LTC3565_12 Datasheet, PDF (1/22 Pages) Linear Technology – 1.25A, 4MHz, Synchronous Step-Down DC/DC Converter

LTC3565
1.25A, 4MHz, Synchronous
Step-Down DC/DC Converter
FEATURES
n _{High Efficiency: Up to 95%}
n _{VIN Range: 2.5V to 5.5V}
n _{High Frequency Operation: Up to 4MHz}
n _{Selectable Low Ripple (Typical 25mVp-p)}
Burst Mode^® Operation: I_Q = 40μA
n _{Stable with Ceramic Capacitors}
n _{Uses Tiny Capacitors and Inductor}
n _{Low RDS(ON) Internal Switches: 0.15Ω}
n _{Current Mode Operation for Excellent Line}
and Load Transient Response
n _{Short-Circuit Protected}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Low Shutdown Current: IQ ≤ 1μA}
n _{Output Voltages from 0.6V to 5V}
n _{Synchronizable to External Clock}
n _{Supports Pre-Biased Outputs}
n _{Small 10-Lead (3mm × 3mm) DFN or MSOP Package}
APPLICATIONS
n _{Notebook Computers}
n _{Digital Cameras}
n _{Cellular Phones}
n _{Handheld Instruments}
n _{Board Mounted Power Supplies}
DESCRIPTION
The LTC^®3565 is a constant frequency, synchronous
step-down DC/DC converter. Intended for medium power
applications, it operates from a 2.5V to 5.5V input voltage
range and has a user-configurable operating frequency up
to 4MHz, allowing the use of tiny, low cost capacitors and
inductors 1mm or less in height. The output voltage is
adjustable from 0.6V to 5.5V. Internal synchronous power
switches provide high efficiency. The LTC3565’s current
mode architecture and external compensation allow the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3565 can be configured for automatic power
saving Burst Mode operation (I_Q = 40μA) to reduce gate
charge losses when the load current drops below the level
required for continuous operation. For reduced noise and
RF interference, the SYNC/MODE pin can be configured to
skip pulses or provide forced continuous operation.
To further maximize battery life, the P-channel MOSFET
is turned on continuously in dropout (100% duty cycle).
In shutdown, the device draws <1μA.
L, LT, LTC, LTM, Linear Technology the Linear logo, Burst Mode and OPTI-LOOP are registered
trademarks of Linear Technology Corporation. Hot Swap and ThinSOT are trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178, 6580258, 6498466, 6611131.
TYPICAL APPLICATION
12.1k
680pF
Step-Down 2.5V/1.25A Regulator
V_IN
2.5V TO 5.5V
SYNC/MODE ^{SVIN PVIN}
RUN
PGOOD
SW
LTC3565
ITH
RT
191k
V_FB
GND
22μF
2.2μH
22pF
931k
294k
V_OUT
2.5V
1.25A
22μF
3565 TA01a
Efficiency and Power Loss vs Output Current
100
1
90
80
0.1
70
60
50
0.01
40
30
20
10
0
0.1
V_IN = 2.7V
V_IN = 3.6V
V_IN = 4.2V
0.001
0.0001
1
10 100 1000 10000
OUTPUT CURRENT (mA)
3565 TA01b
3565fb
1