LTC1629 Datasheet, PDF (1/28 Pages) Linear Technology – PolyPhase, High Efficiency, Synchronous Step-Down Switching Regulators

LTC1629/LTC1629-PG
PolyPhase, High Efficiency,
Synchronous Step-Down Switching Regulators
FEATURES
s _{Dual Controller Operates from One to Twelve Phases}
s _{Reduces Required Input Capacitance and Power}
Supply Induced Noise
s _{Current Mode Control Ensures Current Sharing}
s _{Phase-Lockable Fixed Frequency: 150kHz to 300kHz}
s _{1.8MHz Effective Switching Frequency}
s _{True Remote Sensing Differential Amplifier}
s _OPTI-LOOP^TM _{Compensation Reduces COUT}
s _{±1% Output Voltage Accuracy}
s _{Power Good Output Voltage Monitor (LTC1629-PG)}
s _{Wide VIN Range: 4V to 36V Operation}
s _{Very Low Dropout Operation: 99% Duty Cycle}
s _{Adjustable Soft-Start Current Ramping}
s _{Internal Current Foldback Plus Shutdown Timer}
s _{Overvoltage Soft-Latch Eliminates Nuisance Trips}
s _{Micropower Shutdown}
s _{Available in 28-Lead SSOP Package}
U
APPLICATIO S
s _{Desktop Computers}
s _{Internet Servers}
s _{Large Memory Arrays}
s _{DC Power Distribution Systems}
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP and PolyPhase are trademarks of Linear Technology Corporation.
DESCRIPTIO
The LTC^®1629/LTC1629-PG are multiple phase, dual,
synchronous step-down current mode switching regula-
tor controllers that drive N-channel external power MOSFET
stages in a phase-lockable fixed frequency architecture.
The PolyPhase^TM controller drives its two output stages
out of phase at frequencies up to 300kHz to minimize the
RMS ripple currents in both input and output capacitors.
The output clock signal allows expansion for up to 12
evenly phased controllers for systems requiring 15A to
200A of output current. The multiple phase technique
effectively multiplies the fundamental frequency by the
number of channels used, improving transient response
while operating each channel at an optimum frequency for
efficiency. Thermal design is also simplified.
An internal differential amplifier provides true remote
sensing of the regulated supply’s positive and negative
output terminals as required for high current applications.
A RUN/SS pin provides both soft-start and optional timed,
short-circuit shutdown. Current foldback limits MOSFET
dissipation during short-circuit conditions when the
overcurrent latchoff is disabled. OPTI-LOOP compensa-
tion allows the transient response to be optimized over a
wide range of output capacitance and ESR values. The
LTC1629-PG includes a power good output pin that re-
places the AMPMD control pin of the LTC1629.
TYPICAL APPLICATIO
0.1µF
0.1µF
1000pF
3.3k
16k
16k
V_IN ^LTC1629-PG TG1
BOOST1
SW1
RUN/SS
BG1
PGOOD
I_TH
PGND
SENSE1⁺
SENSE1^–
TG2
SGND
BOOST2
SW2
V_DIFFOUT
EAIN
V_OS–
V_OS+
BG2
INTV_CC
SENSE2⁺
SENSE2^–
10Ω
0.47µF
0.47µF
10µF
10µF ×4
M1
35V
CERAMIC
0.003Ω
L1
M2
1µH
×2
D1
M3
0.003Ω
L2
M4
1µH
×2
D2
C_OUT: T510E108K004AS
D1, D2: UP5840
L1, L2: CEPH149-IROMC
M1, M3: IRF7811
M2, M4: IRF7809
Figure 1. High Current Dual Phase Step-Down Converter
V_IN
5V TO 28V
V_OUT
1.6V/40A
+ C_OUT
1000µF ×2
4V
1629 TA01
1