Tool/software: Code Composer Studio
Hi:
We have a PSU project that requires very low standby consumption from the system bus standby voltage of 4.75V 35mA which the PMBus should still be maintained. We did a bench evaluation that we slowed down the 28035 clock to 2.5MHz and we only turn on the I2C and SPI. The bandgap and all other analog/digital peripheral are turned off. The current consumption is then 3.3V 38mA.
From the data sheet:
1. At 60MHz clock, the typical current consumption is 128mA (=114mA (IDDio) + 14mA(IDDa)) which include all on-chip peripherals.
2. The typical consumption of peripheral excluding SPI and I2C is 42.5mA:
3. At 10MHz, the graph in data sheet project a typical current consumption of 45mA(IDDio) and 14mA(IDDa)
I project for 2.5MHz, the current will be 35mA(IDDio) and 14mA(IDDa) when all peripherals are enabled.
Now, I use (114mA – 42.5mA) to estimate our digital part consumption at 60MHz. It will be 62.7% of the 114mA. Therefore, for 2.5MHz, the current will be 35mA *62.7% = 22mA.
I estimate the current consumption is 22mA + 14mA = 36mA. Now we measured 38mA even after we turn off the bandgap.
For your information, before we turn off the bandgap, current consumption is 46mA. Please advise whether there is room to further reduce the current consumption. Any suggestion are welcome.
