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LT3668EMSE#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28
LT3668
1
3668fa
For more information www.linear.com/LT3668
TYPICAL APPLICATION
FEATURES DESCRIPTION
40V 400mA Step-Down
Switching Regulator with Dual
Fault Protected Tracking LDOs
The LT
®
3668 is a monolithic triple power supply composed
of a 400mA buck switching regulator and two 200mA low
dropout linear tracking regulators (LDOs).This provides a
complete and robust power solution for applications that
require the power supply of a sensor to tightly track the
power supply of a measurement ASIC.
Each tracking 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 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.
The LT3668 is available in a thermally-enhanced 16-lead
MSOP package with exposed pad for low thermal resistance.
No-Load Supply Current
APPLICATIONS
n
Dual Low Dropout Linear Tracking Regulators
n
200mA Outputs with Programmable Current Limits
n
1.6V to 45V Input Range
n
Fault Protected to ±45V
n
Triple Output Supply from a Single Input Requires
Only One Inductor
n
I
Q
= 50μA at 12V
IN
to 6V and 5V with No Load
n
Buck Regulator:
n
Low Ripple (<15mV
P-P
) Burst Mode
®
Operation
n
400mA Output with Internal Power Switch
n
4.3V to 40V Input Operation Range (60V Max)
n
Adjustable 250kHz to 2.2MHz Switching Frequency
n
Power Good Indicator
n
Available in a Thermally-Enhanced 16-Lead
MSOPPackage
n
Fault-Protected Sensor Supply
n
Automotive and Industrial Supplies
n
Power for Portable Instrumentation
L, LT, LT C , LT M, 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.
INPUT VOLTAGE (V)
5
0
SUPPLY CURRENT (µA)
10
30
40
50
100
70
15
25
30
3668 TA01b
20
80
90
60
10
20
35
3668 TA01a
EN2/ILIM2 EN3/ILIM3GND
5V
150mA
10µF
10µF
IN1
LT3668
BOOST
SW
DA
IN3/BD
IN2
FB1
ON OFF EN
PG
RT
OUT2
OUT3
ADJ3
ADJ2
4.7µF
0.22µF
22pF
27µH
232k
6V
100mA
931k
294k
174kf = 600kHz
V
IN
7V TO 40V
TRANSIENT
TO 60V
5V
150mA
(FOLLOWS
OUT3)
22µF
LT3668
2
3668fa
For more information www.linear.com/LT3668
ADJ2, ADJ3 Voltage ................................................±45V
OUT2, OUT3 Voltage ...............................................±45V
IN2 Voltage .............................................................±45V
OUT2 – IN2 Differential Voltage ..............................±45V
OUT3 – IN3/BD Differential Voltage ........................±45V
OUT2 – ADJ2 Differential Voltage ...........................±45V
OUT3 – ADJ3 Differential Voltage ...........................±45V
IN1, EN Voltage (Note 3) ...........................................60V
IN1 Reverse Voltage ...............................................–0.3V
EN Pin Current .......................................................–1mA
IN3/BD Voltage .........................................................30V
BOOST Pin Voltage ...................................................50V
BOOST Pin Above SW Pin ......................................... 30V
RT Voltage ..................................................................2V
FB1 Voltage ................................................................. 6V
EN2/ILIM2, EN3/ILIM3 Voltage ...................................4V
PG Voltage ................................................................30V
Operating Junction Temperature Range (Notes 4, 5)
E-, I-Grade ......................................... −40°C to 125°C
H-Grade ............................................. −40°C to 150°C
