stynx
Well-known member
I have checked the core voltage of my dual 200Mhz card and found that there was about 2.8-2.9V on the output pin of the LT1580.
Checking the resistors (R1/R2) in the data sheet*, there was a recommendation of 110Ω for both resistors when 2.5V is to be set.
The resistors on the card were 118Ω for R2 and 100Ω for R1 on both LDO for the two processors. This would result in 2.725V core voltage instead of 2.5V (recommended for 604e CPUs). The higher measured voltage may be due to the measure point being directly on the LDO output, essentially measuring the voltage between the LDO-output and common ground.
I then swapped the 4 resistors for 110Ω resistors and checked the LDO-output.
It is still too high with about 2.75V and i am a bit stumped why that would be?
I measured other LDOs used on 604e-cards and they typically use LT1580-2.5 Versions, which has a fixed output of 2.5V.
This i could measure as about 2.6V, where some cards were having on point 2.5V but most were around 2.6V.
The card seems to run a bit cooler now and has shown no problems so far (rendering C4D scenes).
Good cooling is still needed, since the card will heat up a lot when it just sits there.
*(the data sheet is attached)
Does anyone have an idea, why the LDO output on the Dual 200MHz card is so high?
-Jonas
Checking the resistors (R1/R2) in the data sheet*, there was a recommendation of 110Ω for both resistors when 2.5V is to be set.
The resistors on the card were 118Ω for R2 and 100Ω for R1 on both LDO for the two processors. This would result in 2.725V core voltage instead of 2.5V (recommended for 604e CPUs). The higher measured voltage may be due to the measure point being directly on the LDO output, essentially measuring the voltage between the LDO-output and common ground.
I then swapped the 4 resistors for 110Ω resistors and checked the LDO-output.
It is still too high with about 2.75V and i am a bit stumped why that would be?
I measured other LDOs used on 604e-cards and they typically use LT1580-2.5 Versions, which has a fixed output of 2.5V.
This i could measure as about 2.6V, where some cards were having on point 2.5V but most were around 2.6V.
The card seems to run a bit cooler now and has shown no problems so far (rendering C4D scenes).
Good cooling is still needed, since the card will heat up a lot when it just sits there.
*(the data sheet is attached)
Does anyone have an idea, why the LDO output on the Dual 200MHz card is so high?
-Jonas