Hello, we want to add an additional 20uA current range to MAX32010, which of the following approaches is better?
- Connect a 45k ohm resistor in serial to the default 5k between the pin RD and DUT_NODE and use a STSP analog switch to short the 45k for 200uA range.
- Use an external amplifier controlled by the pin EXTSEL
We prefer the method 1 since we don't need to use an amplifier with HiZ output (or additional switch) but want to make sure it works. The datasheet section External Mode Support states (shown below) "an external amplifier can be used to provide a current range below the lowest current range included within the device". Can you clarify what is the 'lowest current range included with the device'?
External Mode Support
The MAX32010 includes resources to drive an external amplifier to provide a current range beyond the highest range (or below the lowest current range) included within the device. A voltage output, AMPOUT, is provided for the input of the external amplifier, and a digital output, EXTSEL, goes high to activate the external amplifier. Feedback inputs VRXP and VRXM connect across the external amplifier’s current-sense resistor. The external amplifier must have a high-impedance output when not selected (EXTSEL = low), if connected as shown in the Functional Diagram.
Also, what is the PSRR at 200kHz to 2MHz? We are thinking to power the device directly from switching power supplies and use LC filter to reduce the ripples locally.
Thanks.
