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| BQ24196_17 Datasheet, PDF (35/50 Pages) Texas Instruments – I2C Controlled 2.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG | |||
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Typical Application (continued)
bq24196
SLUSB98A â OCTOBER 2012 â REVISED DECEMBER 2014
5V USB
15V Adapter
1μF
6.8μF
bq24196
VBUS
SW
PMID
BTST
REGN
SYS
PGND
VREF
10kW
Host
PHY
10kW
2.2kW
PG
SYS
STAT
BAT
10kW
SDA
ILIM
SCL
INT
OTG
CE
TS1
TS2
PSEL
Power Pad
2.2μH
47nF
4.7μF
SYS: 3.5V-4.35V
10μF
10μF
353W 10μF
(1.5A max)
REGN
5.52kW
31.23kW
10kW
(103-AT)
Figure 37. bq24196 with PSEL, USB On-The-Go (OTG), and Single Thermistor Connection
9.2.1 Design Requirements
Table 18. Design Requirements
DESIGN PARAMETER
Input voltage
Input current limit
Fast charge current
Boost mode output current
EXAMPLE VALUE
3.9 V to 17 V
3000 mA
2500 mA
1.3 A
9.2.2 Detailed Design Procedure
9.2.2.1 Inductor Selection
The bq24196 has 1.5-MHz switching frequency to allow the use of small inductor and capacitor values. The
Inductor saturation current should be higher than the charging current (ICHG) plus half the ripple current (IRIPPLE):
( ) ISAT ³ ICHG + 1/ 2 IRIPPLE
(4)
The inductor ripple current depends on input voltage (VBUS), duty cycle (D = VBAT/VVBUS), switching frequency
(fs) and inductance (L):
IRIPPLE
=
VIN
´ D ´ (1- D)
¦s ´ L
(5)
The maximum inductor ripple current happens with D = 0.5 or close to 0.5. Usually inductor ripple is designed in
the range of (20 to 40%) maximum charging current as a trade-off between inductor size and efficiency for a
practical design. Typical inductor value is 2.2 µH.
Copyright © 2012â2014, Texas Instruments Incorporated
Product Folder Links: bq24196
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