USB3751A-2-A4-TR

USB375x USB 2.0 Protection IC with Battery Charger Detection Features • Dead Battery Provision Support (USB375x-1 only) - Allows 100 mA trickle charging from VBUS when attached to a Standard Downstream Port (SDP) while not enumerated - Built-in 100mA current limiting option • Microchip RapidCharge Anywhere™ Provides: - 3-times the charging current through a USB port over traditional solutions - USB-IF Battery Charging 1.2 compliance to any portable device - Charging current up to 1.5Amps via compatible USB host or dedicated charger - Dedicated Charging Port (DCP), Charging (CDP) & Standard (SDP) Downstream Port support • flexPWR® Technology - Extremely low current design ideal for battery powered applications - Maximizes power delivered to the system • Industrial Operating Temperature -40°C to +85°C • 16-Pin QFN RoHS compliant package; (3.0 mm x 3.0 mm x 0.9 mm height • VBUS Over-Voltage Protection - Protects internal circuits from VBUS up to 9V - Over-Voltage/Under-Voltage Lockout opens VBUS switch - Interrupt to indicate Over-Voltage/Under-Voltage Lockout - Integrated Low RDSON FET • USB Port ESD Protection (DP/DM/VBUS) - ±15kV (air discharge) - ±15kV (contact discharge) - IEC 61000-4-2 level 4 ESD protection without external devices • High Speed USB Mux for multiplexing the USB lanes between different functions (USB3750 only) - Switch the USB connector between two different functions - High bandwidth USB switch passes HS USB signals • Provides USB Battery Charger Detection for: - USB-IF Battery Charging compliant Dedicated Charging Ports (DCP) - USB-IF Battery Charging compliant Charging Downstream Port (CDP) - Standard Downstream Port (SDP); i.e. USB host or downstream hub port - Dedicated SE1 type chargers USB375x Block Diagram HS Switch is USB3750 feature only VBUS DM_2 DP DM VBUS ESD Protection USB Connector DP_2 HS USB Switch DP_1 DM_1 DM DP DM VBUS Over-Voltage/Under-Voltage Protection and Current Limiting VOUT GND Charger Detection  2011 - 2014 Microchip Technology Inc. DP I2C Interface SCL SDA INT_B VBUS USB 2.0 PHY, Processor, or Accessory USB 2.0 PHY, Processor, or Accessory Battery Charger/ PMU Processor DS00001824A-page 1 USB375x 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. The errata will specify the revision of silicon and revision of document to which it applies. To determine if an errata sheet exists for a particular device, please check with one of the following: • Microchip’s Worldwide Web site; http://www.microchip.com • Your local Microchip sales office (see last page) When contacting a sales office, please specify which device, revision of silicon and data sheet (include -literature number) you are using. Customer Notification System Register on our web site at www.microchip.com to receive the most current information on all of our products. DS00001824A-page 2  2011 - 2014 Microchip Technology Inc. USB375x Table of Contents 1.0 Introduction ..................................................................................................................................................................................... 4 2.0 Pin Layout ....................................................................................................................................................................................... 5 3.0 Electrical Specifications .................................................................................................................................................................. 7 4.0 General Operation ........................................................................................................................................................................ 12 5.0 Application Notes .......................................................................................................................................................................... 