LTC3609 Datasheet, PDF (1/24 Pages) Linear Technology – 32V, 6A Monolithic Synchronous Step-Down DC/DC Converter

FEATURES
n _{6A Output Current}
n _{Wide VIN Range = 4V to 32V (36V Maximum)}
n _{Internal N-Channel MOSFETs}
n _{True Current Mode Control}
n _{Optimized for High Step-Down Ratios}
n _{tON(MIN) ≤ 100ns}
n _{Extremely Fast Transient Response}
n _{Stable with Ceramic COUT}
n _{±1% 0.6V Voltage Reference}
n _{Power Good Output Voltage Monitor}
n _{Adjustable On-Time/Switching Frequency}
n _{Adjustable Current Limit}
n _{Programmable Soft-Start}
n _{Output Overvoltage Protection}
n _{Optional Short-Circuit Shutdown Timer}
n _{Low Shutdown IQ: 15μA}
n _{Available in a 7mm × 8mm 52-Pin QFN Package}
APPLICATIONS
n _{Point of Load Regulation}
n _{Distributed Power Systems}
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5481178, 6100678, 6580258, 5847554, 6304066.
LTC3609
32V, 6A Monolithic
Synchronous Step-Down
DC/DC Converter
DESCRIPTION
The LTC^®3609 is a high efficiency, monolithic synchronous
step-down DC/DC converter that can deliver up to 6A output
current from a 4V to 32V (36V maximum) input supply. It
uses a valley current control architecture to deliver very
low duty cycle operation at high frequency with excellent
transient response. The operating frequency is selected
by an external resistor and is compensated for variations
in V_IN and V_OUT.
The LTC3609 can be configured for discontinuous or
forced continuous operation at light load. Forced continu-
ous operation reduces noise and RF interference while
discontinuous mode provides high efficiency by reducing
switching losses at light loads.
Fault protection is provided by internal foldback current
limiting, an output overvoltage comparator and an optional
short-circuit shutdown timer. Soft-start capability for sup-
ply sequencing is accomplished using an external timing
capacitor. The regulator current limit is user programmable.
A power good output voltage monitor indicates when
the output is in regulation. The LTC3609 is available in a
compact 7mm × 8mm QFN package.
TYPICAL APPLICATION
High Efficiency Step-Down Converter
0.1μF ^VOUT
100pF
1000pF
15.8k
V_ON
I_ON
RUN/SS V_IN
LTC3609
SW
I_TH
BOOST
187k
1.2μH
0.22μF
V_IN
4V TO 32V
10μF
x3
100μF
x2
V_OUT
2.5V
6A
SGND INTV_CC
FCB
V_RNG
PGOOD ^PGND
EXTV_CC V_FB
3609 TA01a
4.7μF
30.1k
9.53k
Efficiency and Power Loss vs
Load Current
100
90
EFFICIENCY
10000
80
1000
70
60
50
100
POWER LOSS
40
30
20
10 ^VOUT ^{= 2.5V}
EXTV_CC = 5V
0
0.01
0.1
1
LOAD CURRENT (A)
10
V_IN = 12V
V_IN = 25V
1
10
3609 TA01b
3609f
1