LTM2884_15 LINER
Document overview
- Manufacturer or author: Provided By www.digicamel.com(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 24
Technical content
For more information www.linear .com/L TM2884 Typical applicaTion FeaTures DescripTion Isolated USB Transceiver with Isolated Power The LT M®2884 is a complete galvanically isolated USB 2.0 compatible μ Module® ( micromodule) transceiver. An upstream supply powers both sides of the interface through an integrated, isolated DC/DC converter. The LTM2884 is ideal for isolation in host, hub, bus split- ter or peripheral device applications. It is compatible with USB 2.0 full speed (12Mbps) and low speed (1.5Mbps) operation. Automatic speed selection configures integrated pull-up resistors on the upstream port to match those sensed on the downstream device. The isolator µModule technology uses coupled inductors and an isolated power transformer to provide 2500VRMS of isolation between the upstream and downstream USB interface. This device is ideal for systems requiring isolated ground returns or large common mode voltage variations. Uninterrupted communication is guaranteed for common mode transients greater than 30kV/μs. Enhanced ESD protection allows this part to withstand up to ±15kV (human body model) on the USB transceiver interface pins to local supplies and ±15kV through the isolation barrier to supplies without latch-up or damage. Powered 2.5W Isolated Hub Port
applicaTions
n Isolated USB T ransceiver: 2500VRMS for 1 Minute n USB 2.0 Full Speed and Low Speed Compatible n Integrated Isolated DC/DC Converter, External or Bus Powered n Auto-Configuration of Bus Speed n 2.5W (500mA at 5V) Output Power from External Input Supply (V CC = 8.6V to 16.5V) n 1W (200mA at 5V) Output Power from USB Bus Supply (V BUS) n 3.3V LDO Output Supply Signal References VLO, VLO2 n High Common Mode T ransient Immunity: 30kV/μs n ESD: ±15kV HBM on USB Interface Pins n 15mm × 15mm × 5mm Surface Mount BGA Package n Isolated USB Interfaces n Host, Hub, or Device Isolation n Industrial/Medical Data Acquisition L, LT, LT C, LT M, Linear Technology, the Linear logo and µModule are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Bus Powered 1W Isolated Peripheral Device
2884 TA01a
4.4V TO 16.5V VBUS VBUS2 8.6V TO 16.5V 100µF VCC SPNDPWR D1+ D1– VCC2 VLO2 D2+ DOWNSTREAM USB PORT D2– GND2GND15k 15k PWR HUB µC
2884 TA01b
D1– VLO2 D2+ D2– PWR 1.5k
For more information www.linear .com/L TM2884 pin conFiguraTionabsoluTe MaxiMuM raTings Supply Voltages 0.3V to (VLO + 0.3V) Operating Ambient Temperature Range (Note 3) 40°C to 125°C 5°C 5°C (Note 1) BGA PACKAGE 44-LEAD (15mm × 15mm × 5mm) TOP VIEW 2 1 4 3 5 6 7 8 9 11 10 D1– D1+ SPND- PWR ON VLO VBUS VCCGND D2– D2+ VLO2 VCC2GND2 GND2 GND GND2 F G H L J K E A B C D TJMAX = 125°C, PCB = JESD51-9 2s2p: θJA = 18.7°C/W, θJCtop = 16°C/W, θJCbottom = 5.7°C/W, θJB = 5.6°C/W PCB = DC1746A: θJA = 33.5°C/W, θJCtop = 15.7°C/W, θJCbottom = 6.1°C/W, θJB = 5.3°C/W HEAT FLOW: θJA = NORMAL, θJCtop = 100%, θJCbottom = 100%, θJB = 100% WEIGHT = 2.4g orDer inForMaTion PART NUMBER PAD OR BALL FINISH PART MARKING PACKAGE TYPE MSL RA TING TEMPERATURE RANGEDEVICE FINISH CODE LTM2884CY#PBF SAC305 (RoHS) LTM2884Y e1 BGA 4 0°C to 70°C LTM2884IY#PBF –40°C to 85°C LTM2884HY#PBF –40°C to 105°C
- Device temperature grade is indicated by a label on the shipping container.
