Comparator with Wide Common Mode Range...

[Ricketty C]

Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Pimpom]

On 7/18/2020 9:19 PM, Ricketty C wrote:

Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

 

[Ricketty C]

On Saturday, July 18, 2020 at 12:51:25 PM UTC-4, Pimpom wrote:

On 7/18/2020 9:19 PM, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3..3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

The input common mode range pf the LM393 is 0 to Vcc-2. That\'s my problem. On a 3.3 volt supply it only leaves 1.3 volts of working range.

No need for speed, most parameters are relaxed. I\'d like to keep the Iq to less than 150-200 uA. We have 15 volts in the design, so I\'d like to have a part that can be used directly on that voltage if needed. These comparators are mostly detecting thresholds to sound alarms or the one I\'m using now shuts off power to the motor. High precision is not really required.

I found the TLV1702A which meets all the criteria. But it\'s a bit pricey at $0.80 in quantity. The LM393 are two for a quarter.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 12:51:25 PM UTC-4, Pimpom wrote:

On 7/18/2020 9:19 PM, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3..3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

The input common mode range pf the LM393 is 0 to Vcc-2. That\'s my problem. On a 3.3 volt supply it only leaves 1.3 volts of working range.

No need for speed, most parameters are relaxed. I\'d like to keep the Iq to less than 150-200 uA. We have 15 volts in the design, so I\'d like to have a part that can be used directly on that voltage if needed. These comparators are mostly detecting thresholds to sound alarms or the one I\'m using now shuts off power to the motor. High precision is not really required.

I found the TLV1702A which meets all the criteria. But it\'s a bit pricey at $0.80 in quantity. The LM393 are two for a quarter.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 12:51:25 PM UTC-4, Pimpom wrote:

On 7/18/2020 9:19 PM, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3..3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

The input common mode range pf the LM393 is 0 to Vcc-2. That\'s my problem. On a 3.3 volt supply it only leaves 1.3 volts of working range.

No need for speed, most parameters are relaxed. I\'d like to keep the Iq to less than 150-200 uA. We have 15 volts in the design, so I\'d like to have a part that can be used directly on that voltage if needed. These comparators are mostly detecting thresholds to sound alarms or the one I\'m using now shuts off power to the motor. High precision is not really required.

I found the TLV1702A which meets all the criteria. But it\'s a bit pricey at $0.80 in quantity. The LM393 are two for a quarter.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 1:11:05 PM UTC-4, Ricketty C wrote:

On Saturday, July 18, 2020 at 12:51:25 PM UTC-4, Pimpom wrote:
On 7/18/2020 9:19 PM, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

The input common mode range pf the LM393 is 0 to Vcc-2. That\'s my problem. On a 3.3 volt supply it only leaves 1.3 volts of working range.

No need for speed, most parameters are relaxed. I\'d like to keep the Iq to less than 150-200 uA. We have 15 volts in the design, so I\'d like to have a part that can be used directly on that voltage if needed. These comparators are mostly detecting thresholds to sound alarms or the one I\'m using now shuts off power to the motor. High precision is not really required.

I found the TLV1702A which meets all the criteria. But it\'s a bit pricey at $0.80 in quantity. The LM393 are two for a quarter.

I also found the LMC6772 which is about $1.

There just don\'t seem to be a lot of choices. I\'m surprised.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 1:11:05 PM UTC-4, Ricketty C wrote:

On Saturday, July 18, 2020 at 12:51:25 PM UTC-4, Pimpom wrote:
On 7/18/2020 9:19 PM, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

The LM393 is rated down to 2V. Anyway, does it have to be fast?
How about a low voltage RR opamp?

The input common mode range pf the LM393 is 0 to Vcc-2. That\'s my problem. On a 3.3 volt supply it only leaves 1.3 volts of working range.

No need for speed, most parameters are relaxed. I\'d like to keep the Iq to less than 150-200 uA. We have 15 volts in the design, so I\'d like to have a part that can be used directly on that voltage if needed. These comparators are mostly detecting thresholds to sound alarms or the one I\'m using now shuts off power to the motor. High precision is not really required.

I found the TLV1702A which meets all the criteria. But it\'s a bit pricey at $0.80 in quantity. The LM393 are two for a quarter.

I also found the LMC6772 which is about $1.

