The above video goes away if you are a member and logged in, so log in now!
Modchip current –
Does anyone ever measured the current that a modchip draws???
**not estimated - MEASURED!!**
The current –
I dont measure the current that a chip draw, but Ill help you how to know it.
Its depend on the chip you use, of course. Use a datasheet and look for the current specification. Read the specification for Dynamic States at 30-60 MHz.
You can use a Multimeter, but remember, the only way that a multimeter has to measure current is connecting a serial resistor in the circuit, so, your impedance will be higher and the current drawn will change. Thats can cause malfunctioning if the resistor connected value is very high.
Or you can read the typycal impedance circuit seen of your chip in the datasheet and calculate aproximately the current by using 3.3V
If you want to make some experiment, I recommend you use and external VCC and GND sources, you are safer about ruining your ps2
well measure between ground and power to the chip you will see something like 160 ohms on the 5 volt chips and 40 ohms on the 3.3v chips...
using ohms law - you can calculate the the base current draw on power up but sleep mode as:
I = 3.3 / 40 = 83mA
I = 5/160 = 32mA
But that does not take into account active mode...
to measure this you wont need a resistor in series as suggested above, that would only be needed if you don't have current on your meter and were going to measure the voltage drop across say a 100ohm resistor to back calculate the current.
All you would need is to bring out two wires as if you were going to install a power switch - one from the power connection point on the MB and the other from the Power conection point on the chip.
Connect the multi-meter between these two wires in current mode set to 200mA mode or above - power up station.
But if this is Gemat from PSX forums he would know all this and is probably just after if anyone has actually already done this and what was the result with a working station for comparison.
Thats me Shadow! Yes I was wandering if someone has already done this!
The awg 30 kynar wire has a resistance of 351ohm/1000m.
So if a 5cm piece is used for power and the current of the chip is 83mA then the voltage will drop from 3.3 to 3.154 V. Isnt this more than enough for the chip to work without any problems?
It is fine for sure for a 5V chip since the current is much less and the % of the voltage drop is not significant!
BTW, in messiah's instructions the power point is indicated as 3,45V! If this is the actual voltage of that spot on the board, with a drop of 0,15 V we have the exact 3.3 voltage that is required, plus the modchip runs a bit cooler!
I think you dont understand what I was trying to mean. First, sorry for my bad English, Im spanish
What I was trying to mean is that when you use a multimeter, "the multimeter" connects on his own a serial resistor to the circuit, its the only way to measure, I dont want to mean that you have to connect it.
Remember there is no way to measure exactly Voltage/Current becuase all kind of multimeter and oscilloscopes has internal impedance and use "Real" Voltage Power (all home multimeter use a 9V Real Voltage Power to measure), so there are really mismeasuring the Voltage/Current and when you are measuring so little current the error may be big if you are not using a good multimeter.
Another thing to explain is that chip IC doesnt drawn the same current all the time because it depends a lot on the dynamic states of the pins. Transistors drawn more current if they are changing its logical status, and even more, if they are pulling-up or drawning down a bus to change a logical value.
So the best way to measure the current is to use a Current Analyzer (is this the name in English??) that can measure the current in 1 millisecond each time and you get a result.
Sorry for my bad English, I hope this time you understand me