Clock Generator IC replacement for the HA7210 - Page 1
Forum section: electronics / projects

author: Zubeneschamali
author_rank: Newbie
timestamp: February 14, 2024, 09:51:27 pm
content: Looks like the Harris HA7210 (https://www.mouser.com/catalog/specsheets/intersil_fn3389.pdf) is no longer around. (Not recommended for new designs and, where it is available, far too expensive or requiring negotiation.)I'd like to find something modern and equivalent.I would normally just go buy an MCU (MSP430 especially given its DCO chain and external clock options.) But I'm targeting hobbyists who may not wish to go through the trouble of finding and installing a toolchain, development board for downloading code, etc.Is there anything akin to the Harris HA7210 these days? (I'm considering going crazy enough to follow this:https://www.aldinc.com/pdf/UltraLowPowerCrystalOsc.pdf. But I'm hoping for something as convenient to use as the HA7210 was.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: February 14, 2024, 10:51:09 pm
content: Quote from: Zubeneschamali on February 14, 2024, 09:51:27 pmHmm, not in a single device. What frequencies actually matter to you ?That part targeted 32k~1Mhz but hardly anyone uses 100k~1MHz xtals in 2024, as they are simply too large.You could look to follow what they did internally, which was vary bias on the inverter oscillator, to cover that range.A part like 74AUP1Z125 has the internal Xtal resistor, and you could pair with a dual-supply translator like Nexperia 74LVC1T45, or TI SN74LXC1T14Parts like these have internal caps and dividers, but they are not widely stocked.https://www.nisshinbo-microdevices.co.jp/en/products/quartz-crystal-oscillator-ic/

author: Zubeneschamali
author_rank: Newbie
timestamp: February 14, 2024, 11:34:00 pm
content: Quote from: PCB.Wiz on February 14, 2024, 10:51:09 pmThe whole point is to be able to support 32.768 kHz tuning fork crystals all the way up to 2+ MHz. The bottom end of 32.768 kHz I cannot sacrifice. That's a requirement. I don't need the full range of the HA7210. 2 MHz would suffice. A large crystal is not a problem. In fact, I'll be using some in the FT-243 package.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: February 15, 2024, 12:00:43 am
content: Quote from: Zubeneschamali on February 14, 2024, 11:34:00 pmThe dual SOT package solution should cover that range, with a change to feed resistor. (like the HA7210 did)If supply current matters, you can experiment with new RRIO comparators like Gainsil GS8709 (325nA 6us) for 32kHz osc and compare those with Level translators.If you want a simple 5V solution for 1-30Mhz, there are Xtal Osc parts like 74LVC1GX04 (reduce the supply for 32kHz)

author: Zubeneschamali
author_rank: Newbie
timestamp: February 15, 2024, 12:14:45 am
content: Quote from: PCB.Wiz on February 15, 2024, 12:00:43 amThanks so much for your thoughts. It really does help.I started to say that I need to meet 5 V logic (HC vs TTL not yet decided.) But to be honest, I'm still in a research stage and I can't say that yet. I'm searching out availability and cost and size and power ... etc. Much to be balanced in the end and I've a lot of hand-build-and-test ahead of me before final decisions get made. (Going to fill up a logbook, for sure.)So you've given me more than I'd hoped. Thanks!I also see that I can get buckets of HA7210 from China, it seems. No idea what's in the epoxy. But that can be tested, too.Thanks again.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: February 15, 2024, 01:49:53 am
content: Thinking some more on this, if you pick a schmitt dual supply level translator like TI SN74LXC1T14, you can experiment with 74AHC1GU04 type unbuffered gates as the oscillator, and even try a ROHM BU4SU69G2 ( a HEF4069 4000 single gate part), which would support 32kHz at a higher bias Vcc, for lower current. HCMOS parts will still draw current, even with Vcc close to 1.2V min of the translator.Adding a BU4S584G2 4000 schmitt could be worth a try, if you are chasing uA, to see if that Icc is less than the input stage Icc of the SN74LXC1T14 when sine driven.The Nexperia 74AHC1GU04 data has table values for 32kHz operation.