AN92554 Implementing Battery Charging Features using HX3.pdf

AN92554
Implementing Battery Charging Features using HX3
Author: Hasib Mannil
Associated Project: No
Associated Part Family: CYUSB330x, CYUSB331x, CYUSB332x
Software Version: NA
Related Application Notes: AN91378
AN92554 introduces the basics of USB battery charging and describes standard and proprietary battery charger
detection mechanisms supported by HX3 on its upstream and downstream ports. This application note also helps you to
understand the HX3-specific features like Ghost Charge and ACA-Dock, and provides the guidelines to implement
various battery charging features.
Contents
Introduction
Introduction .......................................................................1
A Short History of USB Power ...........................................1
Definition of Terms ............................................................2
HX3 Variants .....................................................................3
Ganged Port Power switching ...........................................3
Individual Port Power switching .........................................3
ACA Dock Charging ..........................................................4
Overview of USB Battery Chargers ...................................4
USB-IF BC v1.2 Charging Standard .............................5
HX3 Battery Charging Features ........................................5
How HX3 Asserts Power Control in a System ..............5
Factors Affecting Charging Current to a Portable
Device ..........................................................................6
HX3 Charging Support on Upstream Port .........................9
Ghost Charge™ ......................................................... 11
Configuring Various Charging Methods with Blaster
Plus ............................................................................ 11
HX3 Development Kits ............................................... 12
Battery Charging Hardware Implementation in CY4603 kit
........................................................................................ 13
Hardware Design Considerations ............................... 14
Hardware Recommendations ..................................... 15
Demonstration of Battery Charging feature in CY4603
kit ................................................................................ 15
BC v1.2 Compliance Testing ........................................... 16
Limitations of HX3 Battery Charging ............................... 16
Summary ......................................................................... 16
References ................................................................. 16
Appendix A: Troubleshooting Guide ................................ 17
Appendix B: BC v1.2 Detection Mechanism .................... 19
Worldwide Sales and Design Support ............................. 29
HX3 is a family of USB 3.0 hub controllers compliant with
the USB 3.0 specification revision 1.0. HX3 supports
SuperSpeed (SS), Hi-Speed (HS), Full-Speed (FS), and
Low-Speed (LS) modes. In addition to implementing a
USB 3.0 hub, the HX3 family includes advanced USB
battery charging capabilities to meet the demand for
battery charging over USB.
www.cypress.com
This app note focuses on the battery charging features of
the HX3 product family. The app note begins with a
description of VBUS powered devices, USB battery
charging specification, overview of various USB battery
chargers and HX3 family supporting different battery
charging features. Finally, HX3-based evaluation kits is
described, along with the guidelines for design and
configuration of the charging features in HX3.
A Short History of USB Power
To make the USB technology user friendly, USB-IF has
defined the specification to supply power to the connected
USB devices over a USB cable along with data
communication (also known as bus powered devices).
This helps devices to draw power and also communicate
over a single USB cable. Figure 1 shows an
implementation of USB powered device.
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
Figure 1. USB Interface Signals
Figure 2. USB Port as Power Source
VBUS:
1. 100 mA at plug-in
2. Negotiate power during enumeration
3. Supply negotiated power (up to 500 mA)
PC
Device
VBUS
VBUS
PC
VBUS
D+
DGND
VBUS
GND
D+
DGND
When plugged in to a USB host, a USB device can draw
up to 100 mA. The device is required to communicate its
specific information to the host during the USB
enumeration process. During enumeration, the connected
device informs the host about how much power it would
require from VBUS. If the host is capable of providing the
requested amount of power, it goes ahead and configures
the device accordingly. For example, a device that
requests 200 mA of current at 5 V would be configured if
directly plugged into a PC’s downstream port, but not if
plugged into a bus-powered hub. This is because the PC
can deliver up to 500 mA, but a bus-powered hub can
deliver only 100 mA per downstream port as per USB
specification.
GND
This unsupervised use of USB power is not good for a PC
that is expected to manage power on an orderly basis. For
example, the mug warmer can’t do much with only 2.5 W
of power (the “legal” 5 V @ 500 mA limit), so some of
them draw 5 W, twice the legal limit. (5 W of heat also
does not do much to heat coffee, so USB mug warmers
are not popular). Increasing the wattage further risks
blowing the thermal fuse that protects the USB ports,
causing all of them to go dead until the fuse cools down
and/or the PC is rebooted.
An excellent use of USB power is to charge cell phones
and tablets from the USB connector. This eliminates the
clutter of incompatible wall-warts and cables, requiring
only the USB cable already used for data syncing. To
manage charging, and to provide more than 500 mA of
charging current, the USB-IF (USB Implementer’s Forum)
released the “Battery Charging Specification” version 1.2
in December 2010, here after abbreviated as “BC v1.2”.
For safety reasons, the USB specification requires overcurrent protection on all the downstream ports. The overcurrent protection circuit should remove the power when
the aggregate current drawn by a gang of downstream
ports exceeds the preset value. The specification also
stipulates that an overcurrent fuse must be self-recovering
for the best user experience.
BC v1.2 specification allows compliant portable devices to
charge with up to 1.5 A of current. It defines a new class of
USB ports called Charging Downstream Ports that allow
both charging up to 1.5 A of current and simultaneous
data communication. In comparison, a wall adapter
provides a Dedicated Charging Port, that is not capable of
data communication.
This simple power scheme is effective if everything
plugged into a USB port fully complies to the specification.
However, the market quickly took over and vendors
realized that a cheap source of power was sitting on every
desktop and laptop. USB entered a phase, in which all
types of devices were plugged into USB only to draw
power—mug warmers, fans, mini-refrigerators and lamps
to name a few. These devices make no connection to the
data lines, D+ and D-, but draw all the power they want
from VBUS. The typical load seen by the PC is a power
resistor between VBUS and GND (Figure 2).
Being able to charge from USB has also enabled the
industry to eliminate proprietary wall adapters for most of
the portable devices and phones. The Chinese Industry
specification YD/T 1591-2006 mandated all phones sold in
China to support detection of USB Dedicated Charging
Port (implemented by shorting D+ and D- pins). As of 14
June 2007, all mobile phones applying for a license in
China are required to use a USB port as a power source
for battery charging. The European Union (EU) followed
suit in 2009 to mandate the use of micro-USB connector
as the standard port for charging devices sold in the EU.
Definition of Terms
Note: Electrical specifications noted below are explained
in “Appendix B: BC v1.2 Detection Mechanism”.
Accessory Charger Adaptor (ACA): An ACA is an
adaptor which allows simultaneous connection of a
charger and another device to a single USB port.
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
ACA-Dock: An ACA-Dock is a docking station that has
one upstream port, and optional downstream ports. The
upstream port can be attached to a portable device, and is
capable of sourcing IDEV_CHG (1.5 A) to the portable device.
An ACA-Dock signals that it is an ACA-Dock to the
portable device by enabling VDM_SRC (0.5 V to 0.7 V) on the
D- pin during USB idle, and by pulling the ID
(Identification) pin to ground through a resistance of RID_A
(122 kΩ to 126 kΩ).
Apple Charging: Apple Charging is a proprietary charging
standard supported by HX3 to charge Apple devices such
as iPod, iPad or iPhone. If an Apple device is connected to
a downstream port of HX3, the charging method works in
two modes:

Apple Charging 1 A: The Apple charger (HX3) holds
its D- line at 2.7 V and D+ line at 2 V.

