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LTC3523 の電気的特性と機能

LTC3523のメーカーはLinear Technology Corporationです、この部品の機能は「Synchronous 600mA Step-Up And 400mA Step-Down DC/DC Converters」です。


製品の詳細 ( Datasheet PDF )

部品番号 LTC3523
部品説明 Synchronous 600mA Step-Up And 400mA Step-Down DC/DC Converters
メーカ Linear Technology Corporation
ロゴ Linear Technology Corporation ロゴ 




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LTC3523 Datasheet, LTC3523 PDF,ピン配置, 機能
LTC3523/LTC3523-2
Synchronous 600mA Step-Up
and 400mA Step-Down
DC/DC Converters
FEATURES
DESCRIPTION
Dual High Efficiency DC/DC Converters:
Step-Up (VOUT = 1.8V to 5.25V, ISW = 600mA)
Step-Down (VOUT = 0.615V to 5.5V, IOUT = 400mA)
1.8V to 5.5V Input Voltage Range
www.DataSheetU4Up.ctoom94% Efficiency
Pin Selectable Burst Mode® Operation
45μA Quiescent Current in Burst Mode Operation
1.2MHz (LTC3523) or 2.4MHz (LTC3523-2)
Switching Frequency
Independent Power Good Indicator Outputs
Integrated Soft-Start
Thermal and Overcurrent Protection
<2μA Quiescent Current in Shutdown
Small 16-Lead 3mm × 3mm × 0.75mm QFN Package
APPLICATIONS
Digital Cameras
Medical Instruments
Industrial Handhelds
GPS Navigators
The LTC®3523/LTC3523-2 combine a 600mA step-up
DC/DC converter with a 400mA synchronous step-down
DC/DC converter in a tiny 3mm × 3mm package. The
1.2MHz/2.4MHz switching frequencies minimize the
solution footprint while maintaining high efficiency. Both
converters feature soft-start and internal compensation,
simplifying the design.
Both the step-up and step-down converters are current
mode controlled and utilize an internal synchronous rec-
tifier for high efficiency. The step-up supports 0% duty
cycle operation and the step-down converter supports
100% duty cycle operation to extend battery run time.
If the MODE pin is held high, both converters automati-
cally transition between Burst Mode operation and PWM
operation improving light load efficiency. Fixed, low noise
1.2MHz/2.4MHz PWM operation is selected when MODE
is grounded.
The LTC3523/LTC3523-2 provide a sub-2μA shutdown
mode, overtemperature shutdown and current limit pro-
tection on both converters. The LTC3523/LTC3523-2 are
housed in a 16-lead 3mm × 3mm × 0.75mm QFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
VIN
1.8V TO 3.2V
+
2-CELL
ALKALINE
VOUT1
STEP-UP
OUTPUT
3.3V
200mA
10μF
47μF
4.7μH
VIN1 VIN2 VBAT
SW1 SW2
4.7μH
634k
365k
VOUT
FB1
LTC3523
FB2
MODE
PGOOD1
PGOOD2
SHDN1
SHDN2
GND1 GND2 GND3
VIN
10pF 511k
511k
OFF ON
OFF ON 3523 TA01a
VOUT2
STEP-DOWN
OUTPUT
10μF
1.2V
200mA
LTC3523 Efficiency and Power
Loss vs Load Current
100 1000
90
80
EFFICIENCY
70
100
60
50 P0WER LOSS
10
40
30
20
10
0
0.1
VIN = 2.4V
VOUT1 = 3.3V
VOUT2 = 1.2V
fOSC = 1.2MHz
1
STEP-UP
STEP-DOWN
0.1
1 10 100 1000
LOAD CURRENT (mA)
3523 TA01b
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LTC3523 pdf, ピン配列
LTC3523/LTC3523-2
ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN1 = VIN2 = VIN3 = 2.4V, VOUT = 3.3V, VOUT(STEP-DOWN) = 1.2V unless
otherwise specified.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
MODE Leakage Current
Soft-Start Time
VMODE = 5.5V
0.01 1
500
μA
μs
Step-Up Converter
Input Voltage Range
1.8
5.25 V
Output Voltage Adjust Range
(Note 6)
1.8
5.25 V
Feedback Voltage FB1
www.DataShFeeeetd4bUa.cckoImnput Current FB1
N-Channel Switch Leakage
P-Channel Switch Leakage
N-Channel Switch On Resistance
P-Channel Switch On Resistance
Peak Inductor Current
VFB1 = 1.25V
VSW = 5.5V
VSW = 5.5V, VOUT = 0V
VOUT = 3.3V, ISW = 100mA
VOUT = 5V, ISW = 100mA
VOUT = 3.3V, ISW = 100mA
VOUT = 5V, ISW = 100mA
(Note 7)
1.16 1.20 1.23
0 50
0.20 2
0.20 2
0.36
0.22
0.33
0.31
600 1000
V
nA
μA
μA
Ω
Ω
Ω
Ω
mA
Current Limit Delay to Output
(Note 6)
40 ns
Maximum Duty Cycle
Minimum Duty Cycle
Step-Down Converter
VFB = 1V
VFB = 1.5V
80
87
0
%
%
Input Voltage Range
1.8
5.5 V
Output Voltage Range
(Note 6)
0.615
5.25 V
Feedback Voltage FB2
585 600 615
mV
Feedback Input Current FB2
Reference Voltage Line Regulation
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Duty Cycle
VFB2 = 0.625V
IOUT = 100mA (Notes 5, 6)
IOUT = 100mA, 1.6V < VIN < 5.5V (Note 6)
IOUT = 0mA to 600mA (Note 6)
0 ±50
0.04
0.04
1.0
100
nA
%/V
%/V
%
%
Peak Inductor Current
(Note 7)
400
650
mA
N-Channel Switch On Resistance
P-Channel Switch On Resistance
SW Leakage
VIN2 = 2.4V
VIN2 = 2.4V
VSHDN2 = 0V, VSW2 = 0V or 5V, VIN = 5.5V
0.33
0.58
0.20 2
Ω
Ω
μA
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 reli-
ability and lifetime.
Note 2: The LTC3523/LTC3523-2 are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process control.
Note 3: The LTC3523/LTC3523-2 include an overtemperature shutdown
that is intended to protect the device during momentary overload condi-
tions. Junction temperature will exceed 125°C when the overtemperature
shutdown is active. Continuous operation above the specified maximum
operating junction temperature may impair device reliability.
Note 4: Current is measured into the VOUT pin since the supply is boot-
strapped to the output for the step-up. The current will reflect to the input
supply by: (VOUT/VIN) • Efficiency. The outputs are not switching in sleep.
Note 5: The LTC3523/LTC3523-2 are tested in a propriety test mode that
connects FB2 to the output of the error amplifier.
Note 6: Specification is guaranteed by design and not 100% tested in
production.
Note 7: Current measurements are performed when the LTC3523/
LTC3523-2 are not switching. The current limit values in operation will be
somewhat higher due to the propagation delay of the comparator.
3523f
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3Pages


