Datasheet

DI
L
+ I
CHARGE
I
CHARGE
Ripple
L
OUT
+
V
BAT
ǒ
V
INMAX
* V
BAT
Ǔ
V
INMAX
ƒ DI
L
L
OUT
+
4.2 (16 * 4.2)
16 (1.1 10
6
) (1.33 0.3)
L
OUT
+ 7.06 mH
DI
L
+
V
BAT
ǒ
V
INMAX
* V
BAT
Ǔ
V
INMAX
ƒ L
OUT
DI
L
+
4.2 (16 * 4.2)
16 (1.1 10
6
) (10 10
*6
)
DI
L
+ 0.282 A
I
LPK
+ I
OUT
)
DI
L
2
I
LPK
+ 1.33 )
0.282
2
I
LPK
+ 1.471 A
bq24100, bq24103, bq24103A
bq24104, bq24105, bq24108, bq24109
bq24113, bq24113A, bq24115
www.ti.com SLUS606O –JUNE 2004–REVISED MARCH 2010
bqSWITCHER SYSTEM DESIGN EXAMPLE
The following section provides a detailed system design example for the bq24100.
System Design Specifications:
• V
IN
= 16V
• V
BAT
= 4.2V (1-Cell)
• I
CHARGE
= 1.33 A
• I
PRECHARGE
= I
TERM
= 133 mA
• Safety Timer = 5 hours
• Inductor Ripple Current = 30% of Fast Charge Current
• Initiate Charge Temperature = 0°C to 45°C
1. Determine the inductor value (L
OUT
) for the specified charge current ripple:
(13)
Set the output inductor to standard 10 mH. Calculate the total ripple current with using the 10 mH inductor:
(14)
Calculate the maximum output current (peak current):
(15)
Use standard 10 mH inductor with a saturation current higher than 1.471A. (i.e., Sumida CDRH74-100)
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Product Folder Link(s): bq24100 bq24103 bq24103A bq24104 bq24105 bq24108 bq24109 bq24113 bq24113A
bq24115