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max1044a

Started by 9Lives, December 26, 2011, 02:44:45 AM

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Jeff B.

Just a few random observations about charge pumps.

The LT1054 is a great replacement for for the 1044, it accepts up to 15V for the input voltage and has a current capability of 100mA.
7660 have a maximum input voltage of 12V I think.
7661 and 7662 chips will accept up to around 20-22V at their input.

When you double the voltage you halve the current.  For example using the LT1054 as a voltage doubler reduces it's available current to 50mA.  This is important because if you're using a charge pump with a low maximum output current (MAX1044) at 18V in a circuit with a high current draw you may run into problems.

Charge pumps can be paralleled for increased current capabilities.  Using 2 LT1054 chips would give you 200mA at 9V and 100mA at 18V.  I plan to try this when I box up my Warhead Vibe build to see if it makes any difference over a single charge pump version when dialing it in.

gtr2

Quote from: Jeff B. on January 23, 2012, 06:28:26 PM
Just a few random observations about charge pumps.

The LT1054 is a great replacement for for the 1044, it accepts up to 15V for the input voltage and has a current capability of 100mA.
7660 have a maximum input voltage of 12V I think.
7661 and 7662 chips will accept up to around 20-22V at their input.

When you double the voltage you halve the current.  For example using the LT1054 as a voltage doubler reduces it's available current to 50mA.  This is important because if you're using a charge pump with a low maximum output current (MAX1044) at 18V in a circuit with a high current draw you may run into problems.

Charge pumps can be paralleled for increased current capabilities.  Using 2 LT1054 chips would give you 200mA at 9V and 100mA at 18V.  I plan to try this when I box up my Warhead Vibe build to see if it makes any difference over a single charge pump version when dialing it in.

Hmm, I neglected to see this until you mentioned it.  It makes complete sense.  At the cost of doubling V you halve the mA.  Nothing comes without a price  :D

Josh
1776 EFFECTS STORE     
Contract PCB designer

stecykmi

Quote from: gtr2 on January 23, 2012, 09:34:39 PM
Quote from: Jeff B. on January 23, 2012, 06:28:26 PM
Just a few random observations about charge pumps.

The LT1054 is a great replacement for for the 1044, it accepts up to 15V for the input voltage and has a current capability of 100mA.
7660 have a maximum input voltage of 12V I think.
7661 and 7662 chips will accept up to around 20-22V at their input.

When you double the voltage you halve the current.  For example using the LT1054 as a voltage doubler reduces it's available current to 50mA.  This is important because if you're using a charge pump with a low maximum output current (MAX1044) at 18V in a circuit with a high current draw you may run into problems.

Charge pumps can be paralleled for increased current capabilities.  Using 2 LT1054 chips would give you 200mA at 9V and 100mA at 18V.  I plan to try this when I box up my Warhead Vibe build to see if it makes any difference over a single charge pump version when dialing it in.

Hmm, I neglected to see this until you mentioned it.  It makes complete sense.  At the cost of doubling V you halve the mA.  Nothing comes without a price  :D

Josh

Actually, this is one of the few cases where you almost get something for free.

these switched capacitor charge pumps operate at very high efficiency, usually in the 90% range, greater than 95% for some operating points (but dropping to ~80% for some "worst case" scenarios). this means you're getting almost as much power out as you are putting in (easily proved with the formula for power, P(in) = IV ~= P(out) = (I/2)(2V)(n) where n is efficiency), and this is quiet rare for most energy conversion methods.

Can you imagine if your car was anywhere close to 90% efficient?

rps-10

I have a pedal with a suspected blown MAX1044 (Snarling Dogs Mold Spore) ...So reading this thread could I simply just drop in one of the ICs mentioned as a replacement, or would I need to check the pinouts etc?

jkokura

Or use a max1044. Smallbear has them.

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
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shawnee

Quote from: rps-10 on January 29, 2012, 07:44:00 PM
I have a pedal with a suspected blown MAX1044 (Snarling Dogs Mold Spore) ...So reading this thread could I simply just drop in one of the ICs mentioned as a replacement, or would I need to check the pinouts etc?
You can use a TC1044 with no changes. A TC1044 may be a good choice because it can take a few more volts on the input than the MAX1044 can take. The LT1054 may require you to remove pin 1 if they have 1 and 8 shorted on the pc board (and they cost 3 times as much) so I wouldn't use one unless you needed it for a higher current draw pedal.

rps-10

Quote from: jkokura on January 29, 2012, 07:47:57 PM
Or use a max1044. Smallbear has them.

Jacob

Could do, but as shawnee's post below your's suggests. My thinking is why replace a fragile part with the same if I am going to take that beast apart. So I may as well go for a more reliable part of the same design to save doing it again in the future.
(I'll solder in a DIL socket too while I'm at it)