LTC1735 Linear Technology, LTC1735 Datasheet
LTC1735
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LTC1735 Summary of contents
Page 1
... CMDSH-3 SGND INTV 4.7 F OSENSE FDS6680A MBRS340T3 – SENSE PGND + SENSE Figure 1. High Efficiency Step-Down Converter LTC1735 High Efficiency Switching Regulator U 1735 is a synchronous step-down switching 24V 50V C : PANASONIC EEFUEOG181R OUT C : MARCON THCR70E1H226ZT IN L1: PANASONIC ETQP6FZR0HFA ...
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... Peak Driver Output Current <10 s (TG, BG) .............. 3A INTV Output Current ......................................... 50mA CC Operating Ambient Temperature Range LTC1735C ............................................... LTC1735I ............................................ – Junction Temperature (Note 2) ............................. 125 C Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T ...
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... LTC1735CGN, LTC1735IGN • 130 C/ Note 3: The LTC1735 is tested in a feedback loop that servos V the balance point for the error amplifier (V = 1.2V). ITH Note 4: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See Applications Information. The denotes specifications which apply over the full operating = 25 C ...
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... LTC1735 W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Load Current (3 Operating Modes) 100 EXTV OPEN CC 90 BURST 80 SYNC 70 CONT 10V 3.3V OUT 0. 300kHz O 20 0.001 0.1 10 0.01 1 LOAD CURRENT (A) 1735 G01 Efficiency vs Input Voltage 100 EXTV OPEN 1.6V OUT ...
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... 3.3V OUT R = 0.01 SENSE 2 300kHz O 1.5 CONTINUOUS MODE SYNCHRONIZED 1.0 Burst Mode OPERATION 0 LOAD CURRENT (A) LTC1735 Maximum Current Sense Threshold vs Sense Common Mode Voltage COMMON MODE VOLTAGE (V) 1735 G11 ITH RUN/SS 2 0.7V OSENSE 2.0 1.5 1.0 ...
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... LTC1735 W U TYPICAL PERFOR A CE CHARACTERISTICS Oscillator Frequency vs Temperature 300 C = 47pF OSC 290 280 270 260 250 –40 – 135 110 TEMPERATURE ( C) 1735 G19 Start-Up V OUT 1V/DIV V RUN/SS 5V/DIV I L 5A/DIV 1735 G22 V = 15V 5ms/DIV 1.6V OUT R = 0.16 LOAD V OUT(RIPPLE) ...
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... INTV INTV ). CC TG (Pin 16): High Current Gate Drive for Top N-Channel MOSFET. This is the output of a floating driver with a + and SENSE pins in voltage swing equal to INTV switch node voltage SW. LTC1735 power when higher than 4.7V. See EXTV ...
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... LTC1735 CTIO AL DIAGRA C OSC C 1 SGND 5 OSC SYNC OSC OV + – 0.86V V OSENSE V gm =1.3m FB – 0. 0.86V SD RUN 1.2 A SOFT- 4 START + OVER- 6V CURRENT SLOPE COMP LATCHOFF R C RUN/ 0.8V REF 0. FCB – – 1.2V 0.8V FORCE BOT ...
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... Low Current Operation from an external FB The LTC1735 has three low current modes controlled by the FCB pin. Burst Mode operation is selected when the FCB pin is above 0.8V (typically tied to INTV Mode operation, if the error amplifier drives the I below 0 ...
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... INTV /EXTV CC Power for the top and bottom MOSFET drivers and most of the internal circuitry of the LTC1735 is derived from the INTV pin. When the EXTV CC 5.2V low dropout regulator supplies the INTV from V ...
Page 11
... Lower inductor values (higher I at higher load currents, which can cause a dip in efficiency in the upper range of low current operation. In Burst Mode 500 600 operation, lower inductance values will cause the burst frequency to decrease. 1735 F02 LTC1735 decreases with higher induc OUT V 1 – ...
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... Selection criteria for the power MOSFETs include the “ON” resistance R input voltage and maximum output current. When the LTC1735 is operating in continuous mode the duty cycles for the top and bottom MOSFETs are given by: Main Switch Duty Cycle Synchronous Switch Duty Cycle ...
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... OPTI-LOOP components, so make sure not to over compensate and slow down the response. The = output capaci- OUT minimum capacitance to assure the inductors’ energy is adequately absorbed is: L LTC1735 has been met, the RMS current OUT requirement. RIPPLE(P–P) and allowing 2/3 of the ripple due OUT(MAX) ...
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... Efficiency Considerations section. The junction tempera- ture can be estimated by using the equations given in Note 2 of the Electrical Characteristics. For example, the LTC1735CS is limited to less than 17mA from a 30V supply when not using the EXTV (17mA)(30V)(110 C/W) = 126 C ...
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... U U APPLICATIO S I FOR ATIO EXTV Connection CC The LTC1735 contains an internal P-channel MOSFET switch connected between the EXTV Whenever the EXTV pin is above 4.7V the internal 5.2V CC regulator shuts off, the switch closes and INTV supplied via EXTV until EXTV drops below 4.5V. This ...
