2010 - 2015 Microchip Technology Inc.
DS00001692C-page 1
General Description
The Microchip USB251xB/xBi hub is a family of low-
power, configurable, MTT (multi transaction translator)
hub controller IC products for embedded USB solu-
tions. The x in the part number indicates the number of
downstream ports available, while the B indicates bat-
tery charging support. The Microchip hub supports low-
speed, full-speed, and hi-speed (if operating as a hi-
speed hub) downstream devices on all of the enabled
downstream ports.
Highlights
• High performance, low-power, small footprint hub
controller IC with 2, 3, or 4 downstream ports
• Fully compliant with the USB 2.0 Specification [
1
]
• Enhanced OEM configuration options available
through either a single serial I
2
C EEPROM, or
SMBus slave port
• MultiTRAK
TM
- High-performance multiple transaction trans-
lator which provides one transaction transla-
tor per port
• PortMap
- Flexible port mapping and disable sequenc-
ing
• PortSwap
- Programmable USB differential-pair pin loca-
tions ease PCB design by aligning USB sig-
nal lines directly to connectors
• PHYBoost
- Programmable USB signal drive strength for
recovering signal integrity using 4-level driv-
ing strength resolution
Features
• USB251xB/xBi products are fully footprint com-
patible with USB251x/xi/xA/xAi products as direct
drop-in replacements
—
Cost savings include using the same PCB
components and application of USB-IF Compliance
by Similarity
• Full power management with individual or ganged
power control of each downstream port
• Fully integrated USB termination and pull-up/pull-
down resistors
• Supports a single external 3.3 V supply source;
internal regulators provide 1.2 V internal core volt-
age
• Onboard 24 MHz crystal driver or external
24 MHz clock input
• Customizable vendor ID, product ID, and device
ID
• 4 kilovolts of HBM JESD22-A114F ESD protection
(powered and unpowered)
• Supports self- or bus-powered operation
• Supports the USB Battery Charging specification
Rev. 1.1 for Charging Downstream Ports (CDP)
• The USB251xB/xBi offers the following packages:
- 36-pin SQFN (6x6 mm) (Preferred)
- 36-pin QFN (6x6 mm) (Legacy)
• USB251xBi products support the industrial tem-
perature range of -40ºC to +85ºC
• USB251xB products support the extended com-
mercial temperature range of 0ºC to +85ºC
Applications
• LCD monitors and TVs
• Multi-function USB peripherals
• PC motherboards
• Set-top boxes, DVD players, DVR/PVR
• Printers and scanners
• PC media drive bay
• Portable hub boxes
• Mobile PC docking
• Embedded systems
USB251xB/xBi
USB 2.0 Hi-Speed Hub Controller
USB251xB/xBi
DS00001692C-page 2
2010 - 2015 Microchip Technology Inc.
TO OUR VALUED CUSTOMERS
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The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000).
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To determine if an errata sheet exists for a particular device, please check with one of the following:
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2010 - 2015 Microchip Technology Inc.
DS00001692C-page 3
USB251xB/xBi
Table of Contents
1.0 Introduction ..................................................................................................................................................................................... 4
2.0 Block Diagram ................................................................................................................................................................................. 6
3.0 Pin Information ................................................................................................................................................................................ 7
4.0 Battery Charging Support ............................................................................................................................................................. 17
5.0 Initial Interface/Configuration Options ........................................................................................................................................... 19
6.0 DC Parameters ............................................................................................................................................................................. 39
7.0 AC Specifications .......................................................................................................................................................................... 44
8.0 Package Marking Information ....................................................................................................................................................... 46
9.0 Package Information ..................................................................................................................................................................... 48
Appendix A: Acronyms ........................................................................................................................................................................ 50
Appendix B: References ..................................................................................................................................................................... 51
Appendix C: Data Sheet Revision History .......................................................................................................................................... 52
The Microchip Web Site ...................................................................................................................................................................... 54
Customer Change Notification Service ............................................................................................................................................... 54
Customer Support ............................................................................................................................................................................... 54
Product Identification System ............................................................................................................................................................. 55
USB251xB/xBi
DS00001692C-page 4
2010 - 2015 Microchip Technology Inc.
1.0
INTRODUCTION
The Microchip USB251xB/xBi hub family is a group of low-power, configurable, MTT (multi transaction translator) hub
controller ICs. The hub provides downstream ports for embedded USB solutions and is fully compliant with the USB 2.0
Specification [
1
]. Each of the hub controllers can attach to an upstream port as a full-speed or full-/hi-speed hub. The
hub can support low-speed, full-speed, and hi-speed downstream devices when operating as a hi-speed hub.
