 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
A4450 Datasheet(PDF) 10 Page - Allegro MicroSystems |
|
||||||||||||||||||||||||||||||
A4450 Datasheet(HTML) 10 Page - Allegro MicroSystems |
|
|
10 / 34 page  Buck-Boost Controller with Integrated Buck MOSFET A4450 10 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com FUNCTIONAL DESCRIPTION Overview The A4450 features all the necessary functions to implement an efficient buck or buck-boost regulation to convert automobile battery voltage into a tightly regulated voltage. The regulator can smoothly switch between Buck mode operation and Buck-Boost mode operation, allowing the operation with input voltage greater than or less than the output voltage. The A4450 integrates low RDSON high-side N-MOSFET as a controlled buck switch. The A4450 provides a gate driver output for the external boost switch. As shown in Figure 1, the configuration of typical buck-boost regulator consists of an external freewheeling Schottky diode dictated as buck diode, another Schottky diode dictated as boost diode, an external MOSFET as boost switch, inductor, and output capacitor. The A4450 can provide regulated output voltage rang- ing from 3 to 8 V with up to 1 A DC load. The A4450 employs peak current-mode control to provide superior line and load regulation, pulse-by-pulse current limit, fast transient response, and simple compensation. The A4450 features include a transconductance error amplifier for external compensation network, an enable input (EN), exter- nally set soft-start time, a SYNC/FSET input to set PWM switch- ing frequency or synchronize to external clock, an output voltage range set pin (RNG), a Power-On Reset output (NPOR) pin, and frequency dithering. Protection features of the A4450 include VIN undervoltage lockout, pulse-by-pulse overcurrent protections in Buck-Boost and Buck modes, BOOT capacitor protection, two levels output overvoltage protection, hiccup mode short-circuit protection, LX short-circuit protection, missing buck diode pro- tection, and thermal shutdown. In addition, the A4450 provides open-circuit, adjacent pin short-circuit, and pin-to-ground short- circuit protection at every pin. The A4450 is available in industry-standard QFN-20 package. VOUT VIN Buck Diode Boost Diode Q1 Buck Switch Boost Switch Q2 LX LG A4450 Figure 1: Basic Buck-Boost Regulator Configuration Operation Modes A buck-boost regulator can regulate the output voltage with input voltage greater than or less than the output voltage. However, the buck-boost regulator is not as efficient as the buck regulator. The A4450 is designed as a dual mode controller to resolve this chal- lenge so that the regulator can operate efficiently under the Buck mode when the input voltage is greater than the output voltage. Figure 1 shows the basic buck-boost regulator configuration with dual mode controller A4450. BUCK MODE In case the input voltage is high compared to the output voltage, the regulator will enter Buck mode: buck switch Q1 turns on and off with duty cycle, DBuck, to maintain regulation while boost switch Q2 is off, according to the following equation: VOUT = DBuck × VIN (1) where DBuck is the duty cycle of buck switch. BUCK-BOOST MODE When the input voltage decreases toward to the output voltage, the duty cycle of the buck switch Q1 will increase to maintain regulation. At the same time, once the programmed boost switch duty cycle, DBoost (shown in the equation below), is greater than 0, the boost switch starts to turn on and off with duty cycle DBoost. The regulator then enters Buck-Boost mode. The boost switch duty cycle is determined by the equation below: DBoost = max VIN × 1.844 RNG ) 0,1 – ( (2) where VIN is in Volts (V) and RNG (kΩ) is the resistor connected between RNG pin and GND. The Range resistor RNG (kΩ) programs the targeted output volt- age, VOUT, following the equation below: RNG = VOUT (V) × 1.844 DBUCK0 (3) where DBUCK0 is the preferred buck duty cycle at the instant that the boost switch starts to switch, typically set between 0.60 and 0.65. |
Similar Part No. - A4450 |
|
Similar Description - A4450 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
