LTC3446EDE,LTC3446IDE

Part No.:
LTC3446EDE,LTC3446IDE
Download:
Download
Description:
Monolithic Buck Regulator with Dual VLDO Regulators
File Size:
248 K
Page:
20 Pages
Logo:
Maker:
LINER [ LINEAR TECHNOLOGY ]
PCB Prototype

July 16, 2018:

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PCB Datasheet:1PCB Datasheet:1PCB Datasheet:1PCB Datasheet:1
LTC3446
Monolithic Buck Regulator
with Dual VLDO Regulators
FeaTures
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DescripTion
The LTC
®
3446 combines a synchronous buck DC/DC con-
verter with two very low dropout (VLDO) linear regulators
to provide up to three stepped-down output voltages from
a single input voltage. The input voltage range is ideally
suited for Li-Ion battery-powered applications, as well
as powering low voltage logic from 5V or 3.3V rails. The
output voltage range extends down to 0.4V for the VLDO
regulators and 0.8V for the buck.
The 1A synchronous buck converter provides the main
output with high efficiency, typically 85%. The two 300mA
VLDO regulators can run off the main output to provide
two additional lower voltage outputs. A built-in supply
monitor provides a power good indication.
The buck converter switches at 2.25MHz, allowing the use
of small surface mount inductors and capacitors. Constant
frequency current mode operation produces controlled
output spectrum and fast transient response. A mode-
select pin allows automatic Burst Mode operation to be
enabled for higher efficiency at light load, or disabled for
lower noise operation down to very light loads. The two
VLDO regulators are stable with ceramic output capacitors
as small as 1µF
.
L,
LT, LTC, LTM and Burst Mode are registered trademarks and VLDO, Hot Swap, PowerPath
and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 5481178, 6611131,
6304066, 6498466, 6580258.
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High Efficiency Triple Step-Down Outputs from a
Single Input Supply
1A Synchronous Buck Regulator Provides Main
Step-Down Output and Powers Two 300mA VLDO™
Linear Regulators
Output Voltages as Low as 400mV (VLDO Outputs)
Power Good Output
Input Voltage Range: 2.7V to 5.5V
Independent Enable Pin for Each Supply
Low (140µA Typ) No-Load Quiescent Current with
All Outputs Enabled
Constant Frequency Current Mode Operation
2.25MHz Switching Frequency Uses Small Inductors
Defeatable Automatic Burst Mode
®
Operation for
High Efficiency at Light Loads
±1.5% Reference Accuracy
Overtemperature Protection
Thermally Enhanced 4mm
×
3mm 14-Pin DFN
Package
applicaTions
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Low Power Handheld Devices
Low Voltage and Multivoltage Power for Digital
Logic, I/O, FPGAs, CPLDs, ASICs and CPUs
Typical applicaTion
V
IN
2.9V TO 5.5V
L1
1.8µH
22µF
X7R
V
IN
SW
59k
BUCKFB
LTC3446
LV
IN
PGOOD LV
OUT1
MODESEL
ENBUCK
ENLDO1 LV
FB1
ENLDO2
3.3k
1000pF
47.5k
EFFICIENCY (%)
V
OUT
1.5V
300mA MAX
90
80
70
60
50
40
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
1
10
100
LOAD CURRENT (mA)
1000
3446 TA01b
22µF
X7R
V
OUT
1.8V
400mA MAX
Buck Efficiency vs Buck Load Current
100
Burst Mode
OPERATION
PWM
MODE
DIGITAL
CONTROL
110k
40.2k
2.2µF
X7R
I
TH
LV
OUT2
80.6k
LV
FB2
GND
3446 TA01
2.2µF
X7R
V
OUT
1.2V
300mA MAX
40.2k
L1: TOKO A960AW-1R8M
3446ff
1