LT3506 LINER [Linear Technology], LT3506 Datasheet

Page 1

... Constant frequency and ceramic capacitors combine to produce low, predictable output ripple voltage. With its wide input range of 3.6V to 25V, the LT3506 regulates a wide variety of power sources, from 4-cell batteries and 5V logic rails to unregulated wall transformers, lead acid batteries and distributed-power supplies ...

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... LT3506IFE#PBF LT3506IFE#TRPBF LT3506AIFE#PBF LT3506AIFE#TRPBF LEAD BASED FINISH TAPE AND REEL LT3506EDHD LT3506EDHD#TR LT3506AEDHD LT3506AEDHD#TR LT3506IDHD LT3506IDHD#TR LT3506AIDHD LT3506AIDHD#TR LT3506EFE LT3506EFE#TR LT3506AEFE LT3506AEFE#TR LT3506IFE LT3506IFE#TR LT3506AIFE LT3506AIFE#TR Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. ...

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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3506E/LT3506AE are guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and ...

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... L = 2.2µH 1.2 1 INPUT VOLTAGE (V)* Current Limit vs Duty Cycle 3 25°C A TYPICAL 2.5 2.0 MINIMUM 1.5 1.0 0 DUTY CYCLE (%) Efficiency (LT3506) OUT 100 OUT 10µH (COOPER UP1B-100 25° 15V 25V 1 ...

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... Pull these pins to ground with an open unless power drain to shut down each switching regulator. IN1 FB1 (Pin 16), FB2 (Pin 9): The LT3506 regulates each feedback pin to 800mV. Connect the feedback resistor divider taps to these pins. Exposed Pad (Pin 17): The Exposed Pad of the package provides both electrical contact to ground and good thermal contact to the printed circuit board ...

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... RUN/SS1 0.75V ∑ SLOPE FOLDBACK LOGIC CLK RUN/ GND Figure 2. Block Diagram of the LT3506 with Associated External Components ( Regulators Shown CLK1 INT REG MASTER AND REF OSC CLK2 – ERROR AMP + – ...

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... A power good comparator trips when the FB pin is at 90% of its regulated value. The PG output is an open collector transistor that is off when the output is in regulation, al- lowing an external resistor to pull the PG pin high. Power good is valid when the LT3506 is enabled (either RUN/SS pin is high) and V is greater than ~3.4V pin voltage ...

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... A common application where the maximum duty cycle limits the input voltage range is the conversion 3.3V. The maximum load current that the LT3506 can deliver at 3.3V depends on the accuracy of the 5V input supply. With a low loss inductor (DCR less than 80mW), the LT3506 can deliver 1 ...

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... Input Capacitor Selection /2 L Bypass the input of the LT3506 circuit with a 4.7μF or higher ceramic capacitor of X7R or X5R type. A lower value or a less expensive Y5V type can be used if there is additional bypassing provided by bulk electrolytic or tan- talum capacitors. The following paragraphs describe the input capacitor considerations in more detail ...

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... An alternative to a high value ceramic capacitor is a lower value along with a larger electrolytic capacitor, for example a 1μF ceramic capacitor in parallel with a low ESR tantalum capacitor. For the electrolytic capacitor, a value larger than 22mF (10mF for the LT3506A) will be required to meet the  ESR and ripple current requirements ...

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... For lower voltages, 22μF is adequate but increasing C will improve transient performance. For OUT the LT3506A, 10μF of output capacitance is sufficient at V between 3.3V and 5V. Other types and values can be OUT used. The following discusses tradeoffs in output ripple and transient performance ...

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... D2). However, efficiency may be lower and dissipation in the LT3506 may be higher. Also absent, the LT3506 will still attempt to regulate the output, but will do so with very low efficiency and high dissipation because the switch will not be able to saturate, dropping 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 LT3506 is turned on with its RUN/SS 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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... Frequency Compensation The LT3506 uses current mode control to regulate the output. This simplifies loop compensation. In particular, the LT3506 does not require the ESR of the output capacitor for stability so you are free to use ceramic capacitors to achieve low output ripple and small circuit size. ...

