LT8610AX 42V, 3.5A Synchronous Step-Down Regulator with Operation to 175°C DESCRIPTION FEATURES 100% Tested at 175°C nn ±2% Reference Accuracy Over –40°C to 175°C Range nn Wide Input Voltage Range: 3.7V to 42V nn Ultralow Quiescent Current Burst Mode® Operation nn High Efficiency Synchronous Operation nn 91% Eff. at 0.5A, at 175°C, 3.3V OUT from 12VIN nn 92% Eff. at 0.5A, at 175°C, 5V OUT from 12VIN nn Adjustable and Synchronizable Frequency: 200kHz to 2.2MHz nn No Thermal Shutdown nn Internal Compensation nn Output Soft-Start and Tracking nn Power Good Flag nn Small Thermally-Enhanced 16-Lead MSOP Package nn APPLICATIONS nn Oil and Gas Exploration The LT®8610AX is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator rated to 175°C junction temperature. The LT8610AX is 100% tested a 175°C. Top and bottom power switches are included with all necessary circuitry to minimize the need for external components. Low ripple Burst Mode operation enables high efficiency across a wide range of output currents while keeping the output ripple low. A SYNC pin allows synchronization to an external clock. Internal compensation with peak current mode topology allows the use of small inductors and results in fast transient response and good loop stability. The EN/UV pin has an accurate 1V threshold and can be used to program VIN undervoltage lockout or to shut down the LT8610AX. A capacitor on the TR/SS pin programs the output voltage ramp rate during startup while the PG flag signals when VOUT is within ±9% of the programmed output voltage as well as fault conditions. The LT8610AX is available in small 16-lead MSOP package with exposed pad for low thermal resistance. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 3.3V Step-Down Converter Efficiency at 175°C Efficiency at 175°C 100 VIN 4.7µF 0.1µF 4.7µH EN/UV LT8610AX 100nF SW BIAS TR/SS 49.9k PG 1µF 100k FB INTVCC RT 90 BST GND 10pF SYNC 80 70 60 50 40 30 20 41.2k 60.4k fSW = 700kHz 47µF ×2 1210 X7R VOUT 3.3V 3.5A EFFICIENCY (%) VIN 3.7V TO 42V 8610AX TA01a TA = 175°C 12VIN 10 0 1 10 100 1k LOAD CURRENT (mA) 10k 8610AX TA01b 8610axf For more information www.linear.com/LT8610AX 1 LT8610AX ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VIN, EN/UV, PG...........................................................42V BIAS...........................................................................30V FB, TR/SS Voltage ......................................................4V SYNC Voltage ..............................................................6V Operating Junction Temperature Range (Note 2) LT8610AX............................................... –40 to 175°C Storage Temperature Range.......................–65 to 150°C TOP VIEW SYNC TR/SS RT EN/UV VIN VIN NC GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 17 GND FB PG BIAS INTVCC BST SW SW SW MSE PACKAGE 16-LEAD PLASTIC MSOP θJA = 40°C/W, θJC(PAD) = 10°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION (http://www.linear.com/product/LT8610AX#orderinfo) LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT8610AXMSE#PBF LT8610AXMSE#TRPBF 8610AX 16-Lead Plastic MSOP –40°C to 175°C Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN Minimum Input Voltage VIN Current in Regulation VOUT = 0.97V, VIN = 6V, Output Load = 100μA VOUT = 0.97V, VIN = 6V, Output Load = 1mA Feedback Reference Voltage VIN = 12V TYP MAX l 3.2 3.7 V l l 26 230 100 400 μA μA V V l 0.966 0.950 0.972 0.970 0.978 0.990 UNITS Oscillator Frequency RT = 60.4k l 665 700 735 kHz PG Upper Threshold Offset from VFB VFB Falling l 6 9 12 % PG Lower Threshold Offset from VFB VFB Rising l –12 –9 –6 % 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: Devices are 100% tested at 175°C to the limits shown. For normal operating temperature range specifications, please see the LT8610A/ LT8610AB data sheet. The LT8610AX performance is based on the LT8610AB. 2 Note 3. The LT8610AX is guaranteed over the full –40°C to 175°C operating junction temperature range. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125°C. The LT8610AX has no thermal shutdown. 8610axf For more information www.linear.com/LT8610AX LT8610AX TYPICAL PERFORMANCE CHARACTERISTICS Reference Reference Voltage Voltage Reference Reference Voltage Voltage at at 175°C 175C 45 1000 LOAD = 0.5A 100 N = 347 µ = 968.5 σ = 3.33 90 960 950 30 EFFICIENCY (%) 970 15 940 25 50 75 100 125 150 TEMPERATURE (°C) 175 200 36VIN 50 40 30 12VIN 80 24VIN 70 EFFICIENCY (%) 85 90 36VIN 80 75 70 36VIN 40 30 160 120 100 80 60 40 0.1 1 10 100 LOAD CURRENT (mA) 15 20 25 30 INPUT VOLTAGE (V) 36VIN 75 1k 10k 60 100 200 300 400 500 600 700 800 900 1000 LOAD CURRENT (mA) 8610AX G06 Power Up at 175°C EN 5V/DIV VIN 10V/DIV VOUT 2V/DIV VOUT 2V/DIV PG 2V/DIV SS 2V/DIV PG 2V/DIV SS 2V/DIV 10ms/DIV 20 10 24VIN TA = 175°C 140 5 80 EN Cycling at 175°C TA = 175°C FRONT PAGE APP 3.3VOUT IN REGULATION 180 85 8610AX G05 No Load Input Current at 175°C 200 TA = 175°C fSW = 700kHz 65 0 0.01 8610AX G04 12VIN 70 10 60 100 200 300 400 500 600 700 800 900 1000 LOAD CURRENT (mA) 10k 90 24VIN 20 65 0 95 12VIN 50 1k OUT 100 TA = 175°C fSW = 700kHz 60 1 10 100 LOAD CURRENT (mA) Efficiency at 175°C, VOUT = 5V OUT EFFICIENCY (%) 100 TA = 175°C fSW = 700kHz 90 0.1 8610AX G03 Efficiency Efficiency at at 175°C, 175°C, VVOUT == 5V 5V OUT 95 0 0.01 8610AX G02 Efficiency at 175°C, VOUT = 3.3V 100 EFFICIENCY (%) 24VIN 60 10 0 950 955 960 965 970 975 980 985 990 REFERENCE VOLTAGE (mV) 8610AX G01 INPUT CURRENT (uA) 12VIN 70 20 930 920 OUT TA = 175°C fSW = 700kHz 80 980 NUMBER OF PARTS REFERENCE VOLTAGE (mV) 990 Efficiency Efficiency at at 175°C, 175°C, VVOUT ==3.3V 3.3V 35 8610AX G08 TA = 175°C 10ms/DIV 8610AX G09 40 8610AX G07 8610axf For more information www.linear.com/LT8610AX 3 LT8610AX PIN FUNCTIONS SYNC (Pin 1): External Clock Synchronization Input. Ground this pin for low ripple Burst Mode operation at low output loads. Tie to a clock source for synchronization to an external frequency. Apply a DC voltage of 3V or higher or tie to INTVCC for pulse-skipping mode. When in pulseskipping mode, the IQ will increase to several hundred µA. Do not float this pin. SW (Pins 9, 10, 11): The SW pins are the outputs of the internal power switches. Tie these pins together and connect them to the inductor and boost capacitor. This node should be kept small on the PCB for good performance. TR/SS (Pin 2): Output Tracking and Soft-Start Pin. This pin allows user control of output voltage ramp rate during start-up. A TR/SS voltage below 0.97V forces the LT8610AX to regulate the FB pin to equal the TR/SS pin voltage. When TR/SS is above 0.97V, the tracking function is disabled and the internal reference resumes control of the error amplifier. An internal 2.2μA pull-up current from INTVCC on this pin allows a capacitor to program output voltage slew rate. This pin is pulled to ground with an internal 230Ω MOSFET during shutdown and fault conditions; use a series resistor if driving from a low impedance output. This pin may be left floating if the tracking function is not needed. INTVCC (Pin 13): Internal 3.4V Regulator Bypass Pin. The internal power drivers and control circuits are powered from this voltage. INTVCC maximum output current is 20mA. Do not load the INTVCC pin with external circuitry. INTVCC current will be supplied from BIAS if VBIAS > 3.1V, otherwise current will be drawn from VIN. Voltage on INTVCC will vary between 2.8V and 3.4V when VBIAS is between 3.0V and 3.6V. Decouple this pin to power ground with at least a 1μF low ESR ceramic capacitor placed close to the IC. RT (Pin 3): A resistor is tied between RT and ground to set the switching frequency. EN/UV (Pin 4): The LT8610AX is shut down when this pin is low and active when this pin is high. The hysteretic threshold voltage is 1.00V going up and 0.96V going down. Tie to VIN if the shutdown feature is not used. An external resistor divider from VIN can be used to program a VIN threshold below which the LT8610AX will shut down. VIN (Pins 5, 6): The VIN pins supply current to the LT8610AX internal circuitry and to the internal topside power switch. These pins must be tied together and be locally bypassed. Be sure to place the positive terminal of the input capacitor as close as possible to the VIN pins, and the negative capacitor terminal as close as possible to the GND pins. NC (Pin 7): No Connect. This pin is not connected to internal circuitry. 