LTC1929 Datasheet, PDF (1/24 Pages) Linear Technology – 2-Phase, High Efficiency, Synchronous Step-Down Switching Regulator

FEATURES
s _{2-Phase Single Output Controller}
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 _{True Remote Sensing Differential Amplifier}
s _OPTI-LOOP^TM _{Compensation Improves Transient}
Response
s _{±1% Output Voltage Accuracy}
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}
s _{Short-Circuit Shutdown Timer with Defeat Option}
s _{Overvoltage Soft-Latch Eliminates Nuisance Trips}
s _{Available in 28-Lead SSOP Package}
U
APPLICATIO S
s _{Desktop Computers}
s _{Internet/Network Servers}
s _{Large Memory Arrays}
s _{DC Power Distribution Systems}
Final Electrical Specifications
LTC1929
2-Phase, High Efficiency,
Synchronous Step-Down
Switching Regulator
DESCRIPTIO
August 1999
The LTC^®1929 is a 2-phase, single output, synchronous
step-down current mode switching regulator controller
that drives N-channel external power MOSFET stages in a
phase-lockable fixed frequency architecture. The 2-phase
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 2-phase
technique effectively multiplies the fundamental frequency
by two, 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 by high current applications.
The RUN/SS pin provides soft-start and a defeatable,
timed, latched short-circuit shutdown to shut down both
channels. Internal foldback current limit provides protec-
tion for the external sychronous MOSFETs in the event of
an output fault. OPTI-LOOP compensation allows the
transient response to be optimized over a wide range of
output capacitance and ESR values.
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
10Ω
0.1µF
0.1µF
V_IN
TG1
BOOST1
LTC1929 SW1
RUN/SS
BG1
1000pF
I_TH
10k
100pF
PGND
SENSE1⁺
SENSE1^–
TG2
SGND
BOOST2
8.06k
8.06k
V_DIFFOUT
EAIN
V_OS–
V_OS+
SW2
BG2
INTV_CC
SENSE2⁺
SENSE2^–
0.47µF
0.47µF
10µF
10µF ×4
35V
CERAMIC
L1
1µH
D1
0.002Ω
L2
D2 ^1µH
0.002Ω
C_OUT: T510E108K004AS
L1, L2: CEPH149-1ROMC
Figure 1. High Current 2-Phase Step-Down Converter
V_IN
5V TO 28V
V_OUT
1.6V/40A
+
C_OUT
1000µF ×2
4V
1929 TA01
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1