Datasheet LT3668 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 40V 400mA Step-Down Switching Regulator with Dual Fault Protected Tracking LDOs |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTION. Dual Low Dropout Linear Tracking Regulators. 200mA … |
| File Format / Size | PDF / 386 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Dual Low Dropout Linear Tracking Regulators. 200mA Outputs with Programmable Current Limits
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LT3668 40V 400mA Step-Down Switching Regulator with Dual Fault Protected Tracking LDOs
FEATURES DESCRIPTION
n
Dual Low Dropout Linear Tracking Regulators
The LT®3668 is a monolithic triple power supply composed n
200mA Outputs with Programmable Current Limits
of a 400mA buck switching regulator and two 200mA low n
1.6V to 45V Input Range
dropout linear tracking regulators (LDOs).This provides a n
Fault Protected to ±45V
complete and robust power solution for applications that n
Triple Output Supply from a Single Input Requires
require the power supply of a sensor to tightly track the
Only One Inductor
power supply of a measurement ASIC. n
IQ = 50μA at 12VIN to 6V and 5V with No Load
Each tracking LDO supplies 200mA of output current with n
Buck Regulator:
a typical dropout voltage of 340mV, and each LDO has an n
Low Ripple (<15mVP-P) Burst Mode
®
Operation
accurate resistor programmable current limit. n
400mA Output with Internal Power Switch
n
4.3V to 40V Input Operation Range (60V Max)
Internal protection circuitry includes reverse-battery n Adjustable 250kHz to 2.2MHz Switching Frequency protection, current limiting, thermal limiting and reverse n current protection. Power Good Indicator n Available in a Thermally-Enhanced 16-Lead The buck regulator includes a high efficiency switch, a MSOP Package boost diode, and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast
APPLICATIONS
transient response and good loop stability. Low ripple n Burst Mode operation maintains high efficiency at low Fault-Protected Sensor Supply n output currents while keeping output ripple below 15mV Automotive and Industrial Supplies n in a typical application. Power for Portable Instrumentation L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks The LT3668 is available in a thermally-enhanced 16-lead of Linear Technology Corporation. All other trademarks are the property of their respective MSOP package with exposed pad for low thermal resistance. owners.
TYPICAL APPLICATION
VIN
No-Load Supply Current
7V TO 40V 100 TRANSIENT 4.7µF TO 60V IN1 BOOST 0.22µF 27µH 6V 90 SW 100mA 80 232k 22µF ON OFF EN DA 70 PG LT3668 IN3/BD 931k 60 RT IN2 22pF f = 600kHz 174k FB1 50 294k 40 ADJ2 30 5V ADJ3 SUPPLY CURRENT (µA) 150mA 5V 20 OUT2 OUT3 (FOLLOWS 150mA OUT3) 10µF EN2/ILIM2 GND EN3/ILIM3 10µF 10 0 3668 TA01a 5 10 15 20 25 30 35 INPUT VOLTAGE (V) 3668 TA01b 3668fa For more information www.linear.com/LT3668 1 Document Outline Features Applications Description Typical Application Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Related Parts
FEATURES DESCRIPTION
n
Dual Low Dropout Linear Tracking Regulators
The LT®3668 is a monolithic triple power supply composed n
200mA Outputs with Programmable Current Limits
of a 400mA buck switching regulator and two 200mA low n
1.6V to 45V Input Range
dropout linear tracking regulators (LDOs).This provides a n
Fault Protected to ±45V
complete and robust power solution for applications that n
Triple Output Supply from a Single Input Requires
require the power supply of a sensor to tightly track the
Only One Inductor
power supply of a measurement ASIC. n
IQ = 50μA at 12VIN to 6V and 5V with No Load
Each tracking LDO supplies 200mA of output current with n
Buck Regulator:
a typical dropout voltage of 340mV, and each LDO has an n
Low Ripple (<15mVP-P) Burst Mode
®
Operation
accurate resistor programmable current limit. n
400mA Output with Internal Power Switch
n
4.3V to 40V Input Operation Range (60V Max)
Internal protection circuitry includes reverse-battery n Adjustable 250kHz to 2.2MHz Switching Frequency protection, current limiting, thermal limiting and reverse n current protection. Power Good Indicator n Available in a Thermally-Enhanced 16-Lead The buck regulator includes a high efficiency switch, a MSOP Package boost diode, and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast
APPLICATIONS
transient response and good loop stability. Low ripple n Burst Mode operation maintains high efficiency at low Fault-Protected Sensor Supply n output currents while keeping output ripple below 15mV Automotive and Industrial Supplies n in a typical application. Power for Portable Instrumentation L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks The LT3668 is available in a thermally-enhanced 16-lead of Linear Technology Corporation. All other trademarks are the property of their respective MSOP package with exposed pad for low thermal resistance. owners.
TYPICAL APPLICATION
VIN
No-Load Supply Current
7V TO 40V 100 TRANSIENT 4.7µF TO 60V IN1 BOOST 0.22µF 27µH 6V 90 SW 100mA 80 232k 22µF ON OFF EN DA 70 PG LT3668 IN3/BD 931k 60 RT IN2 22pF f = 600kHz 174k FB1 50 294k 40 ADJ2 30 5V ADJ3 SUPPLY CURRENT (µA) 150mA 5V 20 OUT2 OUT3 (FOLLOWS 150mA OUT3) 10µF EN2/ILIM2 GND EN3/ILIM3 10µF 10 0 3668 TA01a 5 10 15 20 25 30 35 INPUT VOLTAGE (V) 3668 TA01b 3668fa For more information www.linear.com/LT3668 1 Document Outline Features Applications Description Typical Application Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Related Parts
