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LT3973 데이터시트 PDF




Linear에서 제조한 전자 부품 LT3973은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


PDF 형식의 LT3973 자료 제공

부품번호 LT3973 기능
기능 Step-Down Regulator
제조업체 Linear
로고 Linear 로고


LT3973 데이터시트 를 다운로드하여 반도체의 전기적 특성과 매개변수에 대해 알아보세요.




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LT3973 데이터시트, 핀배열, 회로
FEATURES
nn Ultralow Quiescent Current
nn 2.5µA IQ at 12VIN to 3.3VOUT
nn Low Ripple Burst Mode® Operation
nn Output Ripple < 10mVP-P
nn Wide Input Voltage Range: 4.2V to 42V Operating
nn Adjustable Switching Frequency: 200kHz to 2.2MHz
nn Integrated Boost and Catch Diodes
nn 750mA Output Current
nn Excellent Start-Up and Dropout Performance
nn Fixed Output Voltages: 3.3V, 5V
nn 1.9µA IQ at 12VIN
nn Accurate Programmable Undervoltage Lockout
nn Low Shutdown Current: IQ = 0.75µA
nn Internal Catch Diode Current Limit
nn Power Good Flag
nn Thermal Shutdown
nn Small, Thermally Enhanced 10-Lead MSOP and
(3mm × 3mm) DFN Packages
APPLICATIONS
nn Automotive Battery Regulation
nn Power for Portable Products
nn Industrial Supplies
nn Gate Drive Bias
LT3973/LT3973-3.3/LT3973-5
42V, 750mA Step-Down
Regulator with 2.5µA
Quiescent Current and
Integrated Diodes
DESCRIPTION
The LT®3973 is an adjustable frequency monolithic buck
switching regulator that accepts a wide input voltage range
up to 42V, and consumes only 2.5µA of quiescent current.
A high efficiency switch is included on the die along with
the catch diode, boost diode, and the necessary oscillator,
control and logic circuitry. Low ripple Burst Mode operation
maintains high efficiency at low output currents while keep-
ing the output ripple below 10mV in a typical application.
A minimum dropout voltage of 530mV is maintained when
the input voltage drops below the programmed output volt-
age, such as during automotive cold crank. Current mode
topology is used for fast transient response and good loop
stability. A catch diode current limit provides protection
against shorted outputs and overvoltage conditions, with
thermal shutdown providing additional fault protection. An
accurate programmable undervoltage lockout feature is
available, producing a low shutdown current of 0.75µA.
A power good flag signals when VOUT reaches 90% of
the programmed output voltage. The LT3973 is available
in small, thermally enhanced 10-lead MSOP and 3mm ×
3mm DFN packages.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
VIN
5.6V TO 42V
C1
4.7µF
5V Step-Down Converter
OFF ON
215k
VIN BOOST
LT3973
EN/UVLO SW
PG BD
OUT
RT FB
GND
C3
0.47µF
L1
15µH
15pF
1M
316k
VOUT
5V
750mA
C2
22µF
f = 600kHz
3973 TA01a
90 VIN = 12V
80
Efficiency
1000
100
70 10
60 1
50 0.1
40
0.01
0.1 1 10 100
LOAD CURRENT (mA)
0.01
3973 TA01b
For more information www.linear.com/LT3973
3973fb
1




LT3973 pdf, 반도체, 판매, 대치품
LT3973/LT3973-3.3/LT3973-5
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, VBD = 3.3V unless otherwise noted. (Note 2)
EN/UVLO Pin Current
EN/UVLO Voltage Threshold
EN/UVLO Voltage Threshold
EN/UVLO Voltage Hysteresis
VEN/UVLO = 12V
EN/UVLO Falling, VIN ≥ 4.2V
EN/UVLO Rising, VIN ≥ 4.2V
1 30
l 1.09 1.16 1.23
l 1.12 1.19 1.28
30 45
nA
V
V
mV
PG Threshold Offset from Feedback Voltage
PG Hysteresis as % of Output Voltage
VFB Rising
6.5 10 13.5
0.8
%
%
PG Leakage
PG Sink Current
Minimum Switch On-Time
VPG = 3V
VPG = 0.4V
l 220
0.01
350
70
1
µA
µA
ns
Minimum Switch Off-Time (Note 5)
VIN = 10V
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3973E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization, and correlation with statistical process controls. The
LT3973I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3973H is guaranteed over the full –40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetimes. Operating lifetime is derated at junction
temperatures greater than 125°C. The junction temperature (TJ, in °C) is
calculated from the ambient temperature (TA in °C) and power dissipation
(PD, in Watts) according to the formula:
130 180
ns
Note 3: This is the minimum input voltage for operation with accurate FB
reference voltage.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the switch.
Note 5: The LT3973 contains circuitry that extends the maximum duty
cycle if there is sufficient voltage across the boost capacitor. See the
Application Information section for more details.
Note 6: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
when overtemperature protection is active. Continuous operation above
the specified maximum operating junction temperature may impair device
reliability or permanently damage the device.
TJ = TA + (PD • θJA)
where θJA (in °C/W) is the package thermal impedance.
3973fb
4 For more information www.linear.com/LT3973

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LT3973 전자부품, 판매, 대치품
LT3973/LT3973-3.3/LT3973-5
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
Switch VCESAT
600
500
400
300
200
100
0
0 200 400 600 800 1000 1200
SWITCH CURRENT (mA)
3973 G19
Minimum Input Voltage,
VOUT = 5V
6.5
FRONT PAGE APPLICATION
VOUT = 5V
6.0
5.5
TO START/TO RUN
5.0
4.5
4.0
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
3973 G22
BOOST Pin Current
25
20
15
10
5
0
0 200 400 600 800 1000 1200
SWITCH CURRENT (mA)
3973 G20
Start-Up and Dropout
Performance
9 FRONT PAGE APPLICATION
8
7
6 VIN
5
VOUT
4
3
2
1
0
TIME
3973 G23
Minimum Input Voltage,
VOUT = 3.3V
5.0
FRONT PAGE APPLICATION
VOUT = 3.3V
4.5
4.0
TO START/TO RUN
3.5
3.0
2.5
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
3973 G21
Minimum Input Voltage to Switch
4.0
3.5
3.0
2.5
2.0
–50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
3973 G24
VFB Regulation Voltage
1.4
1.2
1.0
0.8
0.6
2.0
2.5 3.0 3.5 4.0 4.5
INPUT VOLTAGE (V)
5.0
3973 G25
Boost Diode Forward Voltage
1.2
1.0
0.8
0.6
0.4
0.2
0
0
150°C
125°C
25°C
–50°C
50 100 150
BOOST DIODE CURRENT (mA)
200
3973 G26
For more information www.linear.com/LT3973
Catch Diode Forward Voltage
1.0
0.8
0.6
0.4
0.2
0
0
150°C
125°C
25°C
–50°C
200 400 600 800 1000 1200
CATCH DIODE CURRENT (mA)
3973 G27
3973fb
7

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