TLC2942

HIGH-PERFORMANCE DUAL PHASE-LOCKED LOOP BUILDING BLOCK

SLAS146B – NOVEMBER 1996 – REVISED JUNE 1997

4

POST OFFICE BOX 655303

detailed description

multichip module

The TLC2942 is a multichip module (MCM) product that uses two TLC2932 chips. A newly developed lead frame

for TLC2942IBD is specially shaped and cut in the package to electrically isolate one chip from another. The

two chips are completely independent from each other to perform the best stable oscillation and locking. If

asynchronous locking operation is required for these two PLL blocks, each TLC2942 VCO and PFD can achieve

the same stability as the single chip TLC2932IPW.

Three NC terminals are on both sides of the package between chip1 and chip2 due to the lead frame shape.

To avoid performance degradation, special attention is needed for each PLL block PCB layout especially for

supply voltage lines and GND patterns.

voltage-controlled oscillator (VCO)

VCO1 and VCO2 have the same typical characteristics. Each VCO oscillation frequency is determined by an

range depends on this register value. The bias resistor value for the minimum temperature coefficient is

nominally 3.3 k

the recommended operating conditions. Figure 1 shows the typical frequency variation and VCO control

voltage.

VCO Oscillation Frequency Range

Bias Resistor (RBIAS)

1/2 VDD

VCO Control Voltage (VCOIN)

Figure 1. VCO1 and VCO2 Oscillation Frequency

VCO output frequency 1/2 divider

Table 1. SELECT1 and SELECT2 Function Table

SELECT1

VCO1 OUTPUT

FREQUENCY

SELECT2

VCO2 OUTPUT

FREQUENCY

Low

fosc1

Low

fosc2

High

1/2 fosc1

High

1/2 fosc2