- Pad or ball finish code is per IPC/JEDEC J-STD-609.
- Terminal Finish Part Marking: www.linear.com/leadfree
- This product is not recommended for second side reflow. For more information, go to: www.linear.com/BGA-assy
- Recommended BGA PCB Assembly and Manufacturing Procedures: www.linear.com/BGA-assy
- BGA Package and T ray Drawings: www.linear.com/packaging
- This product is moisture sensitive. For more information, go to: www.linear.com/BGA-assy
For more information www.linear .com/L TM2884 elecTrical characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VBUS = 5V, GND = GND2 = 0V, ON = VLO, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply VCC Operating Supply Range (Isolated Power Input) l 4.4 12 16.5 V VBUS Operating Supply Range (USB Bus Power Input) l 4.4 5 16.5 V VCC Supply Current Power Off ON = 0V, VCC = 4.4V to 16.5V l 100 500 µA ICC VCC Supply Current Power On ICC2 = 0mA, Figure 1 l 50 100 mA VBUS Supply Current Power Off ON = 0V l 10 100 µA IBUS VBUS Supply Current Power On IVLO = 0mA, Figure 1 l 6 9 mA VBUS Supply Current Suspend Mode SPNDPWR = 3.3V USB Suspend Timeout SPNDPWR = 0, USB Suspend Timeout l l 1.5 500 2.0 µA mA V CC2 Regulated VCC2 Output Voltage, Loaded VCC = 4.4V, ICC2 = 200mA, Figure 1 VCC = 8.6V, ICC2 = 500mA, Figure 1 l l 4.75 4.75 5.25 5.25 V V V CC2 Source Current High Power Mode VCC = 8.6V, Figure 1 l 500 mA VCC2 Source Current Bus Power Mode VCC = VBUS = 4.4V, Figure 1 l 200 mA VLO VLO Regulated Output Voltage IVLO = 0mA to 10mA, Figure 1 l 3.15 3.3 3.45 V VLO Output Voltage Maximum Current Figure 1 l 10 mA VLO2 VLO2 Regulated Output Voltage IVLO2 = 0mA to 10mA, Figure 1 l 3.15 3.3 3.45 V VLO2 Output Voltage Maximum Current Figure 1 l 10 mA USB Input Levels (D1+, D1–, D2+, D2–) VIH Single-Ended Input High Voltage l 2.0 V VIL Single-Ended Input Low Voltage l 0.8 V VHYS Single-Ended Input Hysteresis 200 mV VDIFF Differential Input Sensitivity |(D1+ – D1–)| or |(D2+ – D2–)| l 0.2 V VCM Common Mode Voltage Range |(D1+ + D1–)|/2 or |(D2+ + D2–)|/2 l 0.8 2.5 V Logic Input Levels (ON, SPNDPWR) VIHL Logic Input High Voltage l 2.0 V VILL Logic Input Low Voltage l 0.8 V IINL Logic Input Current l ±1 µA VHYSL Logic Input Hysteresis 200 mV USB Output Levels (D1+, D1–, D2+, D2–) VOL Output Low Voltage RPU = 1.5k to 3.6V, Figure 4 l 0 0.3 V VOH Output High Voltage RPD = 15k to 0V, Figure 4 l 2.8 3.6 V VCRS Differential Output Signal Cross-Point Voltage l 1.3 2.0 V Terminations R PU Bus Pull-Up Resistance on Upstream Facing Port D2 + or D2– Pull-Up to 3.3V 1.425 1.575 kΩ RPD Bus Pull-Down Resistance on Downstream Facing Port D2 + and D2– Pull-Down to GND2 14.25 15.75 kΩ ZDRV USB Driver Output Resistance l 28 44 Ω CINUSB USB T ransceiver Pad Capacitance to GND (Note 2) 10 pF
