LT3990-3.3_15 Datasheet, PDF (1/22 Pages) Linear Technology – 62V, 350mA Step-Down Regulator with 2.5A Quiescent Current and Integrated Diodes

FEATURES
n _{Low Ripple Burst Mode}^® _Operation
2.5µA I_Q at 12V_IN to 3.3V_OUT
Output Ripple < 5mV_P-P
n _{Wide Input Voltage Range: 4.2V to 62V Operating}
n _{Adjustable Switching Frequency: 200kHz to 2.2MHz}
n _{Integrated Boost and Catch Diodes}
n _{350mA Output Current}
n _{Fixed Output Voltages: 3.3V, 5V}
2µA I_Q at 12V_IN
n _{Accurate Programmable Undervoltage Lockout}
n _{FMEA Fault Tolerant (MSOP Package)}
Output Stays at or Below Regulation Voltage During
Adjacent Pin Short or When a Pin is Left Floating
n _{Low Shutdown Current: IQ = 0.7µA}
n _{Internal Sense Limits Catch Diode Current}
n _{Power Good Flag}
n _{Small, Thermally Enhanced 16-Pin MSOP}
and (3mm × 3mm) DFN Packages
APPLICATIONS
n _{Automotive Battery Regulation}
n _{Power for Portable Products}
n _{Industrial Supplies}
LT3990/LT3990-3.3/LT3990-5
62V, 350mA Step-Down
Regulator with 2.5µA
Quiescent Current and
Integrated Diodes
DESCRIPTION
The LT^®3990 is an adjustable frequency monolithic buck
switching regulator that accepts a wide input voltage
range up to 62V, and consumes only 2.5µA of quiescent
current. A high efficiency switch is included on the die
along with the catch diode, boost diode, and the neces-
sary oscillator, control and logic circuitry. Low ripple Burst
Mode operation maintains high efficiency at low output
currents while keeping the output ripple below 5mV in a
typical application. Current mode topology is used for fast
transient response and good loop stability. A catch diode
current limit provides protection against shorted outputs
and overvoltage conditions. An accurate programmable
undervoltage lockout feature is available, producing a low
shutdown current of 0.7µA. A power good flag signals when
V_OUT reaches 90% of the programmed output voltage. The
LT3990 is available in small, thermally enhanced 16-pin
MSOP and 3mm × 3mm DFN packages.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
5V Step-Down Converter
V_IN
6.5V TO 62V
OFF ON
V_IN BOOST
LT3990-5
EN/UVLO SW
PG
BD
0.22µF
33µH
V_OUT
5V
350mA
2.2µF
RT
V_OUT
GND
374k
f = 400kHz
22µF
3990 TA01a
Power Loss
1000
V_IN = 12V
100
10
1
0.1
0.01
0.001 0.01 0.1
1
10
LOAD CURRENT (mA)
100
3990 TA01b
3990fa
1