MC34163 MC33163

10

MOTOROLA ANALOG IC DEVICE DATA

Figure 20. Step–Down Converter

RB

L

2200

1N5822

LVI

1

+

+

–

+

Current

Limit

8

7

6

5

4

3

2

(Bottom View)

+

+

–

16

9

10

11

12

13

14

15

0.25 V

+

RSC

0.075

Vin

12 V

CT

680 pF

1.125 V

15 k

1.25 V

+

45 k

Feedback

Comparator

Q1

Q2

60

Cin

330

CO

Coilcraft LO451–A

CB

0.02

Vout

5.05 V/3.0 A

Low Voltage

Indicator Output

CDLY

RLVI

10 k

+

–

+

Thermal

Oscillator

R

S

Q

Latch

+

+

+

2.0 mA

7.0 V

+

180

µH

Test

Condition

Results

Line Regulation

Vin = 8.0 V to 24 V, IO = 3.0 A

6.0 mV =

± 0.06%

Load Regulation

Vin = 12 V, IO = 0.6 A to 3.0 A

2.0 mV =

± 0.02%

Output Ripple

Vin = 12 V, IO = 3.0 A

36 mVpp

Short Circuit Current

Vin = 12 V, RL = 0.1 Ω

3.3 A

Efficiency, Without Bootstrap

Vin = 12 V, IO = 3.0 A

76.7%

Efficiency, With Bootstrap

Vin = 12 V, IO = 3.0 A

81.2%

Figure 21. External Current Boost Connections for Ipk (Switch) Greater Than 3.4 A

Figure 21A. External NPN Switch

Figure 21B. External PNP Saturated Switch

1

+

+

8

7

6

5

4

3

2

(Bottom View)

Q3

Q2

Q1

1

+

+

8

7

6

5

4

3

2

(Bottom View)

Q2

Q1

+

+

Q3

9

10

11

12

13

14

15

16

9

10

11

12

13

14

15

16