Motore di ricerca datesheet componenti elettronici |
|
FAN48610UC50X Scheda tecnica(PDF) 9 Page - Fairchild Semiconductor |
|
FAN48610UC50X Scheda tecnica(HTML) 9 Page - Fairchild Semiconductor |
9 / 13 page © 2013 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN48610 • Rev. 1.0.0 • 9 Circuit Description FAN48610 is a synchronous boost regulator, typically operating at 2.5 MHz in Continuous Conduction Mode (CCM), which occurs at moderate to heavy load current and low VIN voltages. The regulator’s Pass-Through Mode automatically activates when VIN is above the boost regulator’s set point. Table 2. Operating Modes Mode Description Invoked When: LIN Linear Startup VIN > VOUT SS Boost Soft-Start VIN < VOUT < VOUT(TARGET) BST Boost Operating Mode VOUT= VOUT(TARGET) PT Pass-Through Mode VIN > VOUT(TARGET) Boost Mode Regulation The FAN48610 uses a current-mode modulator to achieve excellent transient response and smooth transitions between CCM and DCM operation. During CCM operation, the device maintains a switching frequency of about 2.5 MHz. In light- load operation (DCM), frequency is naturally reduced to maintain high efficiency. Shutdown and Startup When EN is LOW, all bias circuits are off and the regulator is in Shutdown Mode. During shutdown, current flow is prevented from VIN to VOUT, as well as reverse flow from VOUT to VIN. It is recommended to keep load current draw below 500 mA until the devices successfully executes startup. The following table describes the startup sequence. Table 3. Boost Startup Sequence Start Mode Entry Exit End Mode Timeout (µs) LIN1 VIN > VUVLO, EN=1 VOUT > VIN- 300 mV SS TIMEOUT LIN2 512 LIN2 LIN1 Exit VOUT > VIN- 300 mV SS TIMEOUT FAULT 1024 SS LIN1 or LIN2 Exit VOUT=VOUT(TARG ET) BST OVERLOAD TIMEOUT FAULT 64 LIN Mode When EN is HIGH and VIN > VUVLO, the regulator first attempts to bring VOUT within 300 mV of VIN by using the internal fixed-current source from VIN (Q2). The current is limited to the LIN1 set point. If VOUT reaches VIN-300 mV during LIN1 Mode, the SS Mode is initiated. Otherwise, LIN1 times out after 512 µs and LIN2 Mode is entered. In LIN2 Mode, the current source is incremented to 1.6 A. If VOUT fails to reach VIN-300 mV after 1024 µs, a fault condition is declared and the device waits 20 ms to attempt an automatic restart. Soft-Start (SS) Mode Upon the successful completion of LIN Mode (VOUT>VIN- 300 mV), the regulator begins switching with boost pulses current limited to 50% of nominal level. During SS Mode, if VOUT fails to reach regulation during the SS ramp sequence for more than 64 µs, a fault is declared. If large COUT is used, the reference is automatically stepped slower to avoid excessive input current draw. Boost (BST) Mode This is a normal operating mode of the regulator. Pass-Through (PT) Mode In normal operation, the device automatically transitions from Boost Mode to Pass-Through Mode if VIN goes above the target VOUT. In Pass-Through Mode, the device fully enhances Q2 to provide a very low impedance path from VIN to VOUT. Entry to the Pass-Through Mode is triggered by condition where VIN > VOUT and no switching has occurred during the past 5 µs. To soften the entry into Pass-Through Mode, Q2 is driven as a linear current source for the first 5 µs. Pass-Through Mode exit is triggered when VOUT reaches the target VOUT voltage. During Automatic Pass- Through Mode, the device is short-circuit protected by a voltage comparator tracking the voltage drop from VIN to VOUT; if the drop exceeds 300 mV, a fault is declared. Fault State The regulator enters Fault State under any of the following conditions: V OUT fails to achieve the voltage required to advance from LIN Mode to SS Mode. V OUT fails to achieve the voltage required to advance from SS Mode to BST Mode. Boost current limit triggers for 2 ms during BST Mode. V IN – VOUT > 300 mV; this fault can occur only after successful completion of the soft-start sequence. V IN < VUVLO. Once a fault is triggered, the regulator stops switching and presents a high-impedance path between VIN and VOUT. After waiting 20 ms, an automatic restart is attempted. Over-Temperature The regulator shuts down if the die temperature exceeds 150°C. Restart occurs when the IC has cooled by approximately 20°C. |
Codice articolo simile - FAN48610UC50X |
|
Descrizione simile - FAN48610UC50X |
|
|
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 |