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That drive capability guarantees each TTL output the capability to drive 10 TTL inputs with a guaranteed noise margin of 400mV or greater. TTL outputs will be 400mV or less when low (and sinking 16mA or less), and 2.4V or more when high (and sourcing 400uA or less).

TTL inputs are defined as 'low' if they are less than or equal to 800mV and 'high' if they are greater than or equal to 2V. Without the collector resistor it would behave more like a few ohms (1.6K divided by the current gain of Qp). When Qs is 'off', the base of Qp is pulled to Vcc by Rc, so the effective pullup resistance is limited by the collector resistance Rcp - so it's about 120\$\Omega\$, meaning that for a 50pF load, the time constant is about 6ns. In all the push-pull topologies, the goal is the. Totem pole outputs like this one use an active pullup, which is Qp, Rc and Rcp. Totem-Pole Output Stage PSRR Enhancement The second topological variation is marked by a plate side connection, where the output directly (or indirectly via a coupling capacitor or a zener or a voltage regulator) couples to the top of the phase splitter’s plate resistor. I may also use an open-drain output when interfacing to custom analog drivers. Adafruit Feather nRF52 Bluefruit LE nRF52832.

To compile and run your code on real nRF52 hardware, it is recommended that you have a nRF52 development kit such as. This method is slow as there is only a resistor pull-up bit it is simple if you only want one or two 1.8V outputs and want other outputs to be 3.3v. In this article, you will learn about the Pulse Width Modulation (PWM) module of Nordic nRF52 and the nrfdrvpwm library in nRF5 SDK to control it. It's a component part of the (active) pullup circuit, but it's not a 'pullup resistor'. If you used a totem pole output it would provide excessive voltage in the high state. The primary purpose of the 120\$\Omega\$ resistor is to reduce the current spikes when the output switches (when Qo and Qp are both on simultaneously for a brief moment).