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Opinions on what I've come up with for a 12v-5v automotive circuit?
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Is this a solid solution for a automotive 12v to 5v circuit to power an ATTINY? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary some places won't even talk about it.
From recommendations, scouring datasheets and lots of googling this is what I've come up with so far. It will be placed inside the cabin of a vehicle (not the engine bay) and everything selected is AEC qualified but I don't know if it will actually work as intended or if I don't have enough protection (the ESD/TVS should kill most of the automotive nightmare right?), the other part of my circuit (not shown) is an ATTINY that will operate some auxiliary lighting.
Please don't say just use a usb 12v adapter because I'm not trying to cobble multiple boards together hence trying to nail this circuit so I can include it on my devices pcb, but other than that please school me if I have anything incorrect.
**also note the resistor for the LED is incorrectly rated in the schematic, its supposed to be 150Ohm like the component list. thanks @Oldfart
Components:
- D1: SMA6J5.0CA-TR
- IC1: ZLDO1117QK50TC
- C1: C1210X106M3RACAUTO 10uF 25V
- C2: TPSC107K010R0150 100uF 10v
-- optional, for testing (not really important) --
- R1: ERJ-U06J151V (150Ohm)
- LED1: 150080GS75000
voltage-regulator automotive circuit-protection
asked 2 hours ago
dawm
64
 |Â
show 2 more comments
up vote
1
down vote
favorite
Is this a solid solution for a automotive 12v to 5v circuit to power an ATTINY? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary some places won't even talk about it.
From recommendations, scouring datasheets and lots of googling this is what I've come up with so far. It will be placed inside the cabin of a vehicle (not the engine bay) and everything selected is AEC qualified but I don't know if it will actually work as intended or if I don't have enough protection (the ESD/TVS should kill most of the automotive nightmare right?), the other part of my circuit (not shown) is an ATTINY that will operate some auxiliary lighting.
Please don't say just use a usb 12v adapter because I'm not trying to cobble multiple boards together hence trying to nail this circuit so I can include it on my devices pcb, but other than that please school me if I have anything incorrect.
**also note the resistor for the LED is incorrectly rated in the schematic, its supposed to be 150Ohm like the component list. thanks @Oldfart
Components:
- D1: SMA6J5.0CA-TR
- IC1: ZLDO1117QK50TC
- C1: C1210X106M3RACAUTO 10uF 25V
- C2: TPSC107K010R0150 100uF 10v
-- optional, for testing (not really important) --
- R1: ERJ-U06J151V (150Ohm)
- LED1: 150080GS75000
voltage-regulator automotive circuit-protection
asked 2 hours ago
dawm
64
It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago
 |Â
show 2 more comments
up vote
1
down vote
favorite
up vote
1
down vote
favorite
Is this a solid solution for a automotive 12v to 5v circuit to power an ATTINY? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary some places won't even talk about it.
From recommendations, scouring datasheets and lots of googling this is what I've come up with so far. It will be placed inside the cabin of a vehicle (not the engine bay) and everything selected is AEC qualified but I don't know if it will actually work as intended or if I don't have enough protection (the ESD/TVS should kill most of the automotive nightmare right?), the other part of my circuit (not shown) is an ATTINY that will operate some auxiliary lighting.
Please don't say just use a usb 12v adapter because I'm not trying to cobble multiple boards together hence trying to nail this circuit so I can include it on my devices pcb, but other than that please school me if I have anything incorrect.
**also note the resistor for the LED is incorrectly rated in the schematic, its supposed to be 150Ohm like the component list. thanks @Oldfart
Components:
- D1: SMA6J5.0CA-TR
- IC1: ZLDO1117QK50TC
- C1: C1210X106M3RACAUTO 10uF 25V
- C2: TPSC107K010R0150 100uF 10v
-- optional, for testing (not really important) --
- R1: ERJ-U06J151V (150Ohm)
- LED1: 150080GS75000
voltage-regulator automotive circuit-protection
asked 2 hours ago
dawm
64
Is this a solid solution for a automotive 12v to 5v circuit to power an ATTINY? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary some places won't even talk about it.
From recommendations, scouring datasheets and lots of googling this is what I've come up with so far. It will be placed inside the cabin of a vehicle (not the engine bay) and everything selected is AEC qualified but I don't know if it will actually work as intended or if I don't have enough protection (the ESD/TVS should kill most of the automotive nightmare right?), the other part of my circuit (not shown) is an ATTINY that will operate some auxiliary lighting.
Please don't say just use a usb 12v adapter because I'm not trying to cobble multiple boards together hence trying to nail this circuit so I can include it on my devices pcb, but other than that please school me if I have anything incorrect.
