MPC93R52

MOTOROLA

TIMING SOLUTIONS

10

Figure 11. Single versus Dual Waveforms

TIME (nS)

3.0

2.5

2.0

1.5

1.0

0.5

0

2

4

6

8

10

12

14

OutB

tD = 3.9386

OutA

tD = 3.8956

In

Since this step is well above the threshold region it will not

cause any false clock triggering, however designers may be

uncomfortable with unwanted reflections on the line. To better

match the impedances when driving multiple lines the

situation in Figure 12. “Optimized Dual Line Termination”

should be used. In this case the series terminating resistors

are reduced such that when the parallel combination is added

to the output buffer impedance the line impedance is perfectly

matched.

Figure 12. Optimized Dual Line Termination

14

Ω

MPC93R52

OUTPUT

BUFFER

RS = 22Ω

ZO = 50Ω

RS = 22Ω

ZO = 50Ω

14

Ω + 22Ω k 22Ω = 50Ω k 50Ω

25

Ω = 25Ω

Figure 13. CCLK MPC93R52 AC test reference for Vcc = 3.3V and Vcc = 2.5V

Pulse

Generator

Z = 50

W

RT = 50Ω

ZO = 50Ω

RT = 50Ω

ZO = 50Ω

MPC93R52

DUT

VTT

VTT