Datasheet LTC3827 (Analog Devices)

LTC3827 Low IQ, Dual, 2-Phase Synchronous Step-Down Controller
FEATURES DESCRIPTION
n
Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 10V
The LTC®3827 is a high performance dual step-down n
Low Operating I
switching regulator controller that drives all N-channel
Q: 80μA (One Channel On)
n
Out-of-Phase Controllers Reduce Required Input
synchronous power MOSFET stages. A constant frequency
Capacitance and Power Supply Induced Noise
current mode architecture allows a phase-lockable fre- n
OPTI-LOOP
®
Compensation Minimizes C
quency of up to 650kHz. Power loss and noise due to the
OUT
n
±1% Output Voltage Accuracy
ESR of the input capacitor ESR are minimized by operating n the two controller output stages out of phase.
Wide VIN Range: 4V to 36V Operation
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Phase-Lockable Fixed Frequency 140kHz to 650kHz
The 80μA no-load quiescent current extends operating n Selectable Continuous, Pulse Skipping or
Low Ripple
life in battery-powered systems. OPTI-LOOP compensa- Burst Mode® Operation at Light Loads tion allows the transient response to be optimized over n Dual N-Channel MOSFET Synchronous Drive a wide range of output capacitance and ESR values. The n Very Low Dropout Operation: 99% Duty Cycle LTC3827 features a precision 0.8V reference and a power n Adjustable Output Voltage Soft-Start or Tracking good output indicator. A wide 4V to 36V input supply range n Output Current Foldback Limiting encompasses all battery chemistries. n Power Good Output Voltage Monitor Independent TRACK/SS pins for each controller ramp the n Output Overvoltage Protection output voltage during start-up. Current foldback limits n Low Shutdown IQ: 8μA MOSFET heat dissipation during short-circuit conditions. n Internal LDO Powers Gate Drive from VIN or VOUT n Small 5mm The PLLIN/MODE pin selects among Burst Mode opera- × 5mm QFN Package tion, pulse skipping mode, or continuous inductor cur-
APPLICATIONS
rent mode at light loads. For a leaded package version (28-lead SSOP), see the LTC3827-1 datasheet. n Automotive Systems L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Battery-Operated Digital Devices Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. n All other trademarks are the property of their respective owners. Protected by U.S. Patents Distributed DC Power Systems including 5481178, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 570919.
TYPICAL APPLICATION High Effi ciency Dual 8.5V/3.3V Step-Down Converter Effi ciency and Power Loss
VIN
vs Load Current
+ 4V TO 36V 22μF 100 100000 4.7μF 1μF 50V VIN INTVCC 90 EFFICIENCY V TG1 TG2 IN = 12V; VOUT = 3.3V 10000 80 0.1μF BOOST1 BOOST2 POWER LOSS (mW) 3.3μH 0.1μF 7.2μH 70 1000 SW1 SW2 60 BG1 BG2 50 100 LTC3827 PGND 40 EFFICIENCY (%) POWER LOSS 10 SENSE1+ SENSE2+ 30 0.015Ω 0.015Ω 20 1 10 V SENSE1– SENSE2– OUT1 VOUT2 FIGURE 13 CIRCUIT 3.3V V 0 0.1 FB1 VFB2 8.5V 5A 62.5k 192.5k 3.5A 0.001 0.01 0.1 1 10 100 1000 10000 ITH1 ITH2 LOAD CURRENT (mA) 220pF 150μF 220pF TRACK/SS1 TRACK/SS2 150μF SGND 3827 TA01b 20k 20k 15k 15k 0.1μF 0.1μF 3827 TA01 3827ff 1