22 6.0 Package Information ..................................................................................................................................................................... 25 Appendix A: Data Sheet Revision History ........................................................................................................................................... 27 The Microchip Web Site ...................................................................................................................................................................... 28 Customer Change Notification Service ............................................................................................................................................... 28 Customer Support ............................................................................................................................................................................... 28 Product Identification System ............................................................................................................................................................. 29  2011 - 2014 Microchip Technology Inc. DS00001824A-page 3 USB375x 1.0 INTRODUCTION The USB375x integrates many features that have historically been discrete devices in a mobile product. This device provides significant VBUS protection for the entire system, robust USB interface ESD protection, a USB 2.0 compliant High Speed switch, and USB-IF Battery Charger Detection (revision 1.2) capabilities that are essential to the latest mobile products. Several advanced features allow the USB375x to be optimized for portable applications and to reduce both eBOM part count and printed circuit board (PCB) area. Outstanding ESD robustness eliminates the need for external ESD protection devices. In addition to the integrated ESD protection on the USB interface, the USB375x provides VBUS Over-Voltage Protection (OVP). The USB375x integrated battery charger detection circuitry supports USB-IF Battery Charger Detection. Battery charger detection will begin automatically whenever VBUS rises above the UVLO threshold, and can also be completed manually through the I2C interface. The USB375x can detect a range of USB battery chargers including a Standard Downstream Port (SDP), a Charging Downstream Port (CDP), and a Dedicated Charging Port (DCP). For more information on USB battery charger detection, please see the USB Battery Charging Specification, Revision 1.2 (Note 1). The I2C interface gives processor control over the USB Switch, charger detection, OVLO settings, and status of the USB375x. In addition, custom charger detection can be implemented through the I2C interface. The USB375x family is enabled with Microchip's RapidCharge AnywhereTM which supports USB-IF Battery Charging 1.2 for any portable device (Note 1). RapidCharge AnywhereTM provides three times the charging current through a USB port over traditional solutions which translate up to 1.5 amps via compatible USB host or dedicated charger. In addition, this provides a complete USB charging ecosystem between device and host ports such as Dedicated Charging Port (DCP), Charging (CDP) and Standard (SDP) Downstream Ports. 