MAX8566 Просмотр технического описания (PDF) - Maxim Integrated

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MAX8566

High-Efficiency, 10A, PWM Internal-Switch Step-Down Regulator

Maxim Integrated 

High-Efficiency, 10A, PWM

Internal-Switch Step-Down Regulator

R1

R2

REFIN

C

MAX8566

Figure 2. Soft-Start Implementation with External Reference

Undervoltage Lockout (UVLO)

The UVLO circuitry inhibits switching when VDD is

below 2V. Once VDD rises above 2V, UVLO clears and

the soft-start function activates. A 100mV hysteresis is

built in for glitch immunity.

Monotonic Startup Modes (MODE)

When starting up into a precharged output, the MAX8566

does not discharge the output prior to entering soft-start

(known as monotonic startup). Drive MODE to 1/3 of VDD

to enable monotonic startup mode. Connect MODE to

GND to disable monotonic startup mode.

High-Side MOSFET Driver Supply (BST)

The gate-drive voltage for the high-side, n-channel

switch is generated by a flying-capacitor boost circuit.

The capacitor between BST and LX is charged from the

VLSS supply while the low-side MOSFET is on. When

the low-side MOSFET is switched off, the stored voltage

of the capacitor is stacked above LX to provide the

necessary turn-on voltage for the high-side internal

MOSFET.

Frequency Select (FREQ)

The switching frequency is resistor programmable from

250kHz to 2.4MHz. Set the switching frequency of the

IC with a resistor from FREQ to GND (RFREQ). RFREQ is

calculated as:

RFREQ

=

50kΩ

0.95µs

⎛

× ⎝⎜

1

fs

⎞

− 0.05µs⎠⎟

where fS is the desired switching frequency in Hz.

SYNC Function (SYNC, SYNCOUT)

The MAX8566 features a SYNC function that allows the

switching frequency to be synchronized to any frequen-

cy between 250kHz to 2.4MHz. Drive SYNC with a

C24

OPEN

VIN

2.3V TO 3.6V

C1

C2

10µF

10µF

C3

0.22µF

R1

10Ω

C4

R2

1µF

POWER-GOOD 20kΩ

OUTPUT

R17

20kΩ

R18

10kΩ

23

LSS

18 IN

19 IN

20 IN

21 IN

22 IN

24 VDD

MAX8566

3 PWRGD

27 EN

BST

LX

LX

LX

LX

LX

LX

LX

LX

PGND

PGND

PGND

PGND

PGND

C5

0.047µF

4

5

6

7

8

9

10

11

12

17

16

15

14

13

L1

0.47µH

C6

2kΩ 22µF

3300pF

1

MODE

25

REFIN

28

29

SYNC

FREQ

R3

50kΩ

FB 32

COMP 2

SYNCOUT 30

SS 26

GND

31

R7

16.9kΩ

C9

330pF

C10

22pF

C11

0.022µF

C7

22µF

R5

24.9kΩ

R6

12.4kΩ

VOUT

1.8V AT 10A

R4

100Ω

C8

120pF

Figure 3. Typical Application Circuit

14 ______________________________________________________________________________________

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