LTC3523 電子部品, 半導体
LTC3523/LTC3523-2
PIN FUNCTIONS
SW1 (Pin 5): Step-Up Converter Switch Pin. Connect the
inductor between SW1 and VIN1. Keep these PCB trace
lengths as short and wide as possible to reduce EMI and
voltage overshoot. If the inductor current falls to zero or
SHDN1 is low, an internal 100Ω anti-ringing switch is
connected from SW1 to VIN1 to minimize EMI.
GND1 (Pin 6): Step-Up Converter Power Ground. Connect
this pin to the ground plane.
www.DataSheet4U.com
GND2 (Pin 7): Step-Down Converter Power Ground. Con-
nect this pin to the ground plane.
SW2 (Pin 8): Step-Down Converter Switch Pin. Connect
one end of the inductor to SW2. Keep these PCB trace
lengths as short and wide as possible to reduce EMI and
voltage overshoot.
VIN2 (Pin 9): Step-Down Converter Power Voltage Input.
This pin can be connected to a different supply than VIN1.
This pin must be connected to a valid supply voltage.
MODE (Pin 10): Step-Up and Step-Down Converter Mode
Selection Pin. Do not leave this pin floating.
• MODE = Low: PWM mode
• MODE = High: Automatic Burst Mode operation
PGOOD2 (Pin 11): Step-Down Converter Power Good
Comparator Output. This open-drain output is pulled low
when VFB2 < –9% of its regulation voltage.
FB2 (Pin 12): Step-Down Converter Feedback Input to the
Error amplifier. Connect resistor divider tap to this pin. The
output voltage can be adjusted from 0.6V to 5.5V by:
VOUT(STEP-DOWN)
=
0.6V
⎛⎝⎜1+
R3
R4⎠⎟
If large feedback resistors, above 500k are used, then it
will be necessary to use a lead capacitor connected to the
output voltage and FB2.
SHDN2 (Pin 13): Step-Down Converter Logic Controlled
Shutdown Input. Do not leave this pin floating.
SHDN2 = High: Normal free-running operation,
1.2MHz/2.4MHz typical operating frequency.
SHDN2 = Low: Shutdown, quiescent current < 1μA.
This pin cannot exceed the voltage on VIN2.
GND3 (Pin 14): Analog Ground. The feedback voltage
dividers for each converter must be returned to GND3
for best performance.
Note: When laying out your PCB provide a short direct
path between GND1 and the (–) side of the step-up output
capacitor(s) and GND2 and the step-down output capaci-
tor.These pins are not connected together internally.
VBAT (Pin 15): Analog Voltage Input. Connect this pin to
the higher of VIN1 or VIN2.
SHDN1 (Pin 16): Step-Up Converter Logic Controlled
Shutdown Input.
SHDN1 = High: Normal free-running operation,
1.2MHz/2.4MHz typical operating frequency.
SHDN1 = Low: Shutdown, quiescent current < 1μA.
This pin cannot exceed the voltage on VIN1.
Exposed Pad (Pin 17): Die attach pad must be soldered
to PCB ground for electrical contact and optimum thermal
performance.
See Block Diagram.
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6 Page



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