MAX786

V+

VL

23

22

V+

C1

33

µF

35V

R9

1k

R10

OPEN

6

D2

25

18

16

17

19

15

10

11

7

8

SS3 GND PGND

BST3

DH3

LX3

DL3

CS3

FB3

ON3

ON5

SHDN

D1

BST5

DH5

LX5

DL5

CS5

FB5

REF

SYNC

Q2

Q1

2

14

20

3.3V

OUT

C7

150

µF

10V

C12

150

µF

10V

L1

10

µH

D1

1N5819

SHDN

D1

SYNC

Q1

Q2

C3

1

µF

20V

D3

1N5819

L2

10

µH

R2

0.025

Ω

5V

OUT

C6

330

µF

10V

C2

4.7

µF

C10

33

µF

35V

D2

R1

0.025

Ω

N1

N3

D2

R6

1M

R5

1M

R8

1M

R7

1M

R4

1M

9

27

26

24

1

28

3

13

12

4

5

C9

0.01

µF

SW1C

SW1A

SW1B

R3

1M

21

VH

D2

SS5

VREF (3.3V)

SW1D

N2

N4

C4

0.1

µF

N1 – N4 = Si9410DY

D2 = BAW56L OR TWO 1N4148s

VL (5V)

C8

0.01

µF

ON3

ON5

C5

0.1

µF

Dual-Output Power-Supply

Controller for Notebook Computers

16

______________________________________________________________________________________

Other ways to shut down the MAX786 are suggested

in the applications section of the MAX782/MAX783

data sheet.

__________Applications Information

Low-Voltage (6-Cell) Operation

The standard application circuit can be configured to

accept input voltages from 5.5V to 12V by changing

the oscillator frequency to 200kHz and increasing the

+5V filter capacitor to 660µF. This allows stable opera-

tion at 5V loads up to 2A (the 3.3V side requires no

changes and still delivers 3A).

Figure 6. MAX786 EV Kit Schematic

Table 3. EV Kit Power-Supply Controls (SW1)

SWITCH

NAME

FUNCTION

ON

SETTING

OFF

SETTING

1

SHDN

Enable shutdown

mode

Operate

Shutdown

2

ON3

Enable 3.3V

power supply

3.3V ON

3.3V OFF

3

ON5

Enable 5.0V

power supply

5V ON

5V OFF

4

SYNC

Oscillator

200kHz

300kHz