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LTC3446EDE#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
LTC3446
1
3446ff
Typical applicaTion
FeaTures
applicaTions
DescripTion
Monolithic Buck Regulator
with Dual VLDO Regulators
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.
Buck Efficiency vs Buck Load Current
n
High Efficiency Triple Step-Down Outputs from a
Single Input Supply
n
1A Synchronous Buck Regulator Provides Main
Step-Down Output and Powers Two 300mA VLDO™
Linear Regulators
n
Output Voltages as Low as 400mV (VLDO Outputs)
n
Power Good Output
n
Input Voltage Range: 2.7V to 5.5V
n
Independent Enable Pin for Each Supply
n
Low (140µA Typ) No-Load Quiescent Current with
All Outputs Enabled
n
Constant Frequency Current Mode Operation
n
2.25MHz Switching Frequency Uses Small Inductors
n
Defeatable Automatic Burst Mode
®
Operation for
High Efficiency at Light Loads
n
±1.5% Reference Accuracy
n
Overtemperature Protection
n
Thermally Enhanced 4mm × 3mm 14-Pin DFN
Package
n
Low Power Handheld Devices
n
Low Voltage and Multivoltage Power for Digital
Logic, I/O, FPGAs, CPLDs, ASICs and CPUs
V
IN
59k
L1
1.8µH
47.5k
SW
BUCKFB
LV
IN
LTC3446
GND
22µF
X7R
1000pF
DIGITAL
CONTROL
22µF
X7R
V
OUT
1.8V
400mA MAX
110k
40.2k
2.2µF
X7R
V
OUT
1.5V
300mA MAX
V
IN
2.9V TO 5.5V
LV
OUT1
PGOOD
MODESEL
ENBUCK
ENLDO1
ENLDO2
LV
FB1
80.6k
40.2k
2.2µF
X7R
L1: TOKO A960AW-1R8M
3446 TA01
V
OUT
1.2V
300mA MAX
LV
OUT2
3.3k
I
TH
LV
FB2
LOAD CURRENT (mA)
1
40
EFFICIENCY (%)
50
60
70
80
100
10 100
3446 TA01b
1000
90
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
Burst Mode
OPERATION
PWM
MODE
LTC3446
2
3446ff
pin conFiguraTionabsoluTe MaxiMuM raTings
V
IN
, LV
IN
to GND ......................................... –0.3V to 6V
MODESEL, ENBUCK, ENLDO1,
ENLDO2 to GND .......................................... –0.3V to 6V
BUCKFB to GND .......................................... –0.3V to 6V
LV
FB1
, LV
FB2
to GND .................................... –0.3V to 6V
I
TH
to GND ..... –0.3V to the Lesser of (V
IN
+ 0.3V) or 3V
SW to GND ......–0.3V to the Lesser of (V
IN
+ 0.3V) or 6V
LV
OUT1
, LV
OUT2
to GND .......... –0.3V to the Lesser of (LV
IN
+ 0.3V) or 6V
PGOOD to GND ............................................ –0.3V to 6V
LV
OUT1
, LV
OUT2
Short-Circuit
to GND Duration ............................................... Indefinite
Operating Junction Temperature Range
(Note 2) .................................................. –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
(Note 1)
1
2
3
4
5
6
7
14
13
12
11
10
9
8
SW
ENBUCK
BUCKFB
ENLDO1
LV
FB1
LV
FB2
ENLDO2
MODESEL
V
IN
I
TH
PGOOD
LV
OUT1
LV
IN
LV
OUT2
TOP VIEW
DE PACKAGE
14-LEAD (4mm × 3mm) PLASTIC DFN
15
T
JMAX
= 125°C, θ
JA
= 43°C/W
EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3446EDE#PBF LTC3446EDE#TRPBF 3446 14-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LTC3446IDE#PBF LTC3446IDE#TRPBF 3446 14-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Voltage Range (Note 3)
●
2.7 5.5 V
V
UVLO
V
IN
Undervoltage Lockout Threshold
V
IN
Undervoltage Lockout Hysteresis
V
IN
Rising
●
2.37
10
2.5
30
V
mV
I
Q
V
IN
Quiescent Current (Note 4)
Buck Enabled Only, Not Sleeping
Buck Enabled Only, Sleeping
One LDO Enabled Only
All Three Outputs Enabled, Buck Not Sleeping
