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820-02020 searching for UC710 SN621371
- Thread starter mbcontrol
- Start date
It should work; give it a try.
Apple proprietary chips don't have datasheet available.
However, exist direct equivalents; just not easy to find them.
Texas Instruments builds direct equivalents, with good documentaion.
But they can't reveal anything for the chips designed under Apple demand.
Remember FDMF6808 and FDMF6708/3030; or TPS65982 and CD3215.
Apple proprietary chips don't have datasheet available.
However, exist direct equivalents; just not easy to find them.
Texas Instruments builds direct equivalents, with good documentaion.
But they can't reveal anything for the chips designed under Apple demand.
Remember FDMF6808 and FDMF6708/3030; or TPS65982 and CD3215.
mbcontrol
Member
I tried two chips:
TPS621351RXG with 2.5MHz nominal switching frequency
TPS62136 with 1MHz nominal switching frequency
Both chips initially provide 3.3V for P3V3S2_SW. After 10-15 seconds the voltage drops down. With the 2.5MHz chip to 2.4V and with the 1MHz chip to 0.8V.
Then the board keeps restarting after the gong.
What do you think? Is this because of the chips, or do I have another problem wich have nothing to do with this chips?
TPS621351RXG with 2.5MHz nominal switching frequency
TPS62136 with 1MHz nominal switching frequency
Both chips initially provide 3.3V for P3V3S2_SW. After 10-15 seconds the voltage drops down. With the 2.5MHz chip to 2.4V and with the 1MHz chip to 0.8V.
Then the board keeps restarting after the gong.
What do you think? Is this because of the chips, or do I have another problem wich have nothing to do with this chips?
Not sure about the problem; original UC710 works at 1.5MHz.
The strange thing is output voltage drops to different value, depending on the chip used.
Better to test with donor chip...
The strange thing is output voltage drops to different value, depending on the chip used.
Better to test with donor chip...
mbcontrol
Member
I organiced a known good board and took the original UC710 on my board - same behavior as with TPS621351RXG with 2.5MHz. The Voltage drops down to 2.4V after 10-15 Seconds.
Then i took an TPS621351RXG on the known good board - works perfect. So you can definitely use the TPS621351RXG as a replacement - that's good to know - i had a view damaged UC710 and had always to buy an expensive donor only to get this chip.
But there is still my problem with this board. It shows the Apple logo and a bit of the progress bar on the ext. Display, then it makes an restart.
Do you have any hints what I can look for next?
Then i took an TPS621351RXG on the known good board - works perfect. So you can definitely use the TPS621351RXG as a replacement - that's good to know - i had a view damaged UC710 and had always to buy an expensive donor only to get this chip.
But there is still my problem with this board. It shows the Apple logo and a bit of the progress bar on the ext. Display, then it makes an restart.
Do you have any hints what I can look for next?
If no important data, try DFU restore.
Can you access Disk Utility in Recovery mode?