LM/-Q1 does not rely on output capacitor ESR An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in. LM Synchronous 1MHz A Step-Down Voltage Regulator from the PowerWise® Family The LM Synchronously Rectified Buck Converter features all. The LM Synchronously Rectified Buck Converter Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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Lab 6 in this note.
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Determine the inductance The main parameter affected by the inductor is the amplitude of the inductor current ripple ILR.
To ensure that the on-time is larger than the minimum limit, which is ns, llm3102 value of R1 must satisfy the following equation: Once ILR is selected, L can be determined by: The Constant On-Time COT regulation scheme requires no loop compensation, results in a fast load transient response and simple dahasheet implementation that allows a low component count, and consequently very small overall board space is required for a typical application.
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The input capacitor is calculated from: A nF capacitor is used in this demonstration board. It then drops to zero at turn-off.
LM datasheet, Pinout ,application circuits LM3 Molded Inductor
This user’s guide details the design of a demonstration board which provides a 3. The output capacitor C10, C11 should be connected close to the load and tied directly to the ground plane. The bootstrap capacitor C4 should be connected as close to the SW and BST pins as possible, and the connecting traces should be thick.
Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. The exposed pad is internally connected to the LM IC substrate. No TI components are authorized for use in FDA Class III or similar life-critical medical equipment unless authorized officers of the parties have executed a special agreement specifically governing such use.
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Synchronous 1MHz 2.5A Step-Down Voltage Regulator
Experimentation is usually necessary to determine the minimum value for the output capacitor, as the nature of the load may require a larger value. Information of third parties may be subject to additional restrictions. I wish to measure a very low resistance of the order of an ohm. It must be as neat and compact as possible, and all external components must be as close to their associated pins of the LM as possible.
Judicious positioning of the PC board within the end product, along with the use of any available air flow forced or natural convection can help reduce the junction temperature. The connection from the PGND pin to the input capacitors should be as short and direct as possible.
Additionally the use of thick traces, where possible, can help conduct heat away from the LM Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI.
Vias should be added to connect the ground of the input capacitors to a ground plane, located as close to the capacitor as possible. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. The demonstration board schematic, PCB layout, Bill of Materials, and circuit design descriptions are shown.
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TI is not responsible or liable for any such statements. TI is not responsible or liable for such altered documentation. The average current during the on-time is the load current. Calculate the on-time setting resistor The switching frequency fSW of the demonstration board is affected by the on-time ton of the LM, which is determined by R1.
In this demonstration board, a 10 nF capacitor is used. How much energy is. For a worst case calculation, the input capacitor must be capable of supplying this average load current during the maximum on-time. Using numerous vias to connect the die attached pad to the ground plane is a good practice. Products Applications Audio www. The exposed pad on the bottom of the LM IC package can be soldered to the ground plane, which should extend out from beneath the LM to help dissipate heat. Layout is therefore critical for optimum performance.
Nonetheless, such components are subject to these terms. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI.
The capacitor at the SS pin determines the soft-start time, that is, the time for the reference voltage at the regulation comparator and the output voltage to reach their final value. Typical performance and operating waveforms are also provided for reference. Calculate the feedback resistors The ratio of the feedback resistors can be calculated from the following equation: The design of the demonstration board is detailed below.
LM Datasheet(PDF) – National Semiconductor (TI)
A load which creates significant transients requires a larger output capacitor than a fixed load. The time is determined from the following equation: Protection features include output over-voltage protection, thermal shutdown, VCC undervoltage lock-out, gate drive under-voltage lock-out. The operating frequency remains constant with line variations due to the inverse relationship between the input voltage catasheet the on-time.
Buyer represents and agrees datashewt it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. A low ESR 0.