Datenblatt-Suchmaschine für elektronische Bauteile |
|
ACT2861QI Datenblatt(PDF) 29 Page - Active-Semi, Inc |
|
ACT2861QI Datenblatt(HTML) 29 Page - Active-Semi, Inc |
29 / 91 page ACT2861QI Rev 2.0, 27-Apr-2018 Innovative PowerTM www.active-semi.com ActiveSwitcherTM is a trademark of Active-Semi Copyright © 2018 Active-Semi, Inc. 29 BUCK-BOOST OPERATION The ACT2861 is a monolithic buck-boost charger with On-The-Go (OTG). As a result, it can operate in both charge mode and OTG mode. In charge mode, the IC converts power from VIN to VBAT to charge a 2S to 5S battery. In OTG mode, it converts power from the bat- tery to VIN to provide a regulated output voltage. Four internal, low resistance, NMOS switches minimize the application circuit size and reduce power losses to max- imize efficiency. Internal high side gate drivers, which require only two small external capacitors, further sim- plify the design process. An advanced switch control al- gorithm allows the buck-boost converter to maintain charge or OTG output voltage regulation with input volt- ages that are above, equal to, or below the regulated output voltage. The ACT2861 automatically transitions between these three operating modes, depending on the input to output voltage ratios. Power Stage Figure 6 shows the 4-switch, buck-boost power stage. The converter operates with current mode control. The internal control algorithm reconfigures the IC between a buck, a boost, and a buck-boost topology as needed. This reduces power dissipation and maximizes effi- ciency because only two FETs switch when in it oper- ates in buck or boost mode. Table 2 shows the switch configuration in each topology. Note that this table is valid for Charge mode. In OTG mode, power flows in the opposite direction, so the switching modes are re- versed. The voltage transition between buck to buck- boost and from buck-boost to boost modes is set by I2C bits XOVER_ADJ_BUCK and XOVER_ADJ_BOOST. With a fixed input voltage and an increasing battery volt- age, the IC switches from buck mode to buck-boost mode when VIN – VBAT < XOVER_AJD_BUCK, which is typically 1V. It switches from buck-boost to boost mode when VBAT – VIN > XOVER_ADJ_BOOST, which is typically 2V. These values are set at the factory to optimize efficiency and performance for each CMI. The power stage is bi-directional and provides power in both directions. When charging, power flows from VIN to VBAT. In OTG mode, power flows from VBAT to VIN. Q1-Q4 are all internal, N-ch MOSFETs to minimize size and maximize efficiency. VIN Q1 Q2 Q3 Q4 VBAT L SW1 SW2 Figure 6: 4-Switch Buck-Boost Power Stage Table 2: Buck-Boost Switch Configuration CHARGE MODE BUCK BUCK- BOOST BOOST Q1 SWITCHING SWITCHING ON Q2 SWITCHING SWITCHING OFF Q3 OFF SWITCHING SWITCHING Q4 ON SWITCHING SWITCHING Figure 7 shows the power stage operating modes. A typical example of how the converter switches between modes can be explained with an example using a 15V input source to charge a 4S Li-Ion battery. When fully discharged, the battery voltage is 12V. With VIN=15V and VBAT=12V, the control loop operates in Buck mode at point A. As the battery charges, the operating mode maintains buck mode until it crosses the threshold be- tween buck mode and buck-boost mode. When the bat- teries are charged at 15V, the control loop operates at point B in Buck-Boost mode. The 4S battery reaches charge termination voltage at 17.4V. In this case, the control loop operates at point C, which is still Buck- Boost mode. If the input voltage dropped from 15V to 12V, the control loop will move to point D and operate in Boost mode. |
Ähnliche Teilenummer - ACT2861QI |
|
Ähnliche Beschreibung - ACT2861QI |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller 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 |