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Q&A Converting 5V to ±12V

I would like to convert 5V rail I have on PCB to ±12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirem...

2 answers  ·  posted 5mo ago by 2kind‭  ·  last activity 5mo ago by H_H‭

Question chargepump
#4: Post edited by user avatar Nick Alexeev‭ · 2023-12-03T14:58:32Z (5 months ago)
beautification
  • Converting 5V to +/-12V
  • Converting 5V to ±12V
  • I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - +-12V rail shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it + it is not within acceptable voltage range
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V(to be found) and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
  • I would like to convert 5V rail I have on PCB to ±12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the ±12V rails is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within ±5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - ±12V rails shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to ±10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it + it is not within acceptable voltage range
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to ±12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V(to be found) and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to ±12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
#3: Post edited by user avatar 2kind‭ · 2023-12-03T13:07:08Z (5 months ago)
  • I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - +-12V rail shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it + it is not within acceptable voltage range
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
  • I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - +-12V rail shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it + it is not within acceptable voltage range
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V(to be found) and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
#2: Post edited by user avatar 2kind‭ · 2023-12-03T13:06:38Z (5 months ago)
  • I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - +-12V rail shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
  • I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:
  • - +12V and -12V rail shall serve for powering opamp only
  • - Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
  • - +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
  • - +-12V rail shall be capable of providing no more than 5mA of current
  • - There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps
  • Everything mentioned so far asks for a charge pump, the way how I see it.
  • Some options I found:
  • - Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it + it is not within acceptable voltage range
  • - Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well.
  • - Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
  • - Use 2x dedicated charge pumps - 5V to 12V and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))
  • Questions:
  • - Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
  • - Are there some other way how to do this which I have not covered?
#1: Initial revision by user avatar 2kind‭ · 2023-12-03T13:05:26Z (5 months ago) 
Converting 5V to +/-12V 
I would like to convert 5V rail I have on PCB to +-12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirements:

- +12V and -12V rail shall serve for powering opamp only
- Ripple of the +-12V rail is not of a concern, as the opamp is used in comparator mode(something I would like to swap with the comparator in the future but keeping it for now in the design)
- +12V and -12V rail should be within +-5% ie. acceptable voltage range of rail is (11.4V, 12.6V) both for positive and negative
- +-12V rail shall be capable of providing no more than 5mA of current
- There is a 3V3 powered uC on board with available PWM output which could be used for charge pumps


Everything mentioned so far asks for a charge pump, the way how I see it. 

Some options I found:
- Maxim/Analog have +5V to +-10V converter IC [MAX680/681](https://pdfserv.maximintegrated.com/en/ds/MAX680-MAX681.pdf), with VCC max of 6.2V and V+/V- being +12V/-12V in absolute maximum ratings, I feel like stretching it
- Do a DIY charge pump using PWM uC output - haven't done this earlier so if someone could explain a concept with jellybean components that would be a useful answer as well. 
- Use a standalone 5V to +-12V converter like a [Murata one](https://eu.mouser.com/datasheet/2/281/1/kdc_nmv-2941136.pdf)
- Use 2x dedicated charge pumps - 5V to 12V and 12V to -12V([TC1044S](https://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf))

Questions:
- Could charge pump 5V to +-12V be implemented with 1xPWM output from the uC, how would the circuit look like and what would be the component values(capacitor size, diodes, etc.)?
- Are there some other way how to do this which I have not covered?
chargepump