PTN3381D
Enhanced performance HDMI/DVI level shifter with voltage
regulator, dongle detection and supporting 3 Gbit/s operation
Rev. 2 — 26 July 2012
Product data sheet
1. General description
The PTN3381D is a high-speed level shifter device which converts four lanes of low-swing
AC-coupled differential input signals to DVI v1.0 and HDMI v1.4b compliant open-drain
current-steering differential output signals, up to 3 Gbit/s to support 36-bit deep color, 3D
and 3 Gbit/s modes. Each of these channels provides a level-shifting differential buffer to
translate from low-swing AC-coupled differential signaling on the source side, to
TMDS-type DC-coupled differential current-mode signaling terminated into 50 to 3.3 V
on the sink side. Additionally, the PTN3381D provides a single-ended active buffer for
voltage translation of the HPD signal from 5 V on the sink side to 3.3 V on the source side
and provides a channel with active buffering and level shifting of the DDC channel
(consisting of a clock and a data line) between 3.3 V source-side and 5 V sink-side. The
DDC channel is implemented using active I2C-bus buffer technology providing capacitive
isolation, redriving and level shifting as well as disablement (isolation between source and
sink) of the clock and data lines.
To provide the highest level of integration in external adapter (or: dongle) applications,
PTN3381D includes an on-board 5 V DC regulator. Its output is designed to provide the
required 5 V power supply to the DVI or HDMI connector, thereby eliminating the need for
a separate external regulator. The on-board regulator needs only two external capacitors
to operate, and its output is active whenever a valid 3.3 V is applied to the PTN3381D VDD
pins.
The low-swing AC-coupled differential input signals to the PTN3381D typically come from
a display source with multi-mode I/O, which supports multiple display standards, for
example, DisplayPort, HDMI and DVI. While the input differential signals are configured to
carry DVI or HDMI coded data, they do not comply with the electrical requirements of the
DVI v1.0 or HDMI v1.3a specification. By using PTN3381D, chip set vendors are able to
implement such reconfigurable I/Os on multi-mode display source devices, allowing the
support of multiple display standards while keeping the number of chip set I/O pins low.
See Figure 1.
The PTN3381D main high-speed differential lanes feature low-swing self-biasing
differential inputs which are compliant to the electrical specifications of DisplayPort
Standard v1.2 and/or PCI Express Standard v1.1, and open-drain current-steering
differential outputs compliant to DVI v1.0 and HDMI v1.4b electrical specifications. The
I2C-bus channel actively buffers as well as level-translates the DDC signals for optimal
capacitive isolation. Its I2C-bus control block also provides for optional software HDMI
dongle detect by issuing a predetermined code sequence upon a read command to an
I2C-bus specified address. The PTN3381D also supports power-saving modes in order to
minimize current consumption when no display is active or connected.
