[C6748] Voltage change

lucy_zhu

dear:

In my own design c6748 board, 1.8v voltage into 2.6v voltage.Power chip LTC3545, its output is correct (already measured 1.8v). When connecting the load (DDR and USB), 1.8v change to 2.6v.1.8v pin connection is N14, P14, P3, DDR_DVDD18 (N6, N9, N10, P7, P8, P9, P10, R7, R8, R9), DVDD18 (N14, G6, G10, G11, G12, J13, K5, L6, P13, R13).

I dont know how to find my mistake,I hope you can help me!!!!

Thanks!

over 15 years ago

0 tlee over 15 years ago

TI__Guru 62975 points

Lucy,

Where are you measuring the 2.6V?

-Tommy

0 lucy_zhu over 15 years ago in reply to tlee

Prodigy 190 points

Dear Tommy:

I measured the LTC3545's 1.8v output pin. I connect 1.8v output pin and back-end load with a 0 ohm. When the connection 0 ohm, the measurement is 2.6v. When the disconnect 0 ohm, power measurement is 1.8v, another measure is 0v.

Thank u!

0 tlee over 15 years ago in reply to lucy_zhu

TI__Guru 62975 points

Lucy,

Can you measure the current with a multimeter between the LTC and load? If the current is flowing from C6748 to LTC, there's probably a 3.3V pin in the net somewhere. If the current is flowing from LTC to C6748, you may want to ask Linear if the LTC3545 will output a higher voltage to compensate for voltage drop/load.

-Tommy