Datasheet

DS50PCI401
SNLS292J –JUNE 2009–REVISED APRIL 2013 www.ti.com
FUNCTIONAL DESCRIPTION
The DS50PCI401 is a low power media compensation 4 lane repeater optimized for PCI Express Gen 1 and Gen
2 media including lossy FR-4 printed circuit board backplanes and balanced cables. The DS50PCI401 operates
in two modes: Pin Control Mode (ENSMB = 0) and SMBus Mode (ENSMB = 1).
Pin Control Mode:
When in pin mode (ENSMB = 0) , the repeater is configurable with external pins. Equalization and de-emphasis
can be selected via pin for each side independently. When de-emphasis is asserted VOD is automatically
increased per the De-Emphasis table below for improved performance over lossy media. The receiver detect
pins RXDETA/B provide manual control for input termination (50Ω or >50KΩ). Rate optimization is also pin
controllable, with pin selections for 2.5Gbps, 5Gbps, and auto detect. The receiver electrical idle detect threshold
is also programmable via an optional external resistor on the SD_TH pin.
SMBUS Mode:
When in SMBus mode the equalization, de-emphasis, and termination disable features are all programmable on
a individual lane basis, instead of grouped by sides as in the pin mode case. Upon assertion of ENSMB the
RATE, EQx and DEMx functions revert to register control immediately. The EQx and DEMx pins are converted to
AD0-AD3 SMBus address inputs. The other external control pins remain active unless their respective registers
are written to and the appropriate override bit is set, in which case they are ignored until ENSMB is driven low.
On powerup and when ENSMB is driven low all registers are reset to their default state. If PRSNT is asserted
while ENSMB is high, the registers retain their current state.
Table 2. Equalization Input Select Pins for A and B ports (3–Level Input)
EQ1
(1)
EQ0
(1)
Equalization Level Suggested Use
F F Off Bypass
1 1 Approx. 4 dB at 2.5Ghz 8 inches FR4 (6-mil trace) or less than 1 meter (28 AWG) PCIe cable
0 0 Approx. 9.6 dB at 2.5GHz 14 inches FR4 (6-mil trace) or 1 meter (28 AWG) PCIe cable
F 0 Approx. 11.4 dB at 2.5Ghz 20 inches FR4 (6-mil trace) or 5 meters (26 AWG) PCIe cable
1 0 Approx. 15.5 dB at 2.5Ghz 30 inches FR4 (6-mil trace) or 7 meters (24 AWG) PCIe cable
F 1 Approx. 17 dB at 2.5Ghz 40 inches FR4 (6-mil trace) or 9 meters (24 AWG) PCIe cable
0 1 Approx.19.1 dB at 2.5Ghz 50 inches FR4 (6-mil trace) or 10 meters (24 AWG) PCIe cable
0 F Approx. 20.6 dB at 2.5Ghz 15 meters (24 AWG) PCIe cable
1 F Approx. 26.3 dB at 2.5Ghz >15 meters (24 AWG) PCIe cable
(1) F=Float (don't drive pin, each float pin has an internal 50K Ohm resistor to VDD and GND), 1=High, 0=Low
Table 3. De-Emphasis Input Select Pins for A and B ports (3–Level Input)
RATE DEM1 DEM0
(1
Typical De- Typical DE Pulse
Typical VOD Suggested Use
(1) )
Emphasis Level Width
0/F 0 0 0dB 0ps 1000mV
0/F 0 1 -3.5dB 400ps 1000mV 8 inches FR4 (6-mil trace) or less than 1
meter (28 AWG) PCIe cable
0/F 1 0 -6dB 400ps 1000mV
0/F 1 1 -6dB 400ps enhanced 1000mV 15 inches FR4 (6-mil trace)
0/F 0 F -9dB 400ps enhanced 1000mV
0/F 1 F -12dB 400ps enhanced 1000mV
0/F F 0 -9dB 400ps enhanced 1200mV 30 inches FR4 (6-mil trace)
0/F F 1 -12dB 400ps enhanced 1400mV 40 inches FR4 (6-mil trace)
0/F F F Reserved, don't
use
1/F 0 0 0dB 0ps 1000mV
1/F 0 1 -3.5dB 200ps 1000mV
(1) F=Float (don't drive pin - (each float pin has an internal 50K Ohm resistor to VDD and GND). Enhanced DE Pulse width provides
additional de-emphasis on second bit. VOD = Voltage Output Differential amplitude. When RATE is floated (F=Auto Rate Detection
Active) DE Level and Pulse Width settings follow detected RATE. RATE=0 is 2.5GBps, RATE=1 is 5 GBps
6 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated
Product Folder Links: DS50PCI401