For more information www.linear .com/L TM2884 swiTching characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VBUS = 5V, GND = GND2 = 0V, ON = VLO, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Low Speed USB tLDR Low Speed Data Rate CL = 50pF to 450pF (Note 4) 1.5 Mbps tLR Rise Time Figure 2, CL = 50pF to 600pF l 75 300 ns tLF Fall Time Figure 2, CL = 50pF to 600pF l 75 300 ns tLPRR, tLPFF Propagation Delay Figure 2, CL = 50pF to 600pF l 200 300 ns tLDJ1 Differential Jitter To Next T ransition (Note 2) ±45 ns tLDJ2 Differential Jitter To Paired T ransitions (Note 2) ± 15 ns Full Speed USB t FDR Full Speed Data Rate CL = 50pF (Note 4) 12 Mbps tFR Rise Time Figure 3, CL = 50pF l 4 20 ns tFF Fall Time Figure 3, CL = 50pF l 4 20 ns tFPRR, tFPFF Propagation Delay Figure 3, CL = 50pF l 60 80 115 ns tFDJ1 Differential Jitter To Next T ransition (Note 2) 2 ns tFDJ2 Differential Jitter To Paired T ransitions (Note 2) 1 ns Power Supply Generator VCC2 – GND2 Supply Start-Up Time (ON VLO, VCC2 to 4.5V) RLOAD = 50Ω, CLOAD = 100µF RLOAD = 10Ω, CLOAD = 100µF, VCC = 12V l l ms ms t WUSPND Wake Up from Suspend Mode Resume Signal, SPNDPWR = 0 l 0.25 10 µs ESD (HBM) (Note 2) Isolation Barrier GND to GND2 ±15 kV D1+, D1–, D2+, D2– D1+/D1– to GND, VCC, VBUS, or VLO and D2+/D2– to GND2, VCC2, or VLO2 ±15 kV ON, SPNDPWR ±3 kV isolaTion characTerisTics TA = 25°C. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Isolation Barrier: GND to GND2 VISO Rated Dielectric Insulation Voltage (Notes 6, 7)
1 Minute (Derived from 1 Second Test) 2500 VRMS
1 Second (Note 5) 3000 VRMS
Common Mode T ransient Immunity V BUS = VCC = 5V, ON = 3.3V, 1000V in 33ns T ransient Between GND and GND2 (Note 2) ±30 kV/µs VIORM Maximum Working Insulation Voltage (Notes 2, 5) 560 400 V PEAK VRMS Partial Discharge VPR = 750VRMS (Note 5) <5 pC CTI Comparative T racking Index IEC 60112 (Note 2) 600 VRMS Depth of Erosion IEC 60112 (Note 2) 0.017 mm DTI Distance Through Insulation (Note 2) 0.1 mm Input to Output Resistance (Notes 2, 5) 1012 Ω Input to Output Capacitance (Notes 2, 5) 13 pF Creepage Distance (Notes 2, 5) 9.48 mm
For more information www.linear .com/L TM2884 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Guaranteed by design and not production tested. Note 3: This µModule transceiver includes over temperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when over temperature protection is active. Continuous operation above specified maximum operating junction temperature may result in device degradation or failure. Note 4: Maximum data rate is guaranteed by other measured parameters and is not directly tested. Note 5: Device considered a 2-terminal device. Measurement between groups of pins A1 through B11 shorted together and pins K1 through L11 shorted together. Note 6: The rated dielectric insulation voltage should not be interpreted as a continuous voltage rating. Note 7: In accordance with UL1577, each device is proof tested for the 2500V RMS rating by applying the equivalent positive and negative peak voltage multiplied by an acceleration factor of 1.2 for one second.
