42V, 5A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

The LT8640/LT8640-1 step-down regulator features Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at frequencies up to 3MHz. An ultralow 2.5µA quiescent current—with the output in full regulation—enables applications requiring highest efficiency at very small load currents.

The LT8640/LT8640-1 allows high VIN to low VOUT conversion at high frequency with a fast minimum top switch on-time of 30ns. The SYNC/MODE pin selects between Burst Mode operation, spread spectrum mode, synchronization to an external clock, and either pulse-skipping (LT8640) or forced continuous mode (LT8640-1).

Package

SYNC/MODE ≠ 0

VC COMP

H-GRADE

CLKOUT

INTERNAL CAPS

LT8640

QFN

Pulse-Skipping

Internal

Yes

No

No

LT8640-1

QFN

FCM

Internal

Yes

No

No

LT8640S

LQFN

FCM

Internal

No

Yes

Yes

LT8643S

LQFN

FCM

External

No

Yes

Yes

LT8640S-2

LQFN

FCM

Internal

Yes

Yes

No

LT8643S-2

LQFN

FCM

External

Yes

Yes

No

Applications

* Automotive and Industrial Supplies

* General Purpose Step-Down

* GSM Power Supplies

* Silent Switcher® Architecture

* Ultralow EMI Emissions

* Spread Spectrum Frequency Modulation

* High Efficiency at High Frequency

* Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT

* Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT

* Wide Input Voltage Range: 3.4V to 42V

* 5A Maximum Continuous Output, 7A Peak Transient Output

* Ultralow Quiescent Current Burst Mode® Operation

* 2.5µA IQ Regulating 12VIN to 3.3VOUT

* Output Ripple < 10mVP-P