NCP1081DEG

NCP1081 Integrated High Power PoE-PD Interface & DC-DC Converter Controller Introduction http://onsemi.com The NCP1081 is a member of ON Semiconductor’s high power HIPO Power over Ethernet Powered Device (PoE−PD) product family and represents a robust, flexible and highly integrated solution targeting demanding medium and high power Ethernet applications. It combines in a single unit an enhanced PoE−PD interface supporting 1 the IEEE802.3af and the 802.3at standard and a flexible and TSSOP−20 EP configurable DC−DC converter controller. DE SUFFIX The NCP1081’s exceptional capabilities offer new opportunities for CASE 948AB the design of products powered directly over Ethernet lines, eliminating the need for local power adaptors or power supplies and drastically reducing the overall installation and maintenance cost. ON Semiconductor’s unique manufacturing process and design enhancements allow the NCP1081 to deliver up to 25.5 W for the IEEE802.3at standard and up to 40 W for proprietary high power PoE applications. The NCP1081 enables the IEEE802.3at and implements a two event physical layer classification. Additional proprietary classification procedures support high power power sourcing equipment (PSE) on the market. The unique high power features leverage the significant cost advantages of PoE− enabled systems to a much broader spectrum of products in emerging markets such as NCP1081 = Specific Device Code industrial ethernet devices, PTZ and Dome IP cameras, RFID readers, XXXX = Date Code MIMO WLAN access points, high end VoIP phones, notebooks, etc. Y = Assembly Location The integrated current mode DC−DC controller facilitates isolated ZZ = Traceability Code and non−isolated fly−back, forward and buck converter topologies. It has all the features necessary for a flexible, robust and highly efficient design including programmable switching frequency, duty cycle up to ORDERING INFORMATION See detailed ordering and shipping information in the package 80 percent, slope compensation, and soft start−up. dimensions section on page 2 of this data sheet. The NCP1081 is fabricated in a robust high voltage process and integrates a rugged vertical N−channel DMOS with a low loss current sense technique suitable for the most • Extended Power Ranges up to 40 W demanding environments and capable of withstanding harsh • Programmable Classification Current environments such as hot swap and cable ESD events. • Adjustable Under Voltage Lock Out The NCP1081 complements ON Semiconductor’s ASSP • Programmable Inrush Current Limit portfolio in industrial devices and can be combined with • Programmable Operational Current Limit up to stepper motor drivers, CAN bus drivers and other high− 1100 mA for Extended Power Ranges voltage interfacing devices to offer complete solutions to the industrial and security market. • Over−temperature Protection • Industrial Temperature Range −40°C to 85°C with Full Features Operation up to 150°C Junction Temperature • These are Pb−Free Devices • 0.6 W Hot−swap Pass−switch with Low Loss Current Powered Device Interface Sense Technique • Supporting the IEEE802.3af and the 802.3at Standard • Vertical N−channel DMOS Pass−switch offers the • Supports IEEE802.3at Two Event Layer 1 Robustness of Discrete MOSFETs with Integrated Classification Temperature Control • High Power Layer 1 Classification Indicator © Semiconductor Components Industries, LLC, 2013 May, 2013 − Rev. 7 1 Publication Order Number: NCP1081/D NCP1081 DC−DC Converter Controller PIN DIAGRAM • Current Mode Control • Supports Isolated and Non−isolated DC−DC Converter VPORTP CLASS UVLO INRUSH ILIM1 VPORTN1 RTN VPORTN2 TEST1 TEST2 Applications • Internal Voltage Regulators • Wide Duty Cycle Range with Internal Slope Compensation Circuitry • Programmable Oscillator Frequency • Programmable Soft−start Time SS FB COMP VDDL VDDH GATE ARTN nCLASS_AT CS OSC 1 Exposed Pad (Top View) ORDERING INFORMATION Package Shipping Configuration† Temperature Range NCP1081DEG TSSOP−20 EP (Pb−Free) 74 units / Tube −40°C to 85°C NCP1081DER2G TSSOP−20 EP (Pb−Free) 2500 / Tape & Reel −40°C to 85°C Part Number †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. VPORTP DETECTION CLASS THERMAL SHUT DOWN INTERNAL SUPPLY & BANDGAP CLASSIFICATION VDDH VDDH VDDL VDDL VDDL VDDL 5 mA SS UVLO UVLO VPORT MONITOR VDDL DC−DC CONVERTER CONTROL 5 K 1.2 V FB COMP CS INRUSH ILIM1 INRUSH ILIM1 OSC OSC VDDH HOT SWAP SWITCH GATE CONTROL & CURRENT LIMIT BLOCKS VDDL 20 mA nCLASS_AT ARTN RTN VPORTN1,2 Figure 1. NCP1081 Block Diagram http://onsemi.com 2 NCP1081 SIMPLIFIED APPLICATION DIAGRAMS RJ−45 Rclass Cline DB1 Z_line Rinrush Data Pairs Rilim1 Cpd VPORTP CLASS VDDH INRUSH ILIM1 VDDL CS TEST1 FB ARTN Css OSC DB2 Spare Pairs SS VPORTN2 COMP TEST2 VPORTN1 Voutput LD1 Cload Rd1 nCLASS_AT GATE UVLO R2 Cvddl NCP1081 R1 D1 T1 Cvddh M1 R5 Rslope OC1 Rcs C2 R3 RTN Optocoupler Rosc Z1 C1 R4 Figure 2. Isolated Fly−back Converter Figure 2 shows the integrated PoE−PD switch and DC−DC controller configured to work in a fully isolated application. The output voltage regulation is accomplished with an external opto−coupler and a shunt regulator (Z1). RJ−45 DB1 Cline Rinrush Z_line Data Pairs Rclass Rilim1 Cpd VPORTP CLASS INRUSH ILIM1 nCLASS_AT TEST2 FB OSC COMP Css Rosc Cload Rslope CS VPORTN1 VPORTN2 R3 M1 GATE SS DB2 LD1 Rd1 TEST1 Spare Pairs Cvddl NCP1081 UVLO R2 Cvddh VDDL R1 Voutput T1 VDDH Rcs ARTN RTN R4 C1comp Rcomp C2comp Figure 3. Non−Isolated Fly−back Converter Figure 3 shows the integrated PoE−PD and DC−DC controller configured in a non−isolated fly−back configuration. A compensation network is inserted between the FB and the COMP pin for overall stability of the feedback loop. http://onsemi.com 3 NCP1081 SIMPLIFIED APPLICATION DIAGRAMS D2 RJ−45 Rclass DB1 Cline Z_line Rinrush Data Pairs Rilim1 VPORTP R5 CLASS ILIM1 VDDL LD1 Cvddl Cload NCP1081 R3 Rd1 nCLASS_AT M1 GATE Rslope CS TEST2 R4 FB TEST1 COMP OSC SS VPORTN1 VPORTN2 DB2 Voutput Cpd Cvddh INRUSH UVLO Spare Pairs D1 VDDH R1 R2 T1 Rcs ARTN RTN Css Rosc C1comp Rcomp C2comp Figure 4. Non−Isolated Fly−back with Extra Winding Figure 4 shows the same non−isolated fly−back configuration as Figure 3, but adds a 12 V auxiliary bias winding on the transformer to provide power to the NCP1081 DC−DC controller via its VDDH pin. This topology shuts off the current flowing from VPORTP to VDDH and therefore reduces the internal power dissipation of the PD, resulting in higher overall power efficiency. T1 D3 Cpd RJ−45 Cline Rinrush DB1 Z_line Data Pairs Rclass Rilim1 VPORTP D1 CLASS VDDH INRUSH VDDL NCP1081 M1 GATE TEST2 CS TEST1 FB COMP OSC VPORTN1 VPORTN2 SS DB2 Rd1 nCLASS_AT UVLO Spare Pairs R3 LD1 Cload ILIM1 R1 R2 Voutput D2 Cvddh Cvddl L1 Css Rosc Rslope R4 Rcs ARTN RTN C1comp Rcomp C2comp Figure 5. Non−Isolated Forward Converter Figure 5 shows the NCP1081 used in a non−isolated forward topology. High Power Considerations The NCP1081 is designed to implement various configurations of high−power PoE systems including those based on the IEEE802.3at standard. High power operation can be enabled by a Dual Event Layer 1 classification or a Single Event Layer 1 classification combined with a Layer 2 high power classification. The NCP1081 also supports proprietary designs capable of delivering 25 W to 40 W to the load in two−pair configurations. A separate application note describes these implementations (AND8332). http://onsemi.com 4 NCP1081 Table 1. PIN DESCRIPTIONS Name Pin No. Type 1 Supply Positive input power. Voltage with respect to VPORTN1,2. 6,8 Ground Negative input power. Connected to the source of the internal pass−switch. RTN 7 Ground DC−DC controller power return. Connected to the drain of the internal pass−switch. It must be connected to ARTN. This pin is also the drain of the internal pass−switch. ARTN 14 Ground DC−DC controller ground pin. Must be connected to RTN as a single point ground connection for improved noise immunity. VDDH 16 Supply Output of the 9 V LDO internal regulator. Voltage with respect to ARTN. Supplies the internal gate driver. VDDH must be bypassed to ARTN with a 1 mF or 2.2 mF ceramic capacitor with low ESR. VDDL 17 Supply Output of the 3.3 V LDO internal regulator. Voltage with respect to ARTN. This pin can be used to bias an external low−power LED (1 mA max.) connected to nCLASS_AT, and can also be used to add extra biasing current in the external opto−coupler. VDDL must be bypassed to ARTN with a 330 nF or 470 nF ceramic capacitor with low ESR. CLASS 2 Input Classification current programming pin. Connect a resistor between CLASS and VPORTN1,2. INRUSH 4 Input Inrush current limit programming pin. Connect a resistor between INRUSH and VPORTN1,2. ILIM1 5 Input Operational current limit programming pin. Connect a resistor between ILIM1 and VPORTN1,2. UVLO 3 Input DC−DC controller under−voltage lockout input. Voltage with respect to VPORTN1,2. Connect a resistor−divider from VPORTP to UVLO to VPORTN1,2 to set an external UVLO threshold. GATE 15 Output VPORTP VPORTN1 VPORTN2 Description DC−DC controller gate driver output pin. OSC 11 Input nCLASS_AT 13 Output, Open Drain COMP 18 I/O Output of the internal error amplifier of the DC−DC controller. COMP is pulled−up internally to VDDL with a 5 kW resistor. In isolated applications, COMP is connected to the collector of the opto−coupler. Voltage with respect to ARTN. FB 19 Input DC−DC controller inverting input of the internal error amplifier. In isolated applications, the pin should be strapped to ARTN to disable the internal error amplifier. CS 12 Input Current−sense input for the DC−DC controller. Voltage with respect to ARTN. SS 20 Input Soft−start input for the DC−DC controller. A capacitor between SS and ARTN determines the soft−start timing. TEST1 9 Input Digital test pin must always be connected to VPORTN1,2. TEST2 10 Input Digital test pin must always be connected to VPORTN1,2. EP Internal oscillator frequency programming pin. Connect a resistor between OSC and ARTN. Active−low, open−drain Layer 1 dual−finger classification indicator. Exposed pad. Connected to VPORTN1,2 ground. http://onsemi.com 5 NCP1081 Table 2. ABSOLUTE MAXIMUM RATINGS Symbol Min. Max. Units Input power supply −0.3 72 V Voltage with respect to VPORTN1,2 RTN ARTN Analog ground supply 2 −0.3 72 V Pass−switch in off−state (Voltage with respect to VPORTN1,2) VDDH Internal regulator output −0.3 17 V Voltage with respect to ARTN VDDL Internal regulator output −0.3 3.6 V Voltage with respect to ARTN CLASS Analog output −0.3 3.6 V Voltage with respect to VPORTN1,2 INRUSH Analog output −0.3 3.6 V Voltage with respect to VPORTN1,2 ILIM1 Analog output −0.3 3.6 V Voltage with respect to VPORTN1,2 UVLO Analog input −0.3 3.6 V Voltage with respect to VPORTN1,2 OSC Analog output −0.3 3.6 V Voltage with respect to ARTN Analog input / output −0.3 3.6 V Voltage with respect to ARTN FB Analog input −0.3 3.6 V Voltage with respect to ARTN CS Analog input −0.3 3.6 V Voltage with respect to ARTN SS Analog input −0.3 3.6 V Voltage with respect to ARTN nCLASS_AT Analog output −0.3 3.6 V Voltage with respect to ARTN TEST1 TEST2 Digital inputs −0.3 3.6 V Voltage with respect to VPORTN1,2 Ta Ambient temperature −40 85 °C Tj Junction temperature − 150 °C Junction temperature (Note 1) − 175 °C −55 150 °C 37.6 °C/W 4 − kV 750 − V Machine Model 300 − V Latch−up ±200 − mA System ESD (contact/air) (Note 3) 8/15 − kV VPORTP COMP Tj−TSD Parameter Tstg Storage Temperature TθJA Thermal Resistance, Junction to Air (Note 2) ESD−HBM Human Body Model ESD−CDM Charged Device Model ESD−MM LU ESD−SYS Conditions Thermal shutdown condition Exposed pad connected to VPORTN1,2 ground per JEDEC Standard JESD22 per JEDEC Standard JESD78 Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. 1. Tj−TSD allowed during error conditions only. It is assumed that this maximum temperature condition does not occur more than 1 hour cumulative during the useful life for reliability reasons. 2. Mounted on a 1S2P (3 layer) test board with copper coverage of 25 percent for the signal layers and 90 percent copper coverage for the inner planes at an ambient temperature of 85°C in still air. Refer to JEDEC JESD51−7 for details. 3. Surges per EN61000−4−2, 1999 applied between RJ−45 and output ground and between adapter input and output ground of the evaluation board. The specified values are the test levels and not the failure levels. http://onsemi.com 6 NCP1081 Recommended Operating Conditions Operating conditions define the limits for functional operation and parametric characteristics of the device. Note that the functionality of the device outside the operating conditions described in this section is not warranted. Operating outside the recommended operating conditions for extended periods of time may affect device reliability. All values concerning the DC−DC controller, VDDH, VDDL, and nCLASS_AT blocks are with respect to ARTN. All others are with respect to VPORTN1,2 (unless otherwise noted). Table 3. OPERATING CONDITIONS Symbol Parameter Min. Typ. Max. Units 0 57 V 1.4 9.5 V 23.75 26.25 kW Conditions INPUT SUPPLY VPORT Input supply voltage VPORT = VPORTP − VPORTN1,2 SIGNATURE DETECTION Vsignature Input supply voltage signature detection range Rsignature Signature resistance (Note 4) Offset_current I_VportP + I_Rtn − 1.8 5 mA VPORTP = RTN = 1.4 V Sleep_current I_VportP + I_Rtn − 15 25 mA VPORTP = RTN = 9.5 V Vcl Input supply voltage classification range 13 20.5 V V_mark Mark event voltage range (VPORTP falling) 5.4 − 9.7 V I_mark Current consumption I(VPORTP) + I(Rdet) in Mark Event range 0.5 − 2.0 mA 5.4 V ≤ VPORT ≤ 9.5 V dR_mark Input signature during Mark Event (Note 7) − − 12 kW For information only Vreset Classification Reset range (VPORTP falling) 4.3 4.9 5.4 V Iclass0 Class 0: Rclass 10 kW (Note 6) 0 − 4 mA Iclass0 = I_VportP + I_Rdet Iclass1 Class 1: Rclass 130 W (Note 6) 9 − 12 mA Iclass1 = I_VportP + I_Rdet Iclass2 Class 2: Rclass 69.8 W (Note 6) 17 − 20 mA Iclass2 = I_VportP + I_Rdet Iclass3 Class 3: Rclass 44.2 W (Note 6) 26 − 30 mA Iclass3 = I_VportP + I_Rdet Iclass4 Class 4: Rclass 30.9 W (Note 6) 36 − 44 mA Iclass4 = I_VportP + I_Rdet Iclass5 Class 5: Rclass 22.1 W (Notes 5 and 6) (for proprietary high power applications) 50 − 60 mA Iclass5 = I_VportP + I_Rdet IDCclass Internal current consumption during classification (Note 8) − 600 − mA For information only 20 27 mA CLASSIFICATION CLASSIFICATION INDICATOR nCLASS_AT_i nCLASS_AT current source NCLASS_AT_pd RDS,ON of NCLASS_AT pull down transistor 13 130 W For information only 4. Test done according to the IEEE802.3af 2 Point Measurement. The minimum probe voltages measured at the PoE−PD are 1.4 V and 2.4 V, and the maximum probe voltages are 8.5 V and 9.5 V. 5. This extended classification range can be used with a PSE which also uses this classification range to deliver more current than specified by IEEE802.3. 6. Measured with an external Rdet of 25.5 kW between VPORTP and VPORTN1,2, and for 13 V < VPORT < 20.5 V (with VPORT = VPORTP – VPORTN1,2). Resistors are assumed to have 1% accuracy. 7. Measured with the 2 Point Measurement defined in the IEEE802.3af standard with 5.4 V and 9.5 V the extreme values for V2 and V1. 8. This typical current excludes the current in the Rclass and Rdet external resistors. http://onsemi.com 7 NCP1081 Table 3. OPERATING CONDITIONS Symbol Parameter Min. Typ. Max. Units Conditions UVLO Vuvlo_on Default turn on voltage (VportP rising) − 38 40 V UVLO pin tied to VPORTN1,2 Vuvlo_off Default turn off voltage (VportP falling) 29.5 32 − V UVLO pin tied to VPORTN1,2 Vhyst_int UVLO internal hysteresis − 6 − V UVLO pin tied to VPORTN1,2 Vuvlo_pr UVLO external programming range 25 − 50 V UVLO pin connected to the resistor divider (R1 & R2). For information only Vhyst_ext UVLO external hysteresis − 15 − % UVLO pin connected to the resistor divider (R1 & R2) Uvlo_Filter UVLO on/off filter time − 90 − mS For information only Max Ron specified at Tj = 130°C PASS−SWITCH AND CURRENT LIMITS Ron Pass−switch Rds−on − 0.6 1.2 W I_Rinrush1 Rinrush = 150 kW (Note 9) 95 125 155 mA Measured at RTN− VPORTN1,2 = 3 V I_Rinrush2 Rinrush = 57.6 kW (Note 9) 260 310 360 mA Measured at RTN− VPORTN1,2 = 3 V I_Rilim1 Rilim1 = 84.5 kW (Note 9) 450 510 570 mA Current limit threshold I_Rilim2 Rilim1 = 66.5 kW (Note 9) 600 645 690 mA Current limit threshold I_Rilim3 Rilim1 = 55.6 kW (Note 9) 720 770 820 mA Current limit threshold I_Rilim4 Rilim1 = 38.3 kW (Note 9) 970 1100 1230 mA Current limit threshold 0.8 1 1.2 V RTN−VPORTN1,2 falling; Voltage with respect to VPORTN1,2 − 8.2 − V Voltage with respect to VPORTN1,2 INRUSH AND ILIM1 CURRENT LIMIT TRANSITION Vds_pgood VDS required for power good status Vds_pgood_hyst VDS hysteresis required for power good status 9. The current value corresponds to the PoE−PD input current (the current flowing in the external Rdet and the quiescent current of the device are included). Resistors are assumed to have 1% accuracy. http://onsemi.com 8 NCP1081 Table 3. OPERATING CONDITIONS Symbol Parameter Min. Typ. Max. Units 8.4 9 9.6 V Conditions VDDH REGULATOR VDDH_reg Regulator output voltage (Notes 10 and 11) Ivddh_load + Ivddl_load < 10 mA with 0 < Ivddl_load < 2.25 mA VDDH_Off Regulator turn−off voltage − VDDH_reg + 0.5 V − V VDDH_lim VDDH regulator current limit (Notes 10 and 11) 13 − 26 mA VDDH_Por_R VDDH POR level (rising) 7.3 − 8.3 V VDDH_Por_F VDDH POR level (falling) 6 − 7 V VDDH_ovlo VDDH over−voltage level (rising) 16 − 18.5 V 3.05 3.3 3.55 V For information only VDDL REGULATOR VDDL_reg Regulator output voltage (Notes 10 and 11) 0 < Ivddl_load < 2.25 mA with Ivddh_load + Ivddl_load < 10 mA VDDL_Por_R VDDL POR level (rising) VDDL − 0.2 − VDDL − 0.02 V VDDL_Por_F VDDL POR level (falling) 2.5 − 2.9 V Gate_Tr GATE rise time (10−90%) − − 50 ns Cload = 2 nF, VDDHreg = 9 V Gate_Tf GATE fall time (90−10%) − − 50 ns Cload = 2 nF, VDDHreg = 9 V 1.3 − 3 V For information only GATE DRIVER PWM COMPARATOR VCOMP COMP control voltage range ERROR AMPLIFIER Vbg_fb Reference voltage 1.15 1.2 1.25 V Voltage with respect to ARTN Av_ol DC open loop gain − 80 − dB For information only GBW Error amplifier GBW 1 − − MHz For information only SOFT−START Vss Soft−start voltage range Vss_r Soft−start low threshold (rising edge) Iss Soft−start source current − 1.15 − V 0.35 0.45 0.55 V 3 5 7 mA 324 360 396 mV ns CURRENT LIMIT COMPARATOR CSth CS threshold voltage Tblank Blanking time − 100 − DutyC Maximum duty cycle − 80% − Frange Oscillator frequency range 100 − 500 F_acc Oscillator frequency accuracy For information only OSCILLATOR ±25 Fixed internally kHz % 10. Power dissipation must be considered. Load on VDDH and VDDL must be limited especially if VDDH is not powered by an auxiliary winding. 11. Ivddl_load = current flowing out of the VDDL pin. Ivddh_load = current flowing out of the VDDH pin + current delivered to the Gate Driver (function of the frequency, VDDH voltage & MOSFET gate capacitance). http://onsemi.com 9 NCP1081 Table 3. OPERATING CONDITIONS Symbol Parameter Min. Typ. Max. Units Conditions IvportP1 VPORTP internal current consumption (Note 12) − 2.5 3.5 mA DC−DC controller off IvportP2 VPORTP internal current consumption (Note 13) − 4.7 6.5 mA DC−DC controller on 150 − − °C Tj Tj = junction temperature − 15 − °C Tj Tj = junction temperature CURRENT CONSUMPTION THERMAL SHUTDOWN TSD Thermal shutdown threshold Thyst Thermal hysteresis THERMAL RATINGS Ta Ambient temperature −40 − 85 °C Tj Junction temperature − − 125 150 °C °C 12. Conditions a. No current through the pass−switch b. DC−DC controller inactive (SS shorted to RTN) c. No external load on VDDH and VDDL d. VPORTP = 57 V 13. Conditions a. No current through the pass−switch b. Oscillator frequency = 100 kHz c. No external load on VDDH and VDDL d. Aux winding not used e. 2 nF on GATE, DC−DC controller enabled f. VPORTP = 57 V http://onsemi.com 10 Parametric values guaranteed Max 1000 hours NCP1081 DESCRIPTION OF OPERATION Powered Device Interface The NCP1081 can handle all defined types of classification, IEEE802.3af, 802.3at and proprietary classification. In the IEEE802.3af standard the classification is performed with a Single Event Layer 1 classification. Depending on the current level set during that single event the power level is determined. The IEEE802.3at standard allows two ways of classification which can also be combined. These two approaches enable higher power applications through a variety of PSE equipment. For power injectors and midspans a pure physical hardware handshake is introduced called Two Event Layer 1 classification. This approach allows equipment that has no data link between PSE and PD to classify as high power. Since switches can establish a data link between PSE and PD, a software handshake is possible. This type of handshake is called Layer 2 classification (or Data Link Layer classification). It has the main advantage of having a finer power resolution and the ability for the PSE and PD to participate in dynamic power allocation. The PD interface portion of the NCP1081 supports the IEEE802.3af and 802.3at defined operating modes: detection signature, current source classification, inrush and operating current limits. In order to give more flexibility to the user and also to keep control of the power dissipation in the NCP1081, both current limits are configurable. The device enters operation once its programmable Vuvlo_on threshold is reached, and operation ceases when the supplied voltage falls below the Vuvlo_off threshold. Sufficient hysteresis and Uvlo filter time are provided to avoid false power on/off cycles due to transient voltage drops on the cable. Detection During the detection phase, the incremental equivalent resistance seen by the PSE through the cable must be in the IEEE802.3af standard specification range (23.75 kW to 26.25 kW) for a PSE voltage from 2.7 V to 10.1 V. In order to compensate for the non-linear effect of the diode bridge and satisfy the specification at low PSE voltage, the NCP1081 presents a suitable impedance in parallel with the 25.5 kW Rdet external resistor connected between VPORTP and VPORTN. For some types of diodes (especially Schottky diodes), it may be necessary to adjust this external resistor. When the Detection_Off level is detected (typically 11.5 V) on VPORTP, the NCP1081 turns on its internal 3.3 V regulator and biasing circuitry in anticipation of the classification phase as the next step. Table 4. Single and Dual Event Classification , (where V bg is 1.2 V) VDDA1 1.2 V CLASS Rclass VPORTN1,2 1 Single event physical classification 802.3at 1 Two event physical classification 802.3at 2 Data-link (IP) communication classification A IEEE802.3at compliant PSE using this physical classification performs two classification events and looks for the appropriate response from the PD to check if the PD is IEEE802.3at compatible. The PSE will generate the sequence described in Figure 7. During the first classification finger, the PSE will measure