USB2512B-I/M2

USB251xB/xBi USB 2.0 Hi-Speed Hub Controller General Description Features The Microchip USB251xB/xBi hub is a family of lowpower, configurable, MTT (multi transaction translator) hub controller IC products for embedded USB solutions. The x in the part number indicates the number of downstream ports available, while the B indicates battery charging support. The Microchip hub supports lowspeed, full-speed, and hi-speed (if operating as a hispeed hub) downstream devices on all of the enabled downstream ports. • USB251xB/xBi products are fully footprint compatible with USB251x/xi/xA/xAi products as direct drop-in replacements 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 I2C EEPROM, or SMBus slave port • MultiTRAKTM - High-performance multiple transaction translator which provides one transaction translator per port • PortMap - Flexible port mapping and disable sequencing • PortSwap - Programmable USB differential-pair pin locations ease PCB design by aligning USB signal lines directly to connectors • PHYBoost - Programmable USB signal drive strength for recovering signal integrity using 4-level driving strength resolution  2022 Microchip Technology Inc. and its subsidiaries — 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/pulldown resistors • Supports a single external 3.3 V supply source; internal regulators provide 1.2 V internal core voltage • 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 temperature range of -40ºC to +85ºC • USB251xB products support the extended commercial 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 DS00001692D-page 1 USB251xB/xBi TO OUR VALUED CUSTOMERS It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and enhanced as new volumes and updates are introduced. If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via E-mail at docerrors@microchip.com. We welcome your feedback. Most Current Data Sheet To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at: http://www.microchip.com You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page. The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000). Errata An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current devices. As device/documentation issues become known to us, we will publish an errata sheet. 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DS00001692D-page 2  2022 Microchip Technology Inc. and its subsidiaries 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  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 3 USB251xB/xBi 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: • MultiTRAKTM 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. PHYBoost 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 I2C EEPROM or a microcontroller as an SMBus slave device. When the hub is configured by an I2C EEPROM or over SMBus, the following configurable 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. DS00001692D-page 4  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 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 Conventions Within this manual, the following abbreviations and symbols are used to improve readability. Example BIT FIELD.BIT x…y BITS[m:n] PIN Description Name of a single bit within a field Name of a single bit (BIT) in FIELD Range from x to y, inclusive Groups of bits from m to n, inclusive 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 x Section or Document name Don’t care 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.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 5 USB251xB/xBi 2.0 BLOCK DIAGRAM FIGURE 2-1: USB251XB/XBI HUB FAMILY BLOCK DIAGRAM To upstream VBUS Upstream USB data 24 MHz crystal To I2C EEPROM or SMBus master SDA SCK 3.3 V VDDA Buspower detect/ Vbus pulse Upstream PHY 1.2 V reg Serial interface PLL Serial interface engine Repeater ... 3.3 V TT #1 1.2 V reg Controller TT #x Port controller VDDCR Routing and port re-ordering logic Port #1 PHY#1 USB data downstream OC sense switch driver/ LED drivers OC Port sense power switch/ LED drivers ... Port #x PHY#x USB data downstream OC sense switch driver/ LED drivers OC Port sense power switch/ LED drivers x indicates the number of available downstream ports: 2, 3, or 4 DS00001692D-page 6  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 3.0 PIN INFORMATION This chapter outlines the pinning configurations for each package type available, followed by a corresponding pin list organized alphabetically. The detailed pin descriptions are listed then outlined by function in Section 3.3, "Pin Descriptions (Grouped by Function)," on page 12. 3.1 Pin Configurations The following figures detail the pinouts of the various USB251xB/xBi versions. FIGURE 3-1: USB2512B PIN DIAGRAM SUSP_IND/LOCAL_PWR/NON_REM0 28 18 NC VDDA33 29 17 OCS_N2 USBDM_UP 30 16 PRTPWR2/BC_EN2 USBDP_UP 31 15 VDD33 14 CRFILT 13 OCS_N1 12 PRTPWR1/BC_EN1 11 TEST 10 VDDA33 XTALOUT 32 XTALIN/CLKIN 33 PLLFILT 34 RBIAS 35 VDDA33 36 USB2512B/12Bi (Top View) Ground Pad (must be connected to VSS) Indicates pins on the bottom of the device.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 7 USB251xB/xBi FIGURE 3-2: USB2513B PIN DIAGRAM SUSP_IND/LOCAL_PWR/NON_REM0 28 18 PRTPWR3/BC_EN3 VDDA33 29 17 OCS_N2 USBDM_UP 30 16 PRTPWR2/BC_EN2 USBDP_UP 31 15 VDD33 XTALOUT 32 14 CRFILT XTALIN/CLKIN 33 13 OCS_N1 PLLFILT 34 12 PRTPWR1/BC_EN1 RBIAS 35 11 TEST VDDA33 36 10 VDDA33 USB2513B/13Bi (Top View) Ground Pad (must be connected to VSS) Indicates pins on the bottom of the device. DS00001692D-page 8  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi FIGURE 3-3: USB2514B PIN DIAGRAM SUSP_IND/LOCAL_PWR/NON_REM0 28 18 PRTPWR3/BC_EN3 VDDA33 29 17 OCS_N2 USBDM_UP 30 16 PRTPWR2/BC_EN2 USBDP_UP 31 15 VDD33 XTALOUT 32 14 CRFILT XTALIN/CLKIN 33 13 OCS_N1 PLLFILT 34 12 PRTPWR1/BC_EN1 RBIAS 35 11 TEST VDDA33 36 10 VDDA33 USB2514B/14Bi (Top View) Ground Pad (must be connected to VSS) Indicates pins on the bottom of the device.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 9 USB251xB/xBi 3.2 Pin List (Alphabetical) TABLE 3-1: USB251XB/XBI PIN LIST (ALPHABETICAL) BC_EN1 BC_EN2 Battery Charging Strap Option 12 16 - BC_EN3 18 - BC_EN4 20 Configuration Programming Selection 24 CLKIN External Clock Input 33 CRFILT Core Regulator Filter Capacitor 14 Ground Pad (VSS) Exposed Pad Tied to Ground (VSS) ePad HS_IND Hi-Speed Upstream Port Indicator 25 LOCAL_PWR Local Power Detection 28 NC No Connect CFG_SEL0 CFG_SEL1 USB2514B USB2514Bi Name USB2513B USB2513Bi Symbol USB2512B USB2512Bi Pin Numbers 25 6 - NC 7 - NC 18 - NC 19 8 NC - NC 9 - NC 20 - 21 NC NON_REM0 NON_REM1 OCS_N1 - Non-Removable Port Strap Option 28 Over-Current Sense 13 22 17 OCS_N2 - OCS_N3 19 - OCS_N4 21 PLLFILT PLL Regulator Filter Capacitor 34 PRT_DIS_M1 Downstream Port Disable Strap Option 1 PRT_DIS_M2 3 - PRT_DIS_M3 - PRT_DIS_M4 PRT_DIS_P1 6 Port Disable 4 PRT_DIS_P2 PRT_DIS_P3 PRT_DIS_P4 DS00001692D-page 10 8 2 - 7 - 9  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi TABLE 3-1: USB251XB/XBI PIN LIST (ALPHABETICAL) (CONTINUED) PRTPWR1 PRTPWR2 USB Port Power Enable 12 16 - PRTPWR3 18 - PRTPWR4 RBIAS USB Transceiver Bias 20 35 RESET_N Reset Input 26 SCL Serial Clock 24 SDA Serial Data Signal 22 SMBCLK System Management Bus Clock 24 SMBDATA System Management Bus Data Signal 22 SUSP_IND Active/Suspend Status Indicator 28 Test Pin 11 USB Bus Data 30 TEST USBDM_UP 31 USBDP_UP USBDM_DN1 Hi-Speed USB Data 1 3 USBDM_DN2 - USBDM_DN3 6 - USBDM_DN4 8 USBDP_DN1 2 USBDP_DN2 4 - USBDP_DN3 VDD33 9 Upstream VBUS Power Detection 27 3.3 V Digital Power 15 23 VDD33 VDDA33 7 - USBDP_DN4 VBUS_DET 3.3 V Analog Power 5 VDDA33 10 VDDA33 29 VDDA33 36 XTALIN XTALOUT USB2514B USB2514Bi Name USB2513B USB2513Bi Symbol USB2512B USB2512Bi Pin Numbers Crystal Input 33 Crystal Output 32  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 11 USB251xB/xBi 3.3 Pin Descriptions (Grouped by Function) An N at the end of a signal name indicates that the active (asserted) state occurs when the signal is at a low voltage level. When the N is not present, the signal is asserted when it is at a high voltage level. The terms assertion and negation are used exclusively in order to avoid confusion when working with a mixture of active low and active high signals. The term assert, or assertion, indicates that a signal is active, independent of whether that level is represented by a high or low voltage. The term negate, or