1µA at VOL , VOHData sheet acquired from Harris Semiconductor
The ’HC297 and CD74HCT297 are high-speed silicon gate CMOS devices that are pin-compatible with low power Schottky TTL (LSTTL).
These devices are designed to provide a simple, cost-effective solution to high-accuracy, digital, phase-locked-loop applications. They contain all the necessary circuits, with the exception of the divide-by-N counter, to build first-order phase-locked-loops.
Both EXCLUSIVE-OR (XORPD) and edge-controlled phase detectors (ECPD) are provided for maximum flexibility. The input signals for the EXCLUSIVE-OR phase detector must have a 50% duty factor to obtain the maximum lock-range.
Proper partitioning of the loop function, with many of the building blocks external to the package, makes it easy for the designer to incorporate ripple cancellation (see Figure 2) or to cascade to higher order phase-locked-loops.
The length of the up/down K-counter is digitally programmable according to the K-counter function table. With A, B, C and D all LOW, the K-counter is disabled. With A HIGH and B, C and D LOW, the K-counter is only three stages long, which widens the bandwidth or capture range and shortens the lock time of the loop. When A, B, C and D are all programmed HIGH, the K-counter becomes seventeen stages long, which narrows the bandwidth or capture range and lengthens the lock time. Real-time control of loop bandwidth by manipulating the A to D inputs can maximize the overall performance of the digital phase-locked-loop.
The ’HC297 and CD74HCT297 can perform the classic first order phase-locked-loop function without using analog components. The accuracy of the digital phase-locked-loop (DPLL) is not affected by VCC and temperature variations but depends solely on accuracies of the K-clock and loop propagation delays.
| Typ | Titel | Datum | ||
|---|---|---|---|---|
| * | Data sheet | CD54/74HC297, CD74HCT297 datasheet (Rev. B) | 16 Apr 2003 | |
| Application note | Implications of Slow or Floating CMOS Inputs (Rev. E) | 26 Jul 2021 | ||
| Selection guide | Logic Guide (Rev. AB) | 12 Jun 2017 | ||
| Application note | Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) | 02 Dez 2015 | ||
| User guide | LOGIC Pocket Data Book (Rev. B) | 16 Jan 2007 | ||
| Application note | Semiconductor Packing Material Electrostatic Discharge (ESD) Protection | 08 Jul 2004 | ||
| User guide | Signal Switch Data Book (Rev. A) | 14 Nov 2003 | ||
| Application note | TI IBIS File Creation, Validation, and Distribution Processes | 29 Aug 2002 | ||
| Application note | CMOS Power Consumption and CPD Calculation (Rev. B) | 01 Jun 1997 | ||
| Application note | Designing With Logic (Rev. C) | 01 Jun 1997 | ||
| Application note | SN54/74HCT CMOS Logic Family Applications and Restrictions | 01 Mai 1996 | ||
| Application note | Using High Speed CMOS and Advanced CMOS in Systems With Multiple Vcc | 01 Apr 1996 |
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Das 14-24-LOGIC-EVM-Evaluierungsmodul (EVM) ist für die Unterstützung aller Logikgeräte konzipiert, die sich in einem 14-Pin- bis 24-Pin-D-, DW-, DB-, NS-, PW-, DYY- oder DGV-Gehäuse befinden.
| Gehäuse | Pins | Herunterladen |
|---|---|---|
| PDIP (N) | 16 | Optionen anzeigen |
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