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LTC3858 参数 Datasheet PDF下载

LTC3858图片预览
型号: LTC3858
PDF下载: 下载PDF文件 查看货源
内容描述: 60V低IQ ,双通道,两相同步降压型 [60V Low IQ, Dual, 2-Phase Synchronous Step-Down]
分类和应用:
文件页数/大小: 40 页 / 464 K
品牌: LINEAR [ LINEAR INTEGRATED SYSTEMS ]
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FeaTures
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LTC3890
60V Low I
Q
, Dual, 2-Phase
Synchronous Step-Down
DC/DC Controller
DescripTion
The LTC
®
3890 is a high performance dual step-down
switching regulator DC/DC controller that drives all
N-channel synchronous power MOSFET stages. A constant
frequency current mode architecture allows a phase-
lockable frequency of up to 850kHz. Power loss and noise
due to the ESR of the input capacitor are minimized by
operating the two controller output stages out-of-phase.
The 50μA no-load quiescent current extends operating run
time in battery-powered systems. OPTI-LOOP
®
compensa-
tion allows the transient response to be optimized over
a wide range of output capacitance and ESR values. The
LTC3890 features a precision 0.8V reference and power
good output indicators. A wide 4V to 60V input supply
range encompasses a wide range of intermediate bus
voltages and battery chemistries.
Independent TRACK/SS pins for each controller ramp the
output voltages during start-up. Current foldback limits
MOSFET heat dissipation during short-circuit conditions.
The PLLIN/MODE pin selects among Burst Mode operation,
pulse-skipping mode, or continuous conduction mode at
light loads. For a leaded package version (28-lead Narrow
SSOP), see the LTC3890-1 data sheet.
L,
LT, LTC, LTM, Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by U.S.
Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258,
7230497.
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Wide V
IN
Range: 4V to 60V (65V Abs Max)
Low Operating I
Q
: 50µA (One Channel On)
Wide Output Voltage Range: 0.8V ≤ V
OUT
≤ 24V
R
SENSE
or DCR Current Sensing
Out-of-Phase Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
Phase-Lockable Frequency (75kHz to 850kHz)
Programmable Fixed Frequency (50kHz to 900kHz)
Selectable Continuous, Pulse-Skipping or Low Ripple
Burst Mode
®
Operation at Light Loads
Selectable Current Limit
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Power Good Output Voltage Monitors
Output Overvoltage Protection
Low Shutdown I
Q
: < 14µA
Internal LDO Powers Gate Drive from V
IN
or EXTV
CC
No Current Foldback During Start-Up
Small Low Profile (0.75mm) 5mm
×
5mm QFN Package
applicaTions
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Automotive Always-On Systems
Battery Operated Digital Devices
Distributed DC Power Systems
Typical applicaTion
High Efficiency Dual 8.5V/3.3V Output Step-Down Converter
4.7µF
TG1
4.7µH
0.1µF
V
IN
INTV
CC
TG2
22µF
V
IN
9V TO 60V
100
Efficiency and Power Loss
vs Output Current
V
IN
= 12V
90 V
OUT
= 3.3V
80
70
60
50
40
30
20
1
0.1
10
3890 TA01b
10000
1000
POWER LOSS (mW)
BOOST1
SW1
BG1
LTC3890
BOOST2
SW2
BG2
PGND
SENSE2
+
0.1µF
8µH
EFFICIENCY (%)
100
10
SENSE1
+
0.008Ω
V
OUT1
3.3V
5A
SENSE1
100k
470µF
31.6k
V
FB1
ITH1
1000pF
34.8k
0.01Ω
SENSE2
V
FB2
ITH2
1000pF
34.8k
0.1µF
V
OUT2
8.5V
3A
330µF
10
0
0.0001
0.001
0.01
0.1
1
OUTPUT CURRENT (A)
100k
10.5k
TRACK/SS1 SGND TRACK/SS2
0.1µF
3890 TA01a
3890fb
1