All Three Outputs Enabled, Buck Sleeping
Shutdown
V
BUCKFB
= 0V, I
SW
= 0mA
V
BUCKFB
= 1V, I
SW
= 0mA
V
LVIN
= 1.5V, 10µA LDO Output Load
V
BUCKFB
= 0V, I
SW
= 0mA, V
LVIN
= 1.5V,
10µA Output Load on Each LDO
V
BUCKFB
= 1V, I
SW
= 0mA, V
LVIN
= 1.5V,
10µA Load on Each LDO
V
ENBUCK
= 0V, V
ENLDO1
= 0V, V
ENLDO2
= 0V
310
50
75
400
140
500
75
100
600
210
1
µA
µA
µA
µA
µA
µA
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V unless otherwise specified. (Note 2)
LTC3446
3
3446ff
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V unless otherwise specified. (Note 2)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
PG(THRESH)
PGOOD Threshold (Note 8)
●
8 10 %
R
PGOOD
PGOOD Output Resistance PGOOD Low, Sinking 1mA
●
87 180 Ω
I
PGOOD
PGOOD Hi-Z Leakage Current V
PGOOD
= 6V
●
1 µA
Synchronous Buck Converter
I
BUCKFB
Feedback Current (Note 5)
●
±30 nA
V
BUCKFB
Regulated Feedback Voltage (Note 5)
●
0.788 0.800 0.812 V
∆V
BUCKFB
Feedback Voltage Line Regulation V
IN
= 2.7V to 5.5V (Note 5)
●
0.3 0.5 mV/V
I
MAXP
Maximum Peak Inductor Current V
BUCKFB
= 0V, Duty Cycle < 35% 1.2 1.55 2.0 A
I
MAXN
NMOS Overcurrent Limit 1.8 A
Feedback Voltage Load Regulation
(with Respect to V
ITH
)
V
ITH
= 0.5V to 1V, V
MODESEL
= V
IN
(Note 5) 0.5 mV/V
f
OSC
Oscillator Frequency
●
1.8 2.25 2.7 MHz
R
PFET
R
DS(ON)
of P-Channel FET I
SW
= 500mA 0.13 Ω
R
NFET
R
DS(ON)
of N-Channel FET I
SW
= –500mA 0.14 Ω
I
LSW
SW Leakage V
ENBUCK
= 0V, V
SW
= 0V or 5.5V, V
IN
= 5.5V ±1 µA
V
ENBUCK
Buck Enable Pin Threshold
●
0.3 0.65 1 V
I
ENBUCK
Buck Enable Pin Leakage Current V
ENBUCK
= 5.5V, All Other Pins Grounded
●
1 µA
V
MODESEL
Mode Select Pin Threshold
●
0.3 0.65 1 V
I
MODESEL
Mode Select Pin Leakage Current V
MODESEL
= 5.5V, All Other Pins Grounded
●
1 µA
g
m
Error Amplifier Transconductance V
ITH
= 0.6V 450 700 950 µA/V
Each VLDO: V
IN
= 3.6V, V
LVIN
= 1.5V, V
LVOUT
= 1.2V, Unless Otherwise Specified
V
LVIN
LV
IN
Pin Operating Voltage (Note 6)
●
0.9 5.5 V
I
LVIN
LV
IN
Pin Operating Current I
OUT
= 10µA
●
3 20 µA
LV
IN
Shutdown Current V
ENLDO
= 0V 1.5 2 µA
V
LVFB
Feedback Pin Regulation Voltage (Note 7) 1mA ≤ I
OUT
≤ 300mA, 1.5V ≤ V
LVIN
≤ 5.5V
●
0.395
0.392
0.400
0.400
0.405
0.408
V
V
I
LVFB
Feedback Pin Input Current V
LVFB
at Regulation
●
2 ±10 nA
I
LVOUT(MAX)
Continuous Output Current
●
300 mA
Short-Circuit Output Current 760 mA
V
ENLDOx
LDO Enable Pin Threshold
●
0.3 0.65 1 V
I
ENLDOx
LDO Enable Pin Leakage Current V
ENLDOx
= 5.5V, All Other Pins Grounded
●
1 µA
Output Voltage Load Regulation
(Referred to the LV
FB
Pin)
∆I
OUT
= 1mA to 300mA –1 mV/A
L
VFB
Line Regulation (with Respect to
the L
VIN
Pin)
V
LVIN
= 1.5V to 5.5V, V
IN
= 3.6V, V
LVOUT
= 1.2V,
I
OUT
= 1mA
7.5 µV/V
L
VFB
Line Regulation (with Respect to
the V
IN
Pin)
V
LVIN
= 1.5V, V
IN
= 2.7V to 5.5V, V
LVOUT
= 1.2V,
I
OUT
= 1mA
0.44 mV/V
V
DO
LV
IN
– LV
OUT
Dropout Voltage V
IN
= 2.8V, V
LVIN
= 1.5V, V
LVFB
= 0.37V,
I
OUT
= 300mA (Note 9)
68 175 mV
V
IN
to LV
OUT
Headroom Required for
Regulation (Note 3)
I
LVOUT
= 300mA
l
1.4 V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LTC3446EDE#PBF

Mfr. #:
Buy LTC3446EDE#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Monolithic Buck Regulator with Dual VLDO Regulators
Lifecycle:
New from this manufacturer.
Delivery:
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