elecTrical characTerisTics
For more information www.linear .com/L TM2884 Typical perForMance characTerisTics Low Speed Differential Jitter VCC2 Output Current vs Temperature VCC to VCC2 Efficiency and Power Loss VCC Input Current vs VCC2 Output Current VCC2 Output Voltage vs Load Current Full Speed Propagation Delay vs Temperature Low Speed Propagation Delay vs Temperature Full Speed Differential Jitter TA = 25°C, VCC = 5V, VBUS = 5V, GND = GND2 = 0V, ON = 3.3V, unless otherwise noted. TEMPERATURE (°C) –50 PROPAGATION DELAY (ns) 100 500 100
2884 G01
12525–25 75 CLOAD = 120pF TEMPERATURE (°C) –50 PROPAGATION DELAY (ns) 250 240 230 220 210 200 500 100
2884 G02
12525–25 75 CLOAD = 120pF 10ns/DIV 1V/DIV
2884 G03
JITTER 1.4nsP-P D1– D1+ D2– D2+ 50ns/DIV 1V/DIV
2884 G04
JITTER 7.5nsP-P D1+ D1– D2+ D2– TEMPERATURE (°C) –50 OUTPUT CURRENT (mA) 800 600 700 500 400 300 200 500 100
2884 G05
12525–25 75 VCC = 12V VCC = 5V VCC2 = 4.75V OUTPUT CURRENT (A) INPUT CURRENT (mA) 450 350 400 300 150 200 100 250 0.2 0.6
2884 G07
0.80.4 VCC = 12V VCC = 5V LOAD CURRENT (A) VCC2 (V) 5.25 4.75 5.00 4.50 4.25 4.00 0.40.2 0.8
2884 G08
1.00.6 VCC = 5V VCC = 4.4V VCC = 8.1V VCC = 12V IOUT (A) EFFICIENCY (%) POWER LOSS (W) 1.4 1.2 0.8 1.0 0.6 0.4 0.2 0.2 0.6
2884 G06
0.80.4 VCC = 5V VCC = 5V VCC = 12V VCC = 12V POWER LOSS EFFICIENCY Derating for 125°C Maximum Internal Operating Temperature TEMPERATURE (°C) LOAD CURRENT (A) 0.55 0.45 0.50 0.40 0.25 0.15 0.20 0.35 0.30 0.10 0.05 45 35 55 75 65 95 85 115
2884 G09
VBUS – VCC = 5V VBUS – VCC = 8.6V VBUS – VCC = 12V VBUS – VCC = 16.5V
For more information www.linear .com/L TM2884 Typical perForMance characTerisTics VCC2 = Load Step Response, 0mA to 500mA (VCC = 12V) VCC2 = Load Step Response, 0mA to 200mA (VCC = 5V) ICC vs Temperature Upstream VBUS Droop During Plug-In with CLOAD = 100µF Full Speed Data Start of Packet VCC2 Ripple, VCC = 5V, ICC2 = 200mA VCC2 Start-Up Ramp TA = 25°C, VCC = 5V, VBUS = 5V, GND = GND2 = 0V, ON = 3.3V, unless otherwise noted. 2µs/DIV 100mV/DIV
2884 G10
VCC2 Ripple, VCC = 12V, ICC2 = 500mA 100µs/DIV 500mV/DIV 200mA/DIV
2884 G13
100µs/DIV 500mV/DIV 200mA/DIV
2884 G14
TEMPERATURE (°C) –50 SUPPL Y CURRENT (mA) –25 25 50 75 100
2884 G15
VCC = 12.5V VCC = 16.5V VCC = 5V VCC = 8.1V VCC = 4.4V ICC2 = 0mA 500µs/DIV 1V/DIV
2884 G16
2884 G17
D2– 2µs/DIV 100mV/DIV
2884 G11
500µs/DIV 1V/DIV
2884 G12
VCC2 Droop/Plug-In Response 200µs/DIV 1V/DIV
