LTC3770EG Linear Technology, LTC3770EG Datasheet
LTC3770EG
Specifications of LTC3770EG
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LTC3770EG Summary of contents
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... A wide supply range allows voltages as high as 32V to be stepped down to as low as a 0.6V output. Power supply sequencing is accomplished using an external soft-start timing capacitor. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation registered trademark of Linear Technology Corporation. SENSE All other trademarks are the property of their respective owners ...
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... PGND 22 BG MARGIN1 21 INTV CC MARGIN0 PLLIN 15 PLLFLTR PART MARKING PACKAGE DESCRIPTION LTC3770EG 28-Lead Plastic SSOP 32-Lead (5mm × 5mm) Plastic QFN 3770 http://www.linear.com/leadfree/ http://www.linear.com/tapeandreel/ Voltages .................................. 7V to –0.3V IN Peak Currents ....................................4A CC RMS Currents ...............................50mA CC TOP VIEW SENSE RNG SENSE FB I PGND ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are T SYMBOL PARAMETER Main Control Loop I Input DC Supply Current Q Normal Operation Shutdown Supply Current V Feedback Voltage Accuracy (Note Feedback Voltage Line Regulation FB(LINEREG) V Feedback ...
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... 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 calculated from the ambient temperature T J dissipation P as follows: D LTC3770EG • 130°C/ LTC3770EUH • ...
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TYPICAL PERFORMANCE CHARACTERISTICS On-Time vs Temperature 300 I = 30μA ION VON 250 200 150 100 50 0 –50 – 100 TEMPERATURE (°C) 3770 G04 Error Amplifi Temperature m 1.6 ...
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LTC3770 TYPICAL PERFORMANCE CHARACTERISTICS Track Up FIGURE 12 CIRCUIT TRACK/ TRACK/SS AND OUT 500mV/DIV V OUT 2V/DIV 250ms/DIV Effi ciency vs Load Current 100 FIGURE 12 CIRCUIT 95 DISCONTINUOUS 90 MODE 85 80 CONTINUOUS 75 ...
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TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Foldback 160 RNG 140 120 100 0.1 0.2 0 PIN FUNCTIONS (UH Package/G Package) V (Pin 1/Pin 4): Sense Voltage Range Input. The RNG ...
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LTC3770 PIN FUNCTIONS (UH Package/G Package) sets the ramp rate for the output voltage. When the IC is confi gured to be the slave of two outputs, the V of the master IC is reproduced by a resistor divider and ...
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PIN FUNCTIONS (UH Package/G Package) V (Pin 31/Pin 2): On-Time Voltage Input. Connecting this ON pin to the output voltage makes the on-time proportional The comparator input defaults to 0.6V when the OUT pin is grounded and ...
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LTC3770 OPERATION Main Control Loop The LTC3770 is a current mode controller for DC/DC step-down converters. In normal operation, the top MOSFET is turned on for a fi xed interval determined by a one-shot timer OST. When the top MOSFET ...
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APPLICATIONS INFORMATION The basic LTC3770 application circuit is shown in Figure 12. External component selection is primarily determined by the maximum load current and begins with the selection of the sense resistance and power MOSFET switches. The LTC3770 uses either ...
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LTC3770 APPLICATIONS INFORMATION The ρ term is a normalization factor (unity at 25°C) T accounting for the signifi cant variation in on-resistance with temperature, typically about 0.4%/°C as shown in Figure 1. For a maximum junction temperature of 100°C, using ...
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APPLICATIONS INFORMATION When there resistor connected to the I ON the on-time t is theoretically infi nite, which in turn could ON damage the converter. To prevent this, the LTC3770 will detect this fault condition and provide ...
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LTC3770 APPLICATIONS INFORMATION A reasonable starting point is to choose a ripple current that is about 40 The largest ripple current OUT(MAX) occurs at the highest guarantee that ripple current IN does not exceed ...
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APPLICATIONS INFORMATION Top MOSFET Driver Supply ( external bootstrap capacitor C connected to the BOOST B pin supplies the gate drive voltage for the topside MOSFET. This capacitor is charged through diode D when the switch ...
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... Q ). The junction temperature GATECHG g(TOP) g(BOT) can be estimated from the equations given in Note 2 of the Electrical Characteristics. For example, the LTC3770EG is limited to less than 14mA from a 30V supply 70°C + (14mA)(30V)(130°C/W) = 125°C J External Gate Drive Buffers The LTC3770 drivers are adequate for driving up to about 50nC into MOSFET switches with RMS currents of 50mA ...
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APPLICATIONS INFORMATION TIME (7a) Coincident Tracking Figure 7. Two Different Modes of Output Voltage Tracking V OUT1 TRACK/SS2 PIN R4 R2 (8a) Coincident Tracking Setup Figure 8. Setup for Coincident and Ratiometric Tracking ...
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LTC3770 APPLICATIONS INFORMATION Margining Margining is a way to program the reference voltage to the error amplifi voltage different from the default 0.6V. Margining is useful for customers who want to stress their systems by varying supply ...
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APPLICATIONS INFORMATION oscillators are identical. At this stable operating point the phase comparator output is open and the fi lter capacitor C holds the voltage. The LTC3770 PLLIN pin must be LP driven from a low impedance source such as ...
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LTC3770 APPLICATIONS INFORMATION If you make a change and the input current decreases, then the effi ciency has increased. If there is no change in input current, then there is no change in effi ciency. Checking Transient Response The regulator ...
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... When laying out a PC board follow one of two suggested approaches. The simple PC board layout requires a dedicated ground plane layer. Also, for higher currents recommended to use a multilayer board to help with heat sinking power components. • The ground plane layer should not have any traces and LTC3770EG 28 RUN FCB 27 V ...
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LTC3770 APPLICATIONS INFORMATION When laying out a printed circuit board, without a ground plane, use the following checklist to ensure proper opera- tion of the controller. • Segregate the signal and power grounds. All small signal components should return to ...
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... APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 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. ...
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... High Current Synchronous Step-Down Controller IN LTC3731 3-Phase Synchronous Step-Down Controller LTC3778 Low Synchronous Step-Down Controller OUT SENSE Burst Mode is a trademark of Linear Technology Corporation. Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● Typical Application 2.5V/10A Synchronized at 450kHz FCB 31 ...