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LTC3852 の電気的特性と機能

LTC3852のメーカーはLinearです、この部品の機能は「Synchronous Step-Down DC/DC Controller」です。


製品の詳細 ( Datasheet PDF )

部品番号 LTC3852
部品説明 Synchronous Step-Down DC/DC Controller
メーカ Linear
ロゴ Linear ロゴ 




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LTC3852 Datasheet, LTC3852 PDF,ピン配置, 機能
FEATURES
n Charge Pump Input Range: 2.7V to 5.5V
n Controller Input Range: 4V to 38V
n Integrated Charge Pump Provides 5V Gate Drive to
Logic Level MOSFETs
n RSENSE or DCR Current Sensing
n ±1.25% Output Voltage Accuracy Over Temperature
n Phase-Lockable Fixed Frequency: 250kHz to 750kHz
n Power Good Output Voltage Monitor
n Adjustable Soft-Start Voltage Ramping
n Current Foldback Disabled During Start-Up
n No Reverse Current During Soft-Start
n Selectable Constant Frequency, Pulse-Skipping, or
Burst Mode Operation
n Output Overvoltage Protection
n Very Low Dropout Operation: 99% Duty Cycle
n Available in a 24-Lead (3mm ¥ 5mm) QFN Package
APPLICATIONS
n General Purpose 3.3V Systems
n Lithium-Ion Powered Devices
n Distributed DC Power Systems
LTC3852
Low Input Voltage,
Synchronous Step-Down
DC/DC Controller
DESCRIPTION
The LTC®3852 is a constant frequency, current mode
step-down DC/DC controller which can be powered by an
onboard charge pump. Input supplies as low as 2.7V, when
doubled by the charge pump, provide 5V to the LTC3852’s
control logic and gate drives, supporting a wide selection
of logic-level N-channel power MOSFETs.
The constant-frequency current mode architecture allows for
a phase-lockable fixed frequency of up to 750kHz. The RUN
pin provides a precision enable threshold while the TRACK/SS
pin combines tracking and adjustable soft-start features.
The MODE/PLLIN pin selects among Burst Mode® oper-
ation, pulse-skipping mode, and continuous current mode.
Current foldback limits MOSFET power dissipation during
short-circuit conditions. Reverse current and current
foldback functions are disabled during soft-start. A power
good output pin indicates when the output is within ±10%
of its designed set point.
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 5408150, 5481178,
5705919, 6498466, 6580258, 6611131.
TYPICAL APPLICATION
High Efficiency Synchronous Step-Down Converter
100k
INTVCC
PGO0D
VIN1
MODE/PLLIN TG
FREQ/PLLFLTR SW
95.3k
1nF
BOOST
TRACK/SS
0.1μF
VIN2
INTVCC
ITH LTC3852 BG
12.1k
100pF
GND2
RUN SENSE+
OFF ON
CHARGE PUMP
2.2μF
SHDN
SENSE
C+ VFB
CGND1 VPUMP
3852 TA01
0.1μF
4.7μF
0.36μH
2.1k
22μF
VIN
2.7V TO 5.5V
VOUT
1.2V
+
20A
470μF
×2
0.1μF
20k
1%
40.2k
1%
Efficiency and Power Loss
vs Load Current
100
90
80
70
60
50
40
30
20
10
0
1
5
EFFICIENCY
4.5
4
3.5
3
2.5
2
POWER LOSS
1.5
1
0.5
10
LOAD CURRENT (A)
0
20
3852 TA01a
3852f
1