For more information www.linear .com/L TM2884 pin FuncTions Upstream Side (VCC, VBUS, VLO, GND) D1– ( A1): USB Data Bus Upstream Facing Negative T ransceiver Pin. A 1.5k pull-up resistor is automatically configured to indicate the idle condition of the D2– pin. D1+ ( A2): USB Data Bus Upstream Facing Positive T ransceiver Pin. A 1.5k pull-up resistor is automatically configured to indicate the idle condition of the D2+ pin. SPNDPWR (A3): Suspend Power Control. A high input enables the DC/DC converter shutdown control if the USB bus is suspended. A low input (GND) disables the shut - down control to the DC/DC converter maintaining power to the isolated downstream side during suspend mode. The recovery time from suspend mode may be equivalent to the power supply start-up time if the DC/DC converter was shut down. The SPNDPWR pin is referenced to VLO and GND. ON (A4): Enable for Power and Data Communication Through the Isolation Barrier. If ON is high, the part is enabled. If ON is low, the upstream side is held in reset and the isolated side is unpowered by the DC/DC converter. The ON pin is referenced between VLO and GND. VLO (A5): Internally Regulated 3.3V Logic Voltage Output. The VLO pin is used as a positive reference for the ON and SPNDPWR pins and can source up to 10mA of surplus current. Internally bypassed to GND with 2.2µF. Output supply, no external connection necessary. GND (A6, B1-B11): Upstream Circuit Ground. V BUS (A7): Voltage Supply Input to USB T ransceiver. The operating range is 4.4V to 16.5V. Connect to the USB VBUS supply or an external source. Internally bypassed to GND with 2.2µF. V CC (A8-A11): Voltage Supply Input to DC/DC Converter. The operating range is 4.4V to 16.5V. Connect to an external supply greater than 8.6V for 500mA on VCC2. Connect to the USB VBUS for up to 200mA on VCC2. Connect VCC to VBUS when the peripheral device has an external power source. Internally bypassed to GND with 4.7µF. Isolated Downstream Side (VCC2, VLO2, GND2) GND2 (K1-K11, L3, L4, L6, L7): Downstream Circuit Ground. D2– (L1): USB Data Bus Downstream Facing Negative T ransceiver Pin. The pin has a 15k pull-down resistor to GND2. D2+ (L2): USB Data Bus Downstream Facing Positive T rans- ceiver Pin. The pin has a 15k pull-down resistor to GND2. VLO2 (L5): Internally Regulated 3.3V Logic Voltage Output. The VLO2 pin can source up to 10mA of surplus current. Internally bypassed to GND2 with 2.2µF. Output supply, no external connection necessary. V CC2 (L8-L11): Isolated Voltage Supply Output from DC/ DC Converter. Output voltage is 5V and can support up to 500mA of peripheral device current referenced to GND2. Output current is dependant on input supply voltage and current limit. Internally bypassed to GND2 with 22µF. Output supply, no external connection necessary.
