MC12060
Key Features
- (~) (For MCI 2060); ‘:’’sS~’::”R3 + R4 t R19 5. Operates from a sin~e polarity, low voltage sUPPIY , R2 + ],~~~ [J,J] , .,. 4 ~{;t:;t>, ,%‘( )} (5.0 volts). .* *...,.,. ~?+.,. *<-$. V-VD IQ’-’’*>(
- (~) (For MC1206 ‘1) . GENERAL “: “’$~lR~+{R~711 (R3+ ‘~R13)} The MC 12060 and MC 12061 crystal oscillators are :J&~$i$~ specified for operating frequency ranges of 100 kHz to $y~~~~~$ 2.O MHz, and 2.0 MHz to 20 MHz respectively. Their’ “ ‘ti’:$. While one diode (or one diode pair in the case of Fig~~> outputs consist of a sin~e-ended TTL signal, plus ,,$pm-.’ ure 1) is always forward biased, the remaining diodes are elementary sine wave tid ‘“ECL si~ds. The sim~~~~$~~ ., reverse biased to minimize their capacitance. This is outputs are capable of driving an ac load of ~@#* at acplished with a single polarity supply by using pullup 500 mVp-p (typical) when an external re~~~~Y~@used ~ resistors (R12, R13, R14, RI 5, and R16) from the posito increase the current in the emitter f~~~f” output. tive potential to each switch terminal. Therefore, the The ECL and TTL outputs are capabl~:$~~~ting five and ~ cathodes of the diodes corresponding to the unselected .* ,, . ..T!c, ten gate loads respectively. crystals are pulled up to approximately the supply volt:11 Series resonant crystals conne#ed~&#$ween pins 5 and age. Since one diode (or diode pair) is always selected, 6 are required for use with~#~~$,#scfilatorsl The tot~ ““ current is flowing through R 17 continuously, causing a effective ac series resistan~ ‘{,~~~<talseries resonance revoltage drop. Therefore, the anodes of the unselected ;,, ~.,\> ..*,., sistance plus any addi@na& resistance contributed by diodes will be negative with respect to their cathodes. ~si> ,:$. switching pone,~&)$ be~een these pins must “be less When using a 5.0 volt supply, this reverse bias will be 1.6 than 4 k ohs for$~~3~~# 12060, and less than 155 ohms volts for the MC 12060 and 1.2 volts for the MC 12061 for the MC 120@:~~.,#;i”$ c~stal switching array. For additi~>@formation on these IC’S, see the device data she$ki;&~AEfigineering Bulletins EB-58 and EB-59. ADDITIONAL CONSIDERATIONS A sufficient amount of forward current through the Sch~at$+ ‘“diagrams for the MC 12060 and MC 12061 diode selectirig the desired crystal is required to insure cryg{~$~~ltching circuits are given in Figures 1 and 2 a low value for diode resistance KD (see Figure 3). This is ~~~~~tively. The same basic technique is employed f~~each IC exce
