LT4180 LINER
Document overview
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Technical content
Electrical Specifications Subject to Change TYPICAL APPLICATION FEATURES DESCRIPTION Virtual Remote Sense Controller The L T®4180 solves the problem of providing tight load regulation over long, highly resistive cables without requiring an additional pair of remote sense wires. This Virtual Remote Sense™ device continuously interrogates the line impedance and corrects the power supply output voltage via its feedback loop to maintain a steady voltage at the load regardless of current changes. The L T4180 is a full-featured controller with 5mA opto- isolator sink capability, under/overvoltage lockout, soft-start and a ±1% internal voltage reference. The Virtual Remote Sense feature set includes user-program- mable dither frequency and optional spread spectrum dither . The L T4180 works with any topology and type of isolated or nonisolated power supply, including DC/DC converters and adjustable linear regulators. The L T4180 is available in a 24-pin, SSOP package. Isolated Power Supply with Virtual Remote Sense
APPLICATIONS
n Tight Load Regulation with Highly Resistive Cables without Requiring Remote Sense Wiring n Compatible with Isolated and Nonisolated Power Supplies n ±1% Internal Voltage Reference n 5mA Sink Current Capability n Soft-Correct Reduces Turn-On T ransients n Undervoltage and Overvoltage Protection n Pin-Programmable Dither Frequency n Optional Spread Spectrum Dither n Wide V IN Range: 3.1V to 50V n 24-Pin SSOP Package n 12V High Intensity Lamps n 28V Industrial Systems n High Power (>40 Watts) CAT5 Cable Systems n Wiring Drop Cancellation for Notebook Computer Battery Charging n AC and DC Adaptors n Well-Logging and Other Remote Instrumentation n Surveillance Equipment L, L T , L TC, L TM, Linear Technology and the Linear logo are registered trademarks and Virtual Remote Sense is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. VLOAD vs VWIRE CAT5E CABLE LINE LINE OVFB DIV0 DIV1VIN COSCCOMP DRAIN SENSE DIV2 SPREAD CHOLD1 CHOLD2 CHOLD3 CHOLD4
4180 TA01a
– L T4180 VIRTUAL REMOTE SENSE CL RL RSENSE VWIRING (V) VLOAD (V) 4.97 4.98 4.99 4.96 4.95 0.5 1.5 1 2 2.5 3 4.92 4.91 4.94 5.00 4.93
4180 TAO1b
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS INTVCC, RUN, FB, OV, ROSC, OSC, DIV0, DIV1, DIV2, SPREAD, CHOLD1, CHOLD2, CHOLD3, CHOLD4, DRAIN, COMP , GUARD2, GUARD3, GUARD4, V Operating Junction Temperature Range (Note 2) (Note 1) TOP VIEW GN PACKAGE 24-LEAD NARROW PLASTIC SSOP INTV CC DRAIN COMP CHOLD1 GUARD2 CHOLD2 GUARD3 CHOLD3 GUARD4 CHOLD4 FB GND VIN VPP SENSE RUN OV SPREAD DIV0 DIV1 DIV2 OSC ROSC COSC TJMAX = 150°C, θJA = 85°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE L T4180EGN#PBF L T4180EGN#TRPBF L T4180GN 24-Lead Narrow Plastic SSOP –40°C to 125°C L T4180IGN#PBF L T4180IGN#TRPBF L T4180GN 24-Lead Narrow Plastic SSOP –40°C to 125°C L T4180MPGN#PBF L T4180MPGN#TRPBF L T4180GN 24-Lead Narrow Plastic SSOP –55°C to 125°C Consult L TC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container . For more information on lead free part marking, go to: http://www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear .com/tapeandreel/
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Operating Supply Voltage l 3.10 50 V IVIN Input Quiescent Current ROSC Open, COSC Open, SENSE = V IN l 12 m A VREF Reference Voltage V CHOLD2 = VCHOLD3 = 1.2V , Measured at CHOLD4 During T rack ΔVOUT Clock Phase l 1.209 1.197 1.221 1.221 1.233 1.245 V V I LIM Open-Drain Current Limit With FB = V REF + 200mV , OSC Stopped with Voltage Feedback Loop Closed 51 0 1 5 m A VOL DRAIN Low Voltage V IN = 3V 0.3 V VINTVCC LDO Regulator Output Voltage V IN = 5V 3.15 V The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C, VIN = SENSE = 5V , unless otherwise noted.
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. The L T4180E is guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. Specifi cations over the –40°C The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C, VIN = SENSE = 5V , unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VINTVCC LDO Regulator Output Voltage in Dropout VIN = 2.5V 2.2 V VOV Overvoltage Threshold Rising 1.21 V VOHYST Overvoltage Input Hysteresis V RISING – VFALLING 20 80 mV VRUN Run Threshold Falling 1.21 V VRHYST Run Input Hysteresis V RISING – VFALLING 20 80 mV IFB Input Bias Current –0.2 0.2 μA VOS Current Amplifi er Offset Voltage V IN = 3.5V VIN = 5V VIN = 48V mV mV mV A V(RATIO) Current Amplifi er Gain Ratio A VL/AVH, AV Measured in V/V 0.891 0.9 0.909 ISENSE Current Amplifi er Input Bias Current Measured at SENSE with SENSE = V IN –1 1 μA AV ΔVFB Amplifi er Gain 9.7 10 10.3 V/V ICHOLD1 T rack/Hold Charging Current Measured at CHOLD1 with V CHOLD1 = 1.2V ±60 μA ICHOLD2 T rack/Hold Charging Current Measured at CHOLD2 with V CHOLD2 = 1.2V ±25 μA ICHOLD3 T rack/Hold Charging Current Measured at CHOLD3 with V CHOLD3 = 1.2V ±25 μA ICHOLD4 T rack/Hold Charging Current Measured at CHOLD4 with V CHOLD4 = 1.5V , VCHOLD2 = 1V , VCHOLD3 = 1.2V 10 μA Measured at CHOLD4 with VCHOLD4 = 1.5V , VCHOLD2 = 1.4V , VCHOLD3 = 1.2V –200 μA ISC Soft-Correct Current Measured at CHOLD4 ±1.5 μA ILKG1 T rack/Hold Leakage Current Measured at CHOLD1 with V CHOLD1 = 1.2V ±1 μA ILKG2 T rack/Hold Leakage Current Measured at CHOLD2 with V CHOLD2 = 1.2V ±1 μA ILKG3 T rack/Hold Leakage Current Measured at CHOLD3 with V CHOLD3 = 1.2V ±1 μA ILKG4 T rack/Hold Leakage Current Measured at CHOLD4 with V CHOLD4 = 1.2V ±1 μA fOSC Oscillator Frequency R OSC = 20k, COSC = 1nF 170 200 230 kHz gmFB Voltage Error Amplifi er T ransconductance Measured from FB to COMP, VCOMP = 2V , OSC Stopped with Voltage Feedback Loop Closed 110 μmho gmIAMP Current Amplifi er T ransconductance Measured from SENSE to COMP , VCOMP = 2V , OSC Stopped with Current Feedback Loop Closed 750 μmho to 125°C operating junction temperature range are assured by design characterization and correlation with statistical process controls. The L T4180I is guaranteed over the full –40°C to 125°C operating junction temperature range. The L T4180MP is guaranteed over the full –55°C to 125°C operating junction temperature range. Note 3. Positive current is defi ned as fl owing into a pin.