the classification current which should be 40 mA if the PD is at compliant. If this is the case, the PSE will exit the classification range and will force the line voltage into the Mark Event range. Within this range, the PSE may check the non-valid input signature presented by the PD (using the two point measurement defined in the IEEE802.3af standard). Then the PSE will repeat the same sequence with the second classification finger. A PD which has detected the sequence “Finger + Mark + Finger + Mark” knows the PSE is IEEE802.3at compliant, meaning the PSE will deliver more current on the port. (Note that a PSE IEEE802.3at compliant may apply more than two fingers, but the final result will be the same as two fingers). In classification, the PD regulates a constant current source that is set by the external resistor RCLASS value on the CLASS pin. Figure 6 shows the schematic overview of the classification block. The current source is defined as: VPORTP 802.3af Two Event Layer 1 Classification Classification Current Source Generation R class Handshake An IEEE802.3af compliant PSE performs only One Event Layer 1 classification event by increasing the line voltage into the classification range only once. Once the PSE device has detected the PD device, the classification process begins. The NCP1081 is fully capable of responding and completing all classification handshaking procedures as described next. V bg Layer One Event Layer 1 Classification Classification I class + Standard NCP1081 Figure 6. Classification Block Diagram http://onsemi.com 11 NCP1081 UVLO_on 1st Class Event 20.5 V Class range 1st Mark Event 2nd Class Event 2nd Mark Event 13 V 9.5 V Mark Range 5.4 V Reset Range 0V 2 Fingers Classification with Mark Events (.at spec) Operation Mode: Detection Number of Mark Event: PSE Type identification: X Power On 0 2 1 PSE identified by default as type 1 PSE (af) PSE identified as type 2 PSE (at) Figure 7. Hardware Physical Classification Event Sequence nCLASS_AT Indicator converter). Otherwise, nCLASS_AT will be disabled and will be pulled up to VDDL (3.3 V typ) via an internal current source (20 mA typ) and via the external pull-up resistor. The following scheme illustrates how the nCLASS_AT pin may be configured with the processor of the powered device. An opto-coupler is used to guarantee full isolation between the Ethernet cable and the application. The nCLASS_AT active low open drain output pin can be used to notify to the microprocessor of the powered device that the PSE performed a one or two event hardware classification. If a two event hardware classification has occured and once the PD application is supplied power by the NCP1081 DC-DC converter, the nCLASS_AT pin will be pulled down to ARTN by the internal low voltage NMOS switch (ARTN is the ground connection of the DC-DC Powered Device Application Csup VSUP VDDL VDDL Rbip Rled 20 mA nCLASS_AT Layer 2 Engine IN1 Microprocessor or Microcontroller IN2 Opto 1 Class_AT Features ARTN GND NCP1081 Isolation (Isolated DC/DC converter) Figure 8. Isolated nClass_AT Communication with the Powered Device Application http://onsemi.com 12 NCP1081 As soon as the application is powered by the DC-DC converter and completes initialization, the microprocessor should check if the NCP1081 detected a two event hardware classification by reading its digital input (pin IN1 in this example). If pin IN1 is low, the application knows power is supplied by a IEEE802.3at compliant PSE, and can deliver power up to the level specified by the IEEE802.3at standard. Otherwise the application will have to perform a Layer 2 classification with the PSE. There are several scenarios for which the NCP1081 will not enable its nCLASS_AT pin: • The PSE skipped the classification phase. • The PSE performed a one event hardware classification (it can be a IEEE802.3af or a 802.3at compliant PSE with Layer 2 engine). • The PSE performed a two event hardware classification but it did not properly control the input voltage in the mark voltage window, (for example it crossed the reset range). To define the UVLO threshold externally, the UVLO pin must be connected to the center of an external resistor divider between VPORTP and VPORTN1,2 as shown in Figure 10. The series resistance value of the external resistors must add to 25.5 kW and replaces the internal signature resistor. VPORTP R1 VPORT R2 VPORTN1,2 NCP1081 Figure 10. External UVLO Configuration Power Mode When the classification hand−shake is completed, the PSE and PD devices move into the operating mode. For a Vuvlo_on desired turn−on voltage threshold, R1 