1.1 Reference Documents • Universal Serial Bus Specification, Revision 2.0 • USB Battery Charging Specification, Revision 1.2 (Note 1) Note 1: The device’s Data Contact Detect Timeout parameter does not conform to the USB Battery Charging Specification. However, this will not affect other factors in charger detection. Refer to Table 3-2, “Electrical Specifications,” on page 7 for additional information. DS00001824A-page 4  2011 - 2014 Microchip Technology Inc. USB375x 2.0 PIN LAYOUT 2.1 Pin Diagram The USB375x is available in a QFN (3 x 3 mm) package. The USB3750 pin diagram is detailed in Figure 2-1. The USB3751 pin diagram is detailed in Figure 2-2. DM_1 DP DM DP_2 16 15 14 13 QFN PACKAGE DIAGRAM (USB3750) DM_2 VBUS 2 11 VOUT VBUS 3 10 VOUT VBUS 4 9 VOUT GND INT_B SCL SDA DM_1 DP DM NC 16 15 14 13 QFN PACKAGE DIAGRAM (USB3751) VOUT VBUS 3 10 VOUT VBUS 4 9 VOUT  2011 - 2014 Microchip Technology Inc. 8 11 GND 2 7 VBUS INT_B NC 6 12 SCL 1 5 DP_1 SDA FIGURE 2-2: 8 12 7 1 6 DP_1 5 FIGURE 2-1: DS00001824A-page 5 USB375x 2.2 Pin Definitions The following table details the ball/pin definitions for the package diagrams above. Type/ Direction Pin Name 15 DP Analog 14 DM Analog 1 DP_1 Analog 16 DM_1 Analog 13 DP_2 / NC Analog 12 DM_2 / NC Analog 8 GND Analog Ground. The QFN package flag should also connected to ground. 6 SCL Input I2C Clock input. This pin is an open drain output and requires a 10Kohm pull-up. 5 SDA Open Drain/ IO Bi-Directional I2C data. This pin is an open drain output and requires a 10Kohm pull-up. INT_B Open Drain/ Output Open Drain Interrupt. This pin is an open drain output that is pulled low when an interrupt occurs. A 10Kohm pull-up is required on this pin. 7 9 10 Analog VOUT 11 2 3 Analog VBUS 4 DS00001824A-page 6 Description USB Mux Output USB Mux Input 1 USB Mux Input 2 (USB3750 Only) These pins are No Connects for the USB3751 (do not connect) Overvoltage switch output. This pin is connected to VBUS when the overvoltage protection switch is enabled. It is also the output of the 100mA current limit. The three VOUT pins must be connected together. When VBUS is between UVLO and OVLO VOUT is connected to VBUS. When VBUS is below UVLO or above OVLO the USB375x will tri-state. VBUS pin of the USB connector. The three VBUS pins must be connected together. When the OVP switch is closed, the VBUS pin will be isolated from VOUT. When the OVP switch is open, VBUS will be connected to VOUT. The USB375x is powered from this pin.  2011 - 2014 Microchip Technology Inc. USB375x 3.0 ELECTRICAL SPECIFICATIONS 3.1 Absolute Maximum Ratings TABLE 3-1: ABSOLUTE MAXIMUM RATINGS Description Rating Unit VBUS Voltage to GND -0.3 to 9.0 V VOUT Voltage to GND -0.3 to 7.5 V Any other pin to GND -0.3 to 5.5 V Operating Temperature Range -40 to +85 C Storage Temperature Range -55 to +150 C HBM 8,000 V IEC-61000-4-2 15,000 (Air) 15,000 (Contact) V 1,500 V ESD Rating ESD Rating (SDA, SCL, INT_B) HBM Stresses beyond the Absolute Maximum Ratings may damage the USB375x. 3.2 Electrical Specifications TABLE 3-2: ELECTRICAL SPECIFICATIONS Characteristic Symbol MIN TYP MAX Units Conditions VVBUS = 5.0V, TA = -40C to 85C, all typical values at TA = 27C unless otherwise noted. VBUS Characteristics VBUS Operating range VVBUS 2 9 V VBUS Over Voltage Lockout (USB3750 Only) VOVLO 6.2 6.9 V USB3750 Only VBUS Over Voltage Lockout (USB3751 Only) VOVLO 5.45 6.15 V USB3751 Only VBUS Under Voltage Lockout VUVLO 3.3 3.8 V VBUS Over Voltage Hysteresis VOVLO 3.4 100 VBUS Under Voltage Hysteresis VUVLO Operating Current IDD_OFF (OVP open) mV 100 mV 110 uA VVBUS < VUVLO Operating Current (OVP closed) IDD_ON 75 115 370 uA VUVLO < VVBUS < VOVLO Operating Current (100mA Limit enabled) IDD 150 185 480 uA VUVLO < VVBUS < VOVLO mohm QFN package 1.8 A VUVLO < VVBUS < VOVLO 1 uA VBUS = 5.0V; VOUT = 0V VBUS Switch Characteristics Overvoltage Switch ON Resistance RON_VBUS 70 Overvoltage Switch Current Overvoltage Switch OFF Leakage IOFF_VBUS VBUS Resistance to Ground RVBUS 100 Kohm VBUS Capacitance CVBUS 1.0 uF Charger Detection Characteristics 4.4 < VBUS < 5.5V DP and DM leakage 1 uA 0.0V < Vpin < 3.3V Data Source Voltage VDAT_SRC 0.5 0.7 V IDAT_SRC > 250uA Data Detect Voltage VDAT_REF 0.25 0.4 V  2011 - 2014 Microchip Technology Inc. DS00001824A-page 7 USB375x TABLE 3-2: ELECTRICAL SPECIFICATIONS (CONTINUED) Characteristic Symbol MIN Data Connect Detect Current Source IDP_SRC 7 Data Sink Current IDAT_SINK DP/DM Single Ended RX Threshold VSE_RX SE1 High Current Charger RX Threshold DP/DM Pull Down Resistors TYP MAX Units Conditions 13 uA 50 150 uA 0.8 1.95 V 4.75V < VBUS < 5.25V VSE_RXH 2.1 2.56 V 4.75V < VBUS < 5.25V RPD 14.25 24.8 Kohm 10 ohm USB Mux Characteristics (USB3750 Only) USB Mux On Resistance RON_USB 2.5 0V < Vin < 3.3V 0V < Vin < 0.4V USB Mux Off Leakage IOFF_USB 0.85 On Capacitance CON_USB 9 pF Off Capacitance COFF_USB 6.5 pF Off Isolation -35 dB Crosstalk -40 dB RL = 50 ohm, F = 250MHz 1000 MHz RL = 50 ohm, CL = 0pF Bandwidth (-3dB) BW uA 0V < Vin < 3.3V RL = 50 ohm, F = 250MHz 800 RL = 50 ohm, CL = 5pF 500 RL = 50 ohm, CL = 10pF Control Signal Characteristics Input Logic High Threshold VIN_H V VBUS > UVLO Input Logic Low Threshold VIN_L 0.4 V VBUS > UVLO Output Drive Strength VOUT_L 0.4 V VBUS > UVLO, 4.0mA sink current nA 0 < Vpin < VOUT 2 ms Oscillator Accuracy 20 ms Time to autoclear Soft POR. UVLO and OVLO Release Timer TVLO_ RELEASE 3 6.5 ms UVLO and OVLO Engage Time TVLO_ ENGAGE Data Contact Detect Timeout TDCD_TOUT 1.7 ms 1.4 Control Signal Leakage Current 1 Timing Characteristics Clock Accuracy TCLK Soft POR Reset Time TSOFT_POR 0.5 1 0.5 150 ms Vdat_src and Idat_sink Enable Time TVDPSRC_ON 40 40 80 160 ms Delay from Vdat_det to OVP switch enable TVDPSRC_HICR NT 40 80 160 ms SE1 Charger Detection wait for SE1 timer TCD_SE1 40 80 160 ms Interrupt Self Clear Timer TINT 0.5 1 2 ms See Note 1 Note 1: The device’s Data Contact Detect Timeout (TDCD_TOUT) parameter does not conform to the USB Battery Charging Specification’s TDCD_TOUT minimum of 300 ms. However, this will not affect other factors in charger detection. DS00001824A-page 8  2011 - 2014 Microchip Technology Inc. USB375x 3.3 Timing Diagrams 3.3.1 UVLO AND OVLO TIMING The timing diagram below shows the operation of the OVP switch as VBUS crosses the UVLO and OVLO thresholds. The behavior of the INT_B signal is also shown in Figure 3-1 below. FIGURE 3-1: UVLO AND OVLO TIMING OVLO OVLO UVLO VBUS UVLO Start Chrg Detection VOUT OVP switch enabled OVP switch disabled INT_B OVLO Fall Int. OVLO Int. TVLO_RELEASE 3.3.2 OVP switch disabled TVLO_ENGAGE TINT TVLO_RELEASE TINT TVLO_ENGAGE AUTOMATIC CHARGER DETECTION TIMING The timing diagrams below illustrate the automatic charger detection timing that is followed when implementing the automatic charger detection flow charts shown in this section. FIGURE 3-2: CHARGER DETECTION TIMING SDP (USB3750-1) VBUS UVLO OVP Switch Enable VOUT VDatDet =0 SDP Detected USB X Connect Detect USB Mux Check for SE1 Drive Vdat Source on DP Mux1 En. Mux1 and Mux2 Disabled Mux1 En. INT_B Chrg Det Finish TVLO_Release  2011 - 2014 Microchip Technology Inc. Con. Det. or TDCD_TOUT TCD_SE1 TVDPSRC_ON TVDPSRC_HICRNT TINT DS00001824A-page 9 USB375x FIGURE 3-3: CHARGER DETECTION TIMING SDP (USB3751-X) UVLO OVP Switch Enable (USB3750-2)/ 100mA Current Limit Enable (USB3750-1) VBUS VOUT USB X VDatDet =0 SDP Detected Connect Detect Check for SE1 Drive Vdat Source on DP INT_B Chrg Det Finish Con. Det. or TDCD_TOUT TVLO_Release FIGURE 3-4: TCD_SE1 TVDPSRC_ON TVDPSRC_HICRNT TINT CHARGER DETECTION TIMING DCP OR CDP (USB3751-X) UVLO OVP Switch Enable (USB3750-2)/ 100mA Current limit Enable (USB3750-1) VBUS VOUT VDatDet = 1 USB X Connect Detect If VDatDet = 0 CDP detected If VDatDet = 1 DCP detected Check for SE1 Drive Vdat Source on DP Drive Vdat Source on DM USB Tri-State USB Pass-Thru TCD_SE1 TVDPSRC_ON TVDPSRC_ON TVDPSRC_HICRNT TINT INT_B TVLO_Release DS00001824A-page 10 Con. Det. or TDCD_TOUT  2011 - 2014 Microchip Technology Inc. USB375x FIGURE 3-5: CHARGER DETECTION TIMING SE1 CHARGER (USB3750-1) VBUS UVLO OVP