negation, indicates that a signal is inactive. TABLE 3-2: USB251XB/XBI PIN DESCRIPTIONS Symbol Buffer Type Description UPSTREAM USB 2.0 INTERFACES USBDM_UP USBDP_UP IO-U USB Data: connect to the upstream USB bus data signals (host, port, or upstream hub). VBUS_DET I Detect Upstream VBUS Power: detects the state of the upstream VBUS power. The hub monitors VBUS_DET to determine when to assert the internal D+ pull-up resistor: (signaling a connect event). When designing a detachable hub, this pin should be connected to VBUS on the upstream port via a 2:1 voltage divider. Two 100 k resistors are suggested. For self-powered applications with a permanently attached host, this pin must be connected to a dedicated host control output, or connected to the 3.3 V domain that powers the host (typically VDD33). DOWNSTREAM USB 2.0 INTERFACES USBDP_DN[x:1]/P RT_DIS_P[x:1] IO-U Hi-Speed USB Data: connect to the downstream USB peripheral devices attached to the hub’s port. To disable, use a 10 k pull-up resistor to 3.3 V. Downstream Port Disable Strap Option: when enabled by package and configuration settings (see Table 5-1 on page 19), this pin is sampled at RESET_N negation to determine if the port is disabled. USBDM_DN[x:1]/P RT_DIS_M[x:1] To disable a port, pull up both PRT_DIS_M[x:1] and PRT_DIS_P[x:1] pins for the corresponding port number(s). See Section 3.3.1, on page 14 for pull up details. PRTPWR[x:1]/ O12 USB Power Enable: enables power to USB peripheral devices downstream. BC_EN[x:1] IPD Battery Charging Strap Option: when enabled by package and configuration settings (see Table 5-1), the pin will be sampled at RESET_N negation to determine if ports [x:1] support the battery charging protocol. When supporting the battery charging protocol, the hub also supports external port power controllers. The battery charging protocol enables a device to draw the currents per the USB battery charging specification. See Section 3.3.1, on page 14 for strap pin details. 1 : Battery charging feature is supported for port x 0 : Battery charging feature is not supported for port x OCS_N[x:1] IPU Over-Current Sense: input from external current monitor indicating an over-current condition. RBIAS I-R USB Transceiver Bias: a 12.0 k (+/- 1%) resistor is attached from ground to this pin to set the transceiver’s internal bias settings. DS00001692D-page 12  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi TABLE 3-2: Symbol USB251XB/XBI PIN DESCRIPTIONS (CONTINUED) Buffer Type Description SERIAL PORT INTERFACES SDA/ I/OSD12 Serial Data Signal SMBDATA/ System Management Bus Signal NON_REM1 Non-Removable Port 1 Strap Option: when enabled by package and configuration options (see Table 5-1 on page 19), this pin will be sampled (in conjunction with LOCAL_PWR/SUSP_IND/NON_REM0) at RESET_N negation to determine if ports [x:1] contain permanently attached (non-removable) devices: NON_REM[1:0] NON_REM[1:0] NON_REM[1:0] NON_REM[1:0] = = = = 00 01 10 11 : : : : all ports are removable port 1 is non-removable ports 1 and 2 are non-removable when available, ports 1, 2, and 3 are non-removable When NON_REM[1:0] is chosen such that there is a non-removable device, the hub will automatically report itself as a compound device (using the proper descriptors). RESET_N IS SCL/ I/OSD12 RESET Input: the system can reset the chip by driving this input low. The minimum active low pulse is 1 s. Serial Clock (SCL) SMBCLK/ System Management Bus Clock CFG_SEL0 Configuration Select: the logic state of this multifunction pin is internally latched on the rising edge of RESET_N (RESET_N negation), and will determine the hub configuration method as described in Table 5-1. HS_IND/ I/O12 Hi-Speed Upstream Port Indicator: upstream port connection speed. Asserted = the hub is connected at HS Negated = the hub is connected at FS Note: When implementing an external LED on this pin, the active state is indicated above and outlined in Section 3.3.1.3, on page 15. Configuration Programming Select 1: the logic state of this pin is internally latched on the rising edge of RESET_N (RESET_N negation), and will determine the hub configuration method as described in Table 5-1. CFG_SEL1 MISC XTALIN ICLKx Crystal Input: 24 MHz crystal. This pin connects to either one terminal of the crystal or to an external 24 MHz clock when a crystal is not used. External Clock Input: this pin connects to either one terminal of the crystal or to an external 24 MHz clock when a crystal is not used. CLKIN XTALOUT OCLKx Crystal Output: this is the other terminal of the crystal circuit with 1.2 V p-p output and a weak (< 1mA) driving strength. When an external clock source is used to drive XTALIN/CLKIN, leave this pin unconnected, or use with appropriate caution.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 13 USB251xB/xBi TABLE 3-2: USB251XB/XBI PIN DESCRIPTIONS (CONTINUED) Symbol Buffer Type SUSP_IND/ I/O Description Active/Suspend Status LED: indicates USB state of the hub. Negated = unconfigured; or configured and in USB suspend Asserted = hub is configured and is active (i.e., not in suspend) Local Power: detects availability of local self-power source. LOCAL_PWR/ Low = self/local power source is NOT available (i.e., the hub gets all power from the upstream USB VBus) High = self/local power source is available Non-Removable 0 Strap Option: when enabled by package and configuration settings (see Table 5-1 on page 19), this pin will be sampled (in conjunction with NON_REM[1]) at RESET_N negation to determine if ports [x:1] contain permanently attached (non-removable) devices: NON_REM0 Note: When implementing an external LED on this pin, the active state is outlined below and detailed in Section 3.3.1.3, on page 15. NON_REM[1:0] = 00 : all ports are removable; LED is active high NON_REM[1:0] = 01 : port 1 is non-removable; LED is active low NON_REM[1:0] = 10 : ports 1 and 2 are non-removable; LED is active high NON_REM[1:0] = 11 : (when available) ports 1, 2, and 3 are non-removable; LED is active low IPD TEST Test Pin: treat as a no connect pin or connect to ground. No trace or signal should be routed or attached to this pin. POWER, GROUND, and NO CONNECTS 3.3.1 CRFILT VDD Core Regulator Filter Capacitor: this pin can have up to a 0.1 F low-ESR capacitor to VSS, or be left unconnected. VDD33 3.3 V Power VDDA33 3.3 V Analog Power PLLFILT PLL Regulator Filter Capacitor: this pin can have up to a 0.1 F low-ESR capacitor to VSS, or be left unconnected. VSS Ground Pad/ePad: the package slug is the only VSS for the device and must be tied to ground with multiple vias. NC No Connect: no signal or trace should be routed or attached to all NC pins. CONFIGURING THE STRAP PINS If a pin's strap function is enabled thru the hub configuration selection, (Table 5-1, “Initial Interface/Configuration Options,” on page 19) the strap pins must be pulled either high or low using the values provided in Table 3-3. Each strap option is dependent on the pin’s buffer type, as outlined in the sections that follow. TABLE 3-3: STRAP OPTION SUMMARY Strap Option Non-Removable Internal Pull-Down LED DS00001692D-page 14 Resistor Value Buffer Type 47 - 100 k I/O 10 k IPD 47 - 100 k I/O Notes • Only applicable to port power pins • Contains a built-in resistor  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 3.3.1.1 Non-Removable If a strap pin’s buffer type is I/O, an external pull-up or pull-down must be implemented as shown in Figure 3-4. Use Strap High to set the strap option to 1 and Stap Low to set the strap option to 0. When implementing the Strap Low option, no additional components are needed (i.e., the internal pull-down provides the resistor). FIGURE 3-4: NON-REMOVABLE PIN STRAP EXAMPLE +V R k I/O Strap Pin Strap High I/O Strap Pin Strap Low R k HUB HUB GND 3.3.1.2 Internal Pull-Down (IPD) If a strap pin’s buffer type is IPD (pins BC_EN[x:1]), one of the two hardware configurations outlined below must be implemented. Use the Strap High configuration to set the strap option value to 1 and Strap Low to set the strap option value to 0. FIGURE 3-5: PIN STRAP OPTION WITH IPD PIN EXAMPLE +V R k IPD Strap Pin Strap High HUB IPD Strap Pin HUB VSS 3.3.1.3 Strap Low VSS LED If a strap pin’s buffer type is I/O and shares functionality with an LED, the hardware configuration outlined below must be implemented. The internal logic will drive the LED appropriately (active