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... V feedback current. OSENSE voltage across the Soft-Start/Run Function B The RUN/SS pin is a multipurpose pin that provides a soft- start function and a means to shut down the LTC1735. + INTV . IN CC Soft-start reduces surge currents from V needs to be 100 times increasing the controller’s current limit I can also be used for power supply sequencing ...
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... D1 is progressively lowered from 75mV to 30mV. Under short-circuit conditions with very low duty cycle, the C SS LTC1735 will begin cycle skipping in order to limit the short-circuit current. In this situation the bottom MOSFET (b) 1735 F06 will be conducting the peak current. The short-circuit ripple current is determined by the minimum on-time ...
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... Minimum On-Time Considerations Minimum on-time t is the smallest amount of time ON(MIN) that the LTC1735 is capable of turning the top MOSFET on and off again determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low ...
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... Remember to include this current when choosing resistor values R3 and R4. The internal LTC1735 oscillator can be synchronized to an external oscillator by applying and clocking the FCB pin with a signal above 1.5V external frequency, Burst Mode operation is disabled but cycle skipping is allowed at low load currents since current reversal is inhibited ...
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... LTC1735 U U APPLICATIO S I FOR ATIO Although all dissipative elements in the circuit produce losses, 4 main sources usually account for most of the losses in LTC1735 circuits: 1) LTC1735 INTV current losses, 4) Topside MOSFET CC transition losses. 1) The V current is the DC supply current given in the ...
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... To select values for R1 and R4, first determine the amount of output deregulation allowed. The actual specification for a typical microprocessor allows the output to vary 0.112V. The LTC1735 reference accu- racy is 1%. Using 1% tolerance resistors, the total feedback divider accuracy is about 1% because both feedback resistors are close to the same value ...
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... C10: KEMET T494A475M010AS C12 TO C14: TAIYO YUDEN GMK325F106 16 M1 C15 TO C18: PANASONIC EEFUE0G181R FDS6680A D1: CENTRAL SEMI CMDSH-3 D2: MOTOROLA MBRS340 15 L1: PANASONIC ETQP6F1R0SA M1 TO M3: FAIRCHILD FDS6680A C8 R5: IRC LRF2512-01-R003-J 0. U1: LINEAR TECHNOLOGY LTC1735CS 13 D1 CMDSH MBRS340 M2 FDS6680A + C10 2 C9 4.7 F ...
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... ITH sponse from almost 200mV Refer to Design Solutions 10 for more information about active voltage positioning ITH MIN ( ) . V 1 085 . V LTC1735 pin and resistor R1 that sinks current TH – – 085 ITH NOM ( ) V 1 085 ...
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... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. Although the LTC1735 has a maximum input voltage of 36V, most applications will be limited to 30V by 1735 F09 the MOSFET BV Figure 11 ...
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... Are the signal and power grounds segregated? The LTC1735 PGND pin should tie to the ground plane close to the input capacitor(s). The SGND pin should then connect to PGND and all components that connect to SGND should make a single point tie to the SGND pin. The synchronous MOSFET source pins should connect to the input capacitor(s) ground ...
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... 47pF 1000pF feedback pins. All of these nodes have very large and fast moving signals and therefore should be kept on the “output side” (Pin 9 to Pin 16) of the LTC1735 and occupy minimum PC trace area OSC 2 15 RUN/SS ...
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... BOOST 0. MBR0530 12 INTV CC + 4 FDS6680A MBRD835L 10 PGND 9 V EXTV IN CC LTC1735 50V CER R SENSE V 0.01 OUT 1. 32.4k C OUT + 1% 150 F 6. 25.5k PANASONIC SP 1% SGND C : PANASONIC EEFUEOG151R OUT C : MARCON THCR70LE1H226ZT IN L1: PANASONIC ETQP6F3R3HFA ...
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... CMDSH-3 FMMT625 V OUT 1M C OSC 150pF OSC RUN/SS BOOST C C 2200pF LTC1735 100pF 4 13 FCB SGND INTV CC 47pF OSENSE 10 7 – SENSE PGND 3300pF SENSE EXTV CC 100 ...
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... 50V Si4412DY T1A T1B B • • CMDSH 4 MBRS140T3 Si4412DY OUT2 LTC1735 30V OS-CON 1000pF SEC 35V SENSE AVX 0.012 V OUT 5V 3.5A R2 105k C OUT + 1% 100 F 10V 3 R1 AVX 20k ...
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... LTC1735 PACKAGE DESCRIPTION 0.007 – 0.0098 (0.178 – 0.249) 0.016 – 0.050 (0.406 – 1.270) * 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 ...
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... DWG # 05-08-1610 0.228 – 0.244 (5.791 – 6.197 0.053 – 0.069 (1.346 – 1.752) 0 – 8 TYP 0.014 – 0.019 (0.355 – 0.483) TYP LTC1735 0.386 – 0.394* (9.804 – 10.008 0.150 – 0.157** (3.810 – 3.988 ...
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... Linear Technology Corporation. *DC = Duty Cycle SENSE Linear Technology Corporation 32 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com 3.3V 0 Si4410DY BOOST 14 SW LTC1735 1 CMDSH-3 12 INTV Si4410DY MBRS140T3 10 – PGND ...