https://devzone.nordicsemi.com/f/nordic-q-a/122630/ppk2-interfering-with-device-operation-in-ncp-wi-fi-setupDear Nordic Support Team, We have a system where an MCU is connected to a Wi-Fi module operating in NCP (Network Co-Processor) mode . The MCU controls the Wi-Fi chip to connect to an MQTT broker, subscribe to topics, and publish messages periodicallyen-USTelligent Community 13Tue, 01 Jul 2025 03:09:02 GMThttps://devzone.nordicsemi.com/thread/540954?ContentTypeID=1Tue, 01 Jul 2025 03:09:02 GMT137ad170-7792-4731-bb38-c0d22fbe4515:8d11fbee-cd31-493b-9cea-9f588440a31ahmolesworth<p>Not just an issue with the PPK2, but also with (for example) a standard current meter with auto-ranging. The problem is due to range-changes; when measuring&nbsp; a high current of some mA a low-value series resistor is used which has a voltage drop across the series resistor which indicates the current value. A low current&nbsp;measurement requires a much higher value of series resistor when the same current (actually voltage) measurement resolution is required and this change of resistance is automatic but takes a finite time. When the high-current transmission burst occurs - after a period of time with the low-current high series resistance measurement - the meter/PPK2 switches in the lower-value series resistor, but during the short time while this happens the high-value series resistor is not able to supply the required current and so the delivered voltage starts to fall - sometimes, not always, far enough to cause a device reset.</p> <p>There are two options to fix this. The first is to increase the bulk capacitance downwind of the meter/PPK2 such that the delivered voltage droop - while the sense resistor change takes place - is reduced far enough to avoid the reset. The second is to simply sacrifice high-resolution low-current measurement resolutions and fix the meter/PPK2 scale to always measure with the same series resistance - ie&nbsp;turn off&nbsp;auto-ranging.</p> <p>Regarding the PPK2, Series Resistor Rc for current sense is 1k0 in parallel with none or more of 110R, 11R0, 1R0 and 0R05</p> <p><pre class="ui-code" data-mode="c_cpp">// Resistor Rc for current sense is 1k0 in parallel with none or more of 110R, 11R0, 1R0 and 0R05 // // &lt;- +ve Supply to DUT From VOUT External Battery +ve To VIN &lt;- // +------------------------------+ +-----------------------+ // | | | | // | +---------+ | | +---------+ | // | | GND | | VOUT VIN | | GND -ve | | // +=========O=========+ | +====O=====O=============================O=====O====+ | | Battery // | Vdd (+) | | | | #----+ | | | | | + 3 volts // | | | | | | |Rc AMPERE \ | | | | +-O-+ // | | | | | | +++ \ | | | | | | // | | | | | | | | +-----------O O----# | | | | | // | Device Under Test | | | | | | | | | | | | | | // | DUT | | | | 120k| | | | |120k | | | | | // | | | | | +++ +++ | \ SOURCE +++ | | | | | // | | | | | | | | | \ | | | | | +-O-+ // | | | | | | | +----#--O O-- PPK LDO | | | | | | Gnd (-) // | | | | | | | | | | | +-------+ // | | | | | +++ +++ | | // | | | | | | | | | // | | | | | #-- VDUT VIN --# | | // | | | | | | Sense Sense | | | // | | | | | +++ +++ | | // | | | | | | | | | | | // | | | | | | | | | | | // | | | | | | | | | | | // | | | | | +++ +++ | | // | | | | | | 30k 30k | | | // | | | | +--#--+ +--#--+ | // | | | | | | | // | | | | ===== &lt;&lt;== Common Gnd ==&gt;&gt; ===== | // | | | | === (Common -ve) === | // | Gnd (-) | | | = = | // +=========O=========+ | +===================================================+ // | | PPK-II // +--------------+</pre></p><div style="clear:both;"></div>