G
Guy Macon
- Jan 1, 1970
- 0
Take a look at the following +5DC to -12VDC/-12VDC
voltage multiplier/inverter:
------------o---------O +12VDC OUT
| |
+5VDC IN | | C
O --- -----
| / \ CR
| --- -----
|\| | |
| \ | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/|74HC04 | V
| ---
| / \ CR
--- ---
\ / GND |
V |
o------------ (+8VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o------------ (+4VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o------------ (0VDC)
| |
| |
--- ---
/ \ CR \ / GND
--- V
|\ |
| \ U | | C |
---| O-------| |-------o
| / | | |
|/ 74HC04 |
---
/ \ CR
---
|
|
o-----------| (-4VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o-----------| (-8VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
------------o---------O -12VDC OUT
|
| C
-----
-----
|
|
---
\ / GND
V
(Yes, I know about the noise and poor regulation...)
I haven't worked with these before, and a few questions
come to mind:
DRIVING FREQUENCY:
Is this just a simple matter of making it as fast as
possible while still keeping the gate and diode switching
times at a fraction of a percent? Or are there other
considerations I should be thinking of?
CAPACITOR SIZING
Should the top and bottom C be much larger than the rest?
(They *will* be if I use it to drive a board with bulk
bypass caps on it...) Should the caps on the right be
bigger than the flying caps on the left? How should I
decide how big the flying caps should be?
DRIVING PATTERN:
Assume that the HC inverter is driven by six uP pins, and
that the uP can put out any pattern at any reasonable
frequency. What's the best pattern to drive it with?
Should I switch one gate at a time, rippling upward
through the six gates (in other words, have each driver
be phased 60 degrees (360/6) later than the one
below it)? Or is there a better driving pattern?
voltage multiplier/inverter:
------------o---------O +12VDC OUT
| |
+5VDC IN | | C
O --- -----
| / \ CR
| --- -----
|\| | |
| \ | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/|74HC04 | V
| ---
| / \ CR
--- ---
\ / GND |
V |
o------------ (+8VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o------------ (+4VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o------------ (0VDC)
| |
| |
--- ---
/ \ CR \ / GND
--- V
|\ |
| \ U | | C |
---| O-------| |-------o
| / | | |
|/ 74HC04 |
---
/ \ CR
---
|
|
o-----------| (-4VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
o-----------| (-8VDC)
| |
| | C
--- -----
/ \ CR
--- -----
|\ | |
| \ U | | C | |
---| O-------| |-------o ---
| / | | | \ / GND
|/ 74HC04 | V
---
/ \ CR
---
|
|
------------o---------O -12VDC OUT
|
| C
-----
-----
|
|
---
\ / GND
V
(Yes, I know about the noise and poor regulation...)
I haven't worked with these before, and a few questions
come to mind:
DRIVING FREQUENCY:
Is this just a simple matter of making it as fast as
possible while still keeping the gate and diode switching
times at a fraction of a percent? Or are there other
considerations I should be thinking of?
CAPACITOR SIZING
Should the top and bottom C be much larger than the rest?
(They *will* be if I use it to drive a board with bulk
bypass caps on it...) Should the caps on the right be
bigger than the flying caps on the left? How should I
decide how big the flying caps should be?
DRIVING PATTERN:
Assume that the HC inverter is driven by six uP pins, and
that the uP can put out any pattern at any reasonable
frequency. What's the best pattern to drive it with?
Should I switch one gate at a time, rippling upward
through the six gates (in other words, have each driver
be phased 60 degrees (360/6) later than the one
below it)? Or is there a better driving pattern?