high or low) depending on the sampled strap option. Use the Strap High configuration to set the strap option value to 1 and Strap Low to set the strap option to 0. FIGURE 3-6: LED PIN STRAP EXAMPLE +V R k LED/ Strap High Strap Pin Strap Pin HUB HUB  2022 Microchip Technology Inc. and its subsidiaries R k LED/ Strap Low DS00001692D-page 15 USB251xB/xBi 3.4 Buffer Type Descriptions TABLE 3-4: BUFFER TYPE DESCRIPTIONS Buffer Type I Description Input I/O Input/output IPD Input with internal weak pull-down resistor IPU Input with internal weak pull-up resistor IS Input with Schmitt trigger O12 Output 12 mA I/O12 Input/output buffer with 12 mA sink and 12 mA source Open drain with Schmitt trigger and 12 mA sink. Meets the I2C-Bus Specification [2] requirements. I/OSD12 ICLKx OCLKx I-R I/O-U XTAL clock input XTAL clock output RBIAS Analog input/output defined in USB specification DS00001692D-page 16  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 4.0 BATTERY CHARGING SUPPORT The USB251xB/xBi hub provides support for battery charging devices on a per port basis in compliance with the USB Battery Charging Specification, Revision 1.1. The hub can be configured to individually enable each downstream port for battery charging support either via pin strapping as illustrated in Figure 4-1 or by setting the corresponding configuration bits via I2C EEPROM or SMBus (Section 5.1 on page 19). FIGURE 4-1: BATTERY CHARGING VIA EXTERNAL POWER SUPPLY 3.3 V 5.0 V USB Port Power Controller RSTRAP IN USB251xB/xBi PRTPWR[x:1] OCS_N[x] Note: 4.1 EN VBUS FLAG RSTRAP enables battery charging. USB Battery Charging A downstream port enabled for battery charging turns on port power as soon as the power on reset and hardware configuration process has completed. The hub does not need to be enumerated nor does VBUS_DET need to be asserted for the port power to be enabled. These conditions allow battery charging in S3, S4, and S5 system power states as well as in the fully operational state. The USB Battery Charging Specification does not interfere with standard USB operation, which allows a device to perform battery charging at any time. A port that supports battery charging must be able to support 1.5 amps of current on VBUS. Standard USB port power controllers typically only allow for 0.8 amps of current before detecting an over-current condition. Therefore, the 5 volt power supply, port power controller, or over-current protection devices must be chosen to handle the larger current demand compared to standard USB hub designs. 4.1.1 SPECIAL BEHAVIOR OF PRTPWR PINS The USB251xB/xBi enables VBUS by asserting the port power (PRTPWR) as soon as the hardware configuration process has completed. If the port detects an over-current condition, PRTPWR will be turned off to protect the circuitry from overloading. If an over-current condition is detected when the hub is not enumerated, PRTPWR can only be turned on from the host or if RESET_N is toggled. These behaviors provide battery charging even when the hub is not enumerated and protect the hub from sustained short circuit conditions. If the short circuit condition persists when the hub is plugged into a host system the user is notified that a port has an over-current condition. Otherwise PRTPWR turned on by the host system and the ports operate normally.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 17 USB251xB/xBi 4.2 Battery Charging Configuration The battery charging option can be configured in one of two ways: • When the hub is brought up in the default configuration with strapping options enabled, with the PRTPWR[x:1]/BC_EN[x:1] pins configured. See the following sections for details: - Section 3.3, "Pin Descriptions (Grouped by Function)," on page 12 - Section 3.3.1.2, "Internal Pull-Down (IPD)," on page 15 • When the hub is initialized for configuration over I2C EEPROM or SMBus. Either of these interfaces can be used to configure the battery charging option. 4.2.1 BATTERY CHARGING ENABLED VIA I2C EEPROM OR SMBUS Register memory map location 0xD0 is allocated for battery charging support. The Battery Charging register at location 0xD0 starting from bit 1 enables battery charging for each downstream port when asserted. Bit 1 represents port 1, bit 2 represents port 2, etc. Each port with battery charging enabled asserts the corresponding PRTPWR[x:1] pin. DS00001692D-page 18  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.0 INITIAL INTERFACE/CONFIGURATION OPTIONS The hub must be configured in order to correctly function when attached to a USB host controller. The hub can be configured either internally or externally by setting the CFG_SEL[1:0] pins (immediately after RESET_N negation) as outlined in the table below. See Chapter 11 (Hub Specification) of the USB specification for general details regarding hub operation and functionality. Note: To configure the hub externally, there are two principal ways to interface to the hub: over SMBus or I2C EEPROM. The hub can be configured internally, where several default configurations are available as described in the table below. When configured internally, additional configuration is available using the strap options (listed in Section 3.3.1 on page 14). Strap options are not available when configuring the hub over I2C or SMBus. Note: TABLE 5-1: INITIAL INTERFACE/CONFIGURATION OPTIONS CFG_SEL[1] CFG_SEL[0] 0 0 Default configuration: • Strap options enabled • Self-powered operation enabled • Individual power switching • Individual over-current sensing 0 1 The hub is configured externally over SMBus (as an SMBus slave device): • Strap options disabled • All registers configured over SMBus 1 0 Default configuration with the following overrides: • Bus-powered operation 1 1 The hub is configured over 2-wire I2C EEPROM: • Strap options disabled • All registers configured by I2C EEPROM 5.1 Description Internal Register Set (Common to I2C EEPROM and SMBus) The register set available when configuring the hub to interface over I2C or SMBus is outlined in the table below. Each register has R/W capability, where EEPROM reset values are 0x00. Reserved registers should be written to 0 unless otherwise specified. Contents read from unavailable registers should be ignored. Address Register Name 00h Vendor ID LSB 01h Vendor ID MSB 02h Product ID LSB 03h Product ID MSB 25 04h Device ID LSB B3 05h Device ID MSB 0B  2022 Microchip Technology Inc. and its subsidiaries USB2514B/14Bi USB2513B/13Bi USB2512B/12Bi Default ROM Values (Hexidecimal) 24 04 12 13 14 DS00001692D-page 19 USB251xB/xBi Address Register Name 06h Configuration Data Byte 1 9B 07h Configuration Data Byte 2 20 08h Configuration Data Byte 3 02 09h Non-Removable Devices 00 0Ah Port Disable (Self) 00 0Bh Port Disable (Bus) 00 0Ch Max Power (Self) 01 0Dh Max Power (Bus) 32 0Eh Hub Controller Max Current (Self) 01 0Fh Hub Controller Max Current (Bus) 32 10h Power-on Time 32 11h Language ID High 00 12h Language ID Low 00 13h Manufacturer String Length 00 14h Product String Length 00 15h Serial String Length 00 16h-53h Manufacturer String 00 54h-91h Product String 00 92h-CFh Serial String 00 D0h Battery Charging Enable 00 E0h rsvd 00 F5h rsvd 00 F6h Boost_Up 00 F7h rsvd 00 F8h Boost_x:0 00 F9h rsvd 00 FAh Port Swap 00 FBh Port Map 12 FCh Port Map 34 FD-FEh rsvd 00 FFh Status/Command Note: SMBus register only 00 DS00001692D-page 20 USB2514B/14Bi USB2513B/13Bi USB2512B/12Bi Default ROM Values (Hexidecimal) 00 - 00  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.1 REGISTER 00H: VENDOR ID (LSB) Bit Number Bit Name Description 7:0 VID_LSB Least Significant Byte of the Vendor ID: a 16-bit value that uniquely identifies the Vendor of the user device (assigned by USB-Interface Forum). Set this field using either the SMBus or I2C EEPROM interface options. 5.1.2 REGISTER 01H: VENDOR ID (MSB) Bit Number Bit Name Description 7:0 VID_MSB Most Significant Byte of the Vendor ID: a 16-bit value that uniquely identifies the Vendor of the user device (assigned by USB-Interface Forum). Set this field using either the SMBus or I2C EEPROM interface options. 5.1.3 REGISTER 02H: PRODUCT ID (LSB) Bit Number Bit Name Description 7:0 PID_LSB Least Significant Byte of the Product ID: a 16-bit value that uniquely identifies the Product ID of the user device. Set this field using either the SMBus or I2C EEPROM interface options. 