LT3493 LINER [Linear Technology], LT3493 Datasheet
LT3493
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LT3493 Summary of contents
Page 1
... PWM step-down DC/DC converter with an internal 1.75A power switch. The wide operating input range of 3.6V to 36V (40V maximum) makes the LT3493 ideal for regulating power from a wide variety of sources, including unregulated wall transform- ers, 24V industrial supplies and automotive batteries. ...
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... BOOST Pin Voltage ..................................................50V BOOST Pin Above SW Pin .........................................25V SHDN Pin ..................................................................40V FB Voltage ...................................................................6V Operating Temperature Range (Note 2) LT3493E .............................................. –40°C to 85°C LT3493I ............................................. –40°C to 125°C Maximum Junction Temperature .......................... 125°C Storage Temperature Range ................... –65°C to 150°C ORDER INFORMATION ...
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... Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3493E is guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. The LT3493I specifi ...
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... LT3493 TYPICAL PERFORMANCE CHARACTERISTICS Maximum Load Current 5V 8.2μH OUT 1.60 1.50 TYPICAL 1.40 1.30 1.20 MINIMUM 1.10 1.00 0. (V) IN 3493 G04 Maximum Load Current 3.3V 10μH OUT 1.60 1.50 TYPICAL 1.40 1.30 MINIMUM 1.20 1.10 1.00 0. (V) IN 3493 G21 Switching Frequency 800 780 760 740 720 700 680 ...
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... TO RUN 5.5 5 100 I (mA) OUT 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 75 100 125 150 3493 G17 V SW 5V/DIV 0.5A/DIV V OUT 20mV/DIV 3493 G19 LT3493 T = 25°C unless otherwise noted. A Typical Minimum Input Voltage (V = 3.3V) OUT 5.5 5.3 5.1 4.9 4.7 4.5 4.3 4.1 TO RUN 3.9 3.7 3 100 1000 I (mA) OUT 3493 G15 Switch Current Limit ...
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... This = 0.78V • pin must be locally bypassed. OUT SHDN (Pin 6): The SHDN pin is used to put the LT3493 in shutdown mode. Tie to ground to shut down the LT3493. Tie to 2.3V or more for normal operation. If the shutdown feature is not used, tie this pin to the V provides a soft-start function ...
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... OPERATION (Refer to Block Diagram) The LT3493 is a constant frequency, current mode step- down regulator. A 750kHz oscillator enables an RS fl ip-fl op, turning on the internal 1.75A power switch Q1. An amplifi er and comparator monitor the current fl owing between the V and SW pins, turning the switch off when this current ...
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... As the input voltage is increased, the part is required to switch for shorter periods of time. Delays associated with turning off the power switch dictate the minimum on time of the part. The minimum on time for the LT3493 is ~120ns. Figure 2 illustrates the switching waveforms when the input voltage is increased to V ...
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... D1. The diode must 3493 F03 have a reverse voltage rating equal to or greater than the maximum input voltage. The ON Semiconductor MBRM140 is a good choice rated for 1A continuous forward current and a maximum reverse voltage of 40V. LT3493 + V ) OUT D 3493fb ...
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... This situation is easily avoided; see the Hot Plugging Safely section. Output Capacitor The output capacitor has two essential functions. Along with the inductor, it fi lters the square wave generated by the LT3493 to produce the DC output. In this role it 10 PART SERIES INDUCTANCE RANGE (μH) SIZE (MM) CDRH4D28 1 ...
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... For proper start-up, the minimum input voltage is also limited by the boost circuit. If the input voltage is ramped slowly, or the LT3493 is turned on with its SHDN pin when the output is already in regulation, then the boost capacitor may not be fully charged. Because the boost capacitor is ...
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... LT3493 APPLICATIONS INFORMATION 32.4k FB 10k 32.4k 3.3nF FB 10k 32. 10k Figure 4. Transient Load Response of the LT3493 With Different Output Capacitors as the Load Current is Stepped from 250mA to 1A BOOST LT3493 GND V – BOOST SW OUT MAX BOOST IN OUT (5a LOAD 2A/DIV ...
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... The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LT3493 circuits. However, these capaci- tors can cause problems if the LT3493 is plugged into a live supply (see Linear Technology Application Note 88 for LT3493 TO START ...
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... LT3493 APPLICATIONS INFORMATION SHDN RUN GND 3493 F07a RUN 15k SHDN 0.1μF GND 3493 F07b Figure 7. To Soft-Start the LT3493, Add a Resistor and Capacitor to the SHDN Pin BOOST IN IN LT3493 SHDN SW GND FB D4: MBR0540 Figure 8. Diode D4 Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output ...
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... AI.EI. + 0.1μF Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures Reliable Operation When the LT3493 is Connected to a Live Supply Frequency Compensation The LT3493 uses current mode control to regulate the output. This simplifi es loop compensation. In particular, the LT3493 does not require the ESR of the output capaci- tor for stability allowing the use of ceramic capacitors to achieve low output ripple and small circuit size ...
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... Finally, keep the FB node small so that the ground pin and ground traces will shield it from the SW and BOOST nodes. Include vias near the exposed GND pad of the LT3493 to help remove 3493 F10 heat from the LT3493 to the ground plane. ...
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... APPLICATIONS INFORMATION High Temperature Considerations The die temperature of the LT3493 must be lower than the maximum rating of 125°C. This is generally not a concern unless the ambient temperature is above 85°C. For higher temperatures, care should be taken in the layout of the circuit to ensure good heat sinking of the LT3493. The maximum load current should be derated as the ambient temperature approaches 125° ...
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... MBRM140 GND FB 10k 1μF 3.3V Step-Down Converter 1N4148 V BOOST IN 0.1μF 8.2μH LT3493 SHDN SW 32.4k MBRM140 GND FB 10k 1μF 5V Step-Down Converter 1N4148 V BOOST IN 0.1μF 10μH LT3493 SHDN SW 59k MBRM140 GND FB 11k 1μF V OUT 2.5V 1A, V > 1.2A, V > 10V IN 22μF 3493 TA04 V OUT 3.3V 0.9A, V > 4.5V IN 1.2A, V > 12V IN 10μ ...
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... ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE LT3493 0.40 ± 0. PIN 1 NOTCH R0.20 OR 0.25 45° ...
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... Linear Technology Corporation 20 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 12V Step-Down Converter D1 6V 1k* 0.25W V BOOST IN 0.1μF LT3493 22μH SHDN SW MBRM140 GND FB 1μF * FOR CONTINUOUS OPERATION ABOVE 30V USE TWO 2k, 0.25Ω RESISTORS IN PARALLEL. D1: CMDZ5235B COMMENTS V : 5.5V to 60V ...