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TCA9802: Setup questions

Gregory Duperon
Expert 6030 points
Part Number: TCA9802
Other Parts Discussed in Thread: TCA9800

I have a customer considering designing with the TCA9802.  Here are some initial questions:

1. If TCA9802 is disabled (Pin EN = 0V) and VCCA = 0V (master side power is off) but VCCB=3.3V (slave side power is on). Any adverse effect under a long-term storage mode?

2. Under item1 with EN = 0V, would quiescent supply current specified on datasheet on VCCB be higher or lower when EN = VCCA?

3. Could we reverse power supplies on item1? VCCA is powered by slave side and VCCB is removed at master side during storage. When EN =VCCA by salve side, VCCB will then be activated and turned on by slave side.

4. The SCL frequency we selected is 400Khz. Could we use TCA9800 (only for under maximum 100Khz?) for lower quiescent supply current?

  • 0
    TI__Mastermind 49040 points
    "1. If TCA9802 is disabled (Pin EN = 0V) and VCCA = 0V (master side power is off) but VCCB=3.3V (slave side power is on). Any adverse effect under a long-term storage mode?"
    No, this should be fine.

    "2. Under item1 with EN = 0V, would quiescent supply current specified on datasheet on VCCB be higher or lower when EN = VCCA?"
    The device would technically be in Under voltage lock out. Under this condition, I would suspect that the supply current should be lower.

    "3. Could we reverse power supplies on item1? VCCA is powered by slave side and VCCB is removed at master side during storage. When EN =VCCA by salve side, VCCB will then be activated and turned on by slave side."
    I don't see any problems with this. The device will be held in under voltage lock out.

    "4. The SCL frequency we selected is 400Khz. Could we use TCA9800 (only for under maximum 100Khz?) for lower quiescent supply current?"
    Figure 22/23 of the datasheet seems to indicate that you should be able to meet the rise time requirement for 100KHz even under 400pF load on B side. This looks like a good solution for 100kHz.

    Thanks,
    -Bobby