There just don\'t seem to be a lot of choices. I\'m surprised.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[sea moss]

On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:

Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

 

[Ricketty C]

On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:

On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3..3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:

On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3..3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[sea moss]

On Saturday, July 18, 2020 at 3:50:07 PM UTC-7, Ricketty C wrote:

On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:
On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

OK, I searched on Digikey for open-collector duals, sorted by price. One of the first without \"393\" or \"2903\" in its part number is BU7253. maybe it will work.
https://www.digikey.com/product-detail/en/rohm-semiconductor/BU7253F-E2/BU7253F-E2CT-ND/5720201

 

[sea moss]

On Saturday, July 18, 2020 at 3:50:07 PM UTC-7, Ricketty C wrote:

On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:
On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

OK, I searched on Digikey for open-collector duals, sorted by price. One of the first without \"393\" or \"2903\" in its part number is BU7253. maybe it will work.
https://www.digikey.com/product-detail/en/rohm-semiconductor/BU7253F-E2/BU7253F-E2CT-ND/5720201

 

[Ricketty C]

On Saturday, July 18, 2020 at 7:00:32 PM UTC-4, sea moss wrote:

On Saturday, July 18, 2020 at 3:50:07 PM UTC-7, Ricketty C wrote:
On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:
On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

OK, I searched on Digikey for open-collector duals, sorted by price. One of the first without \"393\" or \"2903\" in its part number is BU7253. maybe it will work.
https://www.digikey.com/product-detail/en/rohm-semiconductor/BU7253F-E2/BU7253F-E2CT-ND/5720201

Thanks for trying. Digikey was the first place I looked after making the first post. So I was able to exclude parts that use too much power, don\'t have the range of Vcc and don\'t have the right output type. Combine with the preferred package (and only selecting reels so each part doesn\'t show up five times) drops the list to 41 devices, mostly flavors of the 393. The LM393A has higher idle current so is excluded, but there are plenty of other variations on the theme that show up but still have the common mode range limitations.

The BU7253 is a good part, but with 15 volts on the board I want to use a part that can be used with that as Vcc/Vdd. So the BU7253 is out. Otherwise a good fit.

Thanks again. I suppose if Digikey and Mouser don\'t have anything better I know what my options are. I just thought I\'d ask if there was something I\'m missing.

I\'m so glad Digikey and Mouser have their searching capabilities. It really makes a big difference in doing this work. Digikey is really good about cleaning up problems in their data base. I\'d say I report issues to them two or three times a year and they are always quick to respond and sound appreciative. Just last week I found reed sensors that had the wire termination descriptions messed up. In one or two days they got back to me that they fixed the one I reported and all the others in that product line. They do a great job.

But not everything you want to select on is in their database. The common mode range is one of the things they don\'t make searchable. Fortunately not many comparators have that issue.

The LM393A is a great chip in many ways. Even when powered from 5V you can yank the inputs and output to 36V without damage. That\'s nice. Just don\'t expect it to function properly while both inputs are above 3 volts.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Saturday, July 18, 2020 at 7:00:32 PM UTC-4, sea moss wrote:

On Saturday, July 18, 2020 at 3:50:07 PM UTC-7, Ricketty C wrote:
On Saturday, July 18, 2020 at 4:15:35 PM UTC-4, sea moss wrote:
On Saturday, July 18, 2020 at 8:49:10 AM UTC-7, Ricketty C wrote:
Selecting parts can be a PITA. Comparators have a LOT of very detailed specs that all need to be checked. I have been using an LM393A that is already in use on the board for some new circuits. I just noticed the common mode range is only up to Vcc-2. With a recent change to the MCU, the power supply for the comparators and MCU was changed to 3.3 volts. So that would make the common mode range 0 to 1.3V. Also, the device is not rated for Vcc below 5V.

I could have all the power pins changed to 5V which is still on the board for some sensors, but then both voltages have to be routed to the comparators which makes the routing harder. Also the power consumption is around 1 mA which is more than it should be in this design. It will be easier to just toss the LM393A and find another part that is lower power, works on 3.3 volts Vcc and works with a large common mode range. Finally, it has to be in stock at various distributors so 10,000 can be ordered without delay and a low price is always good.

I\'m sick of digging through digikey looking for parts. Any suggestions? What\'s your favorite comparator for general work?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Been using TLV1805 recently. $0.85 on Digikey which might be too high for what you\'re looking for.

Thanks for the suggestion. That one is not open drain which is required since most of them are being used as window comparators with the wire ORed outputs. It\'s also a single which is not a show stopper, but makes it more expensive.

OK, I searched on Digikey for open-collector duals, sorted by price. One of the first without \"393\" or \"2903\" in its part number is BU7253. maybe it will work.
https://www.digikey.com/product-detail/en/rohm-semiconductor/BU7253F-E2/BU7253F-E2CT-ND/5720201

Thanks for trying. Digikey was the first place I looked after making the first post. So I was able to exclude parts that use too much power, don\'t have the range of Vcc and don\'t have the right output type. Combine with the preferred package (and only selecting reels so each part doesn\'t show up five times) drops the list to 41 devices, mostly flavors of the 393. The LM393A has higher idle current so is excluded, but there are plenty of other variations on the theme that show up but still have the common mode range limitations.

The BU7253 is a good part, but with 15 volts on the board I want to use a part that can be used with that as Vcc/Vdd. So the BU7253 is out. Otherwise a good fit.

Thanks again. I suppose if Digikey and Mouser don\'t have anything better I know what my options are. I just thought I\'d ask if there was something I\'m missing.

