CBTL12131 Datasheet, PDF (1/29 Pages) NXP Semiconductors – DisplayPort multiplexer for bidirectional video in all-in-one computer systems

CBTL12131
DisplayPort multiplexer for bidirectional video in all-in-one
computer systems
Rev. 1 — 25 February 2011
Product data sheet
1. General description
CBTL12131 is an integrated DisplayPort high-speed path switch/multiplexer that allows
all-in-one computer systems to efficiently manage path switching between different
display modes of operation. With the CBTL12131, video can be routed either from one
DisplayPort source (GPU1) to an integrated DisplayPort panel and simultaneously from a
second DisplayPort source (GPU2) to an external DisplayPort sink; or from an external
DisplayPort source to the integrated DisplayPort panel.
The device is configured as four main Ports A through D, each providing four high-speed
differential lanes for DisplayPort Main Link (ML) channels, one high-speed differential lane
for the DisplayPort AUX channel, and one single-ended lane for the HPD (Hot Plug
Detect) signal. One port (Port A) provides an additional alternate lane for the AUX
channel, in order to allow bypassing of external AC-coupling capacitors for support of the
DDC channel in case an external connected sink is a ‘++DP’ type cable adapter.
For the path supporting the ‘external source to integrated DisplayPort panel’ mode, a
programmable equalizer is provided which allows compensation for channel loss that the
external source or internal sink are unable to adequately compensate for. The equalizer is
self-biasing and is programmable to five gain-frequency curves, of which one is a flat
response and four are active equalization. The equalizer output can also be set to one of
two levels of pre-emphasis (including flat), and also differential swing level can be set to
one of two levels. All options (EQ, pre-emphasis, level) are easily programmed using
board-strapping (resistor, short or open) of three unique Quinary Input programming pins.
The CBTL12131 includes additional features that support use of the external DisplayPort
connector in both directions: either an external sink (monitor or cable adapter) or external
source (notebook computer) can be connected, while CBTL12131 configures the direction
and termination of the related signals accordingly. The port facing the external DisplayPort
connector (Port B) is equipped with dedicated sensing circuitry which detects and reports
the status of the HPD and AUX lines, to support the system controller in determining and
setting the proper connection status. The AUX channel of Port B also has switchable
integrated termination, to allow the system controller to apply the correct DC termination
in case an external DisplayPort source is connected. Moreover, it affords the system
controller the means to detect the type of system (sink, source or all-in-one computer)
connected at Port B, and apply the proper termination required in each scenario.
The CBTL12131 is powered from a single 3.3 V power supply, consumes very little
current while providing low insertion loss and low return loss high-speed differential switch
channels suitable for use in DisplayPort v1.1a interconnect. All switch and configuration
settings can be performed by board-strapping or driving simple CMOS inputs—no
software or bus configuration is required. CBTL12131 is available in a 6 mm × 6 mm