LTC3568_15 Datasheet, PDF (1/18 Pages) Linear Technology – 1.8A, 4MHz, Synchronous Step-Down DC/DC Converter

Features
n _{Uses Tiny Capacitors and Inductor}
n _{High Frequency Operation: Up to 4MHz}
n _{Low RDS(ON) Internal Switches: 0.110Ω}
n _{High Efficiency: Up to 96%}
n _{Stable with Ceramic Capacitors}
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 _{Low Quiescent Current: 60µA}
n _{Output Voltages from 0.8V to 5V}
n _{Selectable Burst Mode}^® _Operation
n _{Sychronizable to External Clock}
n _{Small 3mm × 3mm, 10-Lead DFN Package}
Applications
n _{Notebook Computers}
n _{Digital Cameras}
n _{Cellular Phones}
n _{Handheld Instruments}
n _{Board Mounted Power Supplies}
LTC3568
1.8A, 4MHz, Synchronous
Step-Down DC/DC Converter
Description
The LTC^®3568 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 2mm or less in height. The output voltage
is adjustable from 0.8V to 5V. Internal sychronous 0.11Ω
power switches with 2.4A peak current ratings provide
high efficiency. The LTC3568’s current mode architecture
and external compensation allow the transient response
to be optimized over a wide range of loads and output
capacitors.
The LTC3568 can be configured for automatic power sav-
ing Burst Mode operation to reduce gate charge losses
when the load current drops below the level required for
continuous operation. For reduced noise and RF interfer-
ence, 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)
with a low quiescent current of 60µA. In shutdown, the
device draws <1µA.
L, LT, LTC, LTM, Linear Technology, the Linear logo, OPTI-LOOP and Burst Mode are
registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents including
5481178, 6580258, 6304066, 6127815, 6611131.
Typical Application
V_IN
2.5V TO 5.5V
13k
1000pF
V_IN SYNC/MODE
PV_IN
PGOOD
SV_IN
LTC3568 ^SW
I_TH
SHDN/R_T
V_FB
SGND PGND
324k
22µF
L1
2µH
887k
V_OUT
2.5V/1.8A
22µF + 10µF
412k
NOTE: IN DROPOUT, THE OUTPUT TRACKS
THE INPUT VOLTAGE
3568 F01
Figure 1. Step-Down 1.8A Regulator
Efficiency vs Load Current
100
1000
95
EFFICIENCY
90
100
85
POWER LOSS
80
10
V_IN = 3.3V
V_OUT = 2.5V
75
f_O = 1MHz
Burst Mode
70
OPERATION ₁
1
10
100
1000 10000
LOAD CURRENT (mA)
3568 TA01
3568fa