IC chip for Voltage mod help

[Calchaqui]

Sorry, I got this IC who controls Vdimm and 3.3v outputs in my motherboard, I wanted to do the "voltage mod" putting a resistor between the IC feedback leg and ground, but it seems there no one feedback or reference voltage, will be another way to send 4v to my dimms?
http://www.intersil.com/content/inte.../HIP6501A.html
It says: Simple Control Design −No Compensation Required
Fixed Output Voltages Require No Precision
Must be a way to trick this IC to send higher Vdimm , the leg is DRV2
I really want to do this, so need your advice

[redwire]

Re: IC chip for Voltage mod help

I don't see a way to increase VDIMM past 3.3V because the IC outputs either 2.5V or 3.3V (from the incoming 3.3V rail)- you would have to supply +5V to the mosfet (on DRV2) switch. But the output voltage is set in software and there is no access to the feedback pin, it is internal.

4V is way too much, even for DDR1 memory

source: http://www.ocfreaks.com/ram-overcloc...uide-tutorial/

[Calchaqui]

Re: IC chip for Voltage mod help

I don't see a way to increase VDIMM past 3.3V because the IC outputs either 2.5V or 3.3V (from the incoming 3.3V rail)- you would have to supply +5V to the mosfet (on DRV2) switch. But the output voltage is set in software and there is no access to the feedback pin, it is internal.

4V is way too much, even for DDR1 memory

source: http://www.ocfreaks.com/ram-overcloc...uide-tutorial/

I'm ashame but is SDR DIMM, so 4v is an ok Vdimm. Redwire, what about cutting the DRV2 leg and putting a resistor between 5v out leg of the IC and the cutted trace, to get 4v? . The source of the Vdimm mosfet is already connected directly to 5v ATX.

[redwire]

Re: IC chip for Voltage mod help

The chip has an internal voltage regulator to make VDIMM. DRV2 voltage moves around to obtain 2.5V on VSEN2.
For 3.3V out, the chip instead uses a mosfet switch to hard switch 3.3V to VDIMM.
Making 4V by biasing the mosfet switch sacrifices regulation, and voltage would move around depending on load and temperature.
Instead, you could use a low-drop Vreg with a /shutdown pin (to DRV2) like LT1763
The HIP6501 would only look for undervoltage <3.3V on VSEN2.

[Calchaqui]

Re: IC chip for Voltage mod help

The chip has an internal voltage regulator to make VDIMM. DRV2 voltage moves around to obtain 2.5V on VSEN2.
For 3.3V out, the chip instead uses a mosfet switch to hard switch 3.3V to VDIMM.
Making 4V by biasing the mosfet switch sacrifices regulation, and voltage would move around depending on load and temperature.
Instead, you could use a low-drop Vreg with a /shutdown pin (to DRV2) like LT1763
The HIP6501 would only look for undervoltage <3.3V on VSEN2.

Sorry Redwire, i'm a little stupid, and i dont get the idea very well.



Q1 (PHD45N03LTA)is my active mosfet for Vdimm/V2out, in my mobo Q1 source is 0 ohm to 3.3v ATX (NOT to 5v like I said before), gate is conn. to DRV2 and drain to VSEN2. So to get Vdimm/V2out @4v If I understand you, I must desolder Q1 Source from PCB and solder a wire to 5v ATX with some diode to get down to 4v? and what about VSEN2, will set flag to Fault Protection? do i need to low the voltage next to Vsen2 leg with something to 3.3v? DRV2 moves around what voltages range? I'm really beginner to electronic, so i dont get your idea. Maybe another answer will help me. Thank you man.

[redwire]

Re: IC chip for Voltage mod help

Okay this is still a scary mod to me but how it works right now is the mosfet acts as a switch to give 3.3V for VDIMM. To get more voltage, you have to supply more to the mosfet, which would look like supplying +5V to its drain (I'm not sure why the datasheet says the source is connected to Vin, this seems wrong).

With +5V feeding the mosfet drain (instead of 3.3V) you get too much voltage now, I think you wanted 4V. So I was suggesting to use add low-drop voltage regulator IC set to 4V (or whatever VDIMM you like) with 5V coming into it, to feed the mosfet's drain.

[Calchaqui]

Re: IC chip for Voltage mod help

Okay this is still a scary mod to me but how it works right now is the mosfet acts as a switch to give 3.3V for VDIMM. To get more voltage, you have to supply more to the mosfet, which would look like supplying +5V to its drain (I'm not sure why the datasheet says the source is connected to Vin, this seems wrong).

With +5V feeding the mosfet drain (instead of 3.3V) you get too much voltage now, I think you wanted 4V. So I was suggesting to use add low-drop voltage regulator IC set to 4V (or whatever VDIMM you like) with 5V coming into it, to feed the mosfet's drain.

I think you mean source instead of drain, mosfet source is connected to 3.3vATX, so I must use the low-drop-VR to feed my mosfet source with 4v, isnt it?, but Vsen2 (connected to mosfet drain) will detect those 4v instead of 3.3v and will activate fault flag, so what must i do? and again, really thank u from Argentina.

[redwire]

Re: IC chip for Voltage mod help

VSEN2 is used to detect low voltage, but not high voltage.

[Calchaqui]

Re: IC chip for Voltage mod help

Thnk u redwire