LTC3839 Datasheet, PDF (1/50 Pages) Linear Technology – Fast, Accurate, 2-Phase, Single-Output Step-Down DC/DC Controller

LTC3839
FEATURES
Fast, Accurate, 2-Phase,
Single-Output Step-Down DC/DC
Controller with Differential Output Sensing
DESCRIPTION
n _{Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V}
n _{±0.67% Output Voltage Accuracy Over Temperature,}
Differential Output Voltage Sensing, Allowing Up to
±500mV Line Loss at Remote Ground
n _{Controlled On-Time, Valley Current Mode Control}
n _{Fast Load Transient Response}
n _{Detect Transient (DTR) Reduces VOUT Overshoot}
n _{Frequency Programmable from 200kHz to 2MHz,}
Synchronizable to External Clock
n _{tON(MIN) = 30ns, tOFF(MIN) = 90ns}
n _{Up to 12-Phase Operation}
n _{RSENSE or Inductor DCR Current Sensing}
n _{Overvoltage Protection and Current Limit Foldback}
n _{Power Good Output Voltage Monitor}
n _{Output Voltage Tracking and Adjustable Soft Start-Up}
n _{Thermally Enhanced 32-Pin (5mm × 5mm) QFN}
Package
APPLICATIONS
n _{Distributed Power Systems}
n _{Point-of-Load Converters}
n _{Computing Systems}
n _{Data Communication Systems}
The LTC^®3839 is a 2-phase, single-output PolyPhase^®
synchronous step-down switching regulator controller
that drives all N-channel power MOSFETs. The controlled
on-time, valley current mode control architecture allows for
fast transient response and constant frequency switching
in steady-state operation, independent of V_IN, V_OUT and
load current. Its load-release transient detection feature
significantly reduces overshoot at low output voltages.
Differential output voltage sensing, along with a preci-
sion internal reference, offers an accurate ±0.67% output
regulation, even if the remote output ground deviates from
local ground by ±500mV.
The switching frequency can be programmed from 200kHz
to 2MHz with an external resistor and can be synchronized
to an external clock. Very low t_ON and t_OFF times allow for
near 0% and near 100% duty cycles, respectively. Volt-
age tracking soft start-up and multiple safety features are
provided.
L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, Linear Technology and the Linear logo are
registered trademarks and Hot Swap and Stage Shedding are trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by U.S.
Patents, including 5481178, 5847554, 6580258, 6304066, 6476589, 6774611.
TYPICAL APPLICATION
3.3V/25A Output, 2MHz Step-Down Converter (Refer to Figure 20 for Full Design)
V_IN
4.5V TO 14V
V_OUT
3.3V
25A
100μF ⁺
w6
0.3μH
45.3k
10k
0.1μF
18.7k
SENSE1^–
SENSE1⁺
SENSE2^–
SENSE2⁺
V_IN
INTV_CC
TG1
TG2
LTC3839
SW1
SW2
BOOST1
BOOST2
DRV_CC1
DRV_CC2
BG1
BG2
4.7μF
PGND
MODE/PLLIN
V_OUTSENSE+
V_{OUTSENSE–}
CLKOUT
TRACK/SS ^PHASMD
ITH
RUN
RT
DTR
SGND
0.3μH
0.1μF
3839 TA01a
Efficiency/Power Loss
100
DISCONTINUOUS
MODE
90
10
V_IN = 5V
8
80
FORCED
CONTINUOUS
6
MODE
70
4
60
LOSS
FORCED CM
50
0.1
1
2
LOSS
DCM
0
10
100
LOAD CURRENT (A)
3839 TA01b
3839fa
1