5.1.4 REGISTER 03H: PRODUCT ID (MSB) Bit Number Bit Name Description 7:0 PID_MSB Most Significant Byte of the Product ID: a 16-bit value that uniquely identifies the Product ID of the user device. Set this field using either the SMBus or I2C EEPROM interface options. 5.1.5 REGISTER 04H: DEVICE ID (LSB) Bit Number Bit Name Description 7:0 DID_LSB Least Significant Byte of the Device ID: a 16-bit device release number in BCD format (assigned by OEM). Set this field using either the SMBus or I2C EEPROM interface options. 5.1.6 REGISTER 05H: DEVICE ID (MSB) Bit Number Bit Name Description 7:0 DID_MSB Most Significant Byte of the Device ID: a 16-bit device release number in BCD format (assigned by OEM). Set this field using either the SMBus or I2C EEPROM interface options.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 21 USB251xB/xBi 5.1.7 REGISTER 06H: CONFIG_BYTE_1 Bit Number Bit Name 7 SELF_BUS_PWR Description Self or Bus Power: selects between self- and bus-powered operation. The hub is either self-powered (draws less than 2 mA of upstream bus power) or bus-powered (limited to a 100 mA maximum of upstream power prior to being configured by the host controller). When configured as a bus-powered device, the hub consumes less than 100 mA of current prior to being configured. After configuration, the buspowered hub, along with all associated hub circuitry, any embedded devices (if part of a compound device), and all externally available downstream ports (max 100 mA) must consume no more than 500 mA of upstream VBUS current. The current consumption is system dependent and must not violate the USB 2.0 Specification [1]. When configured as a self-powered device, < 1 mA of upstream VBUS current is consumed and all ports are available. Each port is capable of sourcing 500 mA of current. This field is set over either the SMBus or I2C EEPROM interface options. 0 : bus-powered operation 1 : self-powered operation If dynamic power switching is enabled (Section 5.1.8), this bit is ignored and LOCAL_PWR is used to determine if the hub is operating from self or bus power. 6 rsvd 5 HS_DISABLE Hi-Speed Disable: disables the capability to attach as either a hi- or full-speed device, forcing full-speed attachment only (i.e., no hi-speed support). 0 : hi-/full-speed 1 : full-speed only (hi-speed disabled) 4 MTT_ENABLE Multi-TT Enable: enables one transaction translator per port operation. Selects between a mode where only one transaction translator is available for all ports (single-TT), or each port gets a dedicated transaction translator (multi-TT). 0 : single TT for all ports 1 : multi-TT (one TT per port) 3 EOP_DISABLE EOP Disable: disables End Of Packet (EOP) generation at End Of Frame Time #1 (EOF1) when in full-speed mode. During full-speed operation only, the hub can send EOP when no downstream traffic is detected at EOF1. See the USB 2.0 Specification, Section 11.3.1 for details. 0 : EOP generation is normal 1 : EOP generation is disabled 2:1 CURRENT_SNS Over-Current Sense: selects current sensing on all ports (ganged); a port-byport basis (individual); or none (for bus-powered hubs only). The ability to support current sensing on a ganged or port-by-port basis is hardware implementation dependent. 00 : ganged sensing 01 : individual sensing 1x : over-current sensing not supported (use with bus-powered configurations) 0 PORT_PWR Port Power Switching: enables power switching on all ports (ganged) or a portby-port basis (individual). The ability to support power enabling on a ganged or port-by-port basis is hardware implementation dependent. 0 : ganged switching 1 : individual switching DS00001692D-page 22  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.8 REGISTER 07H: CONFIGURATION DATA BYTE 2 Bit Number Bit Name Description 7 DYNAMIC Dynamic Power Enable: controls the ability of the hub to automatically change from self-powered to bus-powered operation if the local power source is removed or unavailable. It can also go from bus-powered to self-powered operation if the local power source is restored. When dynamic power switching is enabled, the hub detects the availability of a local power source by monitoring LOCAL_PWR. If the hub detects a change in power source availability, the hub immediately disconnects and removes power from all downstream devices. It also disconnects the upstream port. The hub will then re-attach to the upstream port as either a bus-powered hub (if local power is unavailable) or a self-powered hub (if local power is available). 0 : no dynamic auto-switching 1 : dynamic auto-switching capable 6 rsvd 5:4 OC_TIMER Over Current Timer Delay: 00 01 10 11 3 COMPOUND : : : : 0.1 ms 4.0 ms 8.0 ms 16.0 ms Compound Device: indicates the hub is part of a compound device (see the USB Specification for definition). The applicable port(s) must also be defined as having a non-removable device. Note: When configured via strapping options, declaring a port as nonremovable automatically causes the hub controller to report that it is part of a compound device. 0 : no 1 : yes, the hub is part of a compound device 2:0 5.1.9 rsvd REGISTER 08H: CONFIGURATION DATA BYTE 3 Bit Number Bit Name 7:4 rsvd 3 PRTMAP_EN Description Port Mapping Enable: selects the method used by the hub to assign port numbers and disable ports. 0 : standard mode 1 : port mapping mode 2:1 rsvd 0 STRING_EN Enables String Descriptor Support 0 : string support disabled 1 : string support enabled  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 23 USB251xB/xBi 5.1.10 REGISTER 09H: NON-REMOVABLE DEVICE Bit Number Bit Name 7:0 NR_DEVICE Description Non-Removable Device: indicates which port has a non-removable device. 0 : port is removable 1 : port is non-removable Bit Bit Bit Bit Bit Bit Bit Bit 7 6 5 4 3 2 1 0 : : : : : : : : rsvd rsvd rsvd controls controls controls controls rsvd port port port port 4 3 2 1 Note: The device must provide its own descriptor data. When using the default configuration, the NON_REM[1:0] pins will designate the appropriate ports as being non-removable. 5.1.11 REGISTER 0AH: PORT DISABLE FOR SELF-POWERED OPERATION Bit Number Bit Name 7:0 PORT_DIS_SP Description Port Disable Self-Powered: disables one or more ports. 0 = port is available 1 = port is disabled Bit Bit Bit Bit Bit Bit Bit Bit 7 6 5 4 3 2 1 0 : : : : : : : : rsvd rsvd rsvd controls controls controls controls rsvd port port port port 4 3 2 1 During self-powered operation when mapping mode is disabled (PRTMAP_EN = 0), this register selects the ports that will be permanently disabled. These ports are then unavailable and cannot be enabled or enumerated by a host controller. The ports can be disabled in any order, where the internal logic will automatically report the correct number of enabled ports to the USB host. The active ports will be reordered in order to ensure proper function. When using the default configuration, PRT_DIS_P[x:1] and PRT_DIS_M[x:1] pins disable the appropriate ports. DS00001692D-page 24  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.12 REGISTER 0BH: PORT DISABLE FOR BUS-POWERED OPERATION Bit Number Bit Name 7:0 PORT_DIS_BP Description Port Disable Bus-Powered: disables one or more ports. 0 = port is available 1 = port is disabled Bit Bit Bit Bit Bit Bit Bit Bit 7 6 5 4 3 2 1 0 : : : : : : : : rsvd rsvd rsvd controls controls controls controls rsvd port port port port 4 3 2 1 During self-powered operation when mapping mode is disabled (PRTMAP_EN = 0), this selects the ports which will be permanently disabled.These ports are then unavailable and cannot be enabled or enumerated by a host controller. The ports can be disabled in any order, where the internal logic will automatically report the correct number of enabled ports to the USB host. The active ports will be reordered in order to ensure proper function. When using the internal default option, the PRT_DIS_P[x:1] and PRT_DIS_M[x:1] pins disable the appropriate ports. 5.1.13 REGISTER 0CH: MAX POWER FOR SELF-POWERED OPERATION Bit Number Bit Name Description 7:0 MAX_PWR_SP Max Power Self-Powered: the value in 2 mA increments that the hub consumes from an upstream port (VBUS) when operating as a self-powered hub. This value includes the hub silicon along with the combined power consumption (from VBUS) of all associated circuitry on the board. This value also includes the power consumption of a permanently attached peripheral if the hub is configured as a compound device. The embedded peripheral reports 0 mA in its descriptors. Note: 5.1.14 The USB 2.0 Specification does not permit this value to exceed 100 mA REGISTER 0DH: MAX POWER FOR BUS-POWERED OPERATION Bit Number Bit Name Description 7:0 MAX_PWR_BP Max Power Bus-Powered: the value in 2 mA increments that the hub consumes from an upstream port (VBUS) when operating as a bus-powered hub. This value includes the hub silicon along with the combined power consumption (from VBUS) of all associated circuitry on the board. This value also includes the power consumption of a permanently attached peripheral if the hub is configured as a compound device. The embedded peripheral reports 0 mA in its descriptors.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 25 USB251xB/xBi 5.1.15 REGISTER 0EH: HUB CONTROLLER MAX CURRENT FOR SELF-POWERED OPERATION Bit Number Bit Name Description 7:0 HC_MAX_C_SP Hub Controller Max Current Self-Powered: the value in 2 mA increments that the hub consumes from an upstream port (VBUS) when operating as a selfpowered hub. This value includes the hub silicon along with the combined power consumption (from VBUS) of all associated circuitry on the board. This value does NOT include the power consumption of a permanently attached peripheral if the hub is configured as a compound device. The USB 2.0 Specification does not permit this value to exceed 100 mA A value of 50 (decimal) indicates 100 mA, which is the default value. Note: 5.1.16 REGISTER 0FH: HUB CONTROLLER MAX CURRENT FOR BUS-POWERED OPERATION Bit Number Bit Name Description 7:0 HC_MAX_C_BP Hub Controller Max Current Bus-Powered: the value in 2 mA increments that the hub consumes from an upstream port (VBUS) when operating as a buspowered hub. This value will include the hub silicon along with the combined power consumption (from VBUS) of all associated circuitry on the board. This value will not include the power consumption of a permanently attached peripheral if the hub is configured as a compound device. A value of 50 (decimal) would indicate 100 mA, which is the default value. Note: 5.1.17 REGISTER 10H: POWER-ON TIME Bit Number Bit Name 7:0 POWER_ON_TIME 5.1.18 Bit Name 7:0 LANG_ID_H Description USB Language ID: upper 8 bits of a 16-bit ID field REGISTER 12H: LANGUAGE ID LOW Bit Number Bit Name 7:0 LANG_ID_L 5.1.20 Power-On Time: the length of time that it takes (in 2 ms intervals) from the time the host initiated the power-on sequence on a port until the port has adequate power. REGISTER 11H: LANGUAGE ID HIGH Bit Number 5.1.19 Description Description USB Language ID: lower 8 bits of a 16-bit ID field REGISTER 13H: MANUFACTURER STRING LENGTH Bit Number Bit Name 7:0 MFR_STR_LEN DS00001692D-page 26 Description Manufacturer String Length: with a maximum string length of 31 characters (when supported).  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.21 REGISTER 14H: PRODUCT STRING LENGTH Bit Number Bit Name Description 7:0 PRD_STR_LEN Product String Length: with a maximum string length of 31 characters (when supported). 5.1.22 REGISTER 15H: SERIAL STRING LENGTH Bit Number Bit Name 7:0 SER_STR_LEN 5.1.23 Description Serial String Length: with a maximum string length of 31 characters (when supported). REGISTER 16H-53H: MANUFACTURER STRING Bit Number Bit Name Description 7:0 MFR_STR Manufacturer String: UNICODE UTF-16LE per USB 2.0 Specification: with a maximum string length of 31 characters (when supported). The string consists of individual 16-bit UNICODE UTF-16LE characters. The characters will be stored starting with the LSB at the least significant address and the MSB at the next 8-bit location. (Subsequent characters must be stored in sequential contiguous addresses in the same LSB, MSB manner.) Warning: Close attention to the byte order of the selected programming tool should be monitored. Note: 5.1.24 REGISTER 54H-91H: PRODUCT STRING Bit Number Bit Name 7:0 PRD_STR Description Product String: UNICODE UTF-16LE per USB 2.0 Specification When supported, the maximum string length is 31 characters (62 bytes). The string consists of individual 16-bit UNICODE UTF-16LE characters. The characters will be stored starting with the LSB at the least significant address and the MSB at the next 8-bit location. (Subsequent characters must be stored in sequential contiguous address in the same LSB, MSB manner.) Warning: Close attention to the byte order of the selected programming tool should be monitored. Note: 5.1.25 REGISTER 92H-CFH: SERIAL STRING Bit Number Bit Name 7:0 SER_STR Description Serial String: UNICODE UTF-16LE per USB 2.0 specification When supported, the maximum string length is 31 characters (62 bytes). The string consists of individual 16-bit UNICODE UTF-16LE characters. The characters will be stored starting with the LSB at the least significant address and the MSB at the next 8-bit location. (Subsequent characters must be stored in sequential contiguous address in the same LSB, MSB manner.) Warning: Close attention to the byte order of the selected programming tool should be monitored. Note:  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 27 USB251xB/xBi 5.1.26 REGISTER D0H: BATTERY CHARGING ENABLE Bit Number Bit Name 7:0 BC_EN Description Battery Charging Enable: enables the battery charging feature for the corresponding port. 0 : battery charging support is not enabled 1 : battery charging support is enabled Bit Bit Bit Bit Bit Bit Bit Bit 5.1.27 7 6 5 4 3 2 1 0 : : : : : : : : rsvd rsvd rsvd controls controls controls controls rsvd port port port port 4 3 2 1 REGISTER F6H: BOOST_UP Bit Number Bit Name 7:2 rsvd 1:0 BOOST_IOUT Description USB electrical signaling drive strength boost bit for the upstream port. 00 01 10 11 : : : : normal electrical drive strength elevated electrical drive strength elevated electrical drive strength elevated electrical drive strength Note: DS00001692D-page 28 no boost - low (~ 4% boost) - medium (~ 8% boost) - high (~12% boost) Boost could result in non-USB compliant parameters. Therefore, a value of 00 should be implemented unless specific implementation issues require additional signal boosting to correct for degraded USB signalling levels.  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.28 REGISTER F8H: BOOST_4:0 Bit Number Bit Name 7:6 BOOST_IOUT_4 Description USB electrical signaling drive strength boost bit for downstream port 4. 00 01 10 11 5:4 BOOST_IOUT_3 BOOST_IOUT_2 BOOST_IOUT_1 5.1.29 : : : : normal electrical drive strength elevated electrical drive strength elevated electrical drive strength elevated electrical drive strength no boost - low (~4% boost) - medium (~ 8% boost) - high (~12% boost) : : : : normal electrical drive strength elevated electrical drive strength elevated electrical drive strength elevated electrical drive strength no boost - low (~4% boost) - medium (~ 8% boost) - high (~12% boost) USB electrical signaling drive strength boost bit for downstream port 1. 00 01 10 11 Note: no boost - low (~4% boost) - medium (~ 8% boost) - high (~12% boost) USB electrical signaling drive strength boost bit for downstream port 2. 00 01 10 11 1:0 normal electrical drive strength elevated electrical drive strength elevated electrical drive strength elevated electrical drive strength USB electrical signaling drive strength boost bit for downstream port 3. 00 01 10 11 3:2 : : : : : : : : normal electrical drive strength elevated electrical drive strength elevated electrical drive strength elevated electrical drive strength no boost - low (~4% boost) - medium (~ 8% boost) - high (~12% boost) Boost could result in non-USB compliant parameters. Therefore, a value of 00 should be implemented unless specific implementation issues require additional signal boosting to correct for degraded USB signaling levels. REGISTER FAH: PORT SWAP Bit Number Bit Name Description 7:0 PRTSP Port Swap: swaps the upstream USBDP/USBDM pins (USBDP_UP and USBDM_UP) and the downstream USBDP/USBDM pins (USBDP_DN[x:1] and USBDP_DN[x:1]) for ease of board routing to devices and connectors. 0 : USB D+ functionality is associated with the DP pin and D- functionality is associated with the DM pin. 1 : USB D+ functionality is associated with the DM pin and D- functionality is associated with the DP pin. Bit Bit Bit Bit Bit Bit Bit Bit 7 6 5 4 3 2 1 0 : : : : : : : : rsvd rsvd rsvd controls port 4 controls port 3 controls port 2 controls port 1 when set to 1, the upstream port DP/DM is swapped.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 29 USB251xB/xBi 5.1.30 REGISTER FBH: PORTMAP 12 Bit Number Bit Name Description 7:0 PRTR12 PortMap Register for Ports 1 and 2: When a hub is enumerated by a USB host controller, the hub is only permitted to report how many ports it has; the hub is not permitted to select a numerical range or assignment. The host controller will number the downstream ports of the hub starting with the number 1, up to the number of ports that the hub reports having. The host's port number is called the Logical Port Number and the physical port on the hub is the Physical Port Number. When mapping mode is enabled (see PRTMAP_EN, Section 5.1.9 on page 23) the hub's downstream port numbers can be mapped to different logical port numbers (assigned by the host). Note: Contiguous logical port numbers must be implemented, starting from number 1 up to the maximum number of enabled ports. This ensures that the hub's ports are numbered in accordance with the way a host will communicate with the ports. Bit [7:4] Bit [3:0] DS00001692D-page 30 0000 Physical port 2 is disabled 0001 Physical port 2 is mapped to logical port 1 0010 Physical port 2 is mapped to logical port 2 0011 Physical port 2 is mapped to logical port 3 0100 Physical port 2 is mapped to logical port 4 1000 to 1111 rsvd, will default to 0000 value 0000 Physical port 1 is disabled 0001 Physical port 1 is mapped to logical port 1 0010 Physical port 1 is mapped to logical port 2 0011 Physical port 1 is mapped to logical port 3 0100 Physical port 1 is mapped to logical port 4 1000 to 1111 rsvd, will default to 0000 value  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.1.31 REGISTER FCH: PORTMAP 34 Bit Number Bit Name Description 7:0 PRTR34 PortMap Register for Ports 3 and 4: When a hub is enumerated by a USB host controller, the hub is only permitted to report how many ports it has; the hub is not permitted to select a numerical range or assignment. The host controller will number the downstream ports of the hub starting with the number 1, up to the number of ports that the hub reports having. The host's port number is called the Logical Port Number and the physical port on the hub is the Physical Port Number. When mapping mode is enabled (see PRTMAP_EN, Section 5.1.9 on page 23) the hub's downstream port numbers can be mapped to different logical port numbers (assigned by the host). Note: Contiguous logical port numbers must be implemented, starting from number 1 up to the maximum number of enabled ports. This ensures that the hub's ports are numbered in accordance with the way a host will communicate with the ports. Bit [7:4] Bit [3:0]  2022 Microchip Technology Inc. and its subsidiaries 0000 Physical port 4 is disabled 0001 Physical port 4 is mapped to logical port 1 0010 Physical port 4 is mapped to logical port 2 0011 Physical port 4 is mapped to logical port 3 0100 Physical port 4 is mapped to logical port 4 1000 to 1111 rsvd, will default to 0000 value 0000 Physical port 3 is disabled 0001 Physical port 3 is mapped to logical port 1 0010 Physical port 3 is mapped to logical port 2 0011 Physical port 3 is mapped to logical port 3 0100 Physical port 3 is mapped to logical port 4 1000 to 1111 rsvd, will default to 0000 value DS00001692D-page 31 USB251xB/xBi 5.1.32 REGISTER FFH: STATUS/COMMAND Bit Number Bit Name 7:3 rsvd 2 INTF_PW_DN Description SMBus Interface Power Down: 0 : interface is active 1 : interface power down after ACK has completed 1 RESET Reset the SMBus interface and internal memory back to RESET_N assertion default settings. 0 : normal run/idle state 1 : force a reset of registers to their default state 0 USB_ATTACH USB Attach (and write protect) 0 : SMBus slave interface is active 1 : the hub will signal a USB attach event to an upstream device, and the internal memory (address range 0x00-0xFE) is write-protected to prevent unintentional data corruption. 5.2 I2C EEPROM The hub can be configured via a 2-wire (I2C) EEPROM (256x8). See Table 5-1 for details on enabling the I2C EEPROM interface. The I2C EEPROM interface implements a subset of the I2C Master Specification (refer to the Philips Semiconductor Standard I2C-Bus Specification I2C protocol for details). The hub’s interface is designed to attach to a single dedicated I2C EEPROM which conforms to the Standard-mode I2C specification (100 kbit/s transfer rate and 7-bit addressing) for protocol and electrical compatibility. The I2C EEPROM shares the same pins as the SMBus interface, therefore the SMBus interface is not available when the I2C EEPROM interface has been enabled (and vice versa). The hub acts as the master and generates the serial clock SCL, controls the bus access (determines which device acts as the transmitter and which device acts as the receiver), and generates the START and STOP conditions. The hub will read the external EEPROM for configuration data and then attach to the upstream USB host. Note: If no external EEPROM is present, the hub will write 0 to all configuration registers. The hub does not have the capacity to write to the external EEPROM. The hub only has the capability to read from an external EEPROM. The external EEPROM will be read (even if it is blank), and the hub will be configured with the values that are read. Any values read for unsupported registers will not be retained (i.e., they will remain as the default values). Reserved registers should be set to 0 unless otherwise specified. EEPROM reset values are 0x00. Contents read from unavailable registers should be ignored. 5.2.1 I2C SLAVE ADDRESS The 7-bit slave address is 1010000b. Note: 5.2.2 10-bit addressing is not supported. PROTOCOL IMPLEMENTATION The hub will only access an EEPROM using the sequential read protocol as outlined in Chapter 8 of MicroChip 24AA02/24LC02B [4]. 5.2.3 PULL-UP RESISTOR The circuit board designer is required to place external pull-up resistors (10 k recommended) on the SDA/SMBDATA and SCL/SMBCLK/CFG_SEL[0] lines (per SMBus 1.0 Specification [3], and EEPROM manufacturer guidelines) to VDD33 in order to assure proper operation. DS00001692D-page 32  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.2.4 IN-CIRCUIT EEPROM PROGRAMMING The EEPROM can be programmed via automatic test equipment (ATE) by pulling RESET_N low (which tri-states the hub’s EEPROM interface and allows an external source to program the EEPROM). Note: 5.3 The Hub does not have the capacity to write, or “Program,” an external EEPROM. The Hub only has the capability to read external EEPROMs. The external EEPROM will be read (even if it is blank or non-populated), and the Hub will be “configured” with the values that are read. SMBus The Microchip hub can be configured by an external processor via an SMBus interface (see Table 5-1 for details on enabling the SMBus interface). The SMBus interface shares the same pins as the EEPROM interface, and therefore the hub no longer supports the I2C EEPROM interface when the SMBus interface has been enabled. The hub waits indefinitely for the SMBus code load to complete and only appears as a newly connected device on USB after the code load is complete. The hub’s SMBus acts as a slave-only SMBus device. The implementation only supports block write (Section 5.3.2.1) and block read (Section 5.3.2.2) protocols, where the available registers are outlined in Section 5.1 on page 19. Reference the System Management Bus Specification [3] for additional information. 5.3.1 SMBUS SLAVE ADDRESS The 7-bit slave address is 0101100b. The hub will not respond to the general call address of 0000000b. 5.3.2 PROTOCOL IMPLEMENTATION Typical block write and block read protocols are shown in figures 5-2 and 5-3. Register accesses are performed using 7-bit slave addressing, an 8-bit register address field, and an 8-bit data field. The shading shown in the figures during a read or write indicates the hub is driving data on the SMBDATA line; otherwise, host data is on the SDA/SMBDATA line. The SMBus slave address assigned to the hub (0101100b) allows it to be identified on the SMBus. The register address field is the internal address of the register to be accessed. The register data field is the data that the host is attempting to write to the register or the contents of the register that the host is attempting to read. Note: Data bytes are transferred MSB first.