LTC3621-2_15 Datasheet, PDF (1/18 Pages) Linear Technology – 17V, 1A Synchronous Step-Down Regulator with 3.5A Quiescent Current

Features
n _{Wide VIN Range: 2.7V to 17V}
n _{Wide VOUT Range: 0.6V to VIN}
n _{95% Max Efficiency}
n _{Low IQ < 3.5µA, Zero-Current Shutdown}
n _{Constant Frequency (1MHz/2.25MHz)}
n _{Full Dropout Operation with Low IQ}
n _{1A Rated Output Current}
n _{±1% Output Voltage Accuracy}
n _{Current Mode Operation for Excellent Line and Load}
Transient Response
n _{Synchronizable to External Clock}
n _{Pulse-Skipping, Forced Continuous, Burst Mode}^®
Operation
n _{Internal Compensation and Soft-Start}
n _{Overtemperature Protection}
n _{Compact 6-Lead DFN (2mm × 3mm) Package or}
Thermally-Enhanced MS8E Package with Power
Good Output and Independent SGND Pin
Applications
n _{Portable-Handheld Scanners}
n _{Industrial and Embedded Computing}
n _{Automotive Applications}
n _{Emergency Radio}
LTC3621/LTC3621-2
17V, 1A Synchronous
Step-Down Regulator with
3.5µA Quiescent Current
Description
The LTC^®3621/LTC3621-2 is a high efficiency 17V, 1A
synchronous monolithic step-down regulator. The switch-
ing frequency is fixed to 1MHz or 2.25MHz with a ±40%
synchronizing range. The regulator features ultralow quies-
cent current and high efficiencies over a wide V_OUT range.
The step-down regulator operates from an input voltage
range of 2.7V to 17V and provides an adjustable output
range from 0.6V to V_IN while delivering up to 1A of output
current. A user-selectable mode input is provided to allow
the user to trade off ripple noise for light load efficiency;
Burst Mode operation provides the highest efficiency at
light loads, while pulse-skipping mode provides the lowest
voltage ripple. The MODE pin can also be used to allow the
user to sync the switching frequency to an external clock.
LTC3621 Options
PART NAME
LTC3621
LTC3621-3.3
LTC3621-5
LTC3621-2
LTC3621-23.3
LTC3621-25
FREQUENCY
1.00MHz
1.00MHz
1.00MHz
2.25MHz
2.25MHz
2.25MHz
V_OUT
Adjustable
3.3V
5V
Adjustable
3.3V
5V
L, LT, LTC, LTM, Burst Mode, Linear Technology, the Linear logo and LTSpice are registered
trademarks and Hot Swap and LTpowerCAD 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, 6177787, 5705919, 5847554.
Typical Application
2.5V V_OUT with 400mA Burst Clamp, f_SW = 1MHz
V_IN
2.7V TO 17V
10µF
V_IN
SW
LTC3621
RUN
FB
MODE/SYNC
INTV_CC
GND
4.7µH
604k
191k
1µF
22pF
V_OUT
2.5V
1A
22µF
3621 TA01a
Efficiency and Power Loss vs Load at 1MHz
100
0.6
V_IN = 12V
90
80
EFFICIENCY
0.5
70
0.4
60
50
0.3
POWER LOSS
40
30
0.2
20
10
0
0
V_OUT = 5V _0.1
V_OUT = 3.3V
V_OUT = 2.5V
0
0.2 0.4 0.6 0.8
1
LOAD CURRENT (A)
3621 TA01b
For more information www.linear.com/LTC3621
3621fc
1