LTC1629/LTC1629-PG
PolyPhase, High Efficiency,
Synchronous Step-Down Switching Regulators
FEATURES
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DESCRIPTIO
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Dual Controller Operates from One to Twelve Phases
Reduces Required Input Capacitance and Power
Supply Induced Noise
Current Mode Control Ensures Current Sharing
Phase-Lockable Fixed Frequency: 150kHz to 300kHz
1.8MHz Effective Switching Frequency
True Remote Sensing Differential Amplifier
OPTI-LOOP
TM
Compensation Reduces C
OUT
±
1% Output Voltage Accuracy
Power Good Output Voltage Monitor (LTC1629-PG)
Wide V
IN
Range: 4V to 36V Operation
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Soft-Start Current Ramping
Internal Current Foldback Plus Shutdown Timer
Overvoltage Soft-Latch Eliminates Nuisance Trips
Micropower Shutdown
Available in 28-Lead SSOP Package
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.
APPLICATIO S
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Desktop Computers
Internet Servers
Large Memory Arrays
DC Power Distribution Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP and PolyPhase are trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
0.1µF
S
10Ω
10µF
×4
35V
CERAMIC
L1
1µH
D1
V
IN
LTC1629-PG TG1
BOOST1
SW1
M1
S
0.1µF
RUN/SS
1000pF
PGOOD
I
TH
3.3k
S
0.47µF
S
BG1
PGND
SENSE1
+
SENSE1
–
TG2
M3
S
M2
×2
SGND
16k
V
DIFFOUT
S
BOOST2
SW2
BG2
S
S
0.47µF
M4
×2
D2
L2
1µH
0.003Ω
+
EAIN
V
OS –
V
OS
+
INTV
CC
SENSE2
+
SENSE2
–
S
10µF
16k
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
U
V
IN
5V TO 28V
0.003Ω
V
OUT
1.6V/40A
U
U
+
C
OUT
1000µF
×2
4V
1629 TA01
1
LINER [ LINEAR TECHNOLOGY ]
