LT8638S

1

Rev. 0

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TYPICAL APPLICATION

FEATURES

DESCRIPTION

42V, 10A/12A Peak Synchronous

Step-Down Silent Switcher 2

The LT®8638S synchronous step-down regulator

features second generation Silent Switcher architecture

designed to minimize EMI emissions while delivering high

efficiency at high switching frequencies. This includes

the integration of input capacitors to optimize all the fast

current loops inside and make it easy to achieve advertised

EMI performance by reducing layout sensitivity. This

performance makes the LT8638S ideal for noise sensitive

applications and environments.

The fast, clean, low overshoot switching edges enable high

efficiency operation even at high switching frequencies,

leading to a small overall solution size. Peak current mode

control with a 25ns minimum on-time allows high step

down ratios even at high switching frequencies. External

response. PolyPhase operation allows multiple LT8638S

regulators to run with interleaving phase shift to provide

more output current.

Burst Mode operation enables low standby current

consumption, forced continuous mode can control

frequency harmonics across the entire output load

range, or spread spectrum operation can further reduce

EMI emissions. Soft-start and tracking functionality is

accessed via the SS pin, and an accurate input voltage

UVLO threshold can be set using the EN/UV pin.

5V 10A Step-Down Converter

APPLICATIONS

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Ultralow EMI Emissions on Any PCB

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Eliminates PCB Layout Sensitivity

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Internal Bypass Capacitors Reduce Radiated EMI

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Optional Spread Spectrum Modulation

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High Efficiency at High Frequency

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Wide Input Voltage Range: 2.8V to 42V

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10A Maximum Continuous, 12A Peak Transient Output

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Fast Transient Response with External Compensation

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Reference Accuracy: ±1% Over Temperature

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Fast Minimum Switch On-Time: 25ns

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Low Dropout Under All Conditions: 45mV at 1A

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Adjustable and Synchronizable: 200kHz to 3MHz

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Output Soft-Start and Power Good

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Safely Tolerates High Reverse Current

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28-Lead 5mm × 4mm LQFN Package

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AEC-Q100 Qualified for Automotive Applications

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Automotive and Industrial Supplies

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General Purpose Step-Down

All registered trademarks and trademarks are the property of their respective owners. Protected

by U.S. patents, including 8823345.

LT8638S

8638S TA01a

SW

BST

EN/UV

BIAS

RT

FB

GND

15pF

47µF

100k

5V

10A

4.7µF

5.4V TO 42V

38.3k

1µH

0.1µF

1µF

13.7k

330pF

12.1k

EFFICIENCY

POWER LOSS

400kHz, L = 2.2µH

1MHz, L = 1µH

2MHz, L = 0.68µH

LOAD CURRENT (A)

1

2

3

4

5

6

7

8

9

10

65

70

75

80

85

90

95

100

0

0.8

1.6

2.4

3.2

4.0

4.8

5.6

8638S TA01b