LT3493-3 LINER [Linear Technology], LT3493-3 Datasheet
LT3493-3
Related parts for LT3493-3
LT3493-3 Summary of contents
Page 1
... PWM step-down DC/DC converter with an internal 1.75A power switch. The wide operating input range of 6.8V to 36V (40V maximum) makes the LT3493-3 ideal for regulating power from a wide vari- ety of sources, including unregulated wall transformers, 24V industrial supplies and automotive batteries. Its high ...
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... LT3493 ABSOLUTE AXI U RATI GS (Note 1) Input Voltage (V ) .................................................. 40V IN BOOST Pin Voltage .................................................. 50V BOOST Pin Above SW Pin ....................................... 25V SHDN Pin ................................................................ 40V FB Voltage ................................................................. 6V Operating Temperature Range (Note 2) LT3493E-3 ........................................... –40°C to 85°C Maximum Junction Temperature .......................... 125°C Storage Temperature Range ................. – 65°C to 150°C ELECTRICAL CHARACTERISTICS ● ...
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... Note 3: Current limit guaranteed by design and/or correlation to static test. Slope compensation reduces current limit at higher duty cycle. Note 4: Current flows out of pin. Note 5: Current flows into pin 12V 24V IN 0.8 1.0 1.2 3493-3 G01 LT3493-3 = 25°C. A MIN TYP MAX 1.4 1.75 2.2 330 2 1.85 2 2.3 0.3 ...
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... LT3493 TYPICAL PERFOR A CE 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 3493-3 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 3493-3 G21 Switching Frequency 800 780 760 740 720 ...
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... G17 Operating Waveforms, Discontinuous Mode V SW 5V/DIV I L 0.5A/DIV 0 V OUT 20mV/DIV 3493-3 G19 V = 12V 3.3V OUT I = 50mA OUT L = 10µ 10µF OUT LT3493-3 Switch Current Limit 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0 100 DUTY CYCLE (%) 3493-3 G18 3493-3 G20 1µs/DIV 3493-3f 5 ...
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... SHDN (Pin 6): The SHDN pin is used to put the LT3493 shutdown mode. Tie to ground to shut down the LT3493-3. Tie to 2.3V or more for normal operation. If the shutdown feature is not used, tie this pin to the V SHDN also provides a soft-start function; see the Applica- tions Information section ...
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... An internal regulator provides power to the control cir- cuitry. This regulator includes an undervoltage lockout to prevent switching when V pin is used to place the LT3493-3 in shutdown, discon- necting the output and reducing the input current to less than 2µA. The switch driver operates from either the input or from the BOOST pin ...
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... V and BOOST pins. IN The minimum input voltage is determined by either the LT3493-3’s minimum operating voltage of 6.8V its maximum duty cycle. The duty cycle is the fraction of time that the internal switch is on and is determined by the input and output voltages: + ...
Page 9
... 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 LT3493-3 is 130ns. Figure 2 illustrates the switching waveforms when the input voltage is increased to V ...
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... Output Capacitor The output capacitor has two essential functions. Along with the inductor, it filters the square wave generated by the LT3493-3 to produce the DC output. In this role it determines the output ripple so low impedance at the switching frequency is important. The second function is to store energy in order to satisfy transient loads and stabilize the LT3493-3’ ...
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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 LT3493-3 is turned on with its SHDN pin when the output LT3493-3 Comments EEF Series ...
Page 12
... LT3493 APPLICATIO S I FOR ATIO 32.4k FB 10k 32.4k 3.3nF FB 10k 32. 10k Figure 4. Transient Load Response of the LT3493-3 with Different Output Capacitors as the Load Current is Stepped from 250mA to 1A. V BOOST LT3493 GND ≅ – V BOOST SW OUT ≅ V MAX BOOST ...
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... GND RUN 15k SHDN 0.1µF GND Figure 6. To Soft-Start the LT3493-3, Add a Resistor and Capacitor to the SHDN pin restricts the input range to one-half of the absolute maxi- mum rating of the BOOST pin. At light loads, the inductor current becomes discontinu- ous and the effective duty cycle can be very high. This ...
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... SHDN SW GND FB Figure 7. Diode D4 Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output; It Also Protects the Circuit from a Reversed Input. The LT3493-3 Runs Only When the Input is Present Hot Plugging Safely The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LT3493-3 circuits ...
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... AI.EI. + 0.1µF Figure 8. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures Reliable Operation When the LT3493-3 is Connected to a Live Supply Frequency Compensation The LT3493-3 uses current mode control to regulate the output. This simplifies loop compensation. In particular, the LT3493-3 does not require the ESR of the output capacitor for stability allowing the use of ceramic capaci- tors to achieve low output ripple and small circuit size ...
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... The SW and BOOST nodes should be as small as possible. 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 LT3493-3 to help remove heat from the LT3493-3 to the ground plane. High Temperature Considerations The die temperature of the LT3493-3 must be lower than the maximum rating of 125° ...
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... Buck regulator. 0.78V Step-Down Converter 1N4148 BOOST IN 0.1µF 3.3µH LT3493-3 SHDN SW MBRM140 GND FB 2.2µF 1.8V Step-Down Converter 1N4148 BOOST IN LT3493-3 0.1µF 5µH SW SHDN MBRM140 GND FB 2.2µF LT3493-3 V OUT 0.78V 1.2A 47µF 3493-3 TA02 V OUT 1.8V 1.2A 26.1k 22µF 20k 3493-3 TA03 3493-3f 17 ...
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... SHDN MBRM140 GND FB 1µF 3.3V Step-Down Converter 1N4148 V BOOST IN 0.1µF 8.2µH LT3493-3 SW SHDN MBRM140 GND FB 1µF 5V Step-Down Converter 1N4148 V BOOST IN 0.1µF 10µH LT3493-3 SHDN SW MBRM140 GND FB 1µF V OUT 2.5V 1A, V > 1.2A, V > 10V IN 22.1k 22µF 10k 3493-3 TA04 V OUT 3.3V 1A, V > ...
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... 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 LT3493-3 0.40 ± 0.10 TYP 4 6 PIN 1 NOTCH R0.20 OR 0.25 × ...
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... McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 12V Step-Down Converter D1 6V 1k* 0.25W BOOST IN LT3493-3 0.1µF 22µH SHDN SW MBRM140 GND FB 1µF *FOR CONTINUOUS OPERATION ABOVE 30V USE TWO 2k, 0.25W RESISTORS IN PARALLEL. D1: CMDZ5235B COMMENTS V : 5.5V to 60V ...