1 Page





LTC3852 pdf, ピン配列
LTC3852
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C (Note 2), VIN1 = 3.3V, VIN2 = 15V, VRUN = 3.3V, SHDN = 0V,
MODE/PLLIN = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loop (Step-Down Regulator)
VIN2
VFB
IFB
VREFLNREG
VLOADREG
gm
Controller Input Voltage Range
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
Transconductance Amplifier gm
(Note 3); ITH Voltage = 1.2V
(Note 3)
(Notes 3, 9); VIN2 = 6V to 38V
(Note 3)
Measured in Servo Loop;
DITH Voltage = 1.2V to 0.7V
Measured in Servo Loop;
DITH Voltage = 1.2V to 1.6V
(Note 3); ITH = 1.2V;
Sink/Source 5μA
l4
l 0.790
0.800
–10
0.002
38
0.810
–50
0.02
V
V
nA
%/V
l
0.01 0.1
%
l
–0.01 –0.1
%
2 mmho
IQ(VIN2)
Controller Input DC Supply Current
(Note 4) VFB = 0.9V
(RUN = 3.3V)
1.4 mA
Shutdown Supply Current
RUN = 0V
25 50
μA
IQ(VIN1)
Total Input DC Supply Current
Shutdown Supply Current
((RNUotNes=4S, H7D) NVF=B
= 0.9V
3.3V)
(Note 7) RUN = SHDN = 0V
7 mA
5 μA
UVLO
Undervoltage Lockout
Undervoltage Hysteresis
INTVCC Ramping Down
3.25 V
0.4 V
VOVL
ISENSE
ITRACK/SS
VRUN
VRUN(HYS)
VSENSE(MAX)
TG RUP
TG RDOWN
BG RUP
Feedback Overvoltage Lockout
SENSE Pins Current
Soft-Start Charge Current
RUN Pin On Threshold
RUN Pin On Hysteresis
Maximum Current Sense Threshold
TG Driver Pull-Up On-Resistance
TG Driver Pull-Down On-Resistance
BG Driver Pull-Up On-Resistance
Measured at VFB
VTRACK/SS = 0V
VRUN Rising
VFB = 0.7V, VSENSE– = 3.3V
TG High
TG Low
BG High
l 0.86 0.88 0.90
–2.0 2.0
0.5 1
2
l 1.1
1.22 1.35
130
l 40 53 68
2.2
1.2
2.1
V
μA
μA
V
mV
mV
Ω
Ω
Ω
BG RDOWN
TG tr
TG tf
BG tr
BG tf
TG/BG t1D
BG Driver Pull-Down On-Resistance
Top Gate Rise Time
Top Gate Fall Time
Bottom Gate Rise Time
Bottom Gate Fall Time
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
BG Low
CLOAD = 3300pF (Note 5)
CLOAD = 3300pF (Note 5)
CLOAD = 3300pF (Note 5)
1.1 Ω
25 ns
25 ns
25 ns
25 ns
30 ns
BG/TG t1D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
CLOAD = 3300pF (Note 5)
30 ns
tON(MIN)
Minimum On-Time
(Note 6)
90 ns
3852f
3


3Pages


LTC3852 電子部品, 半導体
LTC3852
TYPICAL PERFORMANCE CHARACTERISTICS
Controller Input DC Supply
Current vs Input Voltage (VIN2)
3.0
2.5
2.0
1.5
1.0
0.5
0
4 8 12 16 20 24 28 32 36 40
INPUT VOLTAGE (V)
Controller Burst Mode Peak
Current Sense Threshold
vs ITH Voltage
60
3852 G12
MAXIMUM
50
40
30
20
MINIMUM
10
BURST COMPARATOR FALLING THRESHOLD:
0 VITH = 0.4V
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
VITH (V)
3852 G16
Controller Maximum Current
Sense Threshold
vs Common Mode Voltage
90
80
70
60
50
40
30
20
10
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
VSENSE COMMON MODE VOLTAGE (V)
3852 G14
Controller Maximum Current
Sense Threshold vs Duty Cycle
90
80
70
60
50
40
30
20
10
0
0 20 40 60 80 100
DUTY CYCLE (%)
3852 G17
Controller TRACK/SS Pull-Up
Current vs Temperature
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3852 G19
Controller Shutdown (RUN)
Threshold vs Temperature
1.4
1.3
RUN RISING THRESHOLD (ON)
1.2
RUN FALLING THRESHOLD (OFF)
1.1
1.0
0.9
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3852 G20
6
Controller Maximum Peak Current
Sense Threshold vs ITH Voltage
90
DUTY CYCLE RANGE: 0% TO 100%
80
70
60
50
40
30
20
10
0
–10
–20
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
VITH (V)
3852 G15
Controller Maximum Current
Sense Threshold vs Feedback
Voltage (Current Foldback)
90
80
70
60
50
40
30
20
10
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
FEEDBACK VOLTAGE (V)
3852 G18
Controller Regulated Feedback
Voltage vs Temperature
806
804
802
800
798
796
794
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3852 G21
3852f

6 Page



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[ LTC3852 データシート.PDF ]


データシートを活用すると、その部品の主な機能と仕様を詳しく理解できます。 ピン構成、電気的特性、動作パラメータ、性能を確認してください。


共有リンク

Link :


部品番号部品説明メーカ
LTC3850

2-Phase Synchronous Step-Down Switching Controller

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LTC3850-1

2-Phase Synchronous Step-Down Switching Controller

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LTC3850-2

2-Phase Synchronous Step-Down Switching Controller

Linear Technology
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LTC3851

Synchronous Step-Down Switching Regulator Controller

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