Apple Charging 2.1 A: The Apple charger (HX3)
holds its D+ line at 2.7 V and D- line at 2 V.
Charging Downstream Port (CDP): A Charging
Downstream Port (CDP) is a downstream port that
complies with the USB 2.0 definition of a host or a hub,
and allows a connected portable device to draw a
maximum current of IDEV_CHG (1.5 A). A CDP outputs a
voltage of VDM_SRC (0.5 V to 0.7 V) on its D- line when it
senses a voltage greater than VDAT_REF (0.25 V) and less
than VLGC (0.8 V) on its D+ line.
HX3 Variants
The HX3 family of hub controllers contains variants to
handle various power topologies. The smallest-package
versions are the CYUSB3302 (two downstream ports) and
CYUSB3304 (four downstream ports) in 68-pin QFN
packages.
Ganged Port Power switching
As shown in Figure 3, external power is routed to the
downstream ports via a single power switch (SW). HX3
configuration is done using on-chip ROM for default values
2
or an external I C EEPROM for custom code and/or
configurations. Note that VBUS from the PC is used only
to detect attachment (dotted line) and the external power
unit supplies the VBUS power to the downstream ports.
The external power supply in conjunction with BC v1.2
allows the plugged-in device (such as a phone) to charge
at a higher current before enumeration.
Figure 3. CYUSB3302/04: SuperSpeed Hub with GangSwitched Charger Ports
U
Charging Port: A Charging Port is any port that can
charge a battery powered device: a DCP, CDP, ACADock, or ACA.
Dedicated Charging Port (DCP): A DCP is a
downstream port that provides power to a portable device,
but is not capable of enumerating the portable device. A
DCP sources IDEV_CHG (1.5 A) with a voltage of VCHG (4.75
V to 5.25 V). A DCP indicates its type by placing a resistor
between its D+ and D- pins with a maximum resistance of
RDCP (200 Ω). Typically, D+ and D- are shorted.
Ghost Charge™: Ghost Charge is a Cypress-proprietary
charging method where a downstream port on HX3
emulates a DCP even though the upstream port is not
connected to a host or a hub.
Standard Downstream Port (SDP): A Standard
Downstream Port (SDP) refers to a downstream port that
is compliant with the USB definition of a host or hub. An
SDP pulls the D+ and D- to GND using 15 kΩ resistors
and can provide 500 mA current when the device is
configured.
A USB 3.0 downstream port can provide up to 900 mA
current when the device is configured.
External
Power
PC
Blue: USB signaling
Red: VBUS power
HX3
D1
D2
D3
SW
D4
Individual Port Power switching
Figure 4 illustrates the individual port power switching.
This is supported by HX3 in an 88-QFN-package, which
contains additional pins for individual power switches, and
also pin-strap configuration capability. External power
switches controlled by HX3 have a resistor-settable
current limiting and overcurrent sensing functionality. The
overcurrent condition is sensed by HX3 and reported back
to the PC via the USB. HX3 also automatically shuts down
any downstream port experiencing an overcurrent
condition. For more details on the implementation of the
external power switch controls, refer to the section “How
HX3 Asserts Power Control in a System”
USB Charger: A USB charger is a device with a DCP
such as a wall adapter or car power adapter.
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
Figure 4. CYUSB3312 (Two Downstream Ports) and
CYUSB3314 (Four Downstream Ports) with IndividuallySwitched Charger Ports
Figure 5. CYUSB3324/6/8: SuperSpeed Hub, ACA-Dock
Host
(e.g. tablet)
U
ID
PC
Blue: USB signaling
Red: VBUS power
External
Power
U
Blue: USB signaling
Red: VBUS power
External
Power
SW
HX3
HX3
SW
D1
SW
D2
SW
D3
SW
D1
SW
D4
SW
D2
SW
D3
SW
D4
Overview of USB Battery Chargers
ACA Dock Charging
Many tablets have the USB port for charging and to
function as a USB peripheral. Some newer tablets are
available with the USB port that can operate either as a
host or as a peripheral, known as dual-role, or OTG (OnThe-Go).
In addition to serving as either a USB Host or peripheral
(the “dual-role” part), an OTG device follows a signaling
protocol by which a host and a peripheral could swap roles
without disconnecting and re-connecting the USB cable.
The normal USB connector has four pins (D+, D-, VBUS,
and GND), whereas the OTG connector has five pins.
The additional fifth pin is an Identification (ID) pin, which
was originally used to detect the role of the device (host or
peripheral) . In the BC v1.2 specification, this ID pin is also
used to detect the ACA-Dock capability. This detection is
based on the resistor connected to the ID pin (Figure 5) on
the hub’s upstream port. “ACA-Dock” stands for Accessory
Charger Adapter-Dock, which is part of BC v1.2, described
in detail later in this application note.
Proprietary Chargers
Many devices follow the BC v1.2 specification. However,
there is an installed base of devices that follow proprietary
handshake protocols for battery charging. These
proprietary protocols, often introduced by popular portable
device manufactures, are referred to as proprietary
chargers. These chargers allow the portable devices to
distinguish dedicated chargers or “wall-warts” connected
to their USB ports from standard USB ports.
A standard USB port includes four terminals: D+, D-,
VBUS and GND. In all these charging methods, VBUS
provides the charging current and GND provides the
return path from the portable device. The D+ and D- wires
carry the signaling that allows the connected device to
distinguish a charger from a standard USB port. In a
standard downstream (DS) port, the D+ and D- lines are
both pulled down by 15 kΩ resistors. Proprietary chargers
alter this behavior of D+ and D- lines to allow a connected
portable device to detect a charger. The following sections
outline a few of the popular proprietary chargers.
Dedicated Chargers
In dedicated chargers, the charging method is
implemented either by shorting D+ and D- lines or by
connecting a low-value resistor between the D+ and Dlines. The USB-IF BC v1.2 DCP detection method is also
implemented this way. The dedicated charging port can be
used only for charging and there is no USB data
communication between the device and the charger, host
or hub.
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
Apple Chargers
Table 2. USB Power Standards
Apple devices (iPod, iPhone, and iPad) follow a
proprietary charger detection method to distinguish a
charger from a standard USB port. In this method, a
specific non-zero voltage is applied to the D+ and D- pins
to indicate the charger capability. Table 1 shows the
voltage on the D+ and D- lines provided by Apple chargers
to indicate current capabilities of the charger.
Specification
2
Voltage
on D- (V)
Charging
Current (A)
500 mA
(when
configured
by host)
2.5 W
USB 3.0 (SDP)
900 mA
(when
configured
by host)
4.5 W
CDP
1.5 A
7.5 W
2
0.5
DCP
0.5 A–1.5 A
2.5 W–7.5 W
ACA-Dock
1.5 A
7.5 W
2
2.7
1
2.7
2
2.1
2.7
2.7
2.4
Comments
1
Not in use .
First-generation Apple
Chargers.
Power
USB 2.0 (SDP)
Table 1. Various Apple Chargers
Voltage
on D+ (V)
Current
Battery
Charging
Specification
v1.2
1 A Apple Chargers
2.1 A Apple Chargers
2.4 A Apple Chargers
1
Samsung Chargers
Samsung devices follow multiple charging methods. Some
Samsung devices (Samsung Galaxy Tablets) use a
proprietary charging method in which the D+ and D- pins
are biased to the same potential (~1.2 V). The Samsung
Galaxy S series (S3, S4) devices follow the USB-IF BC
v1.2 charging standard for DCP, CDP, and SDP mode of
operations.
Other Proprieta ry Chargers
In addition to the proprietary outlined earlier in this section,
there are other proprietary chargers such as the ones
followed by older devices from Sony, Blackberry, etc. in
the market.
USB-IF BC v1.2 Charging Standard
When a portable device is attached to a USB host or a
hub, the USB 2.0 specification requires that the portable
device must draw current less than:
The detection of the various BC v1.2 charging mechanism
is discussed in detail in Appendix B: BC v1.2 Detection
Mechanism.
HX3 Battery Charging Features
HX3 supports various battery charging methods for
devices connected to both its downstream and upstream
ports. In addition to BC v1.2, HX3 supports the following
battery charging features

Apple charging: Apple’s proprietary charging method
used in iPad, iPhone, and iPod.

Ghost Charge™: Cypress-proprietary feature wherein
each downstream (DS) port can emulate a Dedicated
Charging Port (DCP) like a wall charger, when a host
is not connected to HX3’s upstream (US) port.

Accessory Charger Adapter Dock (ACA-Dock):
Enables charging and simultaneous data transfer for a
smart phone or a tablet acting as a host compliant
with BC v1.2.
This section describes how HX3 controls power to the
downstream and upstream devices and the types of
battery charging support on these ports.


2.5 mA if the bus is suspended
100 mA if the bus is not suspended and not
configured

How HX3 Asserts Power Control in a
System
500 mA if the bus is not suspended and configured by
the host to draw 500 mA
Figure 6 shows a typical system-level implementation of
how HX3 controls power for a single downstream port. It
shows the HX3 silicon, downstream (DS) port connector,
and a power switch that controls power to the downstream
port.
For portable devices to charge without being configured or
to follow the rules of suspend mode operation, a protocol
is required for the device to distinguish a charging port
from a standard port. USB-IF BC v1.2 standard provides
such a mechanism. Table 2 summarizes the charging
current capabilities when a portable device follows the
USB specification.
1
A local 5 V supply passes through the power switch to
supply VBUS to the downstream port. The power switch is
controlled by the HX3 power enable (DSx_PWREN)
signal.
Not supported in HX3 Silicon.
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
HX3 accepts an overcurrent indication (DSx_OVRCURR),
which it uses to turn OFF power to the port and inform the
host of the error condition. Re-powering the port depends
on the host and the Operating System. If the overcurrent
signal is asserted while HX3 is not connected to a host,
HX3 re-powers the port after removal of the overcurrent
fault. An external power switch asserts the overcurrent
signal if the device connected to the port consumes more
current than the limit set by the power switch. For
example, the Texas Instruments TPS2560DRC uses an
ILIM pin to set the current limit using an external resistor.
Figure 6. Connection between Hub Controller and
Downstream Port (Connector)
Power Switch and
over current detector
HX3 Charging Support on Downstream Ports
USB ports may be used for data communication only or for
charging only or for both data communication and
charging simultaneously. Therefore, based on the system
requirement, HX3’s downstream ports can be configured
to act as one of the following:



Standard downstream port (SDP)
Charging downstream port (CDP)
Dedicated charging port (DCP)
Figure 7. Charging Profile of a Li-Ion Battery
5 V Supply
DSx_PWREN
VBUS
DSx_OVRCURR
D+
HX3 Silicon
DS Port
Connector
D-
TXP/M
RXP/M
GND
Factors Affecting Charging Current to a
Portable Device
The charging current to a portable device is limited by the
following:
1.
The negotiation between the charger’s downstream
port and the portable device being charged.
2.
The system power supply feeding the downstream
port power switch, the current-carrying capacity of the
power switch, and the over-current limit set in the
power switch.
3.
The device’s charging current requirements. Although
the specification states maximum charging current,
there are devices that could charge at levels lower or
higher than the specified limit. System designers
should be aware of this, and design the system for
higher capacity than required by the spec if
necessary.
The charging current also varies with the charge state of
the device’s battery. In the case of Li-ion rechargeable
batteries, the charging current is lower at low-charged and
nearly fully-charged states of the battery, and higher
between these limits. Figure 7 shows the typical charging
profile of a Li-ion battery.
www.cypress.com
Table 3 summarizes the downstream port configuration
options supported by HX3. The ports can be configured
using the Cypress Blaster Plus utility as explained in the
Blaster Plus User Guide.
HX3 provides both global and independent (for each
individual port) port power configuration options to control
charging support (SDP, CDP, or DCP). The global
configuration option “BC_ENABLE” is used to control the
charging support of all the downstream ports. When it is
cleared, all downstream ports act as SDP.
When “BC_ENABLE” is set to “1”, the charging support on
each individual downstream port depends on the port’s
configuration options “DCP_EN” and “CDP_EN”. The
default configuration setting is highlighted in Table 3.
Table 3. Charging Configuration Options on HX3
Downstream Ports
BC_ENABLE
Port BC Configuration
Port Type
DCP_EN
CDP_EN
0
X
X
SDP
1
0
0
SDP
1
0
1
CDP
1
1
X
Apple/DCP
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
HX3 Switching Between Different Charging
Configurations
According to its internal settings (Table 3), HX3
downstream ports act as either an SDP, a CDP, or a DCP
when HX3 is connected to a host. When disconnected
from the host, the downstream ports act as a DCP (Ghost
Charge).
HX3 changes the role of its downstream ports on detection
of a change in the upstream connection and also provides
opportunity to the devices connected on its downstream
ports to switch its role to match the HX3 port type. In
compliance with BC v1.2 specification, HX3 goes through
the following steps to force the attached portable devices
to renegotiate the charging mechanism when HX3
changes the role of the downstream port:



Figure 8: HX3 Downstream Port Power Connection with
VBUS Discharge Path
Power Switch and
over current detector
5 V Supply
DSx_PWREN
VBUS
DSx_OVRCURR
150 uF
DS Port
HX3 Silicon
100 Ω
GND
Stop driving VBUS
Wait for 600 ms
Start driving VBUS
After VBUS is stopped, the 600 ms wait time allows the
downstream port’s VBUS to discharge to VBUS_LKG (0.7
V) by combining the times allowed by the spec for a)
VBUS not driven - TVLD_VLKG (500 ms) and b) VBUS to
be reapplied - TVBUS_REAPP (100 ms).
In hub system designs, it is recommended that the hub
itself provides a discharge path for VBUS on the
downstream ports to discharge below VBUS_LKG as the
connected portable devices may not discharge the VBUS
within TVLD_VLKG. This discharge also ensures a VBUS
power cycle for connected non-charging devices.
The discharge path is turned on when power enable is deasserted. This can also be accomplished by using power
switches that have built-in discharge capability. Figure 8
also shows a 150 µF capacitor on the VBUS output of the
downstream port to meet the inrush current requirement
as per the USB specification.
Every time a change in host connection is detected, HX3
evaluates the charger configurations shown in Table 3 and
switches its role following the role-change procedure
described above.
The conditions and the sequence of HX3 switching
between different charging methods is shown in Figure 9.
The CDP and DCP functions referred in Figure 9 are
elaborated in Figure 10.
The discharge mechanism is illustrated in Figure 8, which
is an enhancement of Figure 6. As shown in Figure 8, the
VBUS discharge can be accomplished by connecting
VBUS (output of the power switch) through a 100 Ω
discharge resistor and a transistor or FET to ground.
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
Figure 9: Flow Chart of HX3 Switching Between Charging Methods
Power-on OR change in
Host Connection
Turn-off DS VBUS
Wait 600 msec
Y
N
Host Attached
Port configured
as DCP
Y
Port Configured for
Ghost charging?
N
PORT_POWER from
Host
N
Y
Turn-on DS VBUS
HX3 in suspend state
N
Y
Perform DCP function
Turn-on DS VBUS
Y
Port Configured
for CDP?
N
Perform CDP function
Wait for device connection
for USB function
www.cypress.com
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
Figure 10: Flow Chart of the HX3 Charger Handshake Procedure
CDP Function
DCP Function
Enable IDP Sink
Monitor VDP
N
VDP >
VDAT_ REF?
N
Apple Charging
enabled AND
VBUS_ DS = 5V
Y
1 . Enable Apple termination
2 . Turnon BC v1.2 detection
Enable DCP termination
Y
Enable VDM_ SRC
N
BC v1.2 portable
device detected
Y
N
VDP <
VDAT_ REF? or
VDP > VLGC
Y
Disable VDM_SRC
1 . Disable Apple termination
2 . Enable DCP termination
DCP Termination :
Short the D+ line to the D- line though 200Ω resistance.
Apple Termination:
HX 3 connects the output of a pair of resistor dividers to
D+/D- pins. The resistor dividers are connected
between VBUS_ DS ( 5 V ) and GND. HX3 supports two
types of Apple termination 1 A or 2.1 A charging
.
N
portable device
disconnected
Y
Disable DCP termination
HX3 Charging Support on Upstream Port
The upstream port of the hub can act as a standard hub
upstream port or an ACA-Dock port. The HX3 family of
products is available in both variants. Refer to the product
selector guide in the HX3 data sheet to select the product
supporting the ACA-Dock feature.
Standard Hub Upstream Port: A standard hub upstream
port monitors VBUS to detect the attachment to a host or a
hub. A bus-powered hub uses VBUS as the power source
for its operation.
www.cypress.com
ACA-Dock: A standard hub connects to an upstream host
and allows charging of downstream-connected devices.
An ACA-Dock adds the capability to charge the (upstream)
host. This allows portable devices with USB hosts (for
example, tablets) to connect to its USB peripherals as
usual, while the ACA-Dock (HX3) simultaneously charges
both host and peripheral(s).
Document No. 001-92554 Rev. **
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Implementing Battery Charging Features using HX3
An ACA-Dock therefore provides VBUS power to the
upstream port (host), in contrast to a standard hub
receiving VBUS power from the host. ACA-Docks are
detected using the fifth pin in the USB connector.called the
ID pin. The ACA-Dock should connect the ID pin with
RID_A (124 kΩ as per BC v1.2 specification) to ground.
This enables the portable devices supporting ACA
capability to act as a host and to draw current from VBUS.
The difference in the system design between a standard
port and ACA-Dock is shown in Figure 11. When
configured to act as ACA-Dock, HX3 provides the same
power controls to the upstream port as it does to the
downstream ports.
HX3 provides a power enable (US_PWREN) signal to
control the power switch connected between the 5 V
supply and VBUS of the upstream port. It also accepts an
overcurrent indicator (US_OVCURR) to turn OFF the
power when an overcurrent fault occurs on the upstream
port.
To inform the upstream portable device that it is attached
to an ACA-Dock, HX3 outputs a voltage of VDM_SRC (0.6 V)
on D- as follows:

HX3 starts outputting VDM_SRC if D+ and D- lines are at
idle J for a time of TCP_VDM_EN (200 ms). Note that idle
J for low speed is D- > VIHZ (min) and D+ < VIL
(max), and full speed is D+ > VIHZ (min) and D- < VIL
(max).