TYPICAL PERFORMANCE CHARACTERISTICS IDRAIN vs VDRAIN Normal Timing Spread Spectrum Timing VLOAD vs VWIRE Load Step in 12V Linear Application Load Step in Buck Application VREF vs Temperature INTV CC vs Temperature Oscillator Frequency vs Temperature VWIRING (V) VLOAD (V) 4.97 4.98 4.99 4.96 4.95 0.5 1.5 1 2 2.5 3 4.92 4.91 4.94 5.00 4.93
4180 G07
200mA TO 700mA LOAD TRANSIENT 100μF LOAD CAP VSENSE 2V/DIV VLOAD 2V/DIV ILOAD 200mA/DIV
4180 G08
RWIRE = 4Ω CL = 100μF 5μs/DIV TRIGGERED ON CHOLD1 500mV/DIV CHOLD1 WITH 15k PULL-DOWN 2V/DIV OSC
4180 G05
1μs/DIV TRIGGERED ON OSC 500mV/DIV CHOLD1 WITH 15k PULL-DOWN 2V/DIV OSC
4180 G06
4180 G09
1.2A TEMPERATURE (°C) –55 VREF (V) 1.2205 1.2210 1.2215 105 1.2200 1.2195 1.2190 –35 –15 5 25 45 65 85 125
4108 G01
TEMPERATURE (°C) –55 INTVCC (V) 3.150 3.160 3.155 3.165 105 3.145 3.140 3.135 –35 –15 5 25 45 65 85 125
4108 G02
TEMPERATURE (°C) –55 FREQUENCY (kHz) 203.0 203.5 204.0 105 202.5 202.0 201.5 –35 –15 5 25 45 65 85 125
4108 G03
ROSC = 20k COSC = 1nF VDRAIN (V) IDRAIN (mA)8 0.7
4180 G04
capacitor provides decoupling and output compensation. on the regulator control pin. additional compensation. It must be left open if unused. GUARD2 (Pin 5): Guard Ring Drive for CHOLD2. GUARD3 (Pin 7): Guard Ring Drive for CHOLD3. GUARD4 (Pin 9): Guard Ring Drive for CHOLD4. should be no greater than 0.1 times the dither frequency. the minimum recommended capacitance is 100pF . frequency is set by this resistor and COSC. also be used with this output. DIV2 (Pin 16): Dither Division Ratio Programming Pin. DIV1 (Pin 17): Dither Division Ratio Programming Pin. DIV0 (Pin 18): Dither Division Ratio Programming Pin. Table 1. Programming the Dither Division Ratio (fOSC/fDITHER) the start-up threshold for the line drop corrector . VPP (Pin 23): Connect this pin to INTVCC. this pin and minimize interconnect resistance.
CORRECTED _REF GM2 OV UV + – GM1 TRACK/ HOLD + – IAMP TRACK/ HOLD INST AMP TRACK/ HOLD TRACK/ HOLD TRACK_HI_FB TRACK_LOW_FB TRACK_DEL TA_FB REF REF REF_OK CHOLD2 FB GUARD2 GUARD3 GUARD4
12 GND
4 CHOLD1
3 COMP
2 DRAIN
21 RUN
TRACK_HI_I FB_SELECT OVERVOL TAGE UNDERVOL TAGE BANDGAP SENSE INTVCC24 VIN LDO VPP TRIM CIRCUIT HI_GAIN RLIM 19SPREAD 18DIV0 17DIV1 16DIV2 15OSC SPREAD SPECTRUM CLOCK GENERATOR OSC MOD CLK
at the load, which may not always be practical. Figure 1. T raditional Remote Sensing Figure 2. Virtual Remote Sensing Figure 3. Simplifi ed Timing Diagram, Virtual Remote Sense
4180 F02
4180 F01
4180 F03
and provides best control loop response. Figure 4. Nonisolated Regulator Interface The closest standard 1% value is 34k. the ITH pin voltage is made more positive. MOSFET for the cascode transistor . Figure 5. Isolated Power Supply Interface Figure 6. Cascoded DRAIN Pin for Isolated Supplies
4180 F04
4180 F05
4180 F06
First determine the settling time (to 1% of fi nal value) of the power supply. The settling time should be the worst-case value (over the whole operating envelope: V IN, ILOAD, etc.). F t Hz SETTLING 1 1 2= For example, if the power supply takes 1ms to settle (worst-case) to within 1% of fi nal value: F e Hz1 1 21 3 500== – Next, determine the propagation time of the wiring. In order to ignore transmission line effects, the dither period should be approximately twenty times longer than this. This will limit dither frequency to: F V ns ft L HzF2 20 1 017= . / Where VF is the velocity factor (or velocity of propagation), and L is the length of the wiring (in feet). For example, assume the load is connected to a power supply with 1000ft of CAT5 cable. Nominal velocity of propagation is approximately 70%. F e kHz2 07 20 1 017 9 1000 34 4== . . .– The maximum dither frequency should not exceed F1 or F2 (whichever is less): f DITHER < min (F1, F2). Continuing this example, the dither frequency should be less than 500Hz (limited by the power supply). With the dither frequency known, the division ratio can be determined: D f fRATIO OSC DITHER == = 250 000 500 500, The nearest division ratio is 512 (set DIV0 = L, DIV1 = DIV2 = H). Based on this division ratio, nominal dither frequency will be: f f D HzDITHER OSC RATIO == = 250 000 512 488, After the dither frequency is determined, the minimum load decoupling capacitor can be determined. This load capacitor must be suffi ciently large to fi lter out the dither signal at the load. C RfLOAD WIRE DITHER = 22 Where CLOAD is the minimum load decoupling capacitance, RWIRE is the minimum wiring resistance of one conduc- tor of the wiring pair , and fDITHER is the minimum dither frequency. Continuing the example, our CAT5 cable has a maximum 9.38Ω/100m conductor resistance. Maximum wiring resistance is: R WIRE = 2 • 1000ft • 0.305m/ft • 0.0938Ω/m R WIRE = 57.2Ω
47pF capacitor . 10k and 10nF are good starting values. smaller value of the compensation capacitor , if necessary. Figure 7. Voltage Divider for Output Voltage, UVL and OVL
4180 F07
Find the equivalent series resistance for R2 and R3 (RSERIES). This resistance will determine the RUN voltage level. nominal output voltage desired. and SENSE should be Kelvin connected to this resistor . whenever an overvoltage condition occurs. Figure 8. Soft-Correct Operation, CHOLD4 = 1μF
4180 F08
sources on the CHOLD pins should be minimized. respective guard ring drivers. Figure 10. Clock Interface for Synchronization (for isolated power supplies). Virtual remote sensing relies on sampling techniques. broadband noise, reducing its effect.
4180 F10
Figure 9. Simplifi ed Leakage Models (with and without Guard Rings)
4180 F09
12V , 500mA Linear Regulator 12V , 600mA Boost Regulator R11 10k 1% 5.36k OV FB DIV0DIV1V IN INTVCC INTVCC VPP COMP GND DRAIN DIV2 CHOLD1 CHOLD2GUARD2 GUARD3 GUARD4 CHOLD3 CHOLD4 C12 10nF
4180 TA03
4.7nF 47pF DFLS220 4.7μH OUTPUT TO WIRING AND LOAD (100mA MINIMUM) 600mA, 6Ω MAX R WIRE 470μF LOAD CAPACITANCEVISHAY IHLP2525CZ-11 1μF R12 41.7k 1nF 3.65k 61.9k R13 1.5k 1μF 0.05 OSC GND VIN 0.1μF R10 84.5k FAULT SHDN VCC SYNC RT SS CLKOUT GND GATE SW1 SW1 SW1 SW2 SW2 SW2 FB VC L T3581EMSE 191k 24.3k 10k 100k 10μF 25V 4.7μF 16V 20k OV FB DIV0DIV1VIN INTVCC INTVCC VPP COMP GND DRAIN DIV2 CHOLD1 CHOLD2GUARD2 GUARD3 GUARD4 CHOLD3 CHOLD4 C10 10nF
4180 TA02
2.2k SENSE SPREAD L T4180EGN C11 470pF 470pF 470pF 4.7nF IRLZ440 OUTPUT TO WIRING AND LOAD 500mA 8Ω MAX R WIRE 330μF LOAD CAPACITANCE 1μF 41.7k 3.74k 63.4k 1μF 0.1Ω OSCGND VIN 20V 27k 10μF 25V 4.7μF 25V 5.36k INTVCC 1nF 22pF VN2222 10k
