LT8686S

1

Rev. 0

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TYPICAL APPLICATION

FEATURES

DESCRIPTION

42V Quad, Gangable, Synchronous,

Monolithic Step-Down Regulator

The LT®8686S is a highly flexible, four-channel, current

mode, monolithic regulator able to power a wide range

of automotive and industrial applications while occupying

minimal board space.

The LT8686S combines two 42V capable 2A buck regu-

lators with two 8V capable 2A buck regulators. The two

42V regulators may be combined to provide up to 4A of

output current using a single inductor. Similarly, the two

8V regulators may be combined to provide up to 4A of

output current using a single inductor. Individual channel

enable, track/soft-start and power good pins provide flex-

ible power supply sequencing and control. The LT8686S

features a Silent Switcher 2 architecture, plus selectable

spread spectrum mode, to provide ultralow EMI/EMC

emissions while delivering high efficiency at high switch-

ing frequencies.

The LT8686S incorporates thermal shutdown and individ-

ual channel cycle-by-cycle current limit for short-circuit

protection and robust operation.

42V Input, Quad Output 2MHz Step-Down Regulator

APPLICATIONS

n

Silent Switcher®2 Architecture

n

Ultralow EMI Emissions

n

Optional Spread Spectrum Modulation

n

Two High Voltage Synchronous Buck Regulators

n

3V to 42V Input Voltage Range

n

Output Currents Up to 2A per Channel

n

Channels May Be Connected in Parallel Using

a Single Inductor

n

Two Low Voltage Synchronous Buck Regulators

n

3V to 8V Input Voltage Range

n

Output Currents up to 2A per Channel

n

Channels May Be Connected in Parallel Using

a Single Inductor

n

12μA IQ All Channels Active and No-Load

n

Flexible Supply Sequencing and Control

n

Adjustable and Synchronizable: 350kHz to 3MHz

n

Available in 32-Pin LQFN (5mm × 5mm)

n

AEC-Q100 Qualified for Automotive Applications

n

Automotive Systems

n

Industrial Controls and Power Supplies

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Efficiency and Loss

HV CHANNEL EFFICIENCY: 12V TO 5V

LV CHANNEL EFFICIENCY: 5V TO 1.8V

HV CHANNEL LOSS

LV CHANNEL LOSS

LOAD CURRENT (A)

0.001

0.01

0.1

1 2

0

10

20

30

40

50

60

70

80

90

100

0

0.5

1.0

1.5

2.0

8686S TA01b

8686S TA01a

BST3

SW3

FB3

BST4

SW4

FB4

BIAS

BST1

SW1

FB1

BST2

SW2

FB2

EN/UVLO

EN2

VIN1

VIN2

EN3

EN4

VIN3

VIN4

6V TO 42V

PG1-4

TRK/SS1-4

RT

SYNC/MODE

OUT1

5V, 2A*

INTVCC

OUT4

1.2V, 2A

VIN

OUT3

1.8V, 2A

GND

OUT2

3.3V, 2A

LT8686S

OUT1

4

4

*CURRENT AVAILABLE FROM OUT1: 2A – IVIN3 – IVIN4 – IBIAS