Datenblatt-Suchmaschine für elektronische Bauteile |
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TS2576CZ5-05 Datenblatt(PDF) 5 Page - Taiwan Semiconductor Company, Ltd |
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TS2576CZ5-05 Datenblatt(HTML) 5 Page - Taiwan Semiconductor Company, Ltd |
5 / 7 page TS2576 5-7 2003/12 rev. A Application Information It is required that VIN must be bypassed with at least a 100µF electrolytic capacitor for stability. Also, it is strongly recommended the capacitor’s leads must be dept short, and located near the regulator as possible. For low operating temperature range, for example, below -25 oC, the input capacitor value may need to be larger. This is due to the reason that the capacitance value of electrolytic capacitors decreases and the ESR increases with lower temperatures and ago. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold temperatures. Output Capacitor An output capacitor is also required to filter the output voltage and is needed for loop stability. The capacitor should be located near the TS2576 using short PC board traces. Low ESR types capacitors are recommended for low output ripple voltage and good stability. Generally, low value or low voltage (less than 12V) electrolytic capacitors usually have higher ESR numbers, For example, the lower capacitor values (220µF - 1000µF) will yield typically 50mV to 150mV of output ripple voltage, while larger-value capacitors will reduce the ripple to approximately 20mV to 50mV. The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the output capacitor and the amplitude of the inductor ripple current (IIND) Output Ripple Voltage = (IIND) x (ESR of COUT) Some capacitors called “high-frequency”, “low-inductance”, or “low-ESR” are recommended to use to further reduce the output ripple voltage to 10mV or 20mV. However, very low ESR capacitors, such as tantalum capacitors, should be carefully evaluated. Catch Diode This diode is required to return path for the inductor current when the switch is off. It should be located close to the TS2576 using short leads and short printed circuit traces as possible. To satisfy the need to fast switching speed and low forward voltage drop, Schottky diodes are widely used to provide the best efficiency, especially in low output voltage switching regulators (less than 5V). Beside, Fast-Recovery, high-efficiency, or ultra fast recovery diodes are also suitable. But some types with an abrupt turn-off characteristic may cause instability and EMI problems. A fast recovery diode with soft recovery characteristics is better choice. Inductor Selection The TS2576 can be used for either continuous or discontinuous modes of operation. Each mode has distinctively different operating characteristics, which can affect the regulator performance and requirements. With relatively heavy load currents, the circuit operates in the continuous mode (inductor current always flowing). But under light Load conditions, the circuit will be force to the discontinuous mode (inductor current falls to zero for a period of time). For light loads (less than approximately 300mA) it may be desirable to operate the regulator in the discontinuous mode, primarily because of the lower inductor values required for the discontinuous mode. Indictors are available in different styles such as pot core, toroid, E-frame, bobbin core, et., as well as different core materials such as ferrites and powdered iron. The least expensive, the bobbin core type, consists of wire wrapped on a ferrite rod core. This type of construction makes for an inexpensive inductor, but since the magnetic flux is not completely contained within the core, it generates more electromagnetic interference (EMI). This EMI can cause problems in sensitive circuits, or can give incorrect scope readings because of induced voltage in the scope probe. An inductor should not be operated beyond its maximum rated current because it may saturate. When an inductor begins to saturate, the inductance decreases rapidly and the inductor begins to look mainly resistive (the DC resistance of the winding). This will cause the switch current to rise very rapidly. Different inductor types have different saturation characteristics, and this should be well considered when selecting as inductor. Feedback Connection For fixed output voltage version, the FB (feedback) pin must be connected to VOUT. For the adjustable version, it is important to place the output voltage ratio resistors near TS2576 as possible in order to minimize the noise introduction. Enable Input It is required that the ENABLE must not be left open. For normal operation, connect this pin to a ”LOW” voltage (typically, below 1.6V). On the other hand, for standby mode, connect this pin with a “HIGH” voltage. This pin can be safely pulled up to +VIN without a resistor in series with it. |
Ähnliche Teilenummer - TS2576CZ5-05 |
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Ähnliche Beschreibung - TS2576CZ5-05 |
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