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NCP605 Datasheet(PDF) 10 Page - ON Semiconductor |
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NCP605 Datasheet(HTML) 10 Page - ON Semiconductor |
10 / 13 page NCP605, NCP606 http://onsemi.com 10 APPLICATIONS INFORMATION The NCP605/NCP606 regulator is self *protected with internal thermal shutdown and internal current limit. Typical application circuits are shown in Figures 1 to 4. Input Decoupling (Cin) A ceramic or tantalum 1.0 mF capacitor is recommended and should be connected close to the NCP605/NCP606 package. Higher capacitance and lower ESR will improve the overall line transient response. Output Decoupling (Cout) The NCP605/NCP606 is a stable component and does not require a minimum Equivalent Series Resistance (ESR) for the output capacitor. The minimum output decoupling value is 1.0 mF and can be augmented to fulfill stringent load transient requirements. The regulator works with ceramic chip capacitors as well as tantalum devices. Larger values improve noise rejection and load regulation transient response. Typical characteristics were measured with Murata ceramic capacitors. GRM219R71E105K (1 mF, 25 V, X7R, 0805) and GRM21BR71A106K (10 mF, 10 V, X7R, 0805). No−Load Regulation Considerations The NCP605/NCP606 adjustable regulator will operate properly under conditions where the only load current is through the resistor divider that sets the output voltage. However, in the case where the NCP605/NCP606 is configured to provide a 1.250 V output, there is no resistor divider. If the part is enabled under no−load conditions, leakage current through the pass transistor at junction temperatures above 85 °C can approach several microamps, especially as junction temperature approaches 150 °C. If this leakage current is not directed into a load, the output voltage will rise up to a level approximately 20 mV above nominal. The NCP605/ NCP606 contains an overshoot clamp circuit to improve transient response during a load current step release. When output voltage exceeds the nominal by approximately 20 mV, this circuit becomes active and clamps the output from further voltage increase. Tying the ENABLE pin to Vin (NCP606 only) will ensure that the part is active whenever the supply voltage is present, thus guaranteeing that the clamp circuit is active whenever leakage current is present. When the NCP606 adjustable regulator is disabled, the overshoot clamp circuit becomes inactive and the pass transistor leakage will charge any capacitance on Vout. If no load is present, the output can charge up to within a few millivolts of Vin. In most applications, the load will present some impedance to Vout such that the output voltage will be inherently clamped at a safe level. A minimum load of 10 mA is recommended. Unlike LP8345, for NCP605/606 fixed voltage versions there is no limitation for minimum load current. Noise Decoupling The NCP605/NCP606 is a low noise regulator and needs no external noise reduction capacitor. Unlike other low noise regulators which require an external capacitor and have slow startup times, the NCP605/NCP606 operates without a noise reduction capacitor, has a typical 8 ms turn−on time and achieves a 50 mVrms overall noise level between 10 Hz and 100 kHz. Enable Operation (NCP606 Only) The enable pin will turn the regulator on or off. The threshold limits are covered in the electrical characteristics table in this data sheet. The turn−on/turn−off transient voltage being supplied to the enable pin should exceed a slew rate of 10 mV/ ms to ensure correct operation. If the enable function is not to be used then the pin should be connected to Vin. Output Voltage Adjust The output voltage can be adjusted from 1 times (Figure 4) to 4 times (Figure 3) the typical 1.250 V regulation voltage via the use of resistors between the output and the ADJ input. The output voltage and resistors are chosen using Equation 1 and Equation 2. Vout + 1.250 1 ) R1 R2 ) IADJ R1 (eq. 1) (eq. 2) R2 ^ R1 Vout 1.25 * 1 Input bias current IADJ is typically less than 150 nA. Choose R1 arbitrarily to minimize errors due to the bias current and to minimize noise contribution to the output voltage. Use Equation 2 to find the required value for R2. Thermal As power in the NCP605/NCP606 increases, it might become necessary to provide some thermal relief. The maximum power dissipation supported by the device is dependent upon board design and layout. Mounting pad configuration on the PCB, the board material, and the ambient temperature affect the rate of junction temperature rise for the part. When the NCP605/NCP606 has good thermal conductivity through the PCB, the junction temperature will be relatively low with high power applications. The maximum dissipation the NCP605/NCP606 can handle is given by: PD(MAX) + TJ(MAX) * TA RQJA (eq. 3) Since TJ is not recommended to exceed 125°C (TJ(MAX)), then the NCP605/NCP606 soldered on 645 mm2, 1 oz copper area, FR4 can dissipate up to 1.3 W when the ambient |
Similar Part No. - NCP605_13 |
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Similar Description - NCP605_13 |
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