Features
• Center Frequency of 18MHz (Typ) at VCC = 5V,
Minimum Center Frequency of 12MHz at VCC = 4.5V
• Choice of Two Phase Comparators
- Exclusive-OR
- Edge-Triggered JK Flip-Flop
• Excellent VCO Frequency Linearity
• VCO-Inhibit Control for ON/OFF Keying and for Low
Standby Power Consumption
• Minimal Frequency Drift
• Zero Voltage Offset Due to Op-Amp Buffer
• Operating Power-Supply Voltage Range
- VCO Section . . . . . . . . . . . . . . . . . . . . . . . . . . 3V to 6V
- Digital Section . . . . . . . . . . . . . . . . . . . . . . . . 2V to 6V
• Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
• Wide Operating Temperature Range . . . -55oC to 125oC
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30% of VCC
at VCC = 5V
• HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility,
VIL= 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Applications
• FM Modulation and Demodulation
• Frequency Synthesis and Multiplication
• Frequency Discrimination
• Tone Decoding
• Data Synchronization and Conditioning
• Voltage-to-Frequency Conversion
• Motor-Speed Control
• Related Literature
- AN8823, CMOS Phase-Locked-Loop Application
Using the CD74HC/HCT7046A and
CD74HC/HCT7046A

Description
The CD74HC7046A and CD74HCT7046A high-speed
silicon-gate CMOS devices, specified in compliance with
JEDEC Standard No. 7A, are phase-locked-loop (PLL)
circuits that contain a linear voltage-controlled oscillator
(VCO), two-phase comparators (PC1, PC2), and a lock
detector. A signal input and a comparator input are common
to each comparator. The lock detector gives a HIGH level at
pin 1 (LD) when the PLL is locked. The lock detector
capacitor must be connected between pin 15 (CLD) and pin
8 (Gnd). For a frequency range of 100kHz to 10MHz, the
lock detector capacitor should be 1000pF to 10pF,
respectively.
The signal input can be directly coupled to large voltage
signals, or indirectly coupled (with a series capacitor) to
small voltage signals. A self-bias input circuit keeps small
voltage signals within the linear region of the input amplifiers.
With a passive low-pass filter, the 7046A forms a secondorder
loop PLL. The excellent VCO linearity is achieved by
the use of linear op-amp techniques.