I\'m so glad Digikey and Mouser have their searching capabilities. It really makes a big difference in doing this work. Digikey is really good about cleaning up problems in their data base. I\'d say I report issues to them two or three times a year and they are always quick to respond and sound appreciative. Just last week I found reed sensors that had the wire termination descriptions messed up. In one or two days they got back to me that they fixed the one I reported and all the others in that product line. They do a great job.

But not everything you want to select on is in their database. The common mode range is one of the things they don\'t make searchable. Fortunately not many comparators have that issue.

The LM393A is a great chip in many ways. Even when powered from 5V you can yank the inputs and output to 36V without damage. That\'s nice. Just don\'t expect it to function properly while both inputs are above 3 volts.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Piotr Wyderski]

Ricketty C wrote:

> Selecting parts can be a PITA.

Indeed, try to select a low I_DSS power MOSFET (down to the nanoamp
level), and you will quickly learn what a royal PITA is.

> What\'s your favorite comparator for general work?

I am unable to define what general work would be in my case. Every
application needs something unique. I have just deployed the LT1716 --
looks pricey, but it has turned out to be the most cost-effective
solution in a low volume design.

Best regard, Piotr

 

[Piotr Wyderski]

Ricketty C wrote:

> Selecting parts can be a PITA.

Indeed, try to select a low I_DSS power MOSFET (down to the nanoamp
level), and you will quickly learn what a royal PITA is.

> What\'s your favorite comparator for general work?

I am unable to define what general work would be in my case. Every
application needs something unique. I have just deployed the LT1716 --
looks pricey, but it has turned out to be the most cost-effective
solution in a low volume design.

Best regard, Piotr

 

[Ricketty C]

On Sunday, July 19, 2020 at 5:49:31 PM UTC-4, Piotr Wyderski wrote:

Ricketty C wrote:

Selecting parts can be a PITA.

Indeed, try to select a low I_DSS power MOSFET (down to the nanoamp
level), and you will quickly learn what a royal PITA is.

What\'s your favorite comparator for general work?

I am unable to define what general work would be in my case. Every
application needs something unique. I have just deployed the LT1716 --
looks pricey, but it has turned out to be the most cost-effective
solution in a low volume design.

Best regard, Piotr

A buck and change is definitely pricey compared to $0.12 for a dual LM393. We were running them on the 5 volt rail, but we changed to a 3.3V processor and moved them to the 3.3V rail. They are comparing the same analog signals that go to the alarms. If given enough thought I\'m sure we could make the cheap part work but it\'s a LOT of I\'s to cross and T\'s to dot to make sure all the voltages work out.

I\'m not actually the guy driving the schematic entry, but he seems to be a lot busier than I am and misses lots of details. He\'s the guy who didn\'t remove the thermal breaks on the the thermal pads of the 5V regulator and motor controller. Many other details missed in the first two sets of boards.

How many of the LT1716 is your board using? This design has eight comparators, so the cost adds up fast.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Sunday, July 19, 2020 at 5:49:31 PM UTC-4, Piotr Wyderski wrote:

Ricketty C wrote:

Selecting parts can be a PITA.

Indeed, try to select a low I_DSS power MOSFET (down to the nanoamp
level), and you will quickly learn what a royal PITA is.

What\'s your favorite comparator for general work?

I am unable to define what general work would be in my case. Every
application needs something unique. I have just deployed the LT1716 --
looks pricey, but it has turned out to be the most cost-effective
solution in a low volume design.

Best regard, Piotr

A buck and change is definitely pricey compared to $0.12 for a dual LM393. We were running them on the 5 volt rail, but we changed to a 3.3V processor and moved them to the 3.3V rail. They are comparing the same analog signals that go to the alarms. If given enough thought I\'m sure we could make the cheap part work but it\'s a LOT of I\'s to cross and T\'s to dot to make sure all the voltages work out.

I\'m not actually the guy driving the schematic entry, but he seems to be a lot busier than I am and misses lots of details. He\'s the guy who didn\'t remove the thermal breaks on the the thermal pads of the 5V regulator and motor controller. Many other details missed in the first two sets of boards.

How many of the LT1716 is your board using? This design has eight comparators, so the cost adds up fast.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[Piotr Wyderski]

Ricketty C wrote:

> A buck and change is definitely pricey compared to $0.12 for a dual LM393.

It depends. In volume it indeed is; small scale specialistic runs call
for using \"how many minutes of your work a buck is\" as a metric.
Engineers are an expensive resource. Hard to find the optimum.

> How many of the LT1716 is your board using?

Exactly one, just for this very specific task. LM393 elsewhere.

Best regards, Piotr

 

[Piotr Wyderski]

Ricketty C wrote:

> A buck and change is definitely pricey compared to $0.12 for a dual LM393.

It depends. In volume it indeed is; small scale specialistic runs call
for using \"how many minutes of your work a buck is\" as a metric.
Engineers are an expensive resource. Hard to find the optimum.

> How many of the LT1716 is your board using?

Exactly one, just for this very specific task. LM393 elsewhere.

Best regards, Piotr