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... Tie the PG pin to any supply with a pull-up resistor that will supply less than 250μA. Note that this pin will be open when the LT3506 is placed in shutdown mode (both RUN/SS pins at ground) regardless of the voltage at the FB pin. Power good is valid ...

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... When the system is placed in shutdown mode by pulling down on RUN/SS1, then output 1 will go low, PG1 will pull down on RUN/SS2, and the LT3506 will enter its low current shutdown state. This disables PG1, and RUN/SS2 ramps up again to enable the LT3506. The circuit will oscillate and pull extra current from the input ...

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... If the inductor is chosen so that it won’t saturate exces- sively, the LT3506 will tolerate a shorted output. There is another situation to consider in systems where the output will be held high when the input to the LT3506 is absent. If the V and one of the RUN/SS pins are allowed to float, IN then the LT3506’ ...

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... APPLICATIO S I FOR ATIO U U Single, Low-Ripple 3.2A Output The LT3506 can generate a single, low-ripple 3.2A output if the outputs of the two switching regulators are tied together and share a single output capacitor. By tying the two FB pins together and the two V two channels will share the load current. There are several advantages to this two-phase buck regulator ...

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... BOOST1 BOOST2 LT3506 0.22µF 0.22µF SW1 SW2 FB1 FB2 1500pF 1500pF 15k RUN/SS1 4.7nF PGOOD2 RUN/SS2 2.2nF PGOOD1 GND L1: COILCRAFT MSS6122-472 L2: COILTRONICS CTX5-1A LT3506/LT3506A L2 3.3µH V OUT2 1.2V 1.5A 16.2k D2 20k 32.4k 68µF 3506 TA01 >12V OUT3 –5V 0.3A D4 22µF 47k L2 2.2µF 4.7µH V ...

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... RUN/SS1 SW2 RUN/SS2 PGOOD1 FB1 PGOOD2 FB2 GND Two Stage Step Down 25V Input to 1.2V Output D3a D3b 22µ IN1 IN2 BOOST1 BOOST2 LT3506 0.22µF 0.22µF SW1 SW2 FB1 FB2 1500pF 1000pF 15k 20k RUN/SS1 PGOOD1 4.7nF ...

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... V V IN1 IN2 BOOST1 BOOST2 LT3506AEDHD 0.1µF 0.1µF SW1 SW2 FB1 FB2 1.5nF 1.5nF 10k RUN/SS1 PGOOD1 4.7nF RUN/SS2 PGOOD2 GND LT3506/LT3506A D3b L1 1.5µH V OUT 0. 1.5µH D2 10k 68µF 3506 TA05 L2 2.2µH V OUT2 1.3V 1.6A 17.4k D2 15k 28k 47µF 3506 TA06 3506afb ...

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... LT3506/LT3506A PAckAge DescRiPtion 4.50 ±0.05 3.10 ±0.05 2.44 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJGD-2) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH ...

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... BSC 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3506/LT3506A 4.90 – 5.10* (.193 – .201) 2.74 (.108) 16 1514 6.40 2.74 (.252) ( ...

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... LT3506/LT3506A RelAteD PARts PART NUMBER DESCRIPTION LT1765 25V, 2.75A (I ), 1.25MHz, High OUT Efficiency Step-Down DC/DC Converter LT1766 60V, 1. 200kHz, High OUT Efficiency Step-Down DC/DC Converter LT1767 25V, 1. 1.25MHz, High OUT Efficiency Step-Down DC/DC Converter LT1940/LT1940L Dual Monolithic 1.4A, 1.1MHz Step- Down Switching Regulator LTC3407/LTC3407-2 Dual 600mA/800mA, 1.5MHz, ...