For more information www.linear .com/L TM2884 block DiagraM 2884 BD 22µF D2+ VLO2 VCC2 15k GND2GND = UPSTREAM SIDE COMMON = DOWNSTREAM SIDE COMMON 15k DOWNSTREAM PORTD2– 4.7µF VCC 2.2µF 3.3V REG 3.3V REG ISOLATED COMMUNICATION INTERFACE ISOLATED COMMUNICATION INTERFACE 2.2µF VBUS VLO ON D1+ D1– 2.2µF DC/DC SPNDPWR UPSTREAM PORT 1.5k 1.5k
2884 F01
Figure 1. Power Supply Loads
2884 F02
2884 F03
Figure 2. Low Speed Timing Measurements Figure 3. Full Speed Timing Measurements
For more information www.linear .com/L TM2884 FuncTional Table USB T ransceiver Functional Table MODE D1+ D1– AUTOMATIC PULL-UP CONNECTION D2+ D2– SPNDPWR Full Speed (Idle) 1.5k Pull-Up Host Pull-Down D1+ Peripheral Pull-Up 15k Pull-Down X Low Speed (Idle) Host Pull-Down 1.5k Pull-Up D1– 15k Pull-Down Peripheral Pull-Up X Disconnected (Idle) Host Pull-Down Host Pull-Down None 15k Pull-Down 15k Pull-Down X Suspend (Idle >3ms) Set at Device Connect Set at Device Connect Set at Device Connect Peripheral or 15k Peripheral or 15k 0 Suspend No Power (Idle >3ms) Set at Device Connect Set at Device Connect Set at Device Connect 15k Pull-Down 15k Pull-Down 3.3V D1 to D2 Data IN+ IN– Set at Device Connect OUT + OUT– X D2 to D1 Data OUT+ OUT– Set at Device Connect IN + IN– X Power Functional Table MODE ON SPNDPWR V CC VBUS DC/DC CONVERTER Off 0 X X X OFF On 3.3V X >4.4V >4.4V ON On, Suspend (Idle >3ms) 3.3V 0 >4.4V >4.4V ON On, Suspend (Idle >3ms), Power Off 3.3V 3.3V >4.4V >4.4V OFF On, USB T ransceiver Only Power Off 3.3V X 0 >4.4V OFF
For more information www.linear .com/L TM2884 The LTM2884 µModule transceiver provides a galvanically isolated robust USB interface, powered by an integrated, regulated DC/DC converter, complete with decoupling capacitors. This flexible device can support a variety of USB configurations, either bus powered or externally powered. Applications include isolation in hosts, hubs, peripherals, or standalone inline bus splitters. Automati- cally configured pull -up resistors are included to represent the condition of the isolated downstream USB bus to the upstream USB bus. The LTM2884 is ideal for use in USB connections where grounds between upstream hub/host and downstream devices can take on different voltages. Isolation in the LTM2884 blocks high voltage differences and eliminates ground loops and is extremely tolerant of common mode transients between ground potentials. Error free operation is maintained through common mode events exceeding 30kV/µs providing excellent noise isolation. The LTM2884 contains a fully integrated DC/DC converter including the transformer, so that no external components are necessary in many configurations. The upstream side contains a flyback converter that regulates the downstream output voltage through primary sensing techniques. The internal power solution is sufficient to support the trans- ceiver interface and supply up to 500mA at 5V through VCC2 to an attached device dependent on the supply voltage and available current on VCC. The integrated USB transceivers on both sides of the iso- lation barrier support full and low speed modes defined in the USB 2.0 specification. The communication through the isolation barrier for USB is bidirectional and as such the LTM2884 determines data flow direction based on which side a start of packet (SOP) begins first. The direction of data is maintained until an end of packet (EOP) pattern is observed or a timeout occurs due to a lack of activity. The USB interface maintains a consistent propagation delay representative of a hub delay and transfers all data. Pull-up resistors integrated in the upstream interface automatically indicate device connections and discon - nections. A downstream device connection automatically selects the proper pull-up resistor at the upstream facing port after sensing the idle state of the downstream device at connection time. Disconnection of a downstream device automatically releases the pull-up resistor on the upstream facing port allowing the upstream 15k pull-down resistors to pull the bus signals to a disconnect condition. This func- tion makes the LTM2884 ideal for host, hub, bus splitter, or peripheral device integration. Isolator µModule T echnology The LTM2884 utilizes isolator µModule technology to translate signals and power across an isolation barrier. Signals on either side of the barrier are encoded into pulses and translated across the isolation boundary us - ing differential signaling through coreless transformers formed in the µModule substrate. This system, complete with data refresh, error checking, safe shutdown on fail, and extremely high common mode immunity, provides a robust solution for bidirectional signal isolation. The µModule technology provides the means to combine the isolated signaling with a USB transceiver and powerful isolated DC/DC converter in one small package. USB T ransceiver Pin Protection The LTM2884 USB transceiver pins D1 +, D1–, D2+, and D2– have protection from ESD and short-circuit faults. The transceiver pins withstand ±15KV HBM ESD events. Overcurrent circuitry on the transceiver pins monitor fault conditions from D1+ and D1– to GND, VLO, or VBUS and from D2+ and D2– to GND2, VLO2, or VCC2. A current detection circuit disables the transceiver pin if the pin sinks about 40mA for greater than 600ns. The V LO and VLO2 output supplies protect the USB transceiver pins from shorts to GND or GND2 respectively with a 40mA current limit. operaTion
to GND2 supporting the downstream bus configuration. K-state to begin a data packet and set the data direction. the LTM2884 isolator with a delay of approximately 80ns. automatic monitoring and reporting of the bus speeds. Figure 4. Idle State Automatic Resistor Setting
2884 F04
SPNDPWR pin, as summarized in Table 1. Table 1. Suspend Mode Operation downstream device or a resume command from the host. when the first state change is detected. the limits set in the USB specification. rent limit is increased so that 500mA is sourced from VCC2. current limit for low power peripherals. specification of 120µF when supporting device plug in. device, or upstream hub application. available to support interface logic to the isolated USB port.
