LT3502 LINER [Linear Technology], LT3502 Datasheet
LT3502
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LT3502 Summary of contents
Page 1
... DC/DC converters with an internal 500mA power switch, in tiny 8-lead 2mm × 2mm DFN and 10-lead MS10 packages. The wide input voltage range 40V makes the LT3502/LT3502A suitable for regulating power from a wide variety of sources, including 24V industrial supplies and automotive batteries. Its high operating frequency allows the use of tiny, low cost inductors and capacitors, resulting in a very small solution ...
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... For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: 2 (Note 1) BD Voltage ..................................................................7V Operating Junction Temperature Range (Note 2) LT3502AE, LT3502E ...........................–40°C to 125°C LT3502AI, LT3502I .............................–40°C to 125°C Storage Temperature Range ...................–65°C to 150° BOOST 6 ...
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... Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2. The LT3502EDC and LT3502AEDC are guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature range. Specifi cations over the –40°C to 125°C operating junction ...
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... LOAD CURRENT (A) 3502 G01 LT3502 5V Effi ciency OUT 100 12V 24V 0.1 0.3 0 0.2 0.4 0.5 LOAD CURRENT (A) 3502 G04 LT3502 Maximum Load Current V = 3.3V 15μH OUT 0.9 0.8 TYPICAL 0.7 MINIMUM 0.6 0.5 0.4 0.3 0.2 0 (V) IN 3502 G07 4 LT3502A 5V Effi ciency OUT ...
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... SHDN PIN VOLTAGE (mV) 3502 G12 Switch Current Limit 1.2 1.0 LT3502 0.8 LT3502A 0.6 0.4 0 100 DUTY CYCLE (%) 3502 G15 LT3502 Maximum V for Full IN Frequency (V = 3.3V) OUT 25° 85° 0.1 ...
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... L 200mA/DIV V OUT 20mV/DIV V = 12V 200ns/DIV 3.3V OUT L = 6.8μ 10μF OUT 250mA OUT (T = 25°C unless otherwise noted) A LT3502 Typical Minimum Input Voltage (V = 3.3V) OUT 0.001 1 0.01 LOAD CURRENT (A) 3502 G20 Discontinuous Mode Waveform V SW 5V/DIV I L 200mA/DIV ...
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... R1/R2). A good value for R2 is 10k. OUT SHDN (Pin 4/Pin 6): The SHDN pin is used to put the LT3502 in shutdown mode. Tie to ground to shut down the LT3502/LT3502A. Tie more for normal operation. If the shutdown feature is not used, tie this pin pin. The SHDN pin also provides soft-start and ...
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... LT3502/LT3502A BLOCK DIAGRAM 8 3502fc ...
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... NPN power switch for effi cient operation. A comparator monitors the current fl owing through the catch diode via the DA pin and reduces the LT3502/ LT3502A’s operating frequency when the DA pin current exceeds the 650mA valley current limit. This frequency ...
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... IN(MAX MIN DC = 0.15 for the LT3502A and 0.08 for the LT3502. MIN 10 Note that this is a restriction on the operating input volt- age for fi xed frequency operation; the circuit will tolerate transient inputs up to the absolute maximum ratings of the V and BOOST pins. The input voltage should be ...
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... Inductor current may reach current limit when operating in pulse skip mode with small valued inductors. In this case, the LT3502/LT3502A will periodically reduce its frequency to keep the inductor valley current to 650mA (Figure 3). Peak inductor current is therefore peak current plus minimum switch delay: V – ...
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... Output Capacitor The output capacitor has two essential functions. Along with the inductor, it fi lters the square wave generated by the LT3502/LT3502A 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 LT3502/LT3502A’ ...
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... ESR. Table 2 lists several capacitor vendors. Figure 4 shows the transient response of the LT3502A with several output capacitor choices. The output is 3.3V. The load current is stepped from 150mA to 400mA and back to 150mA, and the oscilloscope traces show the output voltage ...