HX3 stops outputting VDM_SRC within TCP_VDM_DIS
(10 ms) of any USB activity on D+ and D- lines
The flow chart shown in Figure 12 depicts the HX3
ACA-Dock negotiation procedure to enable the portable
device to detect that it is connected to an ACA-Dock so
that the portable device can act as a host and
simultaneously charge.
For additional details on the implementation of the ACADock feature with HX3, refer to this Knowledge Base
Article.
In Figure 11, it should be noted that in a standard
upstream port implementation, the resistor divider in the
upstream port VBUS allows fast discharge of the line
when VBUS is turned off by an upstream host or hub.
Figure 11: HX3 Upstream Port System Design for a Standard Port (Left) vs. an ACA-Dock (Right)
Standard Upstream Port Connection
ACA Dock Connection
Power Switch and 5 V Supply
over current detector
VBUS
VBUS_US
10 KΩ
US_ PWREN
10 KΩ
US_ OVRCURR
VBUS
US_D+
HX3
Silicon
US_ D+
Upstream
Port
to
host/hub
US_ D-
US_TXP/M
HX3
Silicon
US_ RXP/M
Upstream
Port
to
OTG
enabled
device
US_ D-
US_TXP/M
US_ RXP/M
RID_A
GND
ID
GND
www.cypress.com
Document No. 001-92554 Rev. **
10
Implementing Battery Charging Features using HX3
Figure 12: HX3 ACA-Dock Handshake Procedure
Power-on
Refer to Section 3.3 of the Blaster Plus User Guide for
instructions to enable or disable the Ghost Charge feature
in HX3.
Table 4. HX3 Downstream Port Configuration as DCP
When Host not attached
1. Turn-on VBUS
2. Enable VDM_SRC
3. Apply RDP
4. Enable Host
connection detection
BC_ENABLE
DCP_EN
0
0
X
N
0
1
0
N
0
1
1
Y
1
X
X
Y
Configuring Various Charging Methods with
Blaster Plus
Y
The Blaster Plus utility can be used to change the
configuration bits in HX3 and save the updated
2
2
configuration into the I C EEPROM attached to HX3 I C
bus. HX3 will read the contents of the EEPROM on powerup and override the default configuration. Table 5
summarizes HX3’s configuration options related to
charging that can be modified with the Blaster Plus utility.
Activity on
USB 2.0
lines D+/-
N
Y
1. Disable VDM_SRC
2. Disable Host
connection detection
N
USB 2.0
Suspend detected
The “Allowed access” field of the table shows the features
and options that can be set or cleared. For example, in
parts that do not support the ACA-Dock feature, this
feature cannot be set. However, if the parts support the
ACA-Dock feature, Blaster Plus can be used to disable
this feature.
Table 5. HX3 Charging Configuration Options with Blaster
Plus
Y
Configurations
Ghost Charge™
Ghost Charge is a Cypress-proprietary feature that allows
HX3’s downstream ports to act as a dedicated charging
port when the upstream port is not connected to a host, or
when the host hibernates.
Global
Configuration
Similar to all other battery charging features, this feature
can be enabled globally for all DS ports or independently
for each downstream port. The configuration options for
Ghost Charge are summarized in Table 4.
If the global “GHOST_CHARG_EN” configuration bit is set
to “1”, all downstream ports are enabled for Ghost Charge.
To enable Ghost Charge on an individual downstream
port, both the global Battery Charging Enable bit
“BC_ENABLE” and the DCP Enable bit “DCP_EN” of the
individual DS port must be set to “1”. In the default
configuration of HX3, all downstream ports are configured
to enable Ghost Charge as shown in the highlighted row in
Table 4. A user may want to disable Ghost Charging to
prevent charging during hibernation.
www.cypress.com
Apple/
DCP
GHOST_CHARGE_EN
Host Connection
detected
N
Port BC
Config
Global Config
Port wise
Configuration
Default
Value
Allowed
Access
Set
to
"1"
Clear
to
"0"
ACA_DOCK
Product
selection
N
Y
GHOST_CHARGE_EN
1
N
Y
BC_ENABLE
1
N
Y
APPLE_XA
0
Y
Y
DCP_EN
0
Y
Y
CDP_EN
1
Y
Y
As shown in Figure 13, the Blaster Plus tool displays the
default values read from the HX3 device. Options that are
not accessible for modification are grayed out. Refer to the
Blaster Plus user guide for more information about
invoking the tool and programming the EEPROM.
Document No. 001-92554 Rev. **
11
Implementing Battery Charging Features using HX3
Figure 13. Blaster Plus Showing Charging Configuration Options
HX3 Development Kits
The following HX3 development kits are available to evaluate HX3 features:



CY4609 – HX3 68QFN Development Kit
CY4603 – HX3 88QFN Development Kit
CY4613 – HX3 88QFN Development Kit with ACA-Dock support
Table 6 compares power control and battery charging features in these kits.
Table 6. Comparison of Power Control and Battery Charging Features of HX3 Kits
HX3 Development Kit (DVK)
Features
CY4609
CY4603
CY4613
HX3 part number
CYUSB3304-68LTXC
CYUSB3314-88LTXC
CYUSB3328-88LTXC
Power control mode to DS ports
Ganged
Individual
Individual
AC power adapter included in the kit
5 V, 4 A
5 V, 4 A
12 V, 3 A
Battery Charging – CDP mode
Yes
Yes
Yes
Battery Charging – SDP mode
Yes
Yes
Yes2
Battery Charging – DCP mode
Yes
Yes
Yes2
Apple charging – 1 A mode
Yes
Yes
Yes2
2
In CY4613, battery charging is supported in standard USB 3.0 ports and standard USB 2.0 ports only. Battery charging is not supported in
Shared Link™ SuperSpeed ports. (Shared Link is a Cypress-proprietary feature that doubles the number of USB ports, creating eight ports
from a 4-port hub. For more details, refer to the HX3 datasheet.)
www.cypress.com
Document No. 001-92554 Rev. **
12
Implementing Battery Charging Features using HX3
HX3 Development Kit (DVK)
Features
CY4609
CY4603
CY4613
2
Apple charging – 2.1 A mode
Yes
Yes
Yes
Ghost Charge mode
Yes
Yes
Yes2
ACA-Dock mode in US port
No
No
Yes
Power switches to the DS ports
Yes. One power switch
controls all DS ports.
Yes. Two dual-channel
power switches in
individual power modes.
Yes. Three dual-channel
power switches in individual
power modes.
No
No
Power switches to the US ports
Downstream maximum charging current
Upstream maximum charging current3
3
4.85 A for all 4 DS ports
together
2.1 A per downstream port
N/A
N/A
Yes
3
2.1 A per downstream port3
2.1 A3
Battery Charging Hardware Implementation in CY4603 kit
Figure 14. CY4603 DVK Block Diagram
The CY4603 kit supports BC v1.2, Ghost Charge and Apple charging in all the downstream ports. As shown in Figure 14,
CY4603 uses two dual-channel power switches, which allow monitoring of overcurrent conditions in each downstream port and
shutdown that port when there is an overcurrent condition.
3
CY4609 and CY4603 kits come with 5-V, 4-A AC adapters. The charging current in all DS ports together should not exceed 3 A with the
supplied AC adapter. The CY4613 kit comes with a 12-V, 3-A AC adapter to support higher power requirements. The charging current in all
DS and US ports together should not exceed 5 A with this AC adapter. If a higher charging current is required, use a higher-capacity AC
adapter.
www.cypress.com
Document No. 001-92554 Rev. **
13
Implementing Battery Charging Features using HX3
Hardware Design Considerations
Figure 15 shows the battery charging circuit of the
CY4603 kit. It should be noted that the hardware
examples explained in this section are with the 88-QFN
part (CYUSB3314).
Wherever applicable, consideration of other kits and parts
are called out separately. For more details of other kits,
refer to HX3 DVK User Guide, which is common across
the HX3 kits.
Figure 15: Power Switch Implementation in CY4603
www.cypress.com
Document No. 001-92554 Rev. **
14
Implementing Battery Charging Features using HX3
Hardware Recommendations
1: Selecting the Power Switch: HX3 pins DSx_PWREN
and DSx_OVRCURR interface to external power switches.
These pins are used to control power switches and
sense overcurrent conditions. The maximum current to DS
ports can be configured through the power switch. Refer to
the datasheet of the selected power-switch for details on
setting overcurrent limits.
The power switches should be selected based on the
maximum current required for DS ports. The CY4603 kit
works in individual power mode, and each DS port current
is limited to 2.1 A in the kit. This kit uses a dual-channel
power switch (part number – “TPS2560DRC”), which is
capable of an output current of 2.8 A per channel.
CYUSB330x parts support ganged-power mode, which
allows one power switch to control power to all DS ports.
The CY4609 kit uses a single-channel power switch (part
number – “TPS2556DRBT”).The CY4609 kit output
current from the power switch is limited to 4.85 A.
2: Pull-Up or Pull-Down on DSx_PWREN and
DSx_OVRCURR: The active-state polarity of the
DSx_PWREN and DSx_OVRCURR pins are configurable
in HX3 based on the power switch requirements. If the
power switch requires an active HIGH control, then pull
DSx_PWREN
low
with
10 kΩ resistors. On the other hand, if the power switch
requires an active LOW control, then pull DSx_PWREN
high with 10 kΩ resistors.
3: Power Supply: The main power supply should be rated
adequately to supply the operating current for HX3 and
charging current for all downstream ports.
Demonstration of Battery Charging feature
in CY4603 kit
The detailed instructions to set up and operate CY4603
battery charging feature is available in the CY4603 Quick
Start Guide.
All HX3 DVKs (CY4609, CY4603, and CY4613) are
configured to support the CDP mode on DS ports. The
choice of charging method (CDP or SDP) used to charge
the portable device connected to the DS port is
automatically determined by HX3 through the standard
handshake mechanism explained inUSB-IF BC v1.2
Charging Standard Appendix B: BC v1.2 Detection
Mechanism.
By default, DCP mode is disabled in HX3 DVK when
connected to a host. DCP mode can be enabled for any of
the downstream ports using the Cypress Blaster Plus tool
(Figure 16). Refer to the Blaster Plus user guide for details
on updating HX3 parameters using the Blaster Plus tool.
After DCP mode is enabled, a port cannot be used for
data communication.
Figure 16. Blaster Plus Screenshot to "Enable DCP"
www.cypress.com
Document No. 001-92554 Rev. **
15
Implementing Battery Charging Features using HX3
BC v1.2 Compliance Testing
BC v1.2 compliance tests can be conducted using the
MQP Packet – Master USB – PET Protocol and Electrical
Tester, which is USB-IF certified. This equipment comes
with a GraphicUSB tool which contains a library of tests
based on BC v1.2. Refer to the MQP user manual for
compliance-testing instructions.
Limitations of HX3 Battery Charging
USB based charging and charger detection methods are
rapidly evolving. The particular mechanism used inside a
portable device to detect a charger varies widely among
different device manufacturers and sometimes even
among different devices from the same manufacturer. The
following is a summary of limitations of the HX3 battery
charging support. See Appendix A: Troubleshooting Guide
for more information.

