Datasheet LTC3838-2 (Analog Devices)

LTC3838-2 Dual, Fast, Accurate Step-Down DC/DC Controller with External Reference Voltage and Dual Differential Output Sensing
FeaTures DescripTion
n
Wide VIN Range: 4.5V to 38V
The LTC®3838-2 is a dual-channel, PolyPhase® synchro- n
VOUT1: 0.6V to 5.5V, ±0.67% Output Regulation
nous step-down DC/DC switching regulator controller. Two
Accuracy, with Internal 0.6V VREFERENCE
independent channels drive all N-channel power MOSFETs. n
VOUT2: 0.4V to 5.5V, ±4mV Regulation Accuracy, with
The two channels can also be combined into a multiphase
Differential External VREFERENCE Sensing
single output configuration with external reference. n
Differential Remote Output Sensing; Up to ±500mV
The controlled on-time, valley current mode control architec-
(VOUT1) and ±200mV (VOUT2) Ground Deviations
ture allows for not only fast response to transients without n
Fast Load Transient Response Without Clock Delay
a clock delay, but also constant frequency switching at a n
Detect Transient Release (DTR) Reduces VOUT
steady-load condition. Its proprietary load-release transient
Overshoot
detection feature (DTR) significantly reduces overshoot at n
Frequency Programmable from 200kHz to 2MHz,
low output voltages.
Synchronizable to External Clock
n
t
The switching frequency can be programmed from 200kHz
ON(MIN) = 30ns, tOFF(MIN) = 90ns
n R to 2MHz with an external resistor, and can be synchronized SENSE or Inductor DCR Current Sensing n Overvoltage Protection and Current Limit Foldback to an external clock. Very low tON and tOFF times allow for near n Power Good Output Voltage Monitor 0% and near 100% duty cycles, respectively. Voltage track- n Thermally Enhanced 38-Pin (5mm × 7mm) QFN Package ing soft start-up and multiple safety features are provided. See Table 1 for a comparison of LTC3838, LTC3838-1 and
applicaTions
LTC3838-2. n Power for ASICs with Dynamic Voltage Scaling 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, High Step-Down Ratio of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6580258, Converters That Demand Tight Transient Regulation 6304066, 6476589, 6774611.
Typical applicaTion 1.2V/15A and 0.8V to 2.5V/15A, 350kHz Step-Down Converter (See Figure 16 for Complete Design)
VIN 4.5V TO 38V
Efficiency/Power Loss
SENSE1– SENSE2– SENSE1+ SENSE2+ 100 2.5 FORCED CONTINUOUS MODE VIN INTVCC DISCONTINUOUS MODE TG1 TG2 90 2.0 LTC3838-2 POWER LOSS (W) V 0.56µH SW1 SW2 0.56µH V OUT1 OUT2 80 1.2V BOOST1 BOOST2 0.8V TO 2.5V 1.5 15A 15A EFFICIENCY 0.1µF 0.1µF 10k 20k + 70 DRV + 330µF CC1 DRVCC2 330µF POWER 1.0 ×2 BG1 BG2 ×2 LOSS EFFICIENCY (%) 60 10k 4.7µF 10k 20k PGND 0.4V TO EXTVREF2 1.25V 0.5 50 V + + OUTSENSE1 VDFB2 VIN = 12V V – – V OUTSENSE1 VDFB2 OUT = 1.2V 40 0 TRACK/SS1 TRACK/SS2 0.1 1 10 ITH1 ITH2 LOAD CURRENT (A) 115k RT MODE/PLLIN 38382 TA01b SGND CLKOUT EXTVCC PHASMD RUN1 RUN2 38382 TA01a 38382fa For more information www.linear.com/3838-2 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts