L4978 Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

Fabricante

L4978

2A STEP DOWN SWITCHING REGULATOR

STMicroelectronics 

L4978

Table 6. Electrical Characteristcs

(Tj = 25°C, Cosc = 2.7nF, Rosc = 20kΩ, VCC = 24V, unless otherwise specified). “●" Specification Referred

to Tj from 0 to 125°C

Symbol

Parameter

OSCILLATOR SECTION

Ramp Valley

Ramp peak

Maximum duty cycle

Maximum Frequency

Test Condition

Vcc = 8V

Vcc = 55V

Duty Cycle = 0%

Rosc = 13kΩ, Cosc = 820pF

Min. Typ. Max. Unit

0.78 0.85 0.92

V

2

2.15 2.3

V

9

9.6 10.2

V

95

97

%

300 kHz

Figure 4. Test and evaluation board circuit.

Vi=8V to 55V

C1

220µF

63V

C7

220nF

R1

20K

C2

2.7nF

5

L4978

3

2

7

1

C5

100nF C4

22nF

R2

9.1K

8

4

6

C6

100nF

D1

STPS3L60U

L1

126µH

(77120)

C8

330µF

VO=3.3V/2A

R3

R4

C1=220µF/63V EKE

C2=2.7nF

C5=100nF

C6=100nF

C7=220nF/63V

C8=330µF/35V CG Sanyo

L1=126µH KoolMu 77120 - 55 Turns - 0.5mm

R1=20K

R2=9.1K

D1=STPS3L60U

D98IN834B

VO(V)

3.3

5.1

12

15

18

24

L4978

R3(KΩ)

0

2.7

12

16

20

30

R4(KΩ)

4.7

4.7

4.7

4.7

4.7

Figure 5. PCB and component layout of the figure 4.

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