IC manufacturers are packing more and more analog functionality into ICs. Surprisingly (to me, anyway), this analog integration is occurring with microcontrollers (MCUs), too.
One of my fellow editors, Michael Dunn, wrote a blog recently about something he called “extreme integration.” He was referring to FPGAs that might have up to 1000 pins. From the perspective of analog components, that does seem pretty extreme. But, of course, he's just talking about digital stuff, so it hardly matters.
But wait — from there, he talked about MCUs that had built-in analog functionality. Again, lots of pins — and quite a bit of analog stuff going on. At this point I realized that attention must be paid.
Michael was discussing an eval board from STMicroelectronics that he planned on procuring. Like many of these boards, there were various digital and analog inputs and outputs. So far, just another eval board. But even ignoring the extra op-amp and power supply circuitry on the board, the MCU itself was responsible for most of the analog I/O. Michael notes it had achieved an impressive level of integration.
From the manufacturer's data sheet, we note the following:
The devices offer up to four fast 12-bit ADCs (5Msps or mega-samples per second), up to seven comparators, up to four operational amplifiers, up to two DAC channels, a low-power RTC, up to five general-purpose 16-bit timers, one general-purpose 32-bit timer, and two timers dedicated to motor control. They also feature standard and advanced communication interfaces: up to two I2 Cs, up to three SPIs (two SPIs are with multiplexed full-duplex I2 Ss on STM32F303xB/STM32F303xC devices), three USARTs, up to two UARTs, CAN and USB. To achieve audio-class accuracy, the I2 S peripherals can be clocked via an external PLL.
Those four ADCs running at 5Msps and the two DACs running at 1Msps are not blindingly fast by any means, but it's plenty good enough for industrial data acquisition applications or some audio applications. The audio wouldn't be ultra hi-fi, but it would be acceptable for most applications.
The MCU device (just the IC, not the eval board) sells for about $5 in quantities of 100 pieces. If you were to build your own data acquisition system with four ADCs and just some of the analog parts cited above, you would spend more than $5 for the converters, a barebones MCU, op-amps, and sufficient PC board real estate to hold everything.
Just one more comment about the Eval board: The board has MEMS sensors to monitor acceleration along 3 axii and a compass/magnetometer. Now, if they can move that functionality into the MCU IC, then they will have achieved some amazing integration.
Have you used any of these MCUs that have all these features? How well did they work in your application?