LT3970_15 Datasheet, PDF (1/22 Pages) Linear Technology – 40V, 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 40V 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, 3.42V, 5V}
1.8µA I_Q at 12V_IN
n _{Accurate 1V Enable Pin Threshold}
n _{Low Shutdown Current: IQ = 0.7µA}
n _{Internal Sense Limits Catch Diode Current}
n _{Power Good Flag}
n _{Output Voltage: 1.21V to 25V}
n _{Internal Compensation}
n _{Small 10-Pin MSOP and (3mm × 2mm) DFN Packages}
Applications
n _{Automotive Battery Regulation}
n _{Power for Portable Products}
n _{Industrial Supplies}
LT3970 Series
40V, 350mA Step-Down
Regulator with 2.5µA
Quiescent Current and
Integrated Diodes
Description
The LT^®3970 is an adjustable frequency monolithic buck
switching regulator that accepts a wide input voltage
range up to 40V, 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 enable pin with accurate
threshold 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 LT3970 is
available in small 10-pin MSOP and 3mm × 2mm 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
6V TO 40V
OFF ON
V_IN BOOST
LT3970
EN
SW
PG
BD
2.2µF
RT
FB
GND
226k
f = 600kHz
0.22µF
22µH
22pF
V_OUT
5V
350mA
1M
22µF
316k
3490 TA01a
Efficiency
90
V_IN = 12V
1000
80
100
70
10
60
1
50
0.1
40
0.01
0.1
1
10
LOAD CURRENT (mA)
0.01
100
3970 TA01b
3970fc
1