and R2 can be calculated using the following equations: Under Voltage Lock Out (UVLO) R1 ) R2 + R det The NCP1081 incorporates an under voltage lock out (UVLO) circuit which monitors the input voltage and determines when to apply power to the DC−DC controller. To use the default settings for UVLO (see Table 3), the pin UVLO must be connected to VPORTN1,2. In this case the signature resistor has to be placed directly between VPORTP and VPORTN1,2, as shown in Figure 9. R2 + Rdet 1.2 V ulvo_on R det When using the external resistor divider, the NCP1081 has an external reference voltage hysteresis of 15 percent typical. Inrush and Operational Current Limitations The inrush current limit and the operational current limit are programmed individually by an external Rinrush and Rilim1 resistors respectively connected between INRUSH and VPORTN1,2, and between ILIM1 and VPORTN1,2 as shown in Figure 11. VPORTP VPORT UVLO UVLO VPORTN1,2 NCP1081 Figure 9. Default UVLO Settings http://onsemi.com 13 NCP1081 VDDA1 VDDA1 Vbg1 ILIM1 / INRUSH Ilim_ref NCP1081 VPORTNx Figure 11. Current Limitation Configuration (Inrush & Ilim1 Pins) Inrush 0 Ilim1 1 I_pass_switch & VDS_PGOOD Vds_pgood threshold Current_limit_ON detector VDDA1 VDDA1 VDDA1 2V 1 V / 9.2 V VPORTNx RTN Pass Switch NCP1081 Figure 12. Inrush and Ilim1 Selection Mechanism Thermal Shutdown When VPORT reaches the UVLO_on level, the Cpd capacitor is charged with the INRUSH current (in order to limit the internal power dissipation of the pass−switch). Once the Cpd capacitor is fully charged, the current limit switches from the inrush current to the current limit level (ilim1) as shown in Figure 12. This transition occurs when both following conditions are satisfied: 1. The VDS of the pass−switch is below the Vds_pgood low level (1 V typical). 2. The pass−switch is no longer in current limit mode, meaning the gate of the pass−switch is “high” (above 2 V typical). The operational current limit will stay selected as long as Vds_pgood is true (meaning that RTN−VPORTN1,2 is below the high level of Vds_pgood). This mechanism allows a current level transition without any current spike in the pass−switch because the operational current limit (ilim1) is enabled once the pass−switch is not limiting the current anymore, meaning that the Cpd capacitor is fully charged. The NCP1081 includes thermal protection which shuts down the device in case of high power dissipation. Once the thermal shutdown (TSD) threshold is exceeded, following blocks are turned off: • DC−DC controller • Pass−switch • VDDH and VDDL regulators • CLASS regulator When the TSD error disappears and if the input line voltage is still above the UVLO level, the NCP1081 automatically restarts with the current limit set in the inrush state, the DC−DC controller is disabled and the Css (soft−start capacitor) discharged. The DC−DC controller becomes operational as soon as capacitor Cpd is fully charged. http://onsemi.com 14 NCP1081 DC−DC Converter Controller The NCP1081 implements a current mode DC−DC converter controller which is illustrated in Figure 13. VPORTP OSC VDDL 5 kW 1.2 V Oscillator Reset CLK FB Set CLK VDDL 3.3 V LDO COMP 9 V LDO Current Slope Compensation 10 mA 0 VDDH PWM comp CS Blanking time S Q 1.45 V 11 kW Gate Driver GATE R 2 ARTN Current limit comp VDDL 360 mV 5 mA SS Soft−start Figure 13. DC−DC Controller Block Diagram Internal VDDH and VDDL Regulators and Gate Driver In isolated topologies the error amplifier is not used because it is already implemented externally with the shunt regulator on the secondary side of the DC−DC controller (see Figure 2). Therefore the FB pin must be strapped to ARTN and the output transistor of the opto−coupler has to be connected on the COMP pin where an internal 5 kW pull−up resistor is tied to the VDDL supply (see Figure 13). An internal linear regulator steps down the VPORTP voltage to a 9 V output on the VDDH pin. VDDH supplies the internal gate driver circuit which drives the GATE pin and the gate of the external power MOSFET. The NCP1081 gate driver supports an external MOSFET with high Vth and high input gate capacitance. A second LDO regulator steps down the VDDH voltage to a 3.3 V output on VDDL. VDDL powers the analog circuitry of the DC-DC controller and nCLASS_AT blocks. Moreover it can provide current to light a LED connected on the nCLASS_AT pin. In order to prevent uncontrolled operations, both regulators include power−on−reset (POR) detectors which prevent the DC−DC controller from operating when either VDDH or VDDL is too low. In addition, an over−voltage lockout (OVLO) on