LT3667_15 Datasheet, PDF (1/34 Pages) Linear Technology – 40V 400mA Step-Down Switching Regulator with Dual Fault Protected LDOs

LT3667
40V 400mA Step-Down
Switching Regulator with
Dual Fault Protected LDOs
FEATURES
DESCRIPTION
n _{Triple Output Supply from a Single Input Requires}
Only One Inductor
n _{IQ = 50μA at 12VIN to 5V, 3.3V and 2.5V with No Load}
n _{Buck Regulator:}
Low Ripple (<15mV_P-P) Burst Mode Operation^®
400mA Output with Internal Power Switch
4.3V to 40V Input Operation Range (60V Max)
n _{Dual Low Dropout Linear Regulators}
200mA Outputs with Programmable Current Limits
1.6V to 45V Input Range
Fault Protected to ±45V
n _{Adjustable 250kHz to 2.2MHz Switching Frequency}
n _{Synchronizable Between 300kHz and 2.2MHz}
n _{Programmable Undervoltage Lockout}
n _{Power Good Indicators}
n _{Available in a Thermally-Enhanced 16-Lead MSOP}
and 24-Lead (3mm × 5mm) QFN Packages
APPLICATIONS
n _{Automotive Battery Regulation}
n _{Power for Portable Instrumentation}
n _{Industrial Supplies}
n _{Fault-Protected Sensor Supply}
The LT^®3667 is a monolithic triple power supply composed
of a 400mA buck switching regulator and two 200mA low
dropout linear regulators (LDOs).
The buck regulator includes a high efficiency switch, a
boost diode, and the necessary oscillator, control and
logic circuitry. Current mode topology is used for fast
transient response and good loop stability. Low ripple
Burst Mode operation maintains high efficiency at low
output currents while keeping output ripple below 15mV
in a typical application.
Each LDO supplies 200mA of output current with a typical
dropout voltage of 340mV, and each LDO has an accurate
resistor programmable current limit.
Internal protection circuitry includes reverse-battery
protection, current limiting, thermal limiting and reverse
current protection.
The LT3667 is available in a thermally-enhanced 16-Lead
MSOP and a 24-Pin 3mm x 5mm QFN package with ex-
posed pad for low thermal resistance.
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
V_IN
6V TO 40V
TRANSIENT
TO 60V
4.7µF
UVLO1 IN1
BOOST
2.5V
100mA
ON OFF
174k
340k
4.7µF
158k
EN
PG
RT
OUT2
LT3667
SW
DA
FB1
BD
IN2
IN3
OUT3
FB2
FB3
EN2/ILIM2 GND EN3/ILIM3
0.22µF 22µH
931k
22pF
294k
3.3V
100mA
499k
2.2µF
158k
3667 TA01a
5V
200mA
22µF
For more information www.linear.com/LT3667
100
90
80
70
60
50
40
30
20
10
0
5
No-Load Supply Current
10 15 20 25 30 35
INPUT VOLTAGE (V)
3667 TA01b
3667fb
1