LT8705

39

8705fe

For more information www.linear.com/LT8705

Figure 14. Telecom Voltage Stabilizer

8705 F14a

CSPOUT

CSNOUT

FBOUT

SRVO_FBIN

SRVO_FBOUT

SRVO_IIN

SRVO_IOUT

IMON_IN

IMON_OUT

SYNC

CLKOUT

56.2k

202kHz

CSNIN

TG1 BOOST1

L1

22µH

M4

M1

×2

4.7µF

×4

SW1 BG1 CSP

CSN

LT8705

GND BG2 SW2 BOOST2

48V

5A

36V TO 80V

TG2

CSPIN

SHDN

SWEN

LDO33

MODE

FBIN

RT

SS

3.3nF

220pF

L1: 22µH, WÜRTH 74435572200 OR COILCRAFT SER2918H-223

M1, M3: FAIRCHILD FDMS86104

M2, M4: FAIRCHILD FDMS86101

*2 FROM TG1 TO EACH SEPERATE M1 GATE

**2 FROM BG2 TO EACH SEPERATE M3 GATE

215k

71.5k

100k

20k

1µF

1µF

4.7µF

10k

392k

220µF

×2

4.7µF

×6

4

4.7µF

TO

BOOST1

4.7µF

+

220µF

×2

+

TO

BOOST2

0.22µF

0.22µF

TO

TO

M2

M3

×2

1nF

1nF

2*

2**

10m

10

10

LOAD CURRENT (mA)

10

0

20

30

40

50

60

70

100

1000

8705 F14b

80

90

100

10

10000

COILCRAFT SER2918H-223

WURTH 74435572200

CCM

LOAD CURRENT (mA)

10

0

20

30

40

50

60

70

100

1000

8705 F14c

80

90

100

10

10000

COILCRAFT SER2918H-223

WURTH 74435572200

CCM

Efficiency vs Output Current

(Boost Region)

Efficiency vs Output Current

(Buck Region)

Note: See the front page and the Typical Performance Characteristics section for more curves from this application

circuit using the Coilcraft inductor. The smaller Würth inductor is also suitable in place of the Coilcraft inductor with

some loss in efficiency.

applicaTions inForMaTion