LT3150_15 Datasheet, PDF (1/20 Pages) Linear Technology – Fast Transient Response, Low Input Voltage, Very Low Dropout Linear Regulator Controller

LT3150
Fast Transient Response,
Low Input Voltage, Very Low Dropout
Linear Regulator Controller
FEATURES
s _{Fast Transient Response Optimized with}
Ceramic Output Capacitors
s _{FET RDS(ON) Defines Dropout Voltage}
s _{±1% Reference Tolerance Over Temperature}
s _{Multifunction LDO Shutdown Pin with Latchoff}
s _{Fixed Frequency 1.4MHz Boost Converter Generates}
MOSFET Gate Drive
s _{Internally Compensated Boost Converter Uses Tiny}
Capacitors and Inductor
s _{Independent Boost Converter Shutdown Control}
Permits LDO Output Voltage Supply Sequencing
s _{16-Lead SSOP Package}
U
APPLICATIO S
s _{Microprocessor, ASIC and I/O Supplies}
s _{Very Low Dropout Input-to-Output Conversion}
s _{Logic Termination Supplies}
, LTC and LT are registered trademarks of Linear Technology Corporation.
DESCRIPTIO
The LT^®3150 drives a low cost external N-channel MOSFET
as a source follower to produce a fast transient response,
very low dropout voltage linear regulator. Selection of the
N-channel MOSFET R_DS(ON) allows dropout voltages below
300mV for low V_IN to low V_OUT applications.
The LT3150 includes a fixed frequency boost regulator
that generates gate drive for the N-channel MOSFET. The
internally compensated current mode PWM architecture
combined with the 1.4MHz switching frequency permits
the use of tiny, low cost capacitors and inductors.
The LT3150’s transient load performance is optimized
with ceramic output capacitors. A precision 1.21V refer-
ence accommodates low voltage supplies.
Protection includes a high side current limit amplifier that
activates a fault timer circuit. A multifunction shutdown
pin provides either current limit time-out with latchoff,
overvoltage protection or thermal shutdown. Independent
shutdown control of the boost converter provides on/off
and sequencing control of the LDO output voltage.
TYPICAL APPLICATIO
1.8V to 1.5V, 4A Very Low Dropout Linear Regulator
(Typical Dropout Voltage = 65mV at I_OUT = 4A)
MBR0520L
+ _C1
6.19k
4.7µF 1%
1.37k
1%
LT3150
V_IN2
FB1
SHDN2
SW
V_IN1
SHDN1
SWGND
GND
GND
I_POS
I_NEG
GATE
FB2
COMP
6800pF
L1
10µH
5.1Ω
1.5k
50pF
C_IN: PANASONIC SP SERIES EEFUE0E221R 20%
C1: AVX TAJA475M020R 20V 20%
L1: MURATA LQH32CN100K11 OR SUMIDA CDRH3D16100
+
Si4410
243Ω
1%
1020Ω
1%
C_IN
220µF
2.5V
×2
V_IN
1.8V
V_OUT
1.5V
4A
2.2µF ×10
X5R CERAMIC
0805 CASE
3150 TA01
50mV/DIV
2A/DIV
Transient Response for
0.1A to 4A Output Load Step
20µs/DIV
3150 TA02
3150f
1