LTC3890-2
60V Low I , Dual, 2-Phase
Q
Synchronous Step-Down
DC/DC Controller
DESCRIPTION
FEATURES
The LTC®3890-2 is a high performance dual step-down
switching regulator DC/DC controller that drives all
N-channelsynchronouspowerMOSFETstages.Aconstant
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.
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Wide V Range: 4V to 60V (65V Abs Max)
IN
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Low Operating I : 50µA (One Channel On)
Q
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Wide Output Voltage Range: 0.8V ≤ V
≤ 24V
OUT
R
or DCR Current Sensing
SENSE
Out-of-Phase Controllers Reduce Input Capacitance
and Power Supply Induced Noise
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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
The50μAno-loadquiescentcurrentextendsoperatingrun
timeinbattery-poweredsystems.OPTI-LOOP® compensa-
tion allows the transient response to be optimized over a
wide range of output capacitance and ESR values. A wide
4V to 60V input supply range encompasses a wide range
of intermediate bus voltages and battery chemistries.
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Selectable Current Limit
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Power Good Output Voltage Monitors
Independent TRACK/SS pins for each controller ramp the
outputvoltagesduringstart-up.Currentmodecontrollimits
the inductor current during short-circuit conditions. The
PLLIN/MODE pin selects among Burst Mode operation,
pulse-skipping mode, or continuous conduction mode at
light loads. For versions with different and/or additional
features, see the LTC3890 family summary, Table 1, in the
Pin Functions section of this data sheet.
Low Shutdown I : < 14µA
Q
Internal LDO Powers Gate Drive from V or EXTV
IN
CC
Small Low Profile (0.75mm) 5mm × 5mm QFN Package
AEC-Q100 Qualified for Automotive Applications
APPLICATIONS
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Automotive Always-On Systems
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Battery Operated Digital Devices
All registered trademarks and 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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Distributed DC Power Systems
TYPICAL APPLICATION
High Efficiency Dual 8.5V/3.3V Output Step-Down Converter
Efficiency and Power Loss
V
vs Output Current
IN
9V TO 60V
22µF
ꢓꢉꢉꢉꢉ
ꢓꢉꢉꢉ
ꢓꢉꢉ
ꢓꢉꢉ
ꢖꢉ
ꢕꢉ
ꢒꢉ
ꢛꢉ
ꢙꢉ
ꢚꢉ
ꢔꢉ
ꢗꢉ
4.7µF
ꢜ
ꢜ
ꢝ ꢓꢗꢜ
ꢋꢆ
ꢀꢁꢂ
V
IN
INTV
CC
ꢝ ꢔ.ꢔꢜ
TG1
TG2
0.1µF
0.1µF
BOOST1
SW1
BOOST2
SW2
4.7µH
8µH
BG1
BG2
LTC3890-2
PGND
ꢓꢉ
+
+
SENSE1
SENSE2
0.01Ω
100k
0.008Ω
ꢓ
–
–
V
SENSE2
ꢓꢉ
ꢉ
OUT2
SENSE1
FB1
ITH1
V
OUT1
3.3V
5A
8.5V
3A
V
V
FB2
ꢉ.ꢓ
ꢓꢉ
100k
ITH2
ꢉ.ꢉꢉꢉꢓ ꢉ.ꢉꢉꢓ
ꢉ.ꢉꢓ
ꢉ.ꢓ
ꢓ
470µF
1000pF
34.8k
1000pF
ꢀꢁꢂꢃꢁꢂ ꢄꢁRRꢅꢆꢂ ꢇAꢈ
330µF
TRACK/SS1 SGND TRACK/SS2
0.1µF
10.5k
ꢔꢕꢖꢉꢗ ꢂAꢉꢓꢘ
31.6k
34.8k
0.1µF
38902 TA01a
Rev. A
1
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