the VDDH supply disables the gate driver in case of an open−loop converter with a configuration using the bias winding of the transformer (see Figure 4). Both VDDH and VDDL regulators turn on as soon as VPORT reaches the Vuvlo_on threshold. Soft−Start The soft−start function provided by the NCP1081 allows the output voltage to ramp up in a controlled fashion, eliminating output voltage overshoot. This function is programmed by connecting a capacitor CSS between the SS and ARTN pins. While the DC−DC controller is in POR, the capacitor CSS is fully discharged. After coming out of POR, an internal current source of 5 mA typically starts charging the capacitor CSS to initiate soft−start. When the voltage on SS pin has reached 0.45 V (typical), the gate driver is enabled and DC−DC operation starts with a duty cycle limit which increases with the SS pin voltage. The soft−start function is finished when the SS pin voltage goes above 1.6 V for which the duty cycle limit reaches its maximum value of 80 percent. Soft−start can be programmed by using the following equation: Error Amplifier In non−isolated converter topologies, the high gain internal error amplifier of the NCP1081 and the internal 1.2 V reference voltage regulate the DC−DC output voltage. In this configuration, the feedback loop compensation network should be inserted between the FB and COMP pins as shown in Figures 3, 4 and 5. t SS(ms) + 0.23 http://onsemi.com 15 C SS(nF) NCP1081 Current Limit Comparator conduction mode (CCM) and when the duty cycle is close or above 50 percent, the NCP1081 integrates a current slope compensation circuit. The amplitude of the added slope compensation is typically 110 mV over one cycle. As an example, for an operating switching frequency of 250 kHz, the internal slope provided by the NCP1081 is 27.5 mV/ mA typically. The NCP1081 current limit block behind the CS pin senses the current flowing in the external MOSFET for current mode control and cycle−by−cycle current limit. This is performed by the current limit comparator which, on the CS pin, senses the voltage across the external Rcs resistor located between the source of the MOSFET and the ARTN pin. The NCP1081 also provides a blanking time function on CS pin which ensures that the current limit and PWM comparators are not prematurely trigged by the current spike that occurs when the switching MOSFET turns on. DC−DC Controller Oscillator The frequency is configured with the Rosc resistor inserted between OSC and ARTN, and is defined by the following equation: R OSC(kW) + Slope Compensation Circuitry To overcome sub−harmonic oscillations and instability problems that exist with converters running in continuous 38600 F OSC(kHz) The duty cycle limit is fixed internally at 80 percent. http://onsemi.com 16 MECHANICAL CASE OUTLINE PACKAGE DIMENSIONS TSSOP−20 EP CASE 948AB−01 ISSUE O SCALE 1:1 DATE 17 JUN 2008 B D DETAIL B B 20 e/2 0.20 C A-B D 11 2X 10 TIPS E1 DETAIL B ÉÉÉ ÉÉÉ PIN 1 REFERENCE 1 E b b1 ÍÍÍÍ ÍÍÍÍ ÍÍÍÍ D c c1 10 e 20X A SECTION B−B b 0.10 TOP VIEW M C A-B D DIM A A1 A2 b b1 c c1 D E E1 e L L2 M P P1 M A2 B 0.05 C B A DETAIL A END VIEW 0.08 C 20X NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.07 IN EXCESS OF THE LEAD WIDTH AT MMC. DAMBAR CANNOT BE LOACTED ON THE LOWER RADIUS OR THE FOOT OF THE LEAD. 4. DIMENSIONS b, b1, c, c1 TO BE MEASURED BETWEEN 0.10 AND 0.25 FROM LEAD TIP. 5. DATUMS A AND B ARE ARE DETERMINED AT DATUM H. DATUM H IS LOACTED AT THE MOLD PARTING LINE AND COINCIDENT WITH LEAD WHERE THE LEAD EXITS THE PLASTIC BODY. 6. DIMENSION D DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.15 PER SIDE. DIMENSION E1 DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.15 PER SIDE. D AND E1 ARE DETERMINED AT DATUM H. SIDE VIEW A1 C SEATING PLANE H L2 P SEATING PLANE L DETAIL A P1 GAUGE PLANE C GENERIC MARKING DIAGRAM* XXXX XXXX ALYWG G BOTTOM VIEW SOLDERING FOOTPRINT XXXX A L Y W G 4.30 6.76 3.10 20X 0.98 MILLIMETERS MAX MIN --1.10 0.05 0.15 0.85 0.95 0.19 0.30 0.19 0.25 0.09 0.20 0.09 0.16 6.40 6.60 6.40 BSC 4.30 4.50 0.65 BSC 0.50 0.70 0.25 BSC 0_ 8_ --4.20 --3.00 = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package (Note: Microdot may be in either location) *This information is generic. Please refer to device data sheet for actual part marking. 20X 0.65 PITCH 0.35 DIMENSIONS: MILLIMETERS DOCUMENT NUMBER: DESCRIPTION: 98AON30874E TSSOP−20 EXPOSED PAD Electronic versions are uncontrolled except when accessed directly from the Document Repository. Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red. 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