DESCRIPTION
The LT®8609S is a compact, high efficiency, high speed
synchronous monolithic step-down switching regulator
that consumes only 1.7μA of non-switching quiescent
current. The LT8609S can deliver 2A of continuous current
with peak loads of 3A (<1sec) to support applications
such as GSM transceivers which require high transient
loads. Top and bottom power switches are included with
all necessary circuitry to minimize the need for external
components. Low ripple Burst Mode operation enables
high efficiency down to very low output currents while
keeping the output ripple below 10mVP-P. A SYNC pin
allows synchronization to an external clock, or spread
spectrum modulation of switching frequencies for low
EMI operation. Internal compensation with peak current
mode topology allows the use of small inductors and
results in fast transient response and good loop stability.
The EN/UV pin has an accurate 1V threshold and can be
used to program VIN undervoltage lockout or to shut down
the LT8609S reducing the input supply current to 1μA. A
capacitor on the TR/SS pin programs the output voltage
ramp rate during start-up while the PG flag signals when
VOUT is within ±8.5% of the programmed output voltage
as well as fault conditions. The LT8609S is available in a
small 16-lead 3mm × 3mm LQFN package.

FEATURES
n Silent Switcher® 2 Architecture
n Ultralow EMI Emissions on Any PCB
n Eliminates PCB Layout Sensitivity
n Internal Bypass Capacitors Reduce Radiated EMI
n Optional Spread Spectrum Modulation
n Wide Input Voltage Range: 3.0V to 42V
n Ultralow Quiescent Current Burst Mode® Operation:
n <2.5μA IQ Regulating 12VIN to 3.3VOUT
n Output Ripple <10mVP-P
n High Efficiency 2MHz Synchronous Operation:
n >93% Efficiency at 1A, 12VIN to 5VOUT
n 2A Maximum Continuous Output, 3A Peak Transient Output
n Fast Minimum Switch-On Time: 45ns
n Adjustable and Synchronizable: 200kHz to 2.2MHz
n Allows Use of Small Inductors
n Low Dropout
n Peak Current Mode Operation
n Internal Compensation
n Output Soft-Start and Tracking
n Small 16-Lead 3mm × 3mm LQFN Package
n AEC-Q100 Qualified for Automotive Applications

APPLICATIONS
n General Purpose Step Down
n Low EMI Step Down