Samsung-proprietary chargers (D+/D- pins biased to
~1.2 V)

Apple 2.4 A chargers (D+/D- pins biased at 2.7 V)
Summary
This application note began by introducing the evolution of
USB battery charging from proprietary chargers to a
universal battery charging specification from the USB-IF
that is employed in the present generation of smart
phones, tablets, and other portable devices. It then
introduced HX3, a SuperSpeed hub with charging
capabilities. HX3 charging complies with the current USB
charging specification, and supports unique features such
as Ghost Charge and ACA-Dock. HX3 system design
guidelines along with a troubleshooting guide are
presented to ensure the maximum power reaches the
device with minimal losses in the power switches,
connectors and cables.
www.cypress.com
As the USB port becomes the de facto port for charging
devices requiring less than 10 W, a newer standard called
USB-PD (USB – Power Delivery) is being introduced
where power up to 100 W (and VBUS 20 V) can be
delivered. Cypress is well-positioned to provide the next
generation of products supporting USB-PD to make USB
port as the power of choice.
References
1.
HX3 Datasheet (001-73643)
2.
Battery
Charging
Dec. 7, 2010
3.
Technical Requirement and Test Method of Charger
and Interface for Mobile Telecommunication Terminal
Equipment, YD/T 1591-2006, Dec. 14, 2006
4.
Universal Serial Bus Revision 3.1 Specification,
Jul. 26, 2013
5.
Universal Serial Bus Revision 2.0 Specification,
Apr. 27, 2000
6.
HX3 Blaster Plus User Guide (001-90185)
Specification
revision
1.2,
About the Author
Name:
Hasib Mannil
Title:
Systems Engr Sr Staff
Document No. 001-92554 Rev. **
16
Implementing Battery Charging Features using HX3
Appendix A: Troubleshooting Guide
This section answers frequently asked
regarding HX3 battery charging support.
questions
2.
Custom BC v1.2 Charging: This indicates that the
device connected to the downstream port identifies
itself as a Charging device but the current drawn
exceeds the 1.5 A limit (IDEV_CHG) as per BC v1.2.
1. What are the battery charging capabilities and
limitations of HX3?
There is no limitation in HX3 with respect to battery
charging current. The charging current of the
downstream ports and the upstream port are
controlled by the external power switches as
explained in the HX3 Battery Charging Features
section.
The different battery
summarized in Table 7.
charging
methods
HX3 is involved in the handshake with the portable
device connected to the DS port, but the actual
current driven to the DS ports is determined by the
external power switch and the capacity of the power
supply.
are
For example, consider the CY4603 schematic. The
CY4603 kit uses two dual-channel TPS2560 power
switches. These switches have an adjustable current
limit settings that can be set from 250 mA–2.8 A. In
CY4603 kit, the current limit of TPS2560 is set at 2.1
A. Therefore, the maximum current supplied by
CY4603 kit is 2.1 A per port.
Table 7. Charge Current Capability of Various Battery
Chargers
Battery
Chargers
Max
Charging
Current
CY4609, CY4603, and
CY4613 kits
Max Charging Current
3.
BC v1.2
(Charging
Downstream
Port)
1.5 A
1.5 A
1.5 A
1.5 A
(See Questions 2,3)
The 450 mV drop is due to the following resistance:


Apple Charging
(1 A Mode)
1A
1A
Apple Charging
(2.1 A Mode)
2.1 A
2.1 A
Apple Charging
(2.4 A Mode)
2.4 A
NA
Samsung
Charging
Standard
2.4 A
1.5 A
ACA-Dock
(Upstream
Charging)
1.5 A
1.5 A
Dedicated
Charging Port
1.5 A
1.5 A (See Questions 2,3)
YD/T 1591-2006
1.5 A
1.5 A (See Questions 2,3)
Standard USB
3.0 DS Port
900 mA
900 mA
Standard USB
2.0 DS Port
500 mA
500 mA
www.cypress.com
What are the risks involved in using Custom BC v1.2
Charging (drawing more than 1.5A)?
According to the USB 3.1 specification, the maximum
voltage drop of the VBUS line at the connector of the
DS device is 450 mV when the maximum current (900
mA) is being supplied on the VBUS line.
Custom BC v1.2
(Charging
Downstream
Port)
What is Custom BC v1.2 Charging? How does HX3
support custom charging?
Contact resistance of the connectors (30 mΩ)
Equivalent series resistance of the USB cable (3
meters = 380 mΩ)
USB 3.0: maximum voltage drop assuming 0.9 A =
2 * (0.9 A * (190 mΩ + 30 mΩ * 2)) = 450 mV
BC v1.2: maximum voltage drop assuming 1.5 A =
2 * (1.5 A * (190 mΩ + 30 mΩ * 2)) = 750 mV
Custom BC v1.2: maximum voltage drop assuming
2.1 A = 2 * (2.1 A * (190 mΩ + 30 mΩ * 2)) = 910 mV
There is a risk that a custom BC v1.2 charging design
will not be able to supply proper VBUS voltage to the
portable device if the charging current causes a higher
voltage drop. The system power supply has to be
designed considering the steady state voltage drops
due to the connector and cable resistances and the
current requirement of the portable device. Figure 17
shows the steady state voltage drops under worstcase condition.
Document No. 001-92554 Rev. **
17
Implementing Battery Charging Features using HX3
Figure 17. Voltage Drop at Various Locations from Host or
Hub to a Device (Worst-case Topology)
Refer to Question 1 for summary of battery
chargers.

6.
How do I modify CY4609, CY4603, and CY4613 kits
to drive greater than 2.1 A of current?
The CY4609, CY4603, and CY4613 kits support a
maximum current source of 2.1 A out of the box.
These kits can be modified to support a current drive
of 2.4 A by adjusting the current limit of the TPS2560
power switches. The current limit can be configured
by modifying on-board resistor values.
Choice of Resistor: Designing the current limiting
resistor value for a specific current is available in the
TPS2560
Power
Switch
datasheet
(http://www.ti.com/lit/ds/slvs930a/slvs930a.pdf)
"Table 1: Common RILIM Resistor Selections" defines
the mapping between the nominal current limit and the
resistor value.
CY4609 Kit: Change the resistor R3 to make all the
four DS ports to support higher currents. The location
of the resistor is available at page 5 of the CY4609
schematic.
CY4603 Kit: Change the resistors R40 and R49 to
make all the four DS ports to support higher currents.
The location of the resistor is available at page 6 of
the CY4603 schematic.
CY4613 Kit: Change the resistors R3, R5, R10, and
R11 to make the US port and all the four DS ports to
support higher currents. The location of the resistors
is available at page 6 of the CY4613 schematic.
5.
The CY4609, CY4603, and CY4613 kits do not charge
the devices connected to the downstream (DS) ports
at the maximum charging current. Why?
There are two possible reasons:

The type of device connected on the DS port
constrains the charging current it can accept.
www.cypress.com
What data transfer rate does HX3 support when a
USB 3.0 Host is connected to the US port in ACADock mode?
HX3 supports the full USB 3.0 data rate of 5 Gbps.
(Source: USB 3.1 Specification)
4.
The power supply used on the CY4609, CY4603,
and CY4613 can drive a maximum of 4 A, which is
shared across all DS ports. If you have CDPcompliant devices connected on all four DS ports,
a maximum current of 1 A can be driven on each
DS port.
7.
How do I know if a portable device supports OTG?
In CY4613 kit, remove the J27 jumper and short the
middle pin of the J27 jumper to the 4th pin of J23
(connect RID to ground). If the portable device
connected to the US port of CY4613 enumerates,
then the portable device supports the USB OTG
functionality.
8.
Will the ACA-Dock feature work on all portable
devices that support OTG?
Not all OTG-capable portable devices supports the
ACA-Dock feature.
The following instructions help you identify if an OTGcapable portable device supports the ACA-Dock
feature.

Make sure the CY4613 board is set up for the
ACA-Dock functionality (Refer Step 9 of the
CY4613 Quick Start Guide) .

Remove Jumper J26.

Connect the portable device to the US port of
CY4613 and check the voltage on pin 1 of
Jumper J26.

If the measured voltage is ~5 V, then the portable
device does not support the ACA-Dock feature; if
the value is ~0 V, then the ACA-Dock feature is
supported.
The expected behavior of portable devices which
support the OTG feature and the ACA-Dock mode is
the simultaneous data transfer and US charging.
The expected behavior of portable devices which
support the OTG feature, but does not support the
ACA-Dock mode is data transfer only and no US
charging.
For more details on testing the ACA-Dock feature with
the CY4613 kit, refer to this Knowledge Base Article
Document No. 001-92554 Rev. **
18
Implementing Battery Charging Features using HX3
Appendix B: BC v1.2 Detection Mechanism
This appendix introduces the various detection
mechanism and protocol followed by the portable devices
and the chargers supporting BC v1.2. First, different
connectivity configurations are shown. Next, the various
mechanisms required to implement detection of a charger
are introduced. Finally, the steps necessary to distinguish
between an SDP and charging port and to differentiate
CDP and DCP charging ports are introduced.
Figure 18 shows several examples of how a portable
device can be connected to an SDP or a charging port. In
the first example, the portable device is connected to an
4
5
SDP, a DCP, or a CDP using a Standard -A to micro-B
cable. In the second example, a captive cable from the
DCP is connected to a portable device. In the third
example, an ACA-Dock is connected to a portable device.
In this case, there is no cable between the dock and the
device, but the dock contains a captive micro-A plug. The
ACA-Dock requires a power source which is indicated by
the “Prop Chgr” in Figure 18.
Figure 18. Examples of a Portable Device Connected to
an SDP or a Charging Port
Charging Port Detection
Figure 18 shows the various charger blocks (CDP, DCP,
SDP, ACA-Dock) that a portable device requires to detect
when connected to a charging port. The charger blocks
perform five main functions described as follows.
VBUS Detect
The portable device must have a session-valid comparator
which is used to detect the condition when VBUS is
greater than the session-valid threshold (0.8 V–4 V) in the
portable device.
Data Contact Detect (DCD)
This is an optional block to check whether the portable
device data pins have made contact during an attach
event. As shown in Figure19, IDP_SRC (25 µA–175 µA)
on D+ and RDM_DWN (15 kΩ) on D- are turned ON. If the
D+ line goes LOW, then it indicates that the portable
device is connected to either a charging port or a standard
port and the primary detection is checked thereafter. If
DCD is not implemented, the portable device waits up to
900 ms before proceeding to performing primary
detection. HX3 does not support DCD.
Primary Detection
A portable device is required to implement primary
detection, which is used to distinguish between a standard
port and a charging port.
Primary Detection DCP
Figure 20 shows the detection mechanism when a
portable device is connected to a dedicated charging port
(DCP). In this mode, the portable device turns on
VDP_SRC (0.5 V–0.7 V) on D+ and checks the voltage on
D-. Because D+ and D- are shorted on the DCP with <
200 Ω, the voltage on D- will be close to VDP_SRC. The
voltage on D- is compared with VDAT_REF (0.25 V–
0.4 V). If D- is greater than VDAT_REF, then the portable
device is attached to either a DCP or a CDP.
Primary Detection CDP
(Source: USB-IF Battery Charging Specification v1.2)
4
Standard –A is a USB plug type that connects to the
“downstream port” of a host or a hub.
Figure 21 shows the detection mechanism when a
portable device is connected to a charging downstream
port (CDP). During primary detection, the portable device
applies VDP_SRC to the D+ line and turns on IDM_SINK
(25 µA–175 µA). The portable device compares the
voltage on D- with VDAT_REF. If the voltage on D- is
greater than VDAT_REF, then the portable device can
proceed to determine if it is connected to a DCP or a CDP.
5
Micro –B is a USB plug type that connects to the portable
device.
www.cypress.com
Document No. 001-92554 Rev. **
19
Implementing Battery Charging Features using HX3
There are two options for CDP to behave when a portable
device is not connected. In the first option, VDM_SRC
(0.5 V–0.7 V) on the CDP should be enabled within
200 ms of a disconnect and disabled within 10 ms of a
connect.
In the second option, the CDP compares the D+ voltage to
VDAT_REF (0.25 V–0.4 V) and to VLGC (0.8 V–2 V). If
the D+ voltage is less than VDAT_REF or greater than
VLGC, the VDM_SRC on the D- line is disabled. When D+
voltage is greater than VDAT_REF and less than VLGC,
the CDP enables VDM_SRC on the D- line. HX3 supports
the second option.
Primary Detection SDP
Figure 22 shows the detection mechanism when a
portable device is connected to a standard downstream
port (SDP). During primary detection, the portable device
applies VDP_SRC to the D+ line and turns on IDM_SINK.
The D- line is pulled LOW through RDM_DWN.
The portable device compares the voltage on D- to
VDAT_REF. When connected to an SDP, the D- line is
less than VDAT_REF, indicating to the portable device
that it is connected to an SDP.
Primary Detection ACA-Dock
Figure 23 shows the detection mechanism when a
portable device supporting ACA detection is connected to
an ACA-Dock. An ACA-Dock is a docking station that has
one upstream port, and optional downstream ports.
When an ACA-Dock is powered and no device is
connected to its upstream port, the pins on the micro-A
plug are biased as follows.
Table 8. Biasing of pins on the micro-A plug
Pin
Biasing
VBUS
VCHG (4.75 V–5.25 V)
D+
VDP_UP (3 V–3.6 V)
D-
VDM_SRC (0.5 V–0.7 V)
ID
RID_A (122 KΩ–126 KΩ) 6
GND
GND
The VBUS pin is powered because the ACA-Dock is ready
to provide power to the portable device connected on its
upstream port. The ACA-Dock pulls D+ to VDP_UP
(3 V–3.6 V) through a 1.5 kΩ resistor because VBUS is
greater than VOTG_SESS_VALID (0.8 V–4 V). The
ACA-Dock enables VDM_SRC on its D- line whenever D+
and D- are inactive (idle J state) for a duration of 200 ms.
It should disable the VDM_SRC within 10 ms of any
activity on the D+ and D- lines.
6
The portable device supporting ACA detection determines
if it is connected to an ACA-Dock based on the following
conditions:




VBUS > VOTG_SESS_VALID (0.8 V–4 V)
D+ at VLGC_HI (2.0 V–3.6 V)
VDAT_REF (0.25 V–0.4 V) < D- < VLGC (0.8 V–
2.0 V)
ID at RID_A
Secondary Detection
Secondary detection is used to distinguish a DCP from a
CDP by the portable device. Portable devices that are not
ready to enumerate within 900 ms are required to support
secondary detection. Portable devices that are ready to
enumerate can bypass secondary detection.
Secondary Detection DCP
Figure 24 shows the secondary-detection mechanism
when a portable device is connected to a DCP. During
secondary detection, the portable device applies
VDM_SRC to the D- line, turns on IDP_SINK, and
compares the voltage on D+ line to VDAT_REF. Because
the voltage on the D+ line is close to D- as they are
shorted with less than 200 Ω, the voltage on D+ line is
greater than VDAT_REF. If the portable device detects
that the voltage at the D+ line is greater than VDAT_REF,
then it knows that it is attached to a DCP.
Secondary Detection CDP
Figure 25 shows the secondary detection mechanism
when a portable device is connected to a CDP. During
secondary detection, the portable device applies
VDM_SRC to the D- line, turns on IDP_SINK, and
compares the voltage on the D+ line to VDAT_REF.
Because the voltage on the D+ line is close to GND as it is
pulled
LOW
using
RDP_DWN
(15 KΩ), the voltage on the D+ line is less than
VDAT_REF. If the portable device detects that the voltage
on the D+ line is less than VDAT_REF, then it knows that
it is attached to a CDP.
ACA Detection
ACA detection for portable devices is optional. Only
portable devices that have a micro-AB receptacle can
support ACA detection because the ACA OTG port has a
captive cable termination in a micro-A plug as shown in
Figure 18 (third example).
For portable devices not supporting the std RID_A value, refer to
http://www.cypress.com/?id=4&rID=96822
www.cypress.com
Document No. 001-92554 Rev. **
20
Implementing Battery Charging Features using HX3
Figure19. Charger Detection Hardware
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
21
Implementing Battery Charging Features using HX3
Figure 20. Primary Detection – DCP
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
22
Implementing Battery Charging Features using HX3
Figure 21. Primary Detection – CDP
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
23
Implementing Battery Charging Features using HX3
Figure 22. Primary Detection -- SDP
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
24
Implementing Battery Charging Features using HX3
Figure 23. Primary Detection -- ACA-Dock
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
25
Implementing Battery Charging Features using HX3
Figure 24. Secondary Detection – DCP
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
26
Implementing Battery Charging Features using HX3
Figure 25. Secondary Detection CDP
(Source: USB-IF Battery Charging Specification v1.2)
www.cypress.com
Document No. 001-92554 Rev. **
27
Implementing Battery Charging Features using HX3
Document History
Document Title: Implementing Battery Charging Features using HX3 - AN92554
Document Number: 001-92554
Revision
ECN
Orig. of
Change
Submission
Date
**
4481475
HBM
09/03/2014
www.cypress.com
Description of Change
New Application Note
Document No. 001-92554 Rev. **
28
Implementing Battery Charging Features using HX3
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29
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