LT3980_15 Datasheet, PDF (1/24 Pages) Linear Technology – 58V, 2A, 2.4MHz Step-Down Switching Regulator with 85A Quiescent Current

LT3980
58V, 2A, 2.4MHz
Step-Down Switching Regulator
with 85µA Quiescent Current
Features
■ _{Wide Input Range: Operation from 3.6V to 58V}
■ _{Overvoltage Lockout Protects Circuits Through 80V}
Transients
■ _{2A Maximum Output Current}
■ _{Low Ripple (<15mVP-P) Burst Mode}^® _Operation:
I_Q = 85µA at 12V_IN to 3.3V_OUT
■ _{Adjustable Switching Frequency: 100kHz to 2.4MHz}
■ _{Low Shutdown Current: IQ < 1µA}
■ _{Catch Diode Current Sense Protects Circuit Through}
Short-Circuit and Input Overvoltage
■ _{Synchronizable Between 250kHz to 2MHz}
■ _{Power Good Flag}
■ _{Saturating Switch Design: 200mΩ On-Resistance}
■ _{Thermal Protection}
■ _{Soft-Start Capability}
■ _{Small 16-Pin Thermally Enhanced MSOP and}
3mm × 4mm DFN Packages
Applications
■ _{Automotive Battery Regulation}
■ _{Distributed Supply Regulation}
■ _{Industrial Supplies}
■ _{Wall Transformer Regulation}
Description
The LT^®3980 is an adjustable frequency (100kHz to
2.4MHz) monolithic buck switching regulator that accepts
input voltages up to 58V (80V transient). A high efficiency
200mΩ switch is included on the die along with a boost
Schottky diode and the necessary oscillator, control, and
logic circuitry. Current mode topology is used for fast
transient response and good loop stability. Catch diode
current sense (DA pin) protects the circuit during input
voltage transients even when a high switching frequency
is used. Low ripple Burst Mode operation maintains high
efficiency at low output currents while keeping output
ripple below 15mV in a typical application. In addition, the
LT3980 can further enhance low output current efficiency
by drawing bias current from the output when V_OUT is
above 3V. Shutdown reduces input supply current to less
than 1µA while a resistor and capacitor on the RUN/SS
pin provide a controlled output voltage ramp (soft-start).
A power good flag signals when V_OUT reaches 91% of
the programmed output voltage. The LT3980 is available
in 16-pin MSOP and 3mm × 4mm DFN packages with
exposed pads for low thermal resistance.
L, LT, LTC, LTM, Linear Technology, Burst Mode 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 58V
TRANSIENT
TO 80V
V_IN
BD
OFF ON
RUN/SS
BOOST
4.75k
10µF
V_C
LT3980
SW
RT
1nF
PG
DA
97.6k
SYNC
GND
FB
V_OUT
5V
2A
0.47µF _10µH
22pF
536k
100k
47µF
3980 TA01
For more information www.linear.com/LT3980
Efficiency, V_OUT = 5V
95
90
V_IN = 12V
85
V_IN = 24V
80
V_IN = 48V
75
70
65
60
55 f = 400kHz
D = DIODES, INC. SBR3U100LP
50
0
0.5
1
1.5
I_LOAD (A)
2
3980 TA01b
3980fa
1