3.3V Isolated Flyback Regulator R17 20k 1% R13 5.36k OV FB DIV0DIV1V IN VOUT SS VIN VINVIN INTVCC INTVCC2 VPP COMP GND DRAIN DIV2 PULSE ENGINEERING PA1277NL PA1277NL CHOLD1 CHOLD2GUARD2 GUARD3 GUARD4 CHOLD3 CHOLD4 C15 0.1μF
4180 TA04
2.74k SENSE SPREADU1 L T4180EGN C16 470pF C14 470pF C13 470pF C12 4.7nF (NANO) C11 47pF BAV21W BAS516 Si4848DY PS2801-1 OUTPUT TO WIRING AND LOAD 3.3V , 3A 0.4Ω MAX R WIRE 1000μF LOAD CAPACITANCE 1μF R15 41.2k C17 3.3nF 523Ω 13.3k 1μF 0.018 RT FB SHDN/ UVLO SYNC GND GATEVC VC VC SENSE 0.1μF R16 36.5k 105k INTVCC2 INTVCC R14 8.66k OSC OSC VIN 18V TO 72V GND 100pF 123 5678 78 32 UPS840 100μF 10V 100μF 10V 10k 4700pF CIN2 1μF 100V CIN1 1μF 100VR6 17.4k L T3758 EMSE R12 100Ω 4.7μF 50V C18 2200pF 250V VIN 51.1 1% R7, 1Ω 0.01μF R11 C10 (OPT .) RCS1 0.040Ω
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 24-Lead Plastic SSOP (Narrow .150 Inch) (Reference L TC DWG # 05-08-1641) .337 – .344* (8.560 – 8.738) GN24 (SSOP) 0204 12 3 4 5 6 7 8 9 10 11 12 .229 – .244 (5.817 – 6.198) .150 – .157** (3.810 – 3.988) 161718192021222324 15 1413 .016 – .050 (0.406 – 1.270) .015 ± .004 0° – 8 ° TYP.0075 – .0098 (0.19 – 0.25) .0532 – .0688 (1.35 – 1.75) .008 – .012 (0.203 – 0.305) TYP .004 – .0098 (0.102 – 0.249) .0250 (0.635) BSC .033 (0.838) REF .254 MIN RECOMMENDED SOLDER PAD LAYOUT .150 – .165 .0250 BSC.0165 ± .0015 .045 ±.005 *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE INCHES (MILLIMETERS) NOTE: 1. CONTROLLING DIMENSION: INCHES 2. DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE
Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear .com © LINEAR TECHNOLOGY CORPORATION 2010 LT 0310 • PRINTED IN USA RELATED PARTS TYPICAL APPLICATION PART NUMBER DESCRIPTION COMMENTS L T3581 Boost/Inverting DC/DC Converter with 3.3A Switch, Soft-Start and Synchronization 2.5V ≤ VIN ≤ 22V , Current Mode Control, 200kHz to 2.5MHz, MSOP-16E and 3mm × 4mm DFN-14 Packages L T3685 36V , 2A, 2.4MHz Step-Down Switching Regulator 3.6V≤ V IN ≤ 36V (60VPK), Integrated Boost Diode, MSOP-10E and 3mm × 3mm DFN Packages L T3573 Isolated Flyback Switching Regulator with 60V Integrated Switch 3V ≤ VIN ≤ 40V , Up to 7W , No Opto-Isolator or Third Winding Required, L T3757 Boost, Flyback, SEPIC and Inverting Controller 2.9V ≤ V IN ≤ 40V , Current Mode Control, 100kHz to 1MHz Programmable Operation Frequency, MSOP-10E and 3mm × 3mm DFN-10 Packages L T3758 Boost, Flyback, SEPIC and Inverting Controller 5.5V ≤ V IN ≤ 100V , Current Mode Control, 100kHz to 1MHz Programmable Operation Frequency, MSOP-10E and 3mm × 3mm DFN-10 Packages L TC3805/ L TC3805-5 Adjustable Fixed 70kHz to 700kHz Operating Frequency Flyback Controller VIN and VOUT Limited Only by External Components, MSOP-10E and 3mm × 3mm DFN-10 Packages R13 17.4k R10 5.36k OV FB DIV0DIV1V IN VIN 22V TO 36V GND VIN BD INTVCC INTVCC INTVCC VPP COMP GND DRAIN DIV2 CHOLD1 CHOLD2GUARD2 GUARD3 GUARD4 CHOLD3 CHOLD4 C13 10nF
4180 TA05
2.01k DFLS240 CMDSH-3 SENSE SPREAD L T4180EGN C14 330pF C12 470pF C11 470pF C10 4.7nF 47pF UI L T3685EDD OUTPUT TO WIRING AND LOAD 12V , 1.5A 2.5Ω MAX R WIRE 470μF LOAD CAPACITANCE 1μF R12 22.1k C15 1.5nF 3.65k 61.9k VISHAY 1HLP2020CZ-11 1μF 0.033 1% BOOST SYNC RT FB VC SW PG RUN/SD 22μF 25V R11 0.1μF 50V 22μF 50V 1μF 50V 100k 68.1k INTVCC 30.1k 10k OSC 0.47μF L1, 10μH 12V 1.5A Buck Regulator