4 BST (Pin 12): This pin is used to provide a drive voltage, higher than the input voltage, to the topside power switch. Place a 0.1µF boost capacitor as close as possible to the IC. BIAS (Pin 14): The internal regulator will draw current from BIAS instead of VIN when BIAS is tied to a voltage higher than 3.1V. For output voltages of 3.3V and above this pin should be tied to VOUT. If this pin is tied to a supply other than VOUT use a 1µF local bypass capacitor on this pin. PG (Pin 15): The PG pin is the open-drain output of an internal comparator. PG remains low until the FB pin is within ±9% of the final regulation voltage, and there are no fault conditions. PG is valid when VIN is above 3.4V, regardless of EN/UV pin state. FB (Pin 16): The LT8610AX regulates the FB pin to 0.970V. Connect the feedback resistor divider tap to this pin. Also, connect a phase lead capacitor between FB and VOUT. Typically, this capacitor is 4.7pF to 10pF. GND (Pin 8, Exposed Pad Pin 17): Ground. These pins are the return path of the internal bottom-side switch and must be tied together. Place the negative terminal of the input capacitor as close to the GND pin and exposed pad as possible. The exposed pad must be soldered to the PCB in order to lower the thermal resistance. 8610axf For more information www.linear.com/LT8610AX LT8610AX APPLICATIONS INFORMATION For Application Information, Block Diagram, and Typical Performance Curves from –40°C to 150°C range, please see the LT8610A/LT8610AB Series data sheet. The LT8610AX will perform similarly to the LT8610AB. The LT8610AX has no thermal shutdown. PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LT8610AX#packaging for the most recent package drawings. MSE Package 16-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1667 Rev F) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.10 (.201) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 8 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 0.305 ±0.038 (.0120 ±.0015) TYP 16 0.50 (.0197) BSC 4.039 ±0.102 (.159 ±.004) (NOTE 3) RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 0.12 REF DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY 9 NO MEASUREMENT PURPOSE 0.280 ±0.076 (.011 ±.003) REF 16151413121110 9 DETAIL “A” 0° – 6° TYP 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 1234567 8 0.50 (.0197) BSC NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 0.86 (.034) REF 0.1016 ±0.0508 (.004 ±.002) MSOP (MSE16) 0213 REV F 8610axf 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 representation that the interconnection of itsinformation circuits as described herein will not infringe on existing patent rights. For more www.linear.com/LT8610AX 5 LT8610AX RELATED PARTS PART NUMBER DESCRIPTION COMMENTS PACKAGE LT1007X Low Noise 200°C Op Amp Low Noise, High Speed Precision Operational Amplifier 8-Lead TO-5 Metal Can LT580X 200°C, 2.5V Voltage Reference Ultra Low Drift, Curvature Corrected Reference 3-Lead TO-52 Metal Can LT581X 200°C, 10V Voltage Reference Ultra Low Drift, Curvature Corrected Reference 3-Lead TO-39 Metal Can LT582X 200°C, 5V Voltage Reference Ultra Low Drift, Curvature Corrected Reference 3-Lead TO-39 Metal Can 6 8610axf Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LT8610AX (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT8610AX LT 0416 • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2016