DATASHEET 12 TO 36 MHZ 6TSOT VCXO ICS726A Description Features Used in conjunction with an external pullable quartz crystal, Uses an inexpensive 12 to 36 MHz external crystal this monolithic integrated circuit replaces more costly Output frequency range of 12 to 36 MHz hybrid (canned) VCXO devices. The ICS726A is designed On-chip VCXO with guaranteed pull range of 115 ppm primarily for data and clock recovery applications such as minimum ADSL modems, set-top box receivers, and telecom systems. VCXO tuning voltage 0 to 3.3 V Packaged in 6-pin TSOT The frequency of the on-chip VCXO is adjusted by an external control voltage to the VIN pin. Since VIN is a high Pb (lead) free package impedance input, it can be driven directly from an PWM RC integrator circuit. Frequency output increases with VIN voltage input. The usable range of VIN is 0 to 3.3 V. Block Diagram VDD VIN X1 Voltage 12-36MHz Controlled 12-36MHz Pullable Crystal Crystal Oscillator X2 GND IDT 12 TO 36 MHZ 6TSOT VCXO 1 ICS726A REV E 021312ICS726A 12 TO 36 MHZ 6TSOT VCXO VCXO Pin Assignment X2 1 6 X1 GND 2 5 VIN CLK 3 4 VDD TSOT-23-6 Pin Descriptions Pin Pin Pin Pin Description Number Name Type 1 X2 Input Crystal connection. Connect to the external pullable crystal. 2 GND Power Connect to ground. 3 CLK Output VCXO CMOS level clock output at the frequency of the crystal. 4 VDD Power Connect to +3.3 V (0.01f decoupling capacitor recommended). 5 VIN Input Voltage input to VCXO 0 to 3.3 V analog input which controls the oscillation frequency of the VCXO. 6 XI Input Crystal connection. Connect to the external pullable crystal. reliability, a crystal device with the recommended External Component Selection parameters (shown below) must be used, and the layout guidelines discussed in the following section shown must be The ICS726A requires a minimum number of external followed. components for proper operation. The frequency of oscillation of a quartz crystal is determined Decoupling Capacitor by its cut and by the load capacitors connected to it. The A decoupling capacitor of 0.01F must be connected ICS726A incorporates on-chip variable load capacitors that between VDD (pin 4) and GND (pin 2), as close to these pull (change) the frequency of the crystal. The crystal pins as possible. For optimum device performance, the specified for use with the ICS726A is designed to have zero decoupling capacitor should be mounted on the component frequency error when the total of on-chip + stray side of the PCB. Avoid the use of vias in the decoupling capacitance is 8.9 pF. circuit. Required Crystal Parameters: Series Termination Resistor Nominal Frequency as required MHz When the PCB trace between the clock output (CLK, pin 3) Initial Accuracy at 25C -20 min/+20 max ppm and the load is over 1 inch, series termination should be Temperature Stability -30 min/+30 max ppm used. To series terminate a 50 trace (a commonly used Aging, 1st year -5 min/+5 max ppm trace impedance) place a 33 resistor in series with the Aging, 10 years -20 min/+20 max ppm clock line, as close to the clock output pin as possible. The Operating Temp. Range, C 0 min/+25 typ/+70 max nominal impedance of the clock output is 20. or Operating Temp. Range, C -40 min/+25 typ/+85 max Quartz Crystal Load Capacitance 8.6 pf Shunt Capacitance, C0 7 pF Max The ICS726A VCXO function consists of the external crystal C0/C1 Ratio 270 Max and the integrated VCXO oscillator circuit. To assure the Equivalent Series Resistance 35 Max best system performance (frequency pull range) and IDT 12 TO 36 MHZ 6TSOT VCXO 2 ICS726A REV E 021312