Datasheet LTC3838-1 (Analog Devices)

LTC3838-1 Dual, Fast, Accurate Step-Down DC/DC Controller with Dual Differential Output Sensing
FeaTures DescripTion
n
Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
The LTC®3838-1 is a dual-channel, PolyPhase® syn- n
Two Independent Channels: Dual/Single Output
chronous step-down DC/DC switching regulator controller. n
Output Voltage Regulation Accuracy: ±0.67%
Two independent channels drive all N-channel power
(VOUT1) and ±0.75% (VOUT2) Over Temperature
MOSFETs. The controlled on-time, valley current mode n
Differential Remote Output Sensing: Up to ±500mV
control architecture allows for not only fast response to
(VOUT1) and ±200mV (VOUT2) Ground Deviations
transients without clock delay, but also constant frequency n
Controlled On-Time, Valley Current Mode Control
switching at steady load condition. Its proprietary load- n
Fast Load Transient Response Without Clock Delay
release transient detection feature (DTR) significantly n
Detect Transient Release (DTR) Reduces VOUT
reduces overshoot at low output voltages.
Overshoot
A precision internal reference enables accurate differential n
Frequency Programmable from 200kHz to 2MHz,
output regulation. The dual channels can either provide
Synchronizable to External Clock
two independent output voltages, or be combined into n
tON(MIN) = 30ns, tOFF(MIN) = 90ns
multiphase single-output configuration. n RSENSE or Inductor DCR Current Sensing n Overvoltage Protection and Current Limit Foldback The switching frequency can be programmed from 200kHz n Power Good Output Voltage Monitor to 2MHz with an external resistor and can be synchronized to n Output Voltage Tracking and Adjustable Soft Start-Up an external clock. Very low tON and tOFF times allow for near n Thermally Enhanced 38-Pin (5mm × 7mm) QFN Package 0% and near 100% duty cycles, respectively. Voltage track- ing soft start-up and multiple safety features are provided.
applicaTions
See Table 1 for a comparison of LTC3838, LTC3838-1 and n Distributed Power Systems; Power Supply for ASIC LTC3838-2. n Computing, Data Storage, Communication Systems L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, µModule, Linear Technology and the Linear logo are n registered trademarks of Linear Technology Corporation. All other trademarks are the property Low Voltage, High Current, and/or High Step-Down Ratio of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6580258, Converters That Demand Tight Load Transient Regulation 6304066, 6476589, 6774611.
Typical applicaTion 1.2V/1.5V, 15A, 350kHz Step-Down Converter (Refer to Figure 16 for Complete Design)
VIN
Efficiency/Power Loss
4.5V TO 38V SENSE1– SENSE2– 100 2.5 FORCED CONTINUOUS MODE SENSE1+ SENSE2+ DISCONTINUOUS MODE V 90 IN INTVCC 2.0 TG1 TG2 POWER LOSS (W) LTC3838-1 80 V 0.56µH SW1 SW2 0.56µH V OUT1 OUT2 EFFICIENCY 1.5 1.2V BOOST1 BOOST2 1.5V 15A 15A 70 0.1µF 0.1µF POWER 10k 15k + 1.0 DRV + 330µF LOSS CC1 DRVCC2 330µF EFFICIENCY (%) 60 ×2 BG1 BG2 ×2 10k/ 10k 10k 4.7µF 15k 0.5 PGND EXTVCC 50 VIN = 12V V + OUTSENSE1+ VDFB2 VOUT = 1.2V V 40 0 OUTSENSE1– V – DFB2 0.1 1 10 TRACK/SS1 TRACK/SS2 LOAD CURRENT (A) ITH1 ITH2 38381 TA01b 115k RT MODE_PLLIN SGND CLKOUT VRNG PHASMD RUN1 RUN2 38381 TA01a 38381fa For more information www.linear.com3838-1 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts