eeworldonline.com | designworldonline.com 6 • 2019 DESIGN WORLD — EE NETWORK 29POWER DELIVERY 3.0
From the USB Implementors
Forum. At left, an example
of an Assured-Capacity
Charger with a total capacity
of 60 W and a USB Charger
certification of 30 W. At right,
an example of Shared-Capacity
Charger with a total capability
of 60 W and a USB Charger
certification of 27 W.USB PD is a specification for handling higher power on
USB and allows a range of devices to charge quickly over a USB
connection. It facilitates negotiation between two devices for a
power contract, so they can determine how much power can be
pulled from the charger. Power Delivery starts at the 5-V setting
and is configurable up to 20 V. Using a standard USB-C cable, it
can handle up to 60 W and will go up to 100 W using a full-
featured USB Type-C (ECMA) cable.
Another point of interest regarding Power Delivery is that it
allows for power to flow both ways, with no set direction based
on circuit or connection. For example, if you were to connect two
phones that support Power Delivery with a USB-C charging cable,
one phone could charge the other and vice versa.
A newly introduced PPS (Programmable Power Supply)
protocol requires that a PPS-capable sink be able to request
adjustments of source output voltage in increments as small as 20
mV. Likewise, the sink can request source current limits in 50-mA
steps. The sink should check in with the source at least every 10 seconds with a voltage/current request. Sources operate in
constant-voltage or current-limit modes depending on the load;
current-limit mode happens only when the sink attempts to draw
more than the negotiated current. POWER DELIVERY 3.0 VS 2.0
There are a number of significant differences between the PD 2.0
specification and the latest 3.0 specification:- Power Delivery Profiles (PDPs): Since the PD 1.0
specification, USB PD’s Power Profiles were a way to
communicate power-supply capabilities to a USB end user.
PDPs are a revamp of Power Profiles that now tell the user
what the power supply can deliver in Watts; a higher value
means more power. A PDP is the highest nominal voltage
times the nominal current reported in fixed Power Delivery
Objects (PDOs).
A simplified model of a
preferred charging regime
for a lithium-ion battery,
as created by the USB
Implementers Forum.Amps
Current into the batteryVoltage on the battery
VoltageTime
Typical lithium-ion charging sequenceCapacity labelsLeCroy — Test and Measurement HB 06-19.indd 29 6/10/19 8:25 AM