1
  • Operating Temperature Max: 125°C
  • Operating Temperature Min: 0°C
  • Operating Voltage Tolerance +: 1%
  • Output Current Max: 3A
  • Output Voltage: 30V
  • Output Voltage Max: 25V
  • Output Voltage Min: 2.5V
  • Package / Case: TO-220
  • Termination Type: Through Hole
  • Voltage Regulator Type: Positive Adjustable
Bertus
 

bountyhunter

Joined Sep 7, 2009
2,512
Here's the schematic for the 1185 on the front page of the data sheet, it's definitely a negative. The 1085 are the positive series but they only go up to 30V. http://cds.linear.com/docs/Datasheet/108345fg.pdf


LT's claim regarding the 1185 is:

It can be used as
a positive output regulator with floating input
or as a
standard negative regulator with grounded input.
They are just trying to pretend it's a positive regulator to sell more parts, but it's not.
 

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Thread Starter

tracecom

Joined Apr 16, 2010
3,944
If I preload the input with a 330 Ω load, the voltage drops to 29.1. That would keep the input voltage below the maximum for the NTE1956. Except for continually wasting 2.56 watts, what's wrong with that?
 

bountyhunter

Joined Sep 7, 2009
2,512
If I preload the input with a 330 Ω load, the voltage drops to 29.1. That would keep the input voltage below the maximum for the NTE1956. Except for continually wasting 2.56 watts, what's wrong with that?
Nothing, as long as the input voltage doesn't drop too low when the full load is put on the regulator output.
 
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