 English |
|
|
|
|
|
|
|
| BQ25703A Datasheet, PDF (70/81 Pages) Texas Instruments – I2C Multi-Chemistry Battery Buck-Boost Charge Controller With System Power Monitor and Processor Hot Monitor | |||
| |||
| ◁ |
bq25703A
SLUSCU1 â MAY 2017
www.ti.com
Ion
=
VREGN - Vplt ,
Ron
Ioff
=
Vplt
Roff
(10)
The conduction loss of the bottom-side MOSFET is calculated with the following equation when it operates in
synchronous continuous conduction mode:
Pbottom = (1 - D) x ICHG 2 x RDS(on)
(11)
When charger operates in non-synchronous mode, the bottom-side MOSFET is off. As a result all the
freewheeling current goes through the body-diode of the bottom-side MOSFET. The body diode power loss
depends on its forward voltage drop (VF), non-synchronous mode charging current (INONSYNC), and duty cycle (D).
PD = VF x INONSYNC x (1 - D)
(12)
The maximum charging current in non-synchronous mode can be up to 0.25 A for a 10-mΩ charging current
sensing resistor or 0.5 A if battery voltage is below 2.5 V. The minimum duty cycle happens at lowest battery
voltage. Choose the bottom-side MOSFET with either an internal Schottky or body diode capable of carrying the
maximum non-synchronous mode charging current.
9.2.3 Application Curves
CH1: VBUS
CH2: VDDA
CH3: CHRG_OK
CH4: VSYS
2-cell without battery
Figure 49. Power Up from 20 V
CH1: VBUS
CH2: SW1
CH3: SW2
CH4: IL
3-cell VBAT = 10 V
Figure 51. Power Off from 12 V
CH1: VBUS
CH2: VDDA
CH3: CHRG_OK
CH4: VSYS
2-cell without battery
Figure 50. Power Up from 5 V
CH1: VBUS
CH2: SW1
CH3: SW2
CH4: VSYS with 9Vos
VBUS 5 V to 20 V
Figure 52. System Regulation
70
Submit Documentation Feedback
Copyright © 2017, Texas Instruments Incorporated
|
▷ |
German
Russian
Spanish
Italian
Polish
Chinese
Japanese
Korean
French
Portuguese