LTC1435A Linear Technology, LTC1435A Datasheet
LTC1435A
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LTC1435A Summary of contents
Page 1
... LTC1435A 4.7 H CMDSH-3 C INTV B CC 0.1 F SGND BOOST + 4 OSENSE Si4412DY PGND – + SENSE SENSE 1000pF Figure 1. High Efficiency Step-Down Converter LTC1435A Switching Regulator U 1435A is a synchronous step-down switching 35V R SENSE 2 0.033 V OUT 1.6V/ 35.7k + OUT 100 F 6. ...
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... Peak Driver Output Current < (TG, BG) ............. 2A INTV Output Current ........................................ 50mA CC Operating Ambient Temperature Range LTC1435AC ............................................ LTC1435AI ......................................... – Junction Temperature (Note 1)............................. 125 C Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER ...
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... D LTC1435ACG/LTC1435AIG )(130 C/ LTC1435ACS/LTC1435AIS )(110 C/ Note 2: The LTC1435A is tested in a feedback loop which servos V to the balance point for the error amplifier ( TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Input Voltage V = 3.3V OUT 100 V = 3.3V OUT LOAD ...
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... LTC1435A W U TYPICAL PERFORMANCE CHARACTERISTICS Input Supply and Shutdown Current vs Input Voltage 2.5 2 OUT 1.5 EXTV = V CC OUT V = 3.3V 1.0 OUT EXTV = OPEN CC 0.5 SHUTDOWN INPUT VOLTAGE (V) 1435A G07 Normalized Oscillator Frequency vs Temperature –5 –10 – 40 – ...
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... 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. power when- CC LTC1435A Soft Start: Load Current vs Time 1435A G17 is higher than 4.7V. See EXTV 5V. OUT OUT ...
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... FOLDBACK CURRENT LIMITING OPTION U OPERATION (Refer to Functional Diagram) Main Control Loop The LTC1435A uses a constant frequency, current mode step-down architecture. During normal operation, the top MOSFET is turned on each cycle when the oscillator sets the RS latch, and turned off when the main current com- parator I resets the RS latch ...
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... Comparator OV guards against transient overshoots > 7.5% by turning off the top MOSFET and keeping it off until the fault is removed. Low Current Operation The LTC1435A is capable of Burst Mode operation in which the external MOSFETs operate intermittently based on load demand. The transition to low current operation begins when comparator I ...
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... LTC1435A U U APPLICATIONS INFORMATION The value calculated from the desired operating OSC frequency: 4 1.37( OSC Frequency (kHz) A graph for selecting C vs frequency is given in Figure OSC 2. As the operating frequency is increased the gate charge losses will be higher, reducing efficiency (see Efficiency Considerations) ...
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... Selection criteria for the power MOSFETs include the “ON” resistance R , reverse transfer capacitance C DS(ON) put voltage and maximum output current. When the LTC1435A is operating in continuous mode the duty cycles for the top and bottom MOSFETs are given by Main Switch Duty Cycle = ...
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... CC ing frequency as discussed in the Efficiency Considerations section. The junction temperature can be estimated by using = output capacitance the equations given in Note 1 of the Electrical Character- increases istics. For example, the LTC1435A is limited to less than L the output ripple 17mA from a 30V supply: assuming (17mA)(30V)(100 C/W) = 126 C ...
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... SFB BG N-CH R5 SGND PGND Connection 0.22 F BAT85 BAT85 V IN BAT85 TG N-CH VN2222LL R EXTV L1 SENSE CC LTC1435A + SW BG N-CH 1435A F04b PGND and the Boost pin rises IN . The value of the boost capacitor C CC must be greater than OUT ...
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... Figure 5. Setting the LTC1435A Output Voltage Run/ Soft Start Function The RUN/SS pin is a dual purpose pin that provides the soft start function and a means to shut down the LTC1435A. Soft start reduces surge currents from V IN ing the internal current limit. Power supply sequencing can also be accomplished using this pin ...
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... The output voltage will continue to be regulated, but the ripple current and ripple voltage will increase. Therefore this limit should be avoided. The minimum on-time for the LTC1435A in a properly configured application is less than 300ns but increases at low ripple current amplitudes (see Figure 7 appli- ...
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... Note that the transient suppressor should not 12V also begins to LOAD to its OUT can be OUT Figure 9. Automotive Application Protection . No regulator can OUT 50A I PK RATING V IN LTC1435A TRANSIENT VOLTAGE SUPPRESSOR GENERAL INSTRUMENT 1.5KA24A 1435A F09 ). LOAD ...
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... LTC1435A. These items are also illustrated graphically in the layout diagram of Figure 10. Check the following in your layout: 1. Are the signal and power grounds segregated? The LTC1435A signal ground pin must return to the (–) plate of C OUT bottom N-channel MOSFET, anode of the Schottky di- ...
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... U 6. Keep the switching node SW away from sensitive small- signal nodes. Ideally the switch node should be placed at the furthest point from the LTC1435A. 7. SGND should be exclusively used for grounding exter- nal components operating close to the minimum on-time limit, is the sense resistor oriented on the radial axis of the induc- tor? See Figure 8 ...
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... T1: DALE LPE6562-A236 3.3V/4.5A Converter with Foldback Current Limiting V IN 4.5V TO 28V Si4410DY 15 BOOST LTC1435A 0.1 F CMDSH-3 12 INTV Si4410DY 10 PGND 9 OPTIONAL: EXTV CC CONNECT TO 5V LTC1435A 0. IRLL014 35V 2 4. SEC 10 H 3.3 F 1:1.42 35V R SENSE 0.033 V OUT 5V/3.5A R1 35.7k 1% MBRS140T3 C + OUT 100 F 10V R2 2 ...
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... I PROG OUT 3 6 GND NIN PIN C16 0. C17 10k 0. GND I PROG R PROG 18 C4 0.1 F C11 C5 56pF 0.1 F LTC1435A OSC 2 15 RUN/SS BOOST 0.33 F SFB SGND INTV ...
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... BSC 0.010 – 0.015 (0.05 – 0.21) (0.25 – 0.38) S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.004 – 0.010 (0.101 – 0.254) 0.228 – 0.244 (5.791 – 6.197) 0.050 (1.270) TYP LTC1435A 35V 2 MBRS1100T3 24V SEC 10 H 3.3 F 1:2 ...
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... High Efficiency 5V to 3.3V Conversion 15A Full-Featured Single Controller Full-Featured Dual Controllers 1.3A, Li-Ion, NiCd, NiMH, Pb-Acid Charger 5V Standby in Shutdown 5V Standby in Shutdown Creates a Programmable 1. Supply for Intel ® Mobile Pentium II Processor When Used with the LTC1435A 1435af LT/GP 0798 4K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1998 ...