Storage Temperature Range .................. −65°C to 150°C
Lead Temperature (Soldering, 10 sec) ...................300°C
(Notes 1, 2)
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3668EMSE#PBF LT3668EMSE#TRPBF 3668 16-Lead Plastic MSOP –40°C to 125°C
LT3668IMSE#PBF LT3668IMSE#TRPBF 3668 16-Lead Plastic MSOP –40°C to 125°C
LT3668HMSE#PBF LT3668HMSE#TRPBF 3668 16-Lead Plastic MSOP –40°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping
container. Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS
1
2
3
4
5
6
7
8
SW
BOOST
EN
RT
IN3/BD
OUT3
ADJ3
FB1
16
15
14
13
12
11
10
9
DA
IN1
PG
EN3/ILIM3
EN2/ILIM2
IN2
OUT2
ADJ2
TOP VIEW
17
GND
MSE PACKAGE
16-LEAD PLASTIC MSOP
θ
JA
= 40°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LT3668
3
3668fa
For more information www.linear.com/LT3668
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN1
= 12V unless otherwise noted. (Note 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN1
Undervoltage Lockout (Note 6) V
IN2
= 0V, V
IN3/BD
= 0V
l
4 4.3 V
V
IN1
Overvoltage Lockout
l
40 42 44 V
V
IN2
Undervoltage Lockout (Note 6) V
IN1
= 3.5V, V
IN3/BD
= 0V
l
4 4.3 V
Quiescent Current from IN1 V
EN
= 0.3V
V
EN
= 12V, V
IN2
= 0V, Not Switching
l
0.01
13
1
30
µA
µA
Quiescent Current from IN2 V
EN
= 0.3V
V
EN
= 12V, V
IN1
= 0V, V
IN2
= 5V
l
0.01
38
1
80
µA
µA
Quiescent Current from IN1 + IN2 V
EN
= 0.3V, V
IN2
= 5V
V
EN
= 12V, V
IN2
= 5V, Not Switching
l
0.01
40
1
90
µA
µA
Quiescent Current from IN3/BD V
EN
= 0.3V, V
IN3/BD
= 5V
V
EN
= 12V, V
IN3/BD
= 5V
l
0.01
25
1
60
µA
µA
EN Pin Current V
EN
= 12V 0.6 2 µA
EN Input Threshold 0.3 1.1 V
Power Good Pin PG
Leakage Current V
PG
= 5V 0.1 1 µA
Output Voltage Low I
PG
= 40µA
l
0.2 0.3 V
Threshold as % of V
FB1
Pin Voltage Falling
Pin Voltage Rising
88
108
90
110
92
112
%
%
PG Threshold Hysteresis Measured at FB1 Pin 30 mV
Switching Regulator
Switching Frequency R
T
= 37.4k
R
T
= 102k
R
T
= 487k
l
l
l
1.8
0.8
220
2.0
0.94
243
2.1
1.1
300
MHz
MHz
kHz
Minimum Switch Off-T
ime
l
120 190 ns
Switch Current Limit (Note 7) 5% Duty Cycle, V
IN
= 5V, V
FB1
= 0V
90% Duty Cycle, V
IN
= 5V, V
FB1
= 0V
l
l
600
450
750
550
950
800
mA
mA
Switch V
CESAT
I
SW
= 200mA 300 mV
DA Pin Current to Stop Switching
l
420 500 650 mA
Switch Leakage Current V
SW
= 0V 0.05 2 µA
Boost Schottky Diode Forward Voltage I
BOOSTDIODE
= 50mA, V
IN
= NC, V
BOOST
= 0V 900 mV
Boost Schottky Diode Reverse Leakage V
REVERSE
= 12V, V
IN
= NC 0.04 4 µA
Minimum Boost Voltage (Note 8)
l
1.7 2.5 V
BOOST Pin Current I
SW
= 200mA, V
BOOST
= 15V 10 16 mA
Feedback Voltage (FB1)
l
1.188
1.176
1.2
1.2
1.212
1.224
V
mV
FB1 Pin Bias Current Pin V
oltage = 1.2V
l
0.1 20 nA
Reference Voltage Line Regulation 4.2V < V
IN1
< 40V 0.001 0.005 %/V
Each LDO Regulator
Minimum Input Voltage I
LOAD
= 200mA
l
1.6 2.2 V
Output Voltage Range
l
1.1 10 V
Tracking Error V
OUT2/3
-V
ADJ2/3
1.1V ≤ V
ADJ2/3
≤ 5V, I
LOAD
= 1mA –40°C to 125°C
5V < V
ADJ2/3
≤ 10V, I
LOAD
= 1mA –40°C to 125°C
l
l
–6
–20
6
50
mV
mV
1.1V ≤ V
ADJ2/3
≤ 5V, I
LOAD
= 1mA –40°C to 150°C
5V < V
ADJ2/3
≤ 10V, I
LOAD
= 1mA –40°C to 150°C
l
l
–6
–20
15
80
mV
mV
ELECTRICAL CHARACTERISTICS
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LT3668EMSE#PBF

Mfr. #:
Buy LT3668EMSE#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 40V 400mA Step-Down Switching Regulator with Dual Fault Protected Tracking LDOs
Lifecycle:
New from this manufacturer.
Delivery:
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