3.5 Outputs

The Si5341 supports 10 differential output drivers which can be independently configured as differential or LVCMOS. The Si5340 sup-

ports 4 output drivers independently configurable as differential or LVCMOS.

3.5.1 Output Signal Format

The differential output amplitude and common mode voltage are both fully programmable and compatible with a wide variety of signal

formats including LVDS and LVPECL. In addition to supporting differential signals, any of the outputs can be configured as LVCMOS

(3.3 V, 2.5 V, or 1.8 V) drivers providing up to 20 single-ended outputs, or any combination of differential and single-ended outputs.

3.5.2 Differential Output Terminations

The differential output drivers support both ac-coupled and dc-coupled terminations as shown in the figure below.

100

50

50

Internally

self-biased

AC Coupled LVDS/LVPECL

50

50

AC Coupled LVPECL/CML

VDD– 1.3V

50

50

50

50

100

DC Coupled LVDS

OUTx

OUTxb

OUTx

OUTxb

OUTx

OUTxb

Si5341/40

Si5341/40

Si5341/40

AC Coupled HCSL

R1

OUTx

OUTxb

Si5341/40

50

50

R1

R2

R2

Standard

HCSL

Receiver

Option1

3. 3 V

2. 5 V

1. 8 V

442 ohms

332 ohms

243 ohms

56.2 ohms

59 ohms

63.4 ohms

R1

R2

Figure 3.5. Supported Differential Output Terminations

3.5.3 Programmable Common Mode Voltage for Differential Outputs

The common mode voltage (VCM) for the differential modes are programmable so that LVDS specifications can be met and for the best

signal integrity with different supply voltages. When dc coupling the output driver it is essential that the receiver should have a relatively

high common mode impedance so that the common mode current from the output driver is very small.

Si5341/40 Rev D Data Sheet

Functional Description

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