UCHQ613

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 9

www.unisonic.com.tw

QW-R121-030.a



FUNCTIONAL DESCRIPTION

OVERVIEW

The following overview references various industry standards. It is always recommended to consult the latest

standard to ensure the most recent and accurate information.

Rechargeable portable equipment requires an external power source to charge its batteries. USB ports are

convenient locations for charging because of an available 5-V power source. Universally accepted standards are

required to ensure host and client-side devices meet the power management requirements. Traditionally, USB host

ports following the USB 2.0 Specification must provide at least 500 mA to downstream client-side devices. Because

multiple USB devices can be attached to a single USB port through a bus-powered hub, it is the responsibility of the

client-side device to negotiate the power allotment from the host to guarantee the total current draw does not exceed

500 mA. In general, each USB device can subsequently request more current, which is granted in steps of 100 mA

up 500 mA total. The host may grant or deny the request based on the available current.

Additionally, the success of the USB technology makes the micro-USB connector a popular choice for wall adapter

cables. This allows a portable device to charge from both a wall adapter and USB port with only one connector.

One common difficulty has resulted from this. As USB charging has gained popularity, the 500-mA minimum

defined by the USB 2.0 Specification or 900 mA defined in the USB 3.0 Specification, has become insufficient for

many handsets, tablets and personal media players (PMP) which have a higher rated charging current. Wall

adapters and car chargers can provide much more current than 500 mA or 900 mA to fast charge portable devices.

Several new standards have been introduced defining protocol handshaking methods that allow host and client

devices to acknowledge and draw additional current beyond the 500 mA (defined in the USB 2.0 Specification) or

900 mA (defined in the USB 3.0 Specification) minimum while using a single micro-USB input connector.

The UTC UCHQ613 support four of the most common protocols:

• USB Battery Charging Specification, Revision 1.2 (BC1.2)

• Chinese Telecommunications Industry Standard YD/T 1591-2009

• Divider mode

• 1.2 V on both D+ and D– lines

YD/T 1591-2009 is a subset of the BC1.2 specification supported by the vast majority of devices that implement

USB charging. Divider and 1.2-V charging schemes are supported in devices from specific yet popular device

makers. BC1.2 has three different port types, listed as follows.

• Standard downstream port (SDP)

• Charging downstream port (CDP)

• Dedicated charging port (DCP)

The BC1.2 Specification defines a charging port as a downstream facing USB port that provides power for

charging portable equipment.

Table 3 shows different port operating modes according to the BC1.2 Specification.

Table 3. Operating Modes Table

PORT TYPE

SUPPORTS USB2.0

COMMUNICATION

MAXIMUM ALLOWABLE

CURRENT DRAWN BY

PORTABLE EQUIPMENT (A)

SDP (USB 2.0)

YES

0.5

SDP (USB 3.0)

YES

0.9

CDP

YES

1.5

DCP

NO

1.5