OUT

OUT

1

=

o

2

L

C

f

p

´

´

2

2

OUT

OUT

1

C

4

L

0

f

=

p

´

´

2

3 2

-6

OUT

1

C

4

(40

10 )

(1

10 )

=

p

´

´

´

´

(RSNS)

(SNS)

(CHARGE)

V

R

I

=

(SNS)

85mV

R

1.25A

=

BatteryChargeEfficiency

82

83

84

85

86

87

88

89

90

500

600

700

800

900 1000 1100 1200 1300

ChargeCurrent-mA

TOKO

FDK

muRata

Inter-Technical

BatteryChargeLoss

100

200

300

400

500

600

700

800

500

600

700

800

900 1000 1100 1200 1300

ChargeCurrent-mA

T =25°C,

VBUS=5V,

VBAT=3V

A

T =25°C,

VBUS=5V,

VBAT=3V

A

TOKO

FDK

muRata

Inter-Technical

bq24150

bq24151

Select two 0603 X5R 6.3V 10-

µF ceramic capacitors in parallel i.e., muRata GRM188R60J106M.

3. Determine the sense resistor using the following equation:

The maximum sense voltage across sense resistor is 85 mV. In order to get a better current regulation

This is a standard value. If it is not a standard value, then choose the next close value and calculate the real

charge current. Calculate the power dissipation on the sense resistor:

(SNS)

Select 0402 0.125-W 68-m

Ω 2% sense resistor, i.e. Panasonic ERJ2BWGR068.

4. Measured efficiency and total power loss for different inductors are shown in Figure 34.

Figure 34. Measured Efficiency and Power Loss

32

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