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... LT3502/LT3502A APPLICATIONS INFORMATION 32.4k FB 10k 32.4k 50pF FB 10k 32.4k FB 10k Figure 4. Transient Load Response of the LT3502A with Different Output Capacitors as the Load Current is Stepped from 150mA to 400mA BOOST V V LT3502 GND V – V ≅ V BOOST SW OUT MAX V ≅ BOOST IN OUT (5a) ...
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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 LT3502/LT3502A 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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... SHDN 0.1μF GND Figure 7. To Soft Start the LT3502A, Add a Resistor and Capacitor to the SHDN Pin Soft-Start The SHDN pin can be used to soft start the LT3502/LT3502A, reducing the maximum input current during start-up. The SHDN pin is driven through an external RC fi lter to create a voltage ramp at this pin ...
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... The LT3502/LT3502A use current mode control to regulate the output. This simplifi es loop compensation. In particular, IN the LT3502/LT3502A does not require the ESR of the output capacitor for stability allowing the use of ceramic capacitors to achieve low output ripple and small circuit size. Figure 10 shows an equivalent circuit for the LT3502/ LT3502A control loop. The error amp is a transconductance amplifi ...
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... CLOSING SWITCH SIMULATES HOT PLUG + LOW IMPEDANCE ENERGIZED 24V SUPPLY + 10μF 35V AI.EI. + 0.1μF Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures Reliable Operation When the LT3502 is Connected to a Live Supply LT3502 150k C 70pF GND LT3502 V IN 20V/DIV 2.2μ ...
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... C1. 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 LT3502/LT3502A to help remove heat from the LT3502/LT3502A to the ground plane. V OUT ...
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... 10μH 0.1μF 1μF SW LT3502 D1 DA SHDN FB OFF ON GND C1: JMK316BJ107ML L1: LQH43CN100K03 0.1μ BOOST 15μH 0.1μF 1μF SW LT3502 12.5k SHDN FB R2 GND 10k C1: JMK212BJ476MG L1: LQH55DN150M03 V OUT 0.8V 500mA C1 100μF 3502 TA02b V OUT 1.8V 500mA C1 47μF 3502 TA03b 3502fc ...
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... 15μH 1μF 0.1μF SW LT3502 21.3k SHDN FB R2 GND 10k C1: JMK212BJ226MG L1: LQH55DN150M03 BD V BOOST 15μH 0.1μF 1μF SW LT3502 31.6k SHDN FB R2 GND 10k C1: JMK212BJ226MG L1: LQH55DN150M03 V OUT 2.5V 500mA C1 22μF 3502 TA04b V OUT 3.3V 500mA C1 22μF 3502 TA05b 3502fc 21 ...
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... LT3502/LT3502A PACKAGE DESCRIPTION 2.55 ±0.05 0.64 ±0.05 1.15 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF 22 DC Package 8-Lead Plastic DFN (2mm × 2mm) (Reference LTC DWG # 05-08-1719 Rev Ø) 0.70 ± ...
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... DETAIL “A” MAX SEATING PLANE 0.17 – 0.27 (.007 – .011) 0.50 TYP (.0197) BSC LT3502/LT3502A 0.497 ± 0.076 (.0196 ± .003 REF 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 0.86 (.034) REF 0.1016 ± 0.0508 (.004 ± ...
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... QFN, TSSOP16E Packages V : 3.3V to 25V TSSOP20E Package V : 2.5V to 5.5V 3mm × 3mm DFN, MS10E Packages www.linear.com ● BOOST 22μH 0.1μF 1μF SW LT3502 52.3k SHDN FB R2 GND 10k C1: LMK316BJ106ML-BR L1: LQH43CN100K03 = 1.2V 2.5mA 25μA, OUT(MIN 1.2V 1.6mA, I < 1μA, OUT(MIN) ...