LTC3826
30µA I , Dual, 2-Phase
Q
Synchronous Step-Down Controller
FEATURES
DESCRIPTION
The LTC®3826 is a high performance dual step-down
switching regulator controller that drives all N-channel
synchronouspowerMOSFETstages.Aconstantfrequency
current mode architecture allows a phase-lockable fre-
quency of up to 650kHz. 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 Output Voltage Range: 0.8V ≤ V
≤ 10V
OUT
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Ultralow Operating I : 30μA (One Channel On)
Q
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Out-of-Phase Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
OPTI-LOOP® Compensation Minimizes C
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OUT
1ꢀ Output Voltage Accuracy
Wide V Range: 4V to 36V Operation
IN
Phase-Lockable Fixed Frequency 140kHz to 650kHz
Selectable Continuous, Pulse Skipping or Low Ripple
Burst Mode® Operation at Light Loads
The 30μA no-load quiescent current extends operating
life 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
LTC3826 features a precision 0.8V reference and a power
goodoutputindicator.Awide4Vto36Vinputsupplyrange
encompasses all battery chemistries.
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Dual N-Channel MOSFET Synchronous Drive
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Output Current Foldback Limiting
Power Good Output Voltage Monitor
Independent TRACK/SS pins for each controller ramp the
output voltage during start-up. Current foldback limits
MOSFET heat dissipation during short-circuit conditions.
Output Overvoltage Protection
Low Shutdown I : 4μA
Internal LDO Powers Gate Drive from V or V
Small 5mm × 5mm QFN Package
Q
IN
OUT
The PLLIN/MODE pin selects among Burst Mode opera-
tion, pulse skipping mode, or continuous inductor cur-
rent mode at light loads. For a leaded package version
(28-lead SSOP), see the LTC3826-1 data sheet.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
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, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 5705919.
APPLICATIONS
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Automotive Systems
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Battery-Operated Digital Devices
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Distributed DC Power Systems
TYPICAL APPLICATION
High Efficiency Dual 8.5V/3.3V Step-Down Converter
Efficiency and Power Loss
vs Load Current
V
IN
4V TO 36V
100
90
10000
1000
100
10
22μF
50V
4.7μF
V
INTV
CC
IN
TG1
TG2
80
0.1μF
70
BOOST1
SW1
BOOST2
SW2
7.2μH
3.3μH
0.1μF
60
50
BG1
BG2
LTC3826
40
30
20
10
0
PGND
+
+
SENSE1
SENSE1
SENSE2
1
0.015Ω
0.015Ω
–
–
SENSE2
FIGURE 13 CIRCUIT
V
V
8.5V
3.5A
OUT1
3.3V
5A
OUT2
0.1
V
FB1
V
FB2
0.00001 0.0001 0.001 0.01
0.1
1
10
62.5k
192.5k
I
I
OUTPUT CURRENT (A)
TH1
TH2
220pF
15k
220pF
15k
3826 TA01b
150μF
150μF
TRACK/SS1 SGND TRACK/SS2
0.1μF
20k
20k
0.1μF
3826 TA01
3826fc
1