**also note the resistor for the LED is incorrectly rated in the schematic, its supposed to be 150Ohm like the component list. thanks @Oldfart
Components:
- D1: SMA6J5.0CA-TR
- IC1: ZLDO1117QK50TC
- C1: C1210X106M3RACAUTO 10uF 25V
- C2: TPSC107K010R0150 100uF 10v
-- optional, for testing (not really important) --
- R1: ERJ-U06J151V (150Ohm)
- LED1: 150080GS75000
voltage-regulator automotive circuit-protection
voltage-regulator automotive circuit-protection
asked 2 hours ago
dawm
64
asked 2 hours ago
dawm
64
edited 1 hour ago
asked 2 hours ago
dawm
64
asked 2 hours ago
dawm
64
asked 2 hours ago
dawm
64
64
It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago
 |Â
show 2 more comments
It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago
It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago
 |Â
show 2 more comments
3 Answers
3
active
oldest
votes
up vote
2
down vote
You specified a current draw of 800mA. The voltage drop is 12-5=7V thus the regulator will consume 0.8*7=5.6 Watts. That will likely burn your regulator from the board.
Even if you take a different type and a heat sink, you don't want a big heat source in your car.
I strongly suggest you use a ready-made 5V switching regulator. They come in a bit larger TO220 housing.
answered 1 hour ago
Oldfart
7,1032723
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
add a comment |Â
up vote
1
down vote
If you must use a linear regulator (Oldfart is right about the unwanted dissipation), then you don't need a LDO. LDO's withstand maybe 20V input voltage; the standard 7805 is rated at 35V, which for automotive applications is desirable. I would also suggest a fuse on the input; if this is undesirable, then possibly a 1-ohm 1W resistor to take the edge off a spike. Finally, a solid ground connection is essential.
answered 1 hour ago
henros
41023
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
add a comment |Â
up vote
0
down vote
I would use unidirectional TVS at the input so that negative spike goes through with minimal residual voltage.
Also note that TVS has to protect 12V input which can be also 15V in normal conditions. You have choosen 5V TVS, which is wrong. Use a SMA6J18A 18V.
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
add a comment |Â
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
You specified a current draw of 800mA. The voltage drop is 12-5=7V thus the regulator will consume 0.8*7=5.6 Watts. That will likely burn your regulator from the board.
Even if you take a different type and a heat sink, you don't want a big heat source in your car.
I strongly suggest you use a ready-made 5V switching regulator. They come in a bit larger TO220 housing.
answered 1 hour ago
Oldfart
7,1032723
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
add a comment |Â
up vote
2
down vote
You specified a current draw of 800mA. The voltage drop is 12-5=7V thus the regulator will consume 0.8*7=5.6 Watts. That will likely burn your regulator from the board.
Even if you take a different type and a heat sink, you don't want a big heat source in your car.
I strongly suggest you use a ready-made 5V switching regulator. They come in a bit larger TO220 housing.
answered 1 hour ago
Oldfart
7,1032723
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
add a comment |Â
up vote
2
down vote
up vote
2
down vote
You specified a current draw of 800mA. The voltage drop is 12-5=7V thus the regulator will consume 0.8*7=5.6 Watts. That will likely burn your regulator from the board.
Even if you take a different type and a heat sink, you don't want a big heat source in your car.
I strongly suggest you use a ready-made 5V switching regulator. They come in a bit larger TO220 housing.
answered 1 hour ago
Oldfart
7,1032723
You specified a current draw of 800mA. The voltage drop is 12-5=7V thus the regulator will consume 0.8*7=5.6 Watts. That will likely burn your regulator from the board.
Even if you take a different type and a heat sink, you don't want a big heat source in your car.
I strongly suggest you use a ready-made 5V switching regulator. They come in a bit larger TO220 housing.
answered 1 hour ago
Oldfart
7,1032723
answered 1 hour ago
Oldfart
7,1032723
answered 1 hour ago
Oldfart
7,1032723
answered 1 hour ago
Oldfart
7,1032723
7,1032723
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
add a comment |Â
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
One of my earlier ideas was with a switching reg but the extra components just to drive it properly took up a lot of real estate on the board design (unless I never came across the one pictured that is all in one?), a friend of mine has been using the AZ1117CH-5.0TRG1 which is the non-automotive version of the ZLDO1117 in a similar application (used on ATVs and circle track cars) with no heat issues (claims it doesn't even get warm) but his circuit lacks the protection i'm trying to figure out.