For more information www.linear .com/L TM2884 applicaTions inForMaTion Supply Current Loading the multiple output supply pins of the LTM2884 affects the supply current on VBUS and VCC. The VBUS input supplies current to the the upstream side of the trans- ceiver and to the VLO pin. The VCC input supplies power to VCC2 and V LO2 through an isolated DC/DC converter. The efficiency (η) of the DC/DC converter is shown in the Typical Performance Characteristics section for 5V and 12V inputs from VCC to VCC2. Supply Current Equations Operating: IBUS = 6mA + IVLO ICC = VCC2 • 6mA + ICC2 + IVLO2( ) η •VCC Suspend: SPNDPWR = 0 IBUS = 1.5mA + IVLO ICC = VCC2 • 6mA + ICC2 + IVLO2( ) η •VCC Suspend: SPNDPWR = VLO IBUS = 0.45mA + IVLO ICC = VCC 45k Off: IBUS = 10µA ICC = VCC 45k USB 2.0 Compatibility The LTM2884 µModule transceiver is compatible with the USB 2.0 specification of full and low speed operation. Some characteristics and implementations may not support full compliance with the USB 2.0 specification. Three specific cases exist within the LTM2884 µModule transceiver and the integrated DC/DC power converter. First, the propagation delay for full speed data of 80ns exceeds the specification for a single hub of 44ns plus the attached cable delay of 26ns. This is due to driving the signal to the 3.3V rail prior to a K-state transition to maintain balanced crossover voltages equivalent to the cross over voltages of the successive data transitions. USB ports commonly drive the idle state bus to the 3.3V rail prior to the k-state start of packet transition. Second, setting SPNDPWR = V LO will cause the DC/DC power converter to turn off during a bus suspend. V CC2 will lose power causing the downstream device to lose enumeration. Remote wake-up, disconnect, and recon- nect events are ignored. A resume command from the host or upstream hub will start the DC/DC converter and wake up the downstream device. The downstream device will require re-enumeration, which causes a failure in USB compliance testing. After a resume command initiates, a delay of 3ms will elapse before the isolated device is fully powered. When SPNDPWR = 0V, the DC/DC power converter remains on during suspend, therefore power and enumeration information is retained. The VCC supply consumes 50mA to support the isolated power during suspend. Separate the VBUS and VCC supplies to comply with the 2.5mA USB 2.0 VBUS suspend current specification. Third, when connecting a low power device to the downstream side of the LTM2884 and V BUS and V CC are connected together, the input current is higher due to the operating current and the efficiency of the DC/DC converter. The operating current of the DC/DC converter and the USB transceiver function is 46mA. The efficiency of the converter is approximately 55%, resulting in a 1/0.55 increase in the input current due to the load current on V CC2. A 100mA load on V CC2 appears as a 181mA load + operating current at V BUS and VCC. In order to meet a 100mA input current, the VCC2 load current must be less than 25mA. This characteristic of an isolated supply may limit the use of the LTM2884 in bus powered hub applica- tions or downstream connection to a bus powered hub. Connect VCC to an external supply to mitigate this concern.
for a detailed discussion of this problem.
