Electronic Components Datasheet Search |
|
ADP3607ARU Datasheet(PDF) 6 Page - Analog Devices |
|
ADP3607ARU Datasheet(HTML) 6 Page - Analog Devices |
6 / 8 page REV. 0 ADP3607 –6– THEORY OF OPERATION The ADP3607 uses a switched capacitor principle to generate a regulated boost voltage from a positive input voltage. An on-board oscillator generates a two-phase clock to control a switching network that transfers charge between the storage capacitors. The switches turn on and off at a 250 kHz rate that is generated from an internal 500 kHz oscillator. The basic principle behind the voltage conversion scheme is illustrated in Figures 14 and 15. S2 S1 VIN VOUT S3 S4 + – CP Figure 14. ADP3607 Switch Configuration Charging the Pump Capacitor During phase one, S1 and S3 are ON, charging the pump ca- pacitor to the input voltage. Before the next phase begins, S1 and S3 are turned OFF, as are S2 and S4 to prevent any over- lap. S2 and S4 are turned ON during the second phase (see Figure 15) and charge stored in the pump capacitor is trans- ferred to the output capacitor. S2 S1 VIN VOUT S3 S4 + – CP Figure 15. ADP3607 Switch Configuration Charging the Output Capacitor During the second phase, the negative terminal of the pump capacitor is connected to VIN through variable resistance switch S4, and the positive terminal is connected to the output, result- ing in a voltage shift at the output terminal. The ADP3607 block diagram is shown on the front page. TEMPERATURE – C 10 1.0 0.01 –50 100 0 50 0.1 ALUMINUM CERAMIC TANTALUM ORGANIC SEMIC Figure 16. ESR vs. Temperature APPLICATION INFORMATION Capacitor Selection The ADP3607’s high internal oscillator frequency permits the use of small capacitors for both the pump and the output ca- pacitors. For a given load current, factors affecting the output voltage performance are: • Pump (CP) and output (CO) capacitance. • ESR of the C P and CO. When selecting the capacitors, keep in mind that not all manu- facturers guarantee capacitor ESR in the range required by the circuit. In general, the capacitor’s ESR is inversely proportional to its physical size, so larger capacitance values and higher volt- age ratings tend to reduce ESR. Since the ESR is also a function of the operating frequency, when selecting a capacitor make sure its value is rated at the circuit’s operating frequency. Another factor affecting capacitor performance is temperature. Figure 16 illustrates the temperature effect on various capaci- tors. If the circuit has to operate at temperatures significantly different from +25 °C, the capacitance and ESR values must be carefully selected to adequately compensate for the change. Various capacitor technologies offer improved performance over temperature; for example, certain tantalum capacitors provide good low temperature ESR but at a higher cost. Table II pro- vides the ratings for different types of capacitor technologies to help the designer select the right capacitors for the application. The exact values of CIN and CO are not critical. However, low ESR capacitors such as solid tantalum and multilayer ceramic capacitors are recommended to minimize voltage loss at high currents. Table III shows a partial list of the recommended low ESR capacitor manufacturers. CAPACITANCE – F 5 0 20 40 60 80 100 120 140 40 10 ADP3607-5 150m 100m 50m 15 20 25 30 35 ILOAD = 50mA Figure 17. Output Ripple Voltage (mV) vs. Capacitance and ESR Input Capacitor A small 1 µF input bypass capacitor (preferably with low ESR) such as tantalum or multilayer ceramic, is recommended to reduce noise and supply transients, and supply part of the peak input current drawn by the ADP3607. A large capacitor is rec- ommended if the input supply is connected to the ADP3607 through long leads, or if the pulse current drawn by the device might affect other circuitry through supply coupling. Output Capacitor The output capacitor (CO) is alternately charged to the CP volt- age when CP is switched in parallel with CO. The ESR of CO introduces steps in the VOUT waveform whenever the charge pump charges CO, which contributes to VOUT ripple. Thus, ceramic or tantalum capacitors are recommended for CO to minimize ripple on the output. Figure 17 illustrates the output ripple voltage effect for various capacitance and ESR values. Note that as the capacitor value increases beyond the point where the dominant contribution to the output ripple is due to the ESR, no significant reduction in VOUT ripple is achieved by added capacitance. Since output current is supplied solely by |
Similar Part No. - ADP3607ARU |
|
Similar Description - ADP3607ARU |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |