LTC3569_15 Datasheet, PDF (1/26 Pages) Linear Technology – Triple Buck Regulator with 1.2A and Two 600mA Outputs and Individual Programmable References

LTC3569
Triple Buck Regulator with
1.2A and Two 600mA Outputs and
Individual Programmable References
Features
n _{Three Independent Current Mode Buck DC/DC}
Regulators (1.2A and 2 × 600mA)
n _{Single Pin Programmable VFB Servo Voltages from}
800mV Down to 425mV (in 25mV Steps)
n _{Pull VFB High to Make Each 600mA Buck a Slave for}
Higher Current Operation
n _{Pulse-Skipping or Burst Mode}^® _Operation
n _{Programmable Switching Frequency}
(1MHz to 3MHz) or Fixed 2.25MHz
n _{Synchronizable (1.2MHz to 3MHz)}
n _{VIN Range 2.5V to 5.5V}
n _{All Regulators Internally Compensated}
n _{PGOOD Output Flag}
n _{Quiescent Current <100µA (All Regulators in Burst}
Mode Operation)
n _{Zero Shutdown Current}
n _{Overtemperature and Short-Circuit Protection}
n _{Tiny 3mm × 3mm, 3mm × 4mm 20-Lead QFN and}
Thermally Enhanced TSSOP FE-16 Packages
Applications
n _{Portable Applications with Multiple Supply Rails}
n _{General Purpose Step-Down DC/DC}
n _{Dynamic Voltage Scaling Applications}
Description
The LTC^®3569 contains three monolithic, synchronous
step-down DC/DC converters. Intended for medium power
applications, it operates over a 2.5V to 5.5V input voltage
range. The operating frequency is adjustable from 1MHz
to 3MHz, allowing the use of tiny, low cost capacitors and
inductors. The three output voltages are independently
programmable by toggling the EN pins up to 15 times,
lowering the 800mV FB references by 25mV per cycle. The
first buck regulator sources load currents up to 1200mA.
The other two buck regulators each provide 600mA.
The two 600mA buck regulators can also be configured
to operate as slave power stages, running in parallel with
another internal buck regulator to supply higher load
currents. When operating as parallel, slave output stages,
discrete external components are shared and available
output currents sum together.
L, LT, LTC, LTM, Linear Technology and the Linear logo 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, 6127815, 6304066,
6498466, 6580258, 6611131, 7170195.
Typical Application
V_IN
2.2µH*
22µF ^{SVIN PVIN SW1}
EN1
FB1
EN2
LTC3569
EN3
MODE
SW2
R_T
FB2
PGOOD
SW3
2.5µH**
2.5µH**
FB3
* WURTH 7440430022
** WURTH 744031002 ^{SGND PGND}
20pF 510k
OUT1 = 2.5V
1200mA
10µF
240k
20pF 300k
OUT2 = 1.8V
600mA
4.7µF
240k
20pF 150k
OUT3 = 1.2V
600mA
4.7µF
300k
3569 TA01a
Efficiency vs Load Current
100
V_IN = 3V
90
80
70
V_IN = 5V
60
50
40
30
20
10
0
0.01 0.1
Burst Mode OPERATION
PULSE-SKIPPING
OUT1 = 2.5V
1 10 100
I_LOAD (mA)
1000 10000
3569 TA01b
3569fe
For more information www.linear.com/LTC3569
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