- Input and output decoupling is not required on peripheral or hub inputs. Add additional low ESR capacitance to reduce noise induction on the power supply connec - tions. Hub/bus splitter outputs require an additional 100µF of low ESR capacitance.
- Do not place copper between the inner columns of pads on the top or bottom of the PCB. This area must remain open to withstand the rated isolation voltage and maintain the creepage distance. RF, Magnetic Field Immunity The isolator µModule technology used within the LTM2884 has been independently evaluated, and successfully passed the RF and magnetic field immunity testing requirements per European Standard EN 55024, in accordance with the following test standards: EN 61000-4-3 Radiated, Radio-Frequency, Electromagnetic Field Immunity EN 61000-4-8 Power Frequency Magnetic Field Immunity EN 61000-4-9 Pulsed Magnetic Field Immunity T ests were performed using an unshielded test card de - signed per the data sheet PCB layout recommendations. Specific limits per test are detailed in T able 2.
Table 2. Test Frequency Field Strength in Figure 5. Results are corrected per IEC 61000-4-20.
Figure 5. PC Board Layout Figure 6. EMI Plot
2884 F06
Figure 7. Bus Powered Inline Bus Splitter Figure 8. USB Hub Upstream Isolator
2884 F08
4 USB
2884 F07
Figure 9. USB Host Integration Figure 10. Powered Peripheral Device with USB Isolation and Low Current Suspend
2884 F09
2884 F10
Figure 11. Bus or Self Powered USB Isolation with Low Current Suspend and Power Plug Detection
2884 F11
Figure 12. Isolated 1W or 2.5W Power Supply
2884 F12
For more information www.linear .com/L TM2884 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package DescripTion 44-Lead (15mm × 15mm × 5.02mm) (Reference L TC DWG # 05-08-1881 Rev A) Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS BALL DESIGNATION PER JESD MS-028 AND JEP95 DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE PACKAGE TOP VIEW PIN “A1” CORNER X Y aaa Z aaa Z PACKAGE BOTTOM VIEW SEE NOTES SUGGESTED PCB LAYOUT TOP VIEW DETAIL A PIN 1 0.000 1.270 2.540 2.540 3.810 1.270 0.3175 0.3175 3.810 5.080 6.350 5.080 6.350 6.350 6.350 5.080 5.080 0.000 DETAIL A Øb (44 PLACES) F G H L J K E A B C D 2 14 35 6 711 8 9 10 DETAIL B SUBSTRATE 0.37 – 0.47 3.95 – 4.05 // bbb Z D A ccc Z DETAIL B PACKAGE SIDE VIEW MOLD CAP Z M X Y Z ddd M Z eee 0.630 ±0.025 Ø 44x SYMBOL A b D E e F G aaa bbb ccc ddd eee MIN 4.82 0.50 4.32 0.71 0.60 NOM 5.02 0.60 4.42 0.78 0.63 15.0 15.0 1.27 12.70 12.70 MAX 5.22 0.70 4.52 0.85 0.66 0.15 0.10 0.20 0.30 0.15 NOTES DIMENSIONS TOTAL NUMBER OF BALLS: 44 E b e e b F G BGA 44 1212 REV A TRAY PIN 1 BEVEL PACKAGE IN TRAY LOADING ORIENTATION COMPONENT PIN “A1” µModule L TMXXXXXX 5. PRIMARY DATUM -Z- IS SEATING PLANE 6. SOLDER BALL COMPOSITION CAN BE 96.5% Sn/3.0% Ag/0.5% Cu OR Sn Pb EUTECTIC
7 PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULL Y SEE NOTES
Figure 13. Self Powered 4-Port Hub with Independent Isolation