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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Documents Flashcards Grammar checker. The Constant On-Time COT regulation scheme requires no loop compensation, results in a fast load transient response and simple circuit implementation that allows a low component count, and consequently very small overall board space is required for a typical application. The operating frequency remains constant with line variations due to the inverse relationship between the input voltage and the on-time.

Protection features include output over-voltage protection, thermal shutdown, VCC undervoltage lock-out, gate drive under-voltage lock-out. This user’s guide details the design of a demonstration board which provides a 3. The demonstration board schematic, PCB layout, Bill of Materials, and circuit design descriptions are shown. Typical performance and operating waveforms are also provided for reference. The design of the demonstration board is detailed below.

Calculate the feedback resistors The ratio of the feedback resistors can be calculated from the following equation: 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.

To ensure that the on-time is larger than the minimum limit, which is ns, the value of R1 must satisfy the following equation: Determine the inductance The main parameter affected by the inductor is the amplitude of the inductor current ripple ILR. Once ILR is selected, L can be determined by: Determine the value of other components C1 and C2: The function of the input capacitor is to supply most of the main MOSFET current during the on-time, and limit the voltage ripple at the VIN pin, assuming that the voltage source feeding to the VIN pin has finite output impedance.

It then drops to zero at turn-off.

LM datasheet, Pinout ,application circuits Synchronous 1MHz A Step-Down Voltage Regulator

The average current during the on-time is the load current. For a worst case calculation, the input capacitor must be capable of supplying this average load current during the maximum on-time. The input capacitor is calculated datashewt A low ESR 0. Low ESR also helps ensure a complete recharge during each off-time.

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. The time is determined from the following equation: C8 should be no smaller than nF for stability, and should be a good quality, low ESR, ceramic capacitor. If the output voltage is higher than 1. In this demonstration board, a 10 nF capacitor is used. Experimentation is usually necessary to determine the minimum value for the output capacitor, as the nature of the load may require a larger value.


A load which creates significant transients requires a larger output capacitor than a fixed load. A nF capacitor is used in this demonstration board. Layout is therefore critical for optimum performance.

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.

The connection from the PGND pin to the input capacitors should be as short and direct as possible. Vias should be added to connect the ground of the input capacitors to a ground plane, located as close to the capacitor as possible. The bootstrap capacitor C4 should be connected as close to the SW and BST pins as possible, and the connecting traces should be thick. The output capacitor C10, C11 should be connected close to the load and tied directly to the ground plane.

AN-1646 LM3102 Demonstration Board

The inductor L1 should be connected close to the SW pin with as short a trace as possible to reduce the potential for EMI electromagnetic interference generation. 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. The exposed pad is internally connected to the LM IC substrate. Additionally the use of thick traces, where possible, can help conduct heat away from the LM Using numerous vias to connect the die attached pad to the ground plane is a good practice.

Judicious positioning of the PC dafasheet within the end product, along with the use of any available air flow forced or natural convection can help reduce the junction temperature. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.

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Synchronous 1MHz 2.5A Step-Down Voltage Regulator

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Products Applications Audio www. I wish to measure a very low resistance of the order of an ohm. How much energy is. Headline Bold Ipsum lorem Headline Light. Lab 6 in this note.