I'm using a PIC24F to interface with an SD card in SPI mode. When the card is idle, the device still draws ~200 uA of current which is unacceptable for this device's purpose. To correct this, I am using a bit-enabled Linear Regulator (NCP694H33HT1GOSCT-ND) to kill power to the SD card's power rail. However, the leakage current remained at ~200 uA even when the SD card's power was cut off. Then I realized that upon physically disconnecting the wires for the SPI clock and Data In to the SD card from the PIC, the current drops down to ~10 uA, which is very acceptable.
So, I am assuming that power is somehow leaking through the PIC24F and the signal lines to the SD card. I have tried reconfiguring those pins as digital outputs set to 0 and as digital inputs, but neither methods have had the same results as physically disconnecting those two lines.
Is there something I'm missing here? I would think that being set as a digital inputs would result in those pins becoming high impedance and thus blocking out the excessive leakage current, but it doesn't seem to be working. Any help would be appreciated.