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All About Docks

DOCK190 Supply Power Delivery Application Note

Since the Targus DOCK190 has two different ways to supply power to the upstream host computer and can supply power and charging to downstream USB devices on both Type-A and Type-C ports, Thee DocKtor thought he’d try to clarify how these power operation capabilities can be used.

USB Type-C Power Delivery Mode

The USB Type-C PD operation can be confusing as it varies depending on the power sink capabilities of the host computer.  If the host device has a Type-C port that can sink (take) USB Type-C Power Delivery at 9, 12, 15, or 20 VDC up to 100W then Thee DocKtor recommends connecting the DOCK190 using the USB Type-C UP port to the host Type-C port using the in-box USB Type-C cable.  It does not matter if this port is USB Type-C Gen 1 or Gen 2 or one of the USB Type-C Alternate Modes (i.e. Thunderbolt or DisplayPort Alt. Mode).  What matters is the Type-C port is either a USB Type-C PD sink port or Dual Role Port (DRP) for power.  Consult your PC manufacturer for this data.

In this mode the docking functions are provided by the USB SuperSpeed connection and the host power and charging is provided by the DOCK190 USB Type-C PD, all through a single 1m 100W USB Type-C SuperSpeed cable.  The ACC1104 adapter and “DC 19.5V OUT” port cables/tips are not needed in this mode.

Legacy Power Delivery Mode

The DOCK190 also supports what is often termed “legacy” or “barrel” 19.5 VDC power for the host PC (Windows, Ubuntu, or Chrome OS) and only at 19.5 VDC (no other voltages) up to 90W.  In this mode host power and charging is supplied via the Targus Universal Power Tip System connected to the host via the DC Cable from the DOCK190 “DC 19.5V OUT” port.

In this mode the ACC1104 USB Type-C to Type-A Adapter Cable is required (cable and adaptor not shown in the picture) for the USB SuperSpeed docking functions (video, USB Hub, GbE).   In this mode DO NOT connect the USB Type-C cable to a host USB Type-C port (USB 3.1, Thunderbolt, DP Alt. Mode, etc.) for the USB SuperSpeed data connection without the ACC1104 in-line.  Connect the ACC1104 to a host USB SuperSpeed Type-A (aka USB 3.0) port.  The reason that the USB Type-C cable cannot be used for the SuperSpeed connection in this case is per the DOCK190 Power Delivery implementation of the USB Type-C PD Specification.

Use Legacy or USB Type-C PD, Not Both

If the host Type-C port (albeit USB Type-C Gen 1 or Gen 2, Thunderbolt, DP Alt. Mode, etc.) is not a USB Type-C PD sink or DRP for power, then the host Type-C port and the DOCK190 USB Type-C port may establish a USB Type-C PD Contract.  When a USB Type-C PD Contract is established with the DOCK190 USB Type-C port, the legacy “DC 19.5V DC OUT” power is no longer available, it is off, and the DC cable connection between the DOCK190 and the host is no longer needed.  Since both the DOCK190 USB Type-C and “DC 19.5V OUT” power are derived in accordance with the USB Type-C PD specification, they cannot be used at the same time no matter the level.

It is important to realize that if the host Type-C port does establish a USB Type-C PD Contract as a source, at any level, the DOCK190 is in USB Type-C Power Delivery Mode but not sourcing power on either the USB Type-C “UP” port nor the “DC 19.5V OUT” port.  It is simply acting as a Universal Docking Station and not as a host power source.

In example, many USB Type-C Thunderbolt ports, especially on high-performance workstation class platforms (Dell Precision, HP ZBook) will establish a 5VDC @ 3A PD source contract for buss powered devices.  They will not sink power nor do they have the ability to sink power; this is compliant with the minimum Thunderbolt port operation.  When such a host Thunderbolt port is connected with the DOCK190 “UP” port, the host and DOCK190 negotiate a PD contract where this minimum host 5VDC @ 3A sink results.  Therefore, the DOCK190 is neither a PD sink or source, and because the PD contract exists on the USB Type-C connection, the legacy source power is also off.

In contract, some USB Type-C Thunderbolt ports, especially on enterprise class platforms (Dell Latitude, HP Elitebook, Lenovo T-Series, MacBooks) will establish not only a 5VDC @ 3A source contract, but also a sink contract (often at 45W, 65W, 87W, or more at varying voltage levels).  These Thunderbolt can be USB Type-C PD source or sink ports, and as a sink will establish a PD contact of 100W or less; this is compliant with optional Thunderbolt PD operation.  When any of these type of host Thunderbolt ports are connected with the DOCK190 “UP” port, the host and dock negotiate a compatible USB Type-C PD Contract and DOCK190 legacy power is off as the DOCK190 is in USB Type-C PD mode.

In any case, if the host Type-C port cannot establish a compatible PD Contract using the USB Type-C cable connection to the DOCK190, or establishes a USB Type-C PD Contract as a 5VDC source (i.e. Thunderbolt to 15W) then the legacy power is shut off even though still needed to power and charge the host!

USB Port Charging

When the DOCK190 is delivering host power in either USB Type-C or Legacy Power Delivery Mode its USB port are capable of suppling power.  The USB 3.1 Gen 1 (aka USB 3.0) SuperSpeed Type-A and Type-C Downstream Facing ports are all 5VDC @ 900mA (4.5W) capable.  The USB Type-A port on the side (with the horizontal lightning bolt above it) of the DOCK190 is capable of 5VDC @ 1500mA (7.5W) BC1.2 fast charging.

This can be confusing as some devices can be powered by both the DOCK190 USB Type-C Upstream Facing Port (UFP) labeled “UP” or Downstream Facing Port (DFP).  In example, a Samsung Galaxy S9 Phone can be connected as an UFP host and a PD contract of 5VDC @ 3A (15W).  Here it is the host for docking functions also.  When connected to the DFP, the S9 will get 5VDC up to 900mA (4.5W) for trickle charging.  Here it is a downstream device for connection to the host USB.

Summary

  • Whenever possible, use the DOCK190 USB Type-C cable for both USB and Power connectivity.
  • When using the legacy power option, use the ACC1104 for USB connectivity.
  • DO NOT connect both the legacy power and then the USB Type-C cable (without the ACC1104) from the DOCK190 to the host.

Feel free to post additional questions about the DOCK190, USB Type-C Power Delivery, or the Type-C Modes here.

 

Categories: Main, Usage, White Paper

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  1. Low PC Battery Disables Targus DOCK190 Legacy Power. – Thee DocKtor's Blog

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