LTC3714 Intel Compatible, Wide Operating Range, Step-Down Controller with Internal Op Amp Fea T Descrip T n True Current Mode with Ultrafast Transient Response The LTC 3714 is a synchronous step-down switching n Stable with Ceramic C regulator controller for CPU power. An output voltage OUT n t < 100ns for Operation from High Input between 0.6V and 1.75V is selected by a 5-bit code (Intel ON(MIN) Ranges mobile VID specification). The controller uses a constant n Supports Active Voltage Positioning on-time, valley current control architecture to deliver very n No Sense Resistor Required low duty cycles without requiring a sense resistor. Oper- n 5-Bit VID Programmable Output Voltage: 0.6V to 1.75V ating frequency is selected by an external resistor and is n Dual N-Channel MOSFET Synchronous Drive compensated for variations in V and V . IN OUT n Programmable Output Offsets Discontinuous mode operation provides high efficiency n Power Good Output Voltage Monitor operation at light loads. A forced continuous control pin n Wide V Range: 4V to 36V IN reduces noise and RF interference and can assist second- n 1% 0.6V Reference ary winding regulation by disabling discontinuous mode n Adjustable Frequency when the main output is lightly loaded. Internal op amp n Programmable Soft-Start allows programmable offsets to the output voltage during n Output Overvoltage Protection power saving modes. n Optional Short-Circuit Shutdown Timer n Fault protection is provided by internal foldback current Forced Continuous Control Pin n limiting, an output overvoltage comparator and optional Logic Controlled Micropower Shutdown: I 30A Q n short-circuit shutdown timer. Soft-start capability for Available in 0.209 Wide 28-Lead SSOP Package supply sequencing is accomplished using an external timing capacitor. The regulator current limit level is user a T programmable. Wide supply range allows operation from n Power Supply for Mobile Pentium Processors and 4V to 36V at the input. Transmeta Processors L, LTC and LT are registered trademarks of Linear Technology Corporation. n Notebook and Portable Computers Pentium is a registered trademark of Intel Corporation. Typical a T LTC3714 R ON Transient Response of 8A to 23A Output Load Step PGOOD I ON INTV CC V IN V C IN SS 5V TO 24V 10F 0.1F M1 1.395V RUN/SS TG 35V IRF7811 L1 4 2 0.68H I SW V TH OUT V C , 0.22F OUT R B 0.6V TO 1.75V C C 1.35V C C BOOST 23A OUT + D 50mV/DIV SGND B 270F CMDSH-3 2V INTV 4 CC M2 D1* 1.213V VID4 BG IRF7811 UPS840 3 VID3 23A SENSE 5-BIT + VID2 I LOAD C VID VCC 0.003* VID1 10A/DIV 4.7F VID0 8A PGND 3714 TA03 V OSENSE 20s/DIV 3714 F01 *OPTIONAL Figure 1. High Efficiency Step-Down Converter 3714f 1 ion pplica ions pplica ion uresLTC3714 a Te Maxi Mu M r a T p in c F T (Note 1) ORDER PART TOP VIEW Input Supply Voltage (V ), I .................. 36V to 0.3V IN ON NUMBER BG 1 28 INTV CC Boosted Topside Driver Supply Voltage PGND 2 27 V LTC3714EG IN (BOOST) ................................................... 42V to 0.3V SENSE 3 26 EXTV CC SW, SENSE Voltages .................................... 36V to 5V SW 4 25 VID4 EXTV , (BOOST SW), RUN/SS, VID0-VID4, CC TG 5 24 VID3 PGOOD, FCB Voltages ................................ 7V to 0.3V BOOST 6 23 V OSENSE V , V Voltages ................. (INTV + 0.3V) to 0.3V ON RNG CC VID0 7 22 VFB I , V , V Voltages ....................... 2.7V to 0.3V TH FB OSENSE VID1 8 21 I ON TG, BG, INTV , EXTV Peak Currents .................... 2A CC CC VID2 9 20 FCB TG, BG, INTV , EXTV RMS Currents ............... 50mA RUN/SS 10 19 SGND CC CC + OPV , OP , OP ..............................................0V to 18V V 11 18 OPOUT IN ON + PGOOD 12 17 OP Operating Ambient Temperature Range V 13 16 OP LTC3714EG (Note 2) ............................40C to 85C RNG I 14 15 OPV IN TH Junction Temperature (Note 3) ............................ 125C Storage Temperature Range .................. 65C to 150C G PACKAGE 28-LEAD PLASTIC SSOP Lead Temperature (Soldering, 10 sec) ...................300C T = 125C, = 130C/W JMAX JA Consult LTC Marketing for parts specified with wider operating temperature ranges. e Trical c T TThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 15V unless otherwise noted. A IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop I Input DC Supply Current Q Normal 900 2000 A Shutdown Supply Current 15 30 A l V Feedback Reference Voltage I = 1.2V (Note 4) 0.594 0.600 0.606 V FB TH V Feedback Voltage Line Regulation V = 4V to 30V (Note 4), I = 1.2V 0.002 %/V FB(LINEREG) IN TH l V Feedback Voltage Load Regulation I = 0.5V to 1.9V (Note 4) 0.05 0.3 % FB(LOADREG) TH g Error Amplifier Transconductance I = 1.2V (Note 4) l 1.4 1.7 2 ms m(EA) TH V Forced Continuous Threshold l 0.57 0.6 0.63 V FCB I Forced Continuous Current V = 0.6V 1 2 A FCB FCB t On-Time I = 60A, V = 1.5V 200 250 300 ns ON ON ON t Minimum On-Time I = 180A, V = 0V 50 100 ns ON(MIN) ON ON t Minimum Off-Time I = 60A, V = 1.5V 250 400 ns OFF(MIN) ON ON l V Maximum Current Sense Threshold V = 1V, V = 0.56V 113 133 153 mV SENSE(MAX) RNG FB l V = 0V, V = 0.56V 79 93 107 mV RNG FB l V = INTV , V = 0.56V 158 186 214 mV RNG CC FB V Minimum Current Sense Threshold V = 1V, V = 0.64V 67 mV SENSE(MIN) RNG FB V = 0V, V = 0.64V 33 mV RNG FB V = INTV , V = 0.64V 93 mV RNG CC FB V Output Overvoltage Fault Threshold 7.5 10 12.5 % FB(OV) V Output Undervoltage Fault Threshold 340 400 460 mV FB(UV) l V RUN Pin Start Threshold 0.8 1.5 2 V RUN/SS(ON) 3714f 2 ics eris harac lec ion igura on ings bsolu