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It achieves 1. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The MP requires a minimum number of readily available standard external components.
A Shutdown Mode Fixed 1. Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. A capacitor is connected between SW and BS pins to form a floating supply across the power switch driver. This pin is the voltage reference for the regulated output voltage. For this reason care must be taken in its layout. This node should be placed outside of the D1 to C1 ground path to prevent switching current spikes from inducing voltage noise into the part.
To prevent current limit run away during a short circuit fault condition, the frequency foldback comparator lowers the oscillator frequency when the FB voltage is below mV. Pull EN above 1. Supply Voltage. C1 is needed to prevent large voltage spikes from appearing at the input. Switch Output. C, unless otherwise noted. Current Limit vs Duty Cycle 3. MP Rev.
That is, the EA output voltage is proportional to the peak inductor current. At the beginning of a cycle, M1 is off. The rising edge of the 1.
Its output turns on M1 thus connecting the SW pin and inductor to the input supply. The increasing inductor current is sensed and amplified by the Current Sense Amplifier. The external Schottky rectifier diode D1 conducts the inductor current. The output of the Error Amplifier integrates the voltage difference between the feedback and the 0. The polarity is such that a FB pin voltage lower than 0. Since the EA output voltage is proportional to the peak inductor current, an increase in its voltage also increases current delivered to the output.
Table 1 shows a list of resistor selection for common output voltages. The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor see Figure 1. The input capacitor impedance at the switching frequency should be less than the input source impedance to prevent high frequency switching current from passing through the input.
For most applications, a 4. F capacitor is sufficient. Selecting the Output Capacitor The output capacitor keeps the output voltage ripple small and ensures feedback loop stability. The output capacitor impedance should be low at the switching frequency. For most applications, a 22?
F ceramic capacitor will be sufficient. The external feedback resistors should be placed next to the FB pin. Keep the switch node traces short and away from the feedback network. External Bootstrap Diode It is recommended that an external bootstrap diode be added when the input voltage is no greater than 5V or the 5V rail is available in the system.
This helps improve the efficiency of the regulator. H to 10? Refer to Table 2 for suggested surface mount inductors. For most designs, the required inductance value can be derived from the following equation. IL is the inductor ripple current. See Table 2 for suggested inductors. Please contact MPS for current specifications. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application.
MPS will not assume any legal responsibility for any said applications.
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硅动力 SP1076/MP2259 SOT23-6
It achieves 1. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The MP requires a minimum number of readily available standard external components. A Shutdown Mode Fixed 1. Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved.
MP2259 Buck Converter overview