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 33 USB251xB/xBi 5.3.2.1 Block Write/Read The block write begins with a slave address and a write condition. After the command code, the host issues a byte count which describes how many more bytes will follow in the message. If a slave had 20 bytes to send, the first byte would be the number 20 (14h), followed by the 20 bytes of data. The byte count may not be zero. A block write or read allows a transfer maximum of 32 data bytes. For the following SMBus tables: Note: Denotes Master-to-Slave TABLE 5-2: Denotes Slave-to-Master BLOCK WRITE 1 7 1 1 8 1 S Slave Address Wr A Register Address A ... 8 1 8 1 8 1 8 1 1 Byte Count = N A Data byte 1 A Data byte 2 A Data byte N A P 5.3.2.2 Block Read A block read differs from a block write in that the repeated start condition exists to satisfy the I2C specification’s requirement for a change in the transfer direction. TABLE 5-3: BLOCK READ 1 7 1 1 8 1 1 7 1 1 S Slave Address Wr A Register Address A S Slave Address Rd A ... 8 1 8 1 8 1 8 1 1 Byte Count = N A Data byte 1 A Data byte 2 A Data byte N A P 5.3.2.3 Invalid Protocol Response Behavior Note that any attempt to update registers with an invalid protocol will not be updated. The only valid protocols are write block and read block (described above), where the hub only responds to the 7-bit hardware selected slave address (0101100b). Also, the only valid registers for the hub are outlined in Section 5.1 on page 19. Attempts to access any other registers will return no response. 5.3.3 SLAVE DEVICE TIMEOUT Devices in a transfer can abort the transfer in progress and release the bus when any single clock low interval exceeds 25 ms (TTIMEOUT, MIN). The master must detect this condition and generate a stop condition within or after the transfer of the interrupted data byte. Slave devices must reset their communication and be able to receive a new START condition no later than 35 ms (TTIMEOUT, MAX). Note: Some simple devices do not contain a clock low drive circuit; this simple kind of device typically resets its communications port after a start or stop condition. The slave device timeout must be implemented. DS00001692D-page 34  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.3.4 STRETCHING THE SCLK SIGNAL The hub supports stretching of the SCLK by other devices on the SMBus. However, the hub does not stretch the SCLK. 5.3.5 SMBUS TIMING The SMBus slave interface complies with the SMBus Specification Revision 1.0 [3]. See Section 2.1, AC Specifications on page 3 for more information. 5.3.6 BUS RESET SEQUENCE The SMBus slave interface resets and returns to the idle state upon a START condition followed immediately by a STOP condition. 5.3.7 SMBUS ALERT RESPONSE ADDRESS The SMBALERT# signal is not supported by the hub. 5.4 Default Configuration To put the hub in the default configuration, strap CFG_SEL[1:0] to 00b. This procedure configures the hub to the internal defaults and enables the strapping options. To place the hub in default configuration with overrides, see Table 5-1 on page 19 for the list of the options. The internal default values are used for the registers that are not controlled by strapping option pins. Refer to Section 5.1 on page 19 for the internal default values that are loaded when this option is selected. For a list of strapping option pins, see Section 5.0, "Initial Interface/Configuration Options", and to configure the strapping pins, see Section 3.3.1 on page 14. 5.5 Reset The hub experiences the following two resets: • Hardware reset via the RESET_N pin • USB bus reset 5.5.1 EXTERNAL HARDWARE RESET_N A valid hardware reset is defined as assertion of RESET_N for a minimum of 1 s after all power supplies are within operating range. While reset is asserted, the hub (and its associated external circuitry) consumes less than 500 A of current from the upstream USB power source. Assertion of RESET_N causes the following: 1. 2. 3. 4. 5. 6. All downstream ports are disabled, and PRTPWR[x:1] to downstream devices is removed (unless BC_EN[x:1] is enabled). The PHYs are disabled, and the differential pairs will be in a high-impedance state. All transactions immediately terminate; no states are saved. All internal registers return to the default state (in most cases, 00h). The external crystal oscillator is halted. The PLL is halted. The hub is operational 500 s after RESET_N is negated. Once operational, the hub will do one of the following, depending on configuration: • Read the strapping pins (default configuration with strapping options enabled) • Read configuration information from the external I2C EEPROM • Wait for configuration over SMBus.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 35 USB251xB/xBi 5.5.1.1 RESET_N for Strapping Option Configuration FIGURE 5-1: RESET_N TIMING FOR DEFAULT CONFIGURATION Hardware reset asserted Drive strap Read outputs to Attach USB CFG_SEL[1:0] inactive levels upstream t1 Attach USB_RESET USB Reset Debounce State Recovery Interval USB_RESET t7 t6 t5 t8 t9 t2 t3 RESET_N VSS t4 CFG_SEL[2:0] don’t care valid don’t care driven by hub if strap is an output VSS Name Description MIN TYP MAX Units t1 RESET_N asserted 1 s t2 CFG_SEL[1:0] setup time 16.7 ns t3 CFG_SEL[1:0] hold time 16.7 t4 Hub outputs driven to inactive logic states t5 USB attach (see notes) t6 Host acknowledges attach and signals USB reset t7 USB_RESET t8 USB_RESET State t9 USB Reset Recovery 1.5 3 100 1400 ns 2 s s ms Host Defined ms Note 5-1 ms 10 ms Note: • When in bus-powered mode, the hub and its associated circuitry must not consume more than 100 mA from the upstream USB power source during t1+t5. • All power supplies must have reached the operating levels mandated in Section 6.0, "DC Parameters", prior to (or coincident with) the assertion of RESET_N. Note 5-1 10 ms for hubs, 50 ms for root ports. DS00001692D-page 36  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 5.5.1.2 RESET_N for EEPROM Configuration FIGURE 5-2: RESET_N TIMING FOR EEPROM MODE Hardware reset asserted Read CFG_SEL[1:0] Read I2C EEPROM t1 Attach USB_RESET USB Reset Debounce USB_RESET Recovery State Interval Attach USB upstream t6 t7 t8 t9 t10 t5 t2 t3 RESET_N t4 VSS CFG_SEL[2:0] don’t care valid don’t care VSS Name t1 Description RESET_N asserted MIN t2 CFG_SEL[1:0] setup time 16.7 CFG_SEL[1:0] hold time 16.7 Hub recovery/stabilization t5 EEPROM read (hub configuration) t6 USB attach (see notes) t7 Host acknowledges attach and signals USB reset t8 USB_RESET t9 USB_RESET state t10 USB Reset Recovery MAX Units s 1 t3 t4 TYP ns 1400 500 40 40 100 ns s ms ms ms hostdefined ms Note 5-2 ms 10 ms Note: • When in bus-powered mode, the hub and its associated circuitry must not consume more than 100 mA from the upstream USB power source during t6+t7+t8+t9. • All power supplies must have reached the operating levels mandated in Section 6.0, "DC Parameters", prior to (or coincident with) the assertion of RESET_N. Note 5-2 10 ms for hubs, 50 ms for root ports.  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 37 USB251xB/xBi RESET_N for SMBus Slave Configuration 5.5.1.3 FIGURE 5-3: RESET_N TIMING FOR SMBUS MODE Hardware reset asserted Read SMBus code Hub PHY Attach USB stabilization upstream CFG_SEL[1:0] load t1 t5 t6 Attach USB_RESET USB Reset Debounce USB_RESET State Recovery Interval t7 t8 t9 t10 t2 t3 RESET_N t4 VSS CFG_SEL[2:0] don’t care valid don’t care VSS Name Description MIN TYP MAX Units t1 RESET_N Asserted 1 s t2 CFG_SEL[1:0] setup time 16.7 ns t3 CFG_SEL[1:0] hold time 16.7 t4 Hub recovery/stabilization t5 SMBus Code Load t6 Hub configuration and USB attach t7 Host acknowledges attach and signals USB reset t8 USB_RESET t9 USB_RESET State 2 1400 ns 500 s 1000 0 100 ms ms ms host-defined Note 5-4 ms ms t10 USB Reset Recovery 10 ms Note 5-3 All power supplies must have reached the operating levels mandated in Section 6.0, "DC Parameters", prior to (or coincident with) the assertion of RESET_N. Note 5-4 5.5.2 10 ms for hubs, 50 ms for root ports. USB BUS RESET In response to the upstream port signaling a reset to the hub, the hub does the following: 1. 2. 3. 4. 5. 