DS15BR400_15 Datasheet, PDF (9/19 Pages) Texas Instruments – 4-Channel LVDS Buffer/Repeater with Pre-Emphasis

DS15BR400, DS15BR401
www.ti.com
SNLS224G – AUGUST 2006 – REVISED APRIL 2013
Bypass capacitors should be placed close to VDD pins. Small physical size capacitors, such as 0402, X7R,
surface mount capacitors should be used to minimize body inductance of capacitors. Each bypass capacitor is
connected to the power and ground plane through vias tangent to the pads of the capacitor. An X7R surface
mount capacitor of size 0402 has about 0.5 nH of body inductance. At frequencies above 30 MHz or so, X7R
capacitors behave as low impedance inductors. To extend the operating frequency range to a few hundred MHz,
an array of different capacitor values like 100 pF, 1 nF, 0.03 µF, and 0.1 µF are commonly used in parallel. The
most effective bypass capacitor can be built using sandwiched layers of power and ground at a separation of 2–3
mils. With a 2 mil FR4 dielectric, there is approximately 500 pF per square inch of PCB.
The center dap of the WQFN package housing the DS15BR400 should be connected to a ground plane through
an array of vias. The via array reduces the effective inductance to ground and enhances the thermal
performance of the WQFN package.
INPUT INTERFACING
The DS15BR400 and DS15BR401 accept differential signals and allow simple AC or DC coupling. With a wide
common mode range, the DS15BR400 and DS15BR401 can be DC-coupled with all common differential drivers
(i.e. LVPECL, LVDS, CML). The following three figures illustrate typical DC-coupled interface to common
differential drivers. Note that the DS15BR400 inputs are internally terminated with a 100Ω resistor while the
DS15BR401 inputs are not, therefore the latter requires external input termination.
LVDS
Driver
OUT+
100: Differential T-Line
IN+
DS15BR400
Receiver
100:
OUT-
IN-
Figure 11. Typical LVDS Driver DC-Coupled Interface to DS15BR400 Input
CML3.3V or CML2.5V
Driver
V_CC
50:
50:
OUT+
100: Differential T-Line
IN+
DS15BR400
Receiver
100:
OUT-
IN-
Figure 12. Typical CML Driver DC-Coupled Interface to DS15BR400 Input
LVPECL
Driver
OUT+
OUT-
150-250:
100: Differential T-Line
IN+
LVDS
Receiver
100:
IN-
150-250:
Figure 13. Typical LVPECL Driver DC-Coupled Interface to DS15BR400 Input
Copyright © 2006–2013, Texas Instruments Incorporated
Submit Documentation Feedback
9
Product Folder Links: DS15BR400 DS15BR401