8

Precision Edge™

SY100EP14U

Micrel

TERMINATION RECOMMENDATIONS

R2

82

Ω

R2

82

Ω

+3.3V

+3.3V

R1

130

Ω

R1

130

Ω

+3.3V

Figure 1. Parallel Termination–Thevenin Equivalent

Note 1.

For +2.5V systems: R1 = 250

Ω, R2 = 62.5Ω

Note 2.

For +5.0V systems: R1 = 82

Ω, R2 = 130Ω

Z = 50

Ω

Z = 50

Ω

50

Ω

50

Ω

50

Ω

+3.3V

+3.3V

“source”“destination”

Figure 2. Three-Resistor “Y–Termination”

Note 1.

Power-saving alternative to Thevenin termination.

Note 2.

Place termination resistors as close to destination inputs as possible.

Note 3.

R

+3.3V

+3.3V

50

Ω

0.01

µF

R2

82

Ω

+3.3V

+3.3V

R1

130

Ω

R1

130

Ω

R2

82

Ω

Q

/Q

+3.3V

Figure 3. Terminating Unused I/O

Note 1.

Unused output (/Q) must be terminated to balance the output.

Note 2.

Micrel's differential I/O logic devices include a V

Note 3.

Connect unused input through 50

Ω to V

Note 4.

For +2.5V systems: R1 = 250

Ω, R2 = 62.5Ω.