Switch Enable VOUT SE1 Detected USB X Connect Detect USB Mux Check for SE1 Mux1 and Mux2 Disabled INT_B Mux1 En. Chrg Det Finish Con. Det. or TDCD_TOUT TVLO_Release FIGURE 3-6: USB Mux1 USB Tri-State TCD_SE1 TVDPSRC_HICRNT TINT CHARGER DETECTION TIMING SE1 CHARGER (USB3751-X) UVLO OVP Switch Enable (USB3750-2)/ 100mA Current Limit Enable (USB3750-1) VBUS VOUT SE1 Detected USB X Connect Detect Check for SE1 INT_B USB Pass-Thru Chrg Det Finish TVLO_Release  2011 - 2014 Microchip Technology Inc. USB Tri-State Con. Det. or TDCD_TOUT TCD_SE1 TVDPSRC_HICRNT TINT DS00001824A-page 11 USB375x 4.0 GENERAL OPERATION The USB375x is an integrated USB protection device, battery charger detection device, and High Speed USB mux (USB3750 only). The USB375x is designed to protect a USB product from electrical overstress on the USB connector. The USB375x includes several features designed to improve the reliability and speed the design of products designed with a USB interface. The USB3750 includes a high bandwidth HS USB mux. The mux allows high speed signals to pass through and still meet HS USB signaling requirements. The USB375x will protect the system from ESD stress events on VBUS, DP, and DM. The USB375x provides ESD protection to the IEC-61000 ESD specification. The low resistance VBUS overvoltage protection switch protects the internal circuitry from VBUS over voltage events. When VBUS is outside the safe operating range VBUS switch will automatically open. The USB375x also includes the capability to detect various USB battery chargers, including those defined in the USB Battery Charging Specification, Revision 1.2. To support the device dead battery conditions as defined in the USB Battery Charging Specification, Revision 1.2, the USB375x-1 has the ability to drive VDAT_SRC on DP which allows a device with a dead battery to draw 100mA from a USB host. This will allow a device to charge a dead battery without violating the USB specifications. The USB375x-1 also includes a current limit to prevent the unconfigured current from exceeding 100mA. Note, this feature is not available with the USB375x-2. The USB3750 block diagram is shown Figure 4-1 and the USB3751 block diagram is shown Figure 4-2. FIGURE 4-1: USB3750 BLOCK DIAGRAM DM VBUS VBUS DP_2 DM_2 DP ESD Protection USB Connector USB3750 HS USB Switch DP_1 DM_1 DM DP DM VBUS Over-Voltage/Under-Voltage Protection and Current Limiting VOUT GND Charger Detection DS00001824A-page 12 DP I2C Interface SCL SDA INT_B VBUS USB 2.0 PHY, Processor, or Accessory USB 2.0 PHY, Processor, or Accessory Battery Charger/ PMU Processor  2011 - 2014 Microchip Technology Inc. USB375x FIGURE 4-2: USB3751 BLOCK DIAGRAM DM VBUS ESD Protection USB Connector USB3751 DP DP_1 DM_1 DM VBUS Over-Voltage/Under-Voltage Protection and Current Limiting VOUT GND Charger Detection 4.1 DP I2C Interface SCL SDA INT_B VBUS USB 2.0 PHY, Processor, or Accessory Battery Charger/ PMU Processor VBUS Protection Switch The USB375x protects the entire system from errant VBUS voltages, whether over-voltage or under-voltage conditions. The device is able to dynamically monitor the VBUS voltage levels and take appropriate action by opening the integrated VBUS Protection Switch when these errant conditions occur. Specifically, when VBUS is below the Under Voltage LockOut (UVLO) level or above the Over Voltage Lock-Out (OVLO) level, the VBUS switch will open thereby disconnecting the VBUS pin from VOUT. See Section 3.3 for UVLO and OVLO timing diagrams. Manual control of the VBUS Switch, as well as switch configuration can be handled through the I2C interface. See Section 4.4.2 for I2C register descriptions. 