All required resistors on the USB ports are integrated into the hub. This includes all series termination resistors and all
required pull-down and pull-up resistors on D+ and D- pins. The over-current sense inputs for the downstream facing
ports have internal pull-up resistors.
The USB251xB/xBi hub family includes programmable features, such as:
• MultiTRAK
TM
Technology: implements a dedicated Transaction Translator (TT) for each port. Dedicated TTs help
maintain consistent full-speed data throughput regardless of the number of active downstream connections.
• PortMap: provides flexible port mapping and disable sequences. The downstream ports of a USB251xB/xBi hub
can be reordered or disabled in any sequence to support multiple platform designs with minimum effort. For any
port that is disabled, the USB251xB/xBi hub controller automatically reorders the remaining ports to match the
USB host controller’s port numbering scheme.
• PortSwap: allows direct alignment of USB signals (D+/D-) to connectors to avoid uneven trace length or crossing
of the USB differential signals on the PCB.
• PHYBoost: enables 4 programmable levels of USB signal drive strength in downstream port transceivers. PHY-
Boost will also attempt to restore USB signal integrity.
1.1
Configurable Features
The USB251xB/xBi hub controller provides a default configuration that may be sufficient for most applications. Strapping
option pins (see
Section 3.3.1 on page 14
) provide additional features to enhance the default configuration. When the
hub is initialized in the default configuration, the following features may be configured using the strapping options:
• Downstream non-removable ports, where the hub will automatically report as a compound device
• Downstream disabled ports
• Enabling of battery charging option on individual ports
• The USB251xB/xBi hub controllers can alternatively be configured by an external I
2
C EEPROM or a microcontrol-
ler as an SMBus slave device. When the hub is configured by an I
2
C EEPROM or over SMBus, the following con-
figurable features are provided:
• Support for compound devices on a port-by-port basis
• Selectable over-current sensing and port power control on an individual or ganged basis to match the circuit board
component selection
• Customizable vendor ID, product ID, and device ID
• Configurable USB signal drive strength
• Configurable USB differential pair pin location
• Configurable delay time for filtering the over-current sense inputs
• Configurable downstream port power-on time reported to the host
• Indication of the maximum current that the hub consumes from the USB upstream port
• Indication of the maximum current required for the hub controller
• Custom string descriptors (up to 31 characters):
- Product
- Manufacturer
- Serial number
• Battery charging USB251xB/xBi products are fully footprint compatible with USB251x/xi/xA/xAi products:
- Pin-compatible
- Direct drop-in replacement
- Use the same PCB components
- USB-IF Compliance by Similarity for ease of use and a complete cost reduction solution
- Product IDs, device IDs, and other register defaults may differ. See
Section 5.1 on page 19
for details.
2010 - 2015 Microchip Technology Inc.
DS00001692C-page 5
USB251xB/xBi
Conventions
Within this manual, the following abbreviations and symbols are used to improve readability.
TABLE 1-1:
SUMMARY OF COMPATIBILITIES BETWEEN USB251XB/XBI AND
USB251X/XI/XA/XAI PRODUCTS
Part
Number
Drop-in Replacement
USB2512
USB2512B
USB2512i
USB2512Bi
USB2512A
USB2512B
USB2512Ai
USB2512Bi
USB2513
USB2513B
USB2513i
USB2513Bi
USB2514
USB2514B
USB2514i
USB2514Bi
Example
Description
BIT
Name of a single bit within a field
FIELD.BIT
Name of a single bit (BIT) in FIELD
x…y
Range from x to y, inclusive
BITS[m:n]
Groups of bits from m to n, inclusive
PIN
Pin Name
zzzzb
Binary number (value zzzz)
0xzzz
Hexadecimal number (value zzz)
zzh
Hexadecimal number (value zz)
rsvd
Reserved memory location. Must write 0, read value indeterminate
code
Instruction code, or API function or parameter
Section Name
Section or Document name
x
Don’t care
<Parameter>
<> indicate a Parameter is optional or is only used under some conditions
{,Parameter}
Braces indicate Parameter(s) that repeat one or more times
[Parameter]
Brackets indicate a nested Parameter. This Parameter is not real and actually
decodes into one or more real parameters.