This week's EYE ON NPI is loud and proud - it's the Diodes Incorporated PAM8019E Class-D Audio Amplifier and Headphone Driver (https://www.digikey.com/en/product-highlight/d/diodes/pam8019e-class-d-audio-amplifiers), a combo audio amplifier that will add high quality analog audio output to your next design without breaking the bank.We've stocked and used the PAM series of audio amplifiers for over a decade, one of our best sellers is the PAM8302 (https://www.adafruit.com/product/2130) breakout which is a monophonic class D amp for basic projects. Things we like about it: its very inexpensive, it's rock solid, 3~5V power, hard to 'pop' and can drive 4~8 ohm output. But it's only one channel and we often get asked if we can stock a stereo Class D. Also, it's pretty common for us to get requests for headphone drivers. The PAM8019E (https://www.digikey.com/short/b3r00dw5) can do both, and has a lot of nice little details.First up, this is an analog in/out amplifier - no PDM or I2S or TDM. So this is good for either all-analog setups or when you have already converted your digital audio to 'line level', about 1Vpp. Since it's stereo out, there's also stereo input: don't worry about DC bias because you can couple in with 1uF and it will internally bias to half-VDD. Unlike the PAM8302 (https://www.digikey.com/en/products/detail/diodes-incorporated/PAM8302AASCR/4033281), this isn't differential input, reference is ground. You can use either the Headphone amp or Speaker amp, but not both: the selection is done with with a digital input pin which will do a smooth pop-free hand off.For the outputs, there's the stereo Class D outputs. These come as two tied-load bridges (https://en.wikipedia.org/wiki/Bridged_and_paralleled_amplifiers#Bridged_amplifier) which means you can just tie the two sides of each speaker to positive/negative without any capacitors. Class D is an efficient amplification architecture (https://en.wikipedia.org/wiki/Class-D_amplifier) and if done at a high enough frequency - in this case around 400KHz - the inductive load of the speaker acts as a filter so no separate RLC is required. For EMI purposes, the datasheet recommends a simple 100MHz 600ohm ferrite bead plus 1uF capacitor just to reduce the sharp square waves. For headphone, the chip uses a Class AB (https://en.wikipedia.org/wiki/Power_amplifier_classes#Class_AB). These are going to give cleaner output because there's no intermediate PWM stage: speakers tend not to be good enough to notice the hiss added from Class D, but headphones are much more sensitive. Also, at the ~50mW output we're talking about, there's not a lot of benefit to optimizing power. Since headphones are by design 'single ended', you will need 220uF caps on the output for high-pass filtering. Some modern audio amps have a 'floating' ground generated to sink the current for cap-less output but these tend to be more expensive and also wouldn't be compatible with line-level inputs.Some nice details we like to see in an amp, especially one this affordable: spread-spectrum so the high frequency PWM isn't centered on one spike, undervoltage-lockout, short-circuit on all outputs, pop-free, non-clip power limiting and separate not-in-line audio level selection. The last one is particularly nice because on the PAM8302 we have to put an analog rheostat in-line with the input pins to reduce the gain from 15x down to 1x or 2x. This would require a stereo pot, which can get scratchy and fail over time. On the PAM8019E (https://www.digikey.com/short/b3r00dw5), the gain is set with a DC voltage which means you can set it with a potentiometer or a DAC output, and you don't have to worry about jitter or scratchiness because there's hysteresis over 64 points.We've already ordered 10 pieces of the Diodes Inc PAM8019E (https://www.digikey.com/short/b3r00dw5) to design a breakout. DigiKey has tons in stock so we recommend you buy some too, at 34 cents a-piece, at reel quantity, it's hard to say no! They're available in 3x3mm or 4x4mm package sizes, both are QFN-20. Order today and you can be bumpin' and boppin' with either speakers or headphones by tomorrow. afternoon.