4.1.1 100MA CURRENT LIMIT (USB375X-1 ONLY) bit The USB375x-1 provides a 100mA current limit feature which allows a portable system with a dead battery to still draw 100mA from a compliant host. When plugged into a Standard Downstream Port (SDP), the USB375x-1 will enable the 100mA current limit until the system controller enables the OVP switch in the I2C registers of the USB375x-1. When plugged into any other charger, the USB375x-1 will enable the 100mA current limit during charger detection, and will disable the 100mA current limit once charger detection has completed. Figure 4-6 details the charger detection flow of the USB375x-1. 4.2 Charger Detection The USB375x includes the circuitry required to implement the USF-IF Battery Charging Specification (revision 1.2). The USB375x will automatically perform a charger detection upon start-up. The USB375x includes a state machine to provide the detection of a wide variety of USB charger detection methods listed in Table 4-1. When any of the USB chargers are plugged into the system, the USB375x will detect a charger plug in event, determine what type of charger it is, and write the type of charger information into the I2C register as shown in the following table. In addition, there are two methods to alert the system that a charger has been detected by the USB375x. The first was through the I2C register as mentioned above. The second is through the INT_B pin. When a compliant charger is plugged in and detected, the USB375x will automatically drive the INT_B signal low. Figure 4-4 details the automatic charger detection flow of the USB3750-1, Figure 4-5 details the automatic charger detection flow of the USB3751-1, and Figure 4-6 details the automatic charger detection flow of the USB3751-2.  2011 - 2014 Microchip Technology Inc. DS00001824A-page 13 USB375x TABLE 4-1: VALID CHARGERS I2C Reg 0 Bits[7:5] (ChargerType) DP/DM Profile USB Charger Type DCP (Dedicated Charging Port, defined in Battery Charging 1.2 specification) Shorted < 200ohm 001 CDP VDP reflected to VDM (Charging Downstream Port, defined in Battery Charging 1.2 specification) 010 (EnhancedChrgDet = 1) SDP (Standard Downstream Port) USB Host or downstream hub port 15Kohm pull-down on DP and DM 011 SE1 Charger Low Current Charger DP = 2.0V DM = 2.0V 100 (SE1ChrgDet =1) SE1 Charger High Current Charger DP = 2.0V DM = 2.7V 101 (SE1ChrgDet =1) 4.2.1 CHARGER DETECTION CIRCUITRY The charger detection circuitry shown Figure 4-3 is used to detect the type charger attached to the USB connector. FIGURE 4-3: USB CHARGER DETECTION BLOCK DIAGRAM ~~ HiCurrent DpSeRx DmSeRx VBUS SeRxEn Charger State Machine ContactDetectEn en IDP_SRC DP VdatSrc To USB Con. VdatSrcEn HostChrgEn DM VdatDet VDAT_REF RPD RPD To USB Con. en en MUX I2C Registers IdatSinkEn IDAT_SINK DpPulldownEn DmPulldownEn I2C Control ~~ Note: The italic names in the Figure 4-3 correspond to bits in the I2C register set. The VdatDet output is qualified with the Linestate[1:0] value. If the Linestate is not equal to 00b the VdatDet signal will not assert. DS00001824A-page 14  2011 - 2014 Microchip Technology Inc. USB375x For the USB3750, EnableMux1 or EnableMux2 should not be set while charger detection operations are performed. During the automatic charger detection EnableMux1 or EnableMux2 will be disabled. These will need to be disabled by the I2C master if a custom charger detection is performed through I2C. 4.2.2 AUTOMATIC CHARGER DETECTION Automatic charger detection will be begin after VBUS crosses the UVLO threshold, and will follow the flow charts shown below in Figure 4-4 and Figure 4-6. The flow chart timing can be found in Section 3.3.2. When automatic charger detection has completed, the INT_B signal will go low, and the type of charger that was detected will be reflected in the ChargerType bits of I2C REG 0 BITS [7:5]. FIGURE 4-4: CHARGER DETECTION FLOW CHART (USB3750-1) Start Chrg Detection ChrgDetComplete = 0 UVLO < VBUS < OVLO Start TVLO_RELEASE Enable IDP_SRC and RPD_DM Enable 100mA after TVLO_RELEASE Release and wait TCD_SE1 SE1? Any UVLO or OVLO Exit Chrg Detection Wait for DP Low or TDCD_TOUT Disable IDP_SRC and RPD_DM =1 =0 Drive DP VDAT_SRC for TVDPSRC_ON =0 VDAT Detect? =1 RxHiCurr? =0 =1 Drive DM VDAT_SRC for TVDPSRC_ON VDAT Detect? =0 =1 SDP Detected DCP Detected CDP Detected SE1 High Current Charger Clear Charger Detection Register Wait TVDPSRC_HICRNT Enable OVP Switch SE1 Low Current Charger Disable 100mA current limit Default USB Mux setting  2011 - 2014 Microchip Technology Inc. Exit Chrg Detection ChrgDetComplete = 1 DS00001824A-page 15 USB375x FIGURE 4-5: CHARGER DETECTION FLOW CHART (USB3751-1) Start Chrg Detection ChrgDetComplete = 0 UVLO < VBUS < OVLO Start TVLO_RELEASE Enable IDP_SRC and RPD_DM Enable 100mA after TVLO_RELEASE Release and wait TCD_SE1 SE1? Any UVLO or OVLO Exit Chrg Detection Wait for DP Low or TDCD_TOUT Disable IDP_SRC and RPD_DM =1 =0 Drive DP VDAT_SRC for TVDPSRC_ON =0 VDAT Detect? =1 =1 RxHiCurr? =0 Drive DM VDAT_SRC for TVDPSRC_ON VDAT Detect? =0 =1 SDP Detected DCP Detected CDP Detected SE1 High Current Charger Clear Charger Detection Register Wait TVDPSRC_HICRNT Enable OVP Switch SE1 Low Current Charger Disable 100mA current limit Exit Chrg Detection ChrgDetComplete = 1 DS00001824A-page 16  2011 - 2014 Microchip Technology Inc. USB375x FIGURE 4-6: CHARGER DETECTION FLOW CHART (USB3751-2) Start Chrg Detection ChrgDetComplete = 0 UVLO < VBUS < OVLO Start TVLO_RELEASE Enable IDP_SRC and RPD_DM Any UVLO or OVLO Exit Chrg Detection Wait for DP Low or TDCD_TOUT Disable IDP_SRC and RPD_DM Release and wait TCD_SE1 SE1? =1 =0 Drive DP VDAT_SRC for TVDPSRC_ON =0 VDAT Detect? =1 =1 RxHiCurr? =0 Drive DM VDAT_SRC for TVDPSRC_ON VDAT Detect? =0 =1 SDP Detected DCP Detected CDP Detected SE1 High Current Charger Clear Charger Detection Register Wait TVDPSRC_HICRNT Enable OVP Switch SE1 Low Current Charger Exit Chrg Detection ChrgDetComplete = 1 4.3 USB Mux (USB3750 Only) The USB mux is designed to pass High Speed USB signals to the USB connector, and allows for two USB inputs to be multiplexed into one USB output. Either switch path is enabled through the I2C interface, and the switch paths are disabled in the event of UVLO or OVLO. The USB Mux is designed to pass USB signals from 0 to 3.3V. It is not designed to pass signals that go above 3.3V or below ground.  2011 - 2014 Microchip Technology Inc. DS00001824A-page 17 USB375x During power-up and charger detection the USB Mux switches will be disabled regardless of the EnableMux1 and EnableMux2 settings. Once power-up and charger detection are complete EnableMux1 is enabled by default. 4.4 USB375x Registers All registers are reset when VBUS goes below UVLO. All registers are accessed through the I2C interface defined below. 4.4.1 I2C INTERFACE The SDA and SCL pins comprise the I2C interface of the USB375x. The I2C master controls all traffic to the USB375x. If the USB375x has a change in status it can assert the INT_B by pulling this line to ground. The USB375x INT_B line will stay low and then auto-clear after 1mS or until cleared by reading the Status Register. This prevents INT_B from masking other interrupts if the line is shared with other I2C devices. SCL, SDA, and INT_B will be tri-stated until VBUS is above the UVLO. VBUS must be present to operate the I2C interface. SCL is an input only pad. SDA is bi-directional and can be configured as an input or an open drain output during I2C operations. SDA, and INT_B are open collector when configured as an output. This requires an external pull-up resistor on SDA and INT_B. The USB375x-1 requires I2C communications in order for the default USB path to be enabled. By default, the 100mA current limit is enabled. Only devices that draw