Datasheet LTC3838 (Analog Devices)

LTC3838 Dual, Fast, Accurate Step- Down DC/DC Controller with Differential Output Sensing
FeaTures DescripTion
n
Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
The LTC®3838 is a dual, PolyPhase® synchronous step-down n
±0.67% Output Voltage Accuracy Over Temperature,
DC/DC switching regulator controller. Two independent
Differential Output Voltage Sensing, Allowing Up to
channels drive all N-channel power MOSFETs. The controlled
±500mV Line Loss at Remote Ground on Channel 1
on-time, valley current mode control architecture allows for n
±1% Output on the Independent 2nd Channel
fast transient response and constant frequency switching n
Controlled On-Time, Valley Current Mode Control
in steady-state operation, independent of VIN, VOUT and n
Fast Load Transient Response
load current. Its load-release transient detection feature n
Detect Transient (DTR) Reduces VOUT Overshoot
significantly reduces overshoot at low output voltages. n
Frequency Programmable from 200kHz to 2MHz,
Differential output voltage sensing, along with a preci-
Synchronizable to External Clock
sion internal reference, offers an accurate ±0.67% output n
tON(MIN) = 30ns, tOFF(MIN) = 90ns
regulation on Channel 1, even if the remote output ground n RSENSE or Inductor DCR Current Sensing deviates from local ground by ±500mV. The second channel n Overvoltage Protection and Current Limit Foldback can either provide an independent ±1% output, or together n Power Good Output Voltage Monitor with the first channel of this controller, serve as one of the n Output Voltage Tracking and Adjustable Soft Start-Up PolyPhase channels for a single-output voltage. n Thermally Enhanced 38-Pin (5mm × 7mm) QFN and TSSOP packages The switching frequency can be programmed from 200kHz to 2MHz with an external resistor, and can be synchronized to
applicaTions
an external clock. Very low tON and tOFF times allow for near 0% and near 100% duty cycles, respectively. Voltage track- n Distributed Power Systems ing soft start-up and multiple safety features are provided. n Point-of-Load Converters L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, µModule, Linear Technology and the Linear logo n Computing Systems are registered trademarks and No RSENSE and UltraFast are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. n Data Communication Systems Patents, including 5481178, 5847554, 6580258, 6304066, 6476589, 6774611.
Typical applicaTion 1.2V/1.5V, 15A, 350kHz, DCR Sense, Step-Down Converter (Refer to Figure 16 for Full Design)
V
Efficiency/Power Loss
IN 4.5V TO 38V 100 2.5 SENSE1– SENSE2– FORCED CONTINUOUS MODE DISCONTINUOUS MODE SENSE1+ SENSE2+ 90 2.0 VIN INTVCC POWER LOSS (W) TG1 TG2 80 LTC3838 EFFICIENCY 1.5 V 0.56µH SW1 SW2 0.56µH V OUT1 OUT2 1.2V BOOST1 BOOST2 1.5V 70 15A 15A POWER 0.1µF 0.1µF 1.0 10k 15k + LOSS DRV + EFFICIENCY (%) 330µF CC1 DRVCC2 330µF 60 ×2 BG1 BG2 ×2 10k 0.5 10k 4.7µF 50 PGND VIN = 12V VOUT = 1.2V VOUTSENSE1+ VFB2 40 0 V 0.1 1 10 OUTSENSE1– LOAD CURRENT (A) TRACK/SS1 TRACK/SS2 3838 F16b ITH1 ITH2 115k 3838 TA01a RT SGND 3838fb For more information www.linear.com/LTC3838 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts