Does TI has any solution for monitoring negative power such as -5.2V and -12V?

Hi Christine,

UCD90xxx sequencers can only monitor positive voltage. However, you can pull-up negative voltages using a resistor divider.

Thanks,

Zhiyuan

Although the pullup resistor solution is simple, it ends up with a low magnitude value for high magnitude voltages and high magnitude value for low magnitude voltages. This is exactly backwards from what the sequencer actually wants.

We have multiple negative domains to monitor and include in our sequence dependency list, so we do the following:

Use a fractional gain inverting opamp. A single supply amp will do with the non-inverting input tied to ground. Make sure the input range is rail to rail. Set the scale such that the output will be mapped into the sequencer's native range. If there is a desire to control noise, a small cap can be placed across the feedback resistor. this solution gives low magnitude readings for low magnitude voltages and high magnitude readings for high magnitude voltages. Only the polarity is missing.

The resistor only solution would have used 2 resistors at minimum. The opamp solution would use a minimum of 2 resistors and a small package opamp, SC70,

SOT23, or BGA. If there is not enough decoupling in the area, a decoupling cap will be needed too. There are many low power opamps to choose from that operate from the same supply as the sequencer. Power supply monitoring doesn't need a lot of bandwidth.

Louis Johnson

1st Detect