– dawm
1 hour ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
All you do is add the protection to the regulator, just as you did with the ZLDO1117QK50TC. See it as a drop-in replacement for the ZLDO1117QK50TC
– Oldfart
55 mins ago
add a comment |Â
up vote
1
down vote
If you must use a linear regulator (Oldfart is right about the unwanted dissipation), then you don't need a LDO. LDO's withstand maybe 20V input voltage; the standard 7805 is rated at 35V, which for automotive applications is desirable. I would also suggest a fuse on the input; if this is undesirable, then possibly a 1-ohm 1W resistor to take the edge off a spike. Finally, a solid ground connection is essential.
answered 1 hour ago
henros
41023
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
add a comment |Â
up vote
1
down vote
If you must use a linear regulator (Oldfart is right about the unwanted dissipation), then you don't need a LDO. LDO's withstand maybe 20V input voltage; the standard 7805 is rated at 35V, which for automotive applications is desirable. I would also suggest a fuse on the input; if this is undesirable, then possibly a 1-ohm 1W resistor to take the edge off a spike. Finally, a solid ground connection is essential.
answered 1 hour ago
henros
41023
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
add a comment |Â
up vote
1
down vote
up vote
1
down vote
If you must use a linear regulator (Oldfart is right about the unwanted dissipation), then you don't need a LDO. LDO's withstand maybe 20V input voltage; the standard 7805 is rated at 35V, which for automotive applications is desirable. I would also suggest a fuse on the input; if this is undesirable, then possibly a 1-ohm 1W resistor to take the edge off a spike. Finally, a solid ground connection is essential.
answered 1 hour ago
henros
41023
If you must use a linear regulator (Oldfart is right about the unwanted dissipation), then you don't need a LDO. LDO's withstand maybe 20V input voltage; the standard 7805 is rated at 35V, which for automotive applications is desirable. I would also suggest a fuse on the input; if this is undesirable, then possibly a 1-ohm 1W resistor to take the edge off a spike. Finally, a solid ground connection is essential.
answered 1 hour ago
henros
41023
answered 1 hour ago
henros
41023
answered 1 hour ago
henros
41023
answered 1 hour ago
henros
41023
41023
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
add a comment |Â
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
a fuse will be added, just haven't looked into what size/type..etc I'm going to require. I thought that using the TVS would help reduce the chance of higher voltages reaching the LDO.
– dawm
1 hour ago
add a comment |Â
up vote
0
down vote
I would use unidirectional TVS at the input so that negative spike goes through with minimal residual voltage.
Also note that TVS has to protect 12V input which can be also 15V in normal conditions. You have choosen 5V TVS, which is wrong. Use a SMA6J18A 18V.
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
add a comment |Â
up vote
0
down vote
I would use unidirectional TVS at the input so that negative spike goes through with minimal residual voltage.
Also note that TVS has to protect 12V input which can be also 15V in normal conditions. You have choosen 5V TVS, which is wrong. Use a SMA6J18A 18V.
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
add a comment |Â
up vote
0
down vote
up vote
0
down vote
I would use unidirectional TVS at the input so that negative spike goes through with minimal residual voltage.
Also note that TVS has to protect 12V input which can be also 15V in normal conditions. You have choosen 5V TVS, which is wrong. Use a SMA6J18A 18V.
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
I would use unidirectional TVS at the input so that negative spike goes through with minimal residual voltage.
Also note that TVS has to protect 12V input which can be also 15V in normal conditions. You have choosen 5V TVS, which is wrong. Use a SMA6J18A 18V.
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
answered 2 hours ago
Marko BurÅ¡iÄÂ
9,3942812
9,3942812
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
add a comment |Â
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Sorry I'm still confused on how TVS diodes operate, using the SMA6J18A with 18V working and clamping at 28.3V to 33.2V that seems to exceed protecting the regulator from higher than needed voltage. Would the TPD1E10B09QDPYRQ1 be better suited?, its working voltage is 9V and clamping is 13V, with the ZLDO1117's SOA curve peak being 10V for 1A that would put me in the SOA during clamping and normal operation right? Datasheet says Vin -Vout on the SOA curve chart, 9-5 = 4V, 13-5 = 8V for a safe 5V 1A output.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
Or do I completely misunderstand TVS diodes completely? Does current flow past a TVS untouched at the working voltage, then starts getting clamped when it goes over the breakdown voltage? That's how I understood it, that is why I picked the SMA6J5.0CA-TR, I thought it would allow at least 5V through it and start clamping it to 9V-13.4V after it reached the breakdown.
– dawm
1 hour ago
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It would be better if you specified the expected current draw. From your text circuit get about (5-1.2)/95 = ~40mA. (B.T.W Your text says 150 ohm, your diagram says 95 ohm...)
– Oldfart
1 hour ago
There are "cigarette lighter" adapters available with selectable voltage outputs...
– Solar Mike
1 hour ago
@Oldfart eek! I changed LEDs and guess I missed updating the schematic, the schematic should be 150ohm just as the component list. The circuit on the other end of the regulated 5v 1A shouldn't be more than 0.8A
– dawm
1 hour ago
@SolarMike yeah.. clearly you skipped reading the last sentence.
– dawm
1 hour ago
They come in a complete package - not "multiple boards" and tend to be very compact and efficient providing a clean supply, and I found the one I bought has been perfect for the multiple uses I have given it.
– Solar Mike
1 hour ago