Motore di ricerca datesheet componenti elettronici |
|
RT5047BF Scheda tecnica(PDF) 12 Page - Richtek Technology Corporation |
|
RT5047BF Scheda tecnica(HTML) 12 Page - Richtek Technology Corporation |
12 / 17 page RT5047BF Copyright © 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5047BF-00 December 2017 12 where D is the duty cycle and η is the boost converter efficiency. Finally, take ESR into consideration, the overall output ripple voltage can be determined by the following equation : OUT OUT IN OUT OSC DI V = I ESR Cf The output capacitor, COUT, should be selected accordingly. Time Time Inductor Current Output Current Output Ripple Voltage (ac) (1-D)TS ΔVOUT1 ΔIL Input Current Figure 1. The Output Ripple Voltage without the Contribution of ESR Schottky Diode Selection Schottky diodes are chosen for their low forward-voltage drop and fast switching speed. However, when making a selection, important parameters such as power dissipation, reverse voltage rating, and pulsating peak current should all be taken into consideration. A s uitable Schottky diode’s reverse voltage rating must be greater than the maximum output voltage and its average current rating must exceed the average output current. The chosen diode should also have a sufficiently low leakage current level, since it increases with temperature. Under-Voltage Lockout (UVLO) The UVLO circuit compares the input voltage at VIN with the UVLO threshold (7.7V rising typically) to ensure that the input voltage is high enough for reliable operation. The 350mV (typ.) hysteresis prevents supply transients from causing a shutdown. Once the input voltage exceeds the UVLO rising threshold, start-up begins. When the input voltage falls below the UVLO falling threshold, all IC internal functions will be turned off by the controller. Over-Current Protection The RT5047BF features an over-current protection function to prevent chip damage from high peak currents. Both the boost converter and the linear regulator have independent current limit. (1) Boost In the boost converter, this is achieved through cycle-by-cycle internal current limit. During the ON-period, the chip senses the inductor current that is flowing into the LX pin. The internal NMOS will be turned off if the peak inductor current reaches the current-limit value of 3A (typ.). (2) LNB When the linear regulator exceeds 550mA (typ.) more than 6ms, the LNB output will be disabled. During this period of time, if the current limit condition disappears, the OCP will be cleared and the part restarts. If the part is still in current limit after this time period, the linear regulator and boost converter will automatically disable to prevent the part from overheating. Short Circuit Protection If the LNB output is shorted to ground, and more than 6ms, the RT5047BF will be disabled 1800ms then enable automatically. Over-Temperature Protection When the junction temperature reaches the critical temperature (typically 140°C), the boost converter and the linear regulator are immediately disabled. When the junction temperature cools down to a lower temperature threshold specified, the RT5047BF will be allowed to restart by normal start operation. FAULT FAULT is a open-drain input. If it is 0, it stands for fault occurred. The FAULT provide the information to show over-current and short circuit protection of the system. |
Codice articolo simile - RT5047BF |
|
Descrizione simile - RT5047BF |
|
|
Link URL |
Privacy Policy |
ALLDATASHEETIT.COM |
Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore 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 |