HC4060 power consumption - Page 1
Forum section: electronics / projects

author: dobsonr741
author_rank: Frequent Contributor
timestamp: October 29, 2023, 02:27:14 am
content: I run an HC4060 on a 32KHz crystal and measured supply current around 1.6mA. Tried on two different vendors, same result. If I keep the 4060 in reset the current is below detectable, <1nA.The >1mA current while counting was a surprise to me. Is it expected?I wanted replace an RTC with 4060, however at this current it's impossible.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 29, 2023, 04:20:54 am
content: Your biasing resistor may be too low.Please post your circuit.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 29, 2023, 04:34:55 am
content: For such a low frequency, try a regular 4060 instead of the fast HC version.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: October 29, 2023, 05:08:23 am
content: Bias resistor is 10M, R2 series driver 2.2K. No discrete capacitors just parasitics on the breadboard. Bumping up R2 from 2.2K to 100K does not make any difference.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 29, 2023, 05:24:07 am
content: You didn't put capacitors to ground? Out of curiosity, have you looked at the output of the oscillator with a scope?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 29, 2023, 09:02:40 am
content: Quote from: dobsonr741 on October 29, 2023, 02:27:14 amThat's entirely expected, as it is a CMOS buffer.The largely linear operation, means Icc is strongly dependent on supply voltage.The older 4000 series like HEF4060 can have lower Icc, and you can get uA levels at 3.3V region operation, ok for 32kHzParts like HEF4069 show how Icc varies with Vcc, and VinOr you could use a part like 74AHC1G4215 at a very low supply (1 ~ 1.5V region) with a level shifting buffer

author: dobsonr741
author_rank: Frequent Contributor
timestamp: October 29, 2023, 03:39:49 pm
content: Waveforms attached with 100K and 2K at R2. I'll accept the fact the cmos inverter of 4060 is in linear mode, and the 1.8mA is not so bad, given the relevant definitive TI app note (http://www.ti.com/lit/an/szza043/szza043.pdf- Appendix C.2 below) quotes even higher current for unbuffered inverter.Even if I go with an RC oscillator on 4060, with 220p/10M/100K for ~22Hz, the current consumption is at 17uA. I want <1uA for my timing budget.RTCs seem to have sophisticated optimized oscillators. Even an STM32's RTC oscillator can be at 300nA current consumption, again, with a dedicated XTAL driver.So the case is closed, I'll use an MCP79401 with RP2040 kept in shutdown with disabled RT6150 or an STM32 with the built in RTC.

author: floobydust
author_rank: Super Contributor
timestamp: October 30, 2023, 03:39:08 am
content: I find Microchip is rollin' out some junky products lately esp. their RTC's - always check thesilicon erratafor deal-breakers.MCP7940X1 Date incrementing at noon.2 Spurious alarm interrupts when matching on minutes.3 Date value changing on month or year write.4 Day of week register value changing after write.They have workarounds but one has to ask WTF they can't fix this stuff after 8 years of silicon revs. I'm seeing issues with newer MCU's as well so I'm avoiding their drama.

author: SeanB
author_rank: Super Contributor
timestamp: October 30, 2023, 05:16:02 am
content: The solution is to use one of the CMOS clock oscillators that support linear operation, or use a CD4007 instead to build the inverter stage, where you can add the resistors in.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 30, 2023, 07:02:45 am
content: Quote from: SeanB on October 30, 2023, 05:16:02 amThe old 4007 allows more control, but adds more parts, and still struggles to go sub 1uA, tho single-digit uA are possible.These days, the RTC parts from lcsc etc are quite low cost, x1302 parts are ~10c in moderate volumes and x8563 parts are ~15c, so I doubt an average new design would choose to use generic logic.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: October 30, 2023, 02:12:15 pm
content: Another choice is TPL5110 when no timekeeping just periodic wake-up is needed. At <30c @1K from TI direct. Clean and simple. At 30nA current power is really low.

author: Peabody
author_rank: Super Contributor
timestamp: October 30, 2023, 04:36:52 pm
content: If it works in the application, the TPL5110 would have the advantage that its DRV output is totem pole. The outputs of most of the RTCs I've looked at are open drain, which means you would need a pullup resistor that sinks current when the output is low.