6. Sets default internal USB address to 0 Sets configuration to: unconfigured Negates PRTPWR[x:1] to all downstream ports unless battery charging (BC_EN[x:1]) is enabled Clears all TT buffers Moves device from suspended to active (if suspended) Complies with Section 11.10 of the USB 2.0 Specification [1] for behavior after completion of the reset sequence. The host then configures the hub and the hub’s downstream port devices in accordance with the USB Specification. Note: The hub does not propagate the upstream USB reset to downstream devices. DS00001692D-page 38  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 6.0 DC PARAMETERS 6.1 Maximum Ratings Parameter Storage Temperature Symbol TSTOR MIN MAX Units -55 150 °C Comments Lead Temperature 3.3 V supply voltage Refer to JEDEC Specification J-STD020D [5] VDD33 VDDA33 4.6 V Voltage on any I/O pin -0.5 5.5 V Voltage on XTALIN -0.5 4.0 V Voltage on XTALOUT -0.5 2.5 V Applies to all packages Note 6-1 • Stresses above the specified parameters could cause permanent damage to the device. This is a stress rating only. Therefore, functional operation of the device at any condition above those indicated in the operation sections of this specification are not implied. • When powering this device from laboratory or system power supplies, it is important that the absolute maximum ratings not be exceeded or device failure can result. Some power supplies exhibit voltage spikes on their outputs when the AC power is switched on or off. In addition, voltage transients on the AC power line may appear on the DC output. When this possibility exists, it is suggested that a clamp circuit be used. 6.2 Operating Conditions Parameter Symbol MIN MAX Units Comments Extended Commercial Operating Temperature TAE 0 85 °C Ambient temperature in still air Industrial Operating Temperature TAI -40 85 °C Ambient temperature in still air 3.3 V supply voltage VDD33 VDDA33 3.0 3.6 V Applies to all parts 3.3 V supply rise time tRT33 Only applies to USB251xBi products 0 400 s See Figure 6-1 and Note 6-2 Voltage on any I/O pin -0.3 5.5 V If any 3.3 V supply voltage drops below 3.0 V, then the MAX becomes: Voltage on XTALIN -0.3 VDD33 V (3.3 V supply voltage) + 0.5  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 39 USB251xB/xBi FIGURE 6-1: SUPPLY RISE TIME MODEL Voltage tRT33 VDD33 3.3 V 100% 90% VSS 10% t90% t10% Time The rise time for the 3.3 V supply can be extended to 100 ms max if RESET_N is actively driven low, typically by another IC, until 1 s after all supplies are within operating range. Note 6-2 TABLE 6-1: DC ELECTRICAL CHARACTERISTICS Parameter Symbol MIN TYP MAX Units Comments I, IS Type Input Buffer Low Input Level VILI High Input Level VIHI 0.8 Input Leakage IIL -10 +10 A Hysteresis (IS only) VHYSI 250 350 mV 0.8 V 2.0 V TTL Levels V VIN = 0 to VDD33 Input Buffer with Pull-Up (IPU) Low Input Level VILI TTL Levels High Input Level VIHI 2.0 Low Input Leakage IILL +35 +90 A VIN = 0 High Input Leakage IIHL -10 +10 A VIN = VDD33 V TTL Levels V Input Buffer with Pull-Down (IPD) Low Input Level VILI High Input Level VIHI 2.0 0.8 Low Input Leakage IILL +10 -10 A VIN = 0 High Input Leakage IIHL -35 -90 A VIN = VDD33 0.3 V V USB251xB/xBi ICLK Input Buffer Low Input Level VILCK High Input Level VIHCK 0.9 Input Leakage IIL -10 DS00001692D-page 40 V +10 A VIN = 0 to VDD33  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi TABLE 6-1: DC ELECTRICAL CHARACTERISTICS (CONTINUED) Parameter Symbol MIN TYP MAX Units 0.4 V Comments O12, I/O12 & I/OSD12 Type Buffer Low Output Level VOL High Output Level VOH IOL = 12 mA @ VDD33 = 3.3 V 2.4 V IOH = -12 mA @ VDD33 = 3.3 V Output Leakage IOL -10 +10 A Hysteresis (SD pad only) IHYSC 250 350 mV VIN = VDD33 (Note 6-1) Note 6-3 Output leakage is measured with the current pins in high impedance. Note 6-4 See USB 2.0 Specification [1] for USB DC electrical characteristics. TABLE 6-2: SUPPLY CURRENT UNCONFIGURED: HI-SPEED HOST (ICCINTHS) Part TYP MAX Units USB2512B/12Bi 40 45 mA USB2513B/13Bi 40 45 mA USB2514B/14Bi 45 50 mA TABLE 6-3: MIN SUPPLY CURRENT UNCONFIGURED: FULL-SPEED HOST (ICCINTFS) Part TYP MAX Units USB2512B/12Bi 35 40 mA USB2513B/13Bi 35 40 mA USB2514B/14Bi 35 40 mA TABLE 6-4: Comments MIN Comments SUPPLY CURRENT CONFIGURED: HI-SPEED HOST (IHCH1) Part MIN TYP MAX Units USB2512B 60 65 mA USB2512Bi 60 70 mA USB2513B 65 70 mA USB2513Bi 65 75 mA USB2514B 70 80 mA USB2514Bi 70 85 mA 1 port base 1 port base + + 25 mA 25 mA USB251xB/xBi Supply Current Configured Hi-Speed Host, each additional downstream port  2022 Microchip Technology Inc. and its subsidiaries Comments This is the base current of one downstream port. mA DS00001692D-page 41 USB251xB/xBi TABLE 6-5: SUPPLY CURRENT CONFIGURED: FULL-SPEED HOST (IFCC1) Part MIN TYP MAX Units USB2512B 45 50 mA USB2512Bi 45 55 mA USB2513B 50 55 mA USB2513Bi 50 60 mA USB2514B 50 60 mA USB2514Bi USB251xB/xBi Supply Current Configured 50 65 mA 1 port base 1 port base mA + + 8 mA 8 mA Full-Speed Host, each additional downstream port TABLE 6-6: Comments Base current of one downstream port SUPPLY CURRENT SUSPEND (ICSBY) Part MIN TYP MAX Units USB2512B 475 1000 A USB2512Bi 475 1200 A USB2513B 500 1100 A USB2513Bi 500 1300 A USB2514B 550 1200 A USB2514Bi 550 1500 A TABLE 6-7: All supplies combined SUPPLY CURRENT RESET (ICRST) Part MIN TYP MAX Units USB2512B 550 1100 A USB2512Bi 550 1250 A USB2513B 650 1200 A USB2513Bi 650 1400 A USB2514B 750 1400 A USB2514Bi 750 1600 A TABLE 6-8: Comments Comments All supplies combined PIN CAPACITANCE Limits Parameter Symbol Clock Input Capacitance Input Capacitance Output Capacitance Note 6-5 MIN TYP MAX Unit Test Condition CXTAL 6 pF All pins except USB pins and the pins under the test tied to AC ground CIN 6 pF (Note 6-5) COUT 6 pF Capacitance TA = 25°C; fc = 1 MHz; VDD33 = 3.3 V DS00001692D-page 42  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 6.2.1 PACKAGE THERMAL SPECIFICATIONS Thermal parameters are measured or estimated for devices with the exposed pad soldered to thermal vias in a multilayer 2S2P PCB per JESD51. Thermal resistance is measured from the die to the ambient air. The values provided are based on the package body, die size, maximum power consumption, 85°C ambient temperature, and 125°C junction temperature of the die. Symbol USB2512B/12Bi USB2513B/13Bi USB2514B/14Bi (°C/W) Velocity (meters/s) 40.1 0 35.0 1 0.5 0 0.7 1 6.3 0 6.3 1 JA JT JC Use the following formulas to calculate the junction temperature: TJ = P x JA + TA TJ = P x JT + TT TJ = P x JC + TC Max Power Supported = (TJ Max. Spec. - TAmb.)/ JA TABLE 6-9: LEGEND Symbol Description TJ Junction temperature P Power dissipated JA Junction-to-ambient-temperature JC Junction-to-top-of-package JT Junction-to-bottom-of-case TA Ambient temperature TC Temperature of the bottom of the case TT Temperature of the top of the case  2022 Microchip Technology Inc. and its subsidiaries DS00001692D-page 43 USB251xB/xBi 7.0 AC SPECIFICATIONS 7.1 Oscillator/Crystal Crystal: Parallel resonant, fundamental mode, 24 MHz 350 ppm. Note: The USB251xB/xBi contains an internal 1 M resistor between the XTALIN and XTALOUT pins. FIGURE 7-1: TYPICAL CRYSTAL CIRCUIT X T A L IN (C S 1 = C B 1 + C X T A L 1 ) C1 C ry s ta l C0 CL C2 XTALOUT (C S 2 = C B 2 + C X T A L 2 ) TABLE 7-1: CRYSTAL CIRCUIT LEGEND Symbol Description In Accordance with C0 Crystal shunt capacitance CL Crystal load capacitance CB Total board or trace capacitance OEM board design CS Stray capacitance Microchip IC and OEM board design CXTAL XTAL pin input capacitance Microchip IC C1 Load capacitors installed on OEM board Calculated values based on Figure 7-2 (Note 7-2) C2 FIGURE 7-2: Crystal manufacturer’s specification (Note 7-1) FORMULA TO FIND THE VALUE OF C1 AND C2 C1 = 2 x (CL – C0) – CS1 C2 = 2 x (CL – C0) – CS2 Note 7-1 C0 is usually included (subtracted by the crystal manufacturer) in the specification for CL and should be set to 0 for use in the calculation of the capacitance formulas in Figure 7-2. However, the PCB itself may present a parasitic capacitance between XTALIN and XTALOUT. For an accurate calculation of C1 and C2, take the parasitic capacitance between traces XTALIN and XTALOUT into account. Note 7-2 Each of these capacitance values is typically around 18 pF. DS00001692D-page 44  2022 Microchip Technology Inc. and its subsidiaries USB251xB/xBi 7.2 External Clock 50% duty cycle  10%, 24 MHz  350 ppm, jitter < 100 ps rms. The external clock is recommended to conform to the signaling level designated in the JESD76-2 Specification [5] on 1.2 V CMOS Logic. XTALOUT should be treated as a weak (