Nexperia B.V. All rights reserved. HEFB. All information provided in this document is subject to legal disclaimers. Product data sheet. CDBE datasheet, CDBE pdf, CDBE data sheet, datasheet, data sheet, pdf, Texas Instruments, CMOS Stage Frequency Divider. CDBE. CDBEE4. ACTIVE. PDIP. N. Green (RoHS. & no Sb/Br). CU NIPDAU. N / A for Pkg Type. to CDBE. CDBM. ACTIVE.

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May 10, 1. Oct 28, I would like some assistance on building this circuit before I purchase the components from Mouser Electronics. Just wanna make sure it works, according to the circuit I found online. I understand how to hook it up. I don’t understand why I need the resistors ce4521be capacitors, or why those specific cv4521be are used on the IC with the crystal. Will it work with the components? Some references and reading material listed below. The Crystal I’ve chosen to use.

My Cart on Mouser, so far I don’t see many other people that wanted to do this on All About Circuits, but I did see this post Lazy Chip – Odd Problem The data sheet is so old it seems, it’s just a lil difficult looking at it. I’ll try to give it another read. May 10, 2. Feb 8, 2, R1 “linearizes” the internal circuit of the oscillator, in effect biasing it so that what is normally a digital on-off circuit behaves more like a high-gain amplifier.

Without the resistor, the input side of the internal circuit can be used as a normal digital clock input. R2 limits the drive power to the crystal. Some crystals require care not to apply excessive drive.

HELP: 1Hz from CD4521B IC and 4.194304 MHz Crystal

At 5 volts the resistor may be unnecessary, but it is necessary to check the datasheet for the crystal to be certain. Low frequency crystals kHz range are usually more fussy about overdrive than high frequency crystals.


All crystal oscillators take some time to “start up” – produce stable full-amplitude output.

Typically the lower the drive to the crystal, the longer it takes to start. Very low power circuits can take tens to hundreds of milliseconds to start. The capacitors are for “loading” the crystal. Crystals are designed to operate with specific load capacitance to operate at their nominal resonant frequency. This circuit operates the crystal in “parallel resonant” mode. Typically the load capacitance required is considerably higher than the capacitance associated with the “pins” of an IC oscillator circuit, so that discrete capacitors can be used to set the capacitance, allowing greater application flexibility.

Cdbe pdf download

The load capacitance that the crystal sees is pin capacitance in parallel with discrete capacitance in series with same thing, other pin.

Often one of the capacitors is a variable type so that the frequency can be trimmed “pulled” by a few parts per million.

Having one 82 pf and one 22 pF cap is very odd – for a crystal in the low megahertz range both caps would typically be in the pF range. You can find information explaining all of this in detail cd44521be the web. Most crystal manufacturers publish applications information.

I also recall an old ap note on oscillators of assorted types with series CMOS gates.

CD4521 PDIP16

Note that the old CD is much much slower cd451be the current HEF and will almost certainly not work with the intended crystal. The HEF part should be fine. May 10, 3. Jun 5, 1, Crystals need loading capacitors from each pin to ground as shown in the circuit. I have usually seen them as equal values, not sure why they are different ones here. The total capacitance which is the two in series needs to be a specific value based on the actual crystal used.


Normally, I would use two equal capacitor as twice the specified capacitance for the crystal, so, in datashewt they equal the required capacitance.

Data sheet acquired from Harris Semiconductor SCHSC — Revised October PDF

The 1M resistor is biasing for the gate that is used in the oscillator. I cannot tell you if these specific values would work.

They may need to be adjusted for the crystal used. Where did you get the table showing 1Hz was ms on and ms off? That is incorrect, it is datasneet on and datasheef off. May 10, 4. Mar 10, 1, The Rs and Cs plus crystal are for creating an accurate timing clock signal. Its an oscillator circuit to feed a clock to the divide chain in the part. May 10, 5.

May 10, 6. May 10, 7.

Datashheet 10, 8. May 10, 9. May 10, Dec 19, 2, If you just need an accurate 1Hz clock signal, I’ll throw this in.

Using a scrapped out PCB from a 1. Some have cd4521he pullup on the coils and others have a pulldown output. This is a pull down for the base of Q1. Posted by FrozenNick in forum: RC 27 MHz transmitter and receiver help Posted by programmer in forum: You May Also Like: What will it do to electronics? Your name or email address: Do you already have an account? No, create datasheft account now. Yes, my password is: Quote of the day.