LM3475MF/NOPB National Semiconductor, LM3475MF/NOPB Datasheet
LM3475MF/NOPB
Specifications of LM3475MF/NOPB
LM3475MFTR
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LM3475MF/NOPB Summary of contents
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... Hysteretic control also provides high efficiency op- eration, even at light loads. The PFET architecture allows for low component count as well as 100% duty cycle and ultra- low dropout operation. Typical Application Circuit © 2005 National Semiconductor Corporation Features n Easy to use control methodology n 0. adjustable output range ...
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Connection Diagram Package Marking and Ordering Information Order Number LM3475MF LM3475MFX Pin Description Pin Name Pin Number FB GND EN VIN PGATE www.national.com Top View 5 Lead Plastic SOT23-5 NS package Number MF05A Package Type Package Marking SOT23-5 S65B SOT23-5 ...
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... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications PGATE FB EN Storage Temperature Power Dissipation (Note 2) ESD Susceptibilty Human Body Model (Note 3) Electrical Characteristics Specifications in Standard type face are for T Range (T = − ...
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Electrical Characteristics Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended to be functional, but device parameter specifications may not be guaranteed. For guaranteed ...
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Typical Performance Characteristics V = 2.5V µ 100 µF, ESR = 100m , and T OUT OUT Quiescent Current vs Input Voltage Hysteresis Voltage vs Input Voltage Efficiency vs Load Current Unless specified otherwise, all ...
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Typical Performance Characteristics = 2.5V µ 100 µF, ESR = 100m , and T OUT Start Up Load Transient Response with External Ramp (Circuit from Figure 3) www.national.com Unless specified otherwise, all curves taken at ...
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Block Diagram Operation Description OVERVIEW The LM3475 is a buck (step-down) DC-DC controller that uses a hysteretic control architecture, which results in Pulse Frequency Modulated (PFM) regulation. The hysteretic con- trol scheme does not utilize an internal oscillator. Switching frequency ...
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Operation Description device enters soft-start. During soft-start, the reference volt- age is ramped up to the nominal value of 0.8V in approxi- mately 4ms. Duty cycle and output voltage will increase as the reference voltage is ramped up. UNDER VOLTAGE ...
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Design Information SETTING OUTPUT VOLTAGE The output voltage is programmed using a resistor divider between V and GND as shown in Figure 2. The feedback OUT resistors can be calculated as follows: Where Vfb is 0.8V typically. The feedback resistor ...
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Design Information (Continued) voltage regulated. The hysteretic control topology is well suited to using ceramic output capacitors. However, ceramic capacitors have a very low ESR, resulting in a 90˚ phase shift of the output voltage ripple. This results in low ...
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Design Information (Continued) The power loss in the PFET consists of switching losses and conducting losses. Although switching losses are difficult to precisely calculate, the equation below can be used to esti- mate total power dissipation. Increasing R power losses ...
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Layout (Continued) Bill of Materials Designator Description C 10µF, 16V, X5R IN C 100µF, 6V, Ta OUT C 1nF, 25V, X7R FF D1 Schottky, 20V 10µH, 3.1A Q1 30V, 2. 0805, 1% FB2 R 2.15k ...
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Layout (Continued) 20070107 FIGURE 7. Top Layer (with External Ramp) (2:1 Scale) FIGURE 8. Bottom Layer (2:1 Scale) 13 20070130 www.national.com ...
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... BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...