|
BQ24105-Q1 Datasheet, PDF (22/35 Pages) Texas Instruments – SYNCHRONOUS SWITCHMODE, LI-ION AND LI-POLYMER CHARGE-MANAGEMENT IC WITH INTEGRATED POWER FETs ( bqSWITCHER™) | |||
|
◁ |
bq24105-Q1
SLUS953 â AUGUST 2009................................................................................................................................................................................................. www.ti.com
2. Determine the output capacitor value (OUT) using 16 kHz as the resonant frequency:
Æo
+
2p
1
ǸLOUT
COUT
COUT + 4p2
1
Æo 2
LOUT
COUT + 4p2
(16
1
103)2
(10
10*6)
COUT + 9.89 mF
(16)
Use standard value 10 µF, 25V, X5R, ±20% ceramic capacitor (i.e., Panasonic 1206 ECJ-3YB1E106M
3. Determine the sense resistor using the following equation:
RSNS
+
VRSNS
ICHARGE
(17)
In order to get better current regulation accuracy (±10%), let VRSNS be between 100 mV and 200 mV. Use
VRSNS = 100 mV and calculate the value for the sense resistor.
RSNS
+
100 mV
1.33 A
RSNS + 0.075 W
(18)
This value is not standard in resistors. If this happens, then choose the next larger value which in this case is
0.1â¦. Using the same equation (15) the actual VRSNS will be 133mV. Calculate the power dissipation on the
sense resistor:
PRSNS + ICHARGE2 RSNS
PRSNS + 1.332 0.1
PRSNS + 176.9 mW
(19)
Select standard value 100 mâ¦, 0.25W 0805, 1206 or 2010 size, high precision sensing resistor. (i.e., Vishay
CRCW1210-0R10F)
4. Determine ISET 1 resistor using the following equation:
RISET1
+
KISET1
RSNS
VISET1
ICHARGE
RISET1
+
1000
0.1
1.0
1.33
RISET1 + 7.5 kW
(20)
Select standard value 7.5 kâ¦, 1/16W ±1% resistor (i.e., Vishay CRCWD0603-7501-F)
5. Determine ISET 2 resistor using the following equation:
RISET2
+
KISET2 VISET2
RSNS IPRECHARGE
RISET2 +
1000
0.1
0.1
0.133
RISET2 + 7.5 kW
(21)
Select standard value 7.5 kâ¦, 1/16W ±1% resistor (i.e., Vishay CRCWD0603-7501-F)
22
Submit Documentation Feedback
Product Folder Link(s): bq24105-Q1
Copyright © 2009, Texas Instruments Incorporated
|
▷ |