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 1mm or less in height. The output voltage is
adjustable from 0.8V to 5.5V. Internal synchronous power
switches provide high efficiency. The LTC3411A’s current
mode architecture and external compensation allow the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3411A can be configured for automatic power
saving Burst Mode operation (I
Q
= 40μA) to reduce gate
charge losses when the load current drops below the level
required for continuous operation. For reduced noise and
RF interference, 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).
In shutdown, the device draws <1μA.
L,
LT, LTC, LTM and Burst Mode are registered 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.
■
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■
■
■
■
Uses Tiny Capacitors and Inductor
High Frequency Operation: Up to 4MHz
Low R
DS(ON)
Internal Switches: 0.15Ω
High Efficiency: Up to 96%
Selectable Low Ripple (25mV
P-P
) Burst Mode
®
Operation: I
Q
= 40μA
Stable with Ceramic Capacitors
Current Mode Operation for Excellent Line
and Load Transient Response
Short-Circuit Protected
Low Dropout Operation: 100% Duty Cycle
Low Shutdown Current: I
Q
≤ 1μA
Output Voltages from 0.8V to 5V
Synchronizable to External Clock
Supports Pre-Biased Outputs
Small 10-Lead 3mm
×
3mm DFN or MSOP Package
APPLICATIONS
■
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■
Notebook Computers
Digital Cameras
Cellular Phones
Handheld Instruments
Board Mounted Power Supplies
TYPICAL APPLICATION
Step-Down 2.5V/1.25A Regulator
V
IN
2.5V TO 5.5V
10μF
SYNC
SYNC/MODE
PGOOD
LTC3411A
PV
IN
SV
IN
SW
22pF
2.2μH
V
OUT
2.5V
1.25A
Efficiency and Power Loss vs Output Current
100
90
80
EFFICIENCY (%)
70
60
50
40
30
0.01
0.1
POWER LOSS (W)
1
I
TH
12.1k
680pF
549k
SHDN/R
T
SGND
PGND
V
FB
887k
22μF
20
10
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
1
100
1000
10
OUTPUT CURRENT (mA)
0.001
412k
0
0.1
0.0001
10000
3411a TA01a
f
O
= 1MHz
Burst Mode OPERATION
3411A TA01b
3411afa
1
LTC3411A
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PV
IN
, SV
IN
Voltages ..................................... –0.3V to 6V
V
FB
, I
TH
, SHDN/R
T
Voltages ..........–0.3V to (V
IN
+ 0.3V)
SYNC/MODE Voltage .....................–0.3V to (V
IN
+ 0.3V)
SW Voltage ..................................–0.3V to (V
IN
+ 0.3V)
PGOOD Voltage ........................................... –0.3V to 6V
Operating Junction Temperature Range
(Notes 2, 5, 8) ........................................ –40°C to 125°C
Storage Temperature Range................... –65°C to 125°C
Lead Temperatu re (Soldering, 10 sec) ............... 300°C
PIN CONFIGURATION
TOP VIEW
SHDN/R
T
SYNC/MODE
SGND
SW
PGND
1
2
3
4
5
11
10 I
TH
9 V
FB
8 PGOOD
7 SV
IN
6 PV
IN
SHDN/R
T
SYNC/MODE
SGND
SW
PGND
1
2
3
4
5
TOP VIEW
10
9
8
7
6
I
TH
V
FB
PGOOD
SV
IN
PV
IN
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W,
θ
JC
= 3°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 120°C/W,
θ
JC
= 10°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3411AEDD#PBF
LTC3411AIDD#PBF
LTC3411AEMS#PBF
LTC3411AIMS#PBF
TAPE AND REEL
LTC3411AEDD#TRPBF
LTC3411AIDD#TRPBF
LTC3411AEMS#TRPBF
LTC3411AIMS#TRPBF
PART MARKING*
LAJM
LAJM
LTAJK
LTAJK
PACKAGE DESCRIPTION
10-Lead (3mm × 3mm) Plastic DFN
10-Lead (3mm × 3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are 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/
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 3.6V, R
T
= 125k unless otherwise specified. (Note 2)
SYMBOL
V
IN
I
FB
V
FB
ΔV
LINEREG
ΔV
LOADREG
g
m(EA)
PARAMETER
Operating Voltage Range
Feedback Pin Input Current
Feedback Voltage
Reference Voltage Line Regulation
Output Voltage Load Regulation
Error Amplifier Transconductance
(Note 3)
(Note 3)
V
IN
= 2.5V to 5.5V
I
TH
= 0.55V to 0.9V
I
TH
Pin Load = ±5μA (Note 3)
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
●
MIN
2.5
0.784
TYP
MAX
5.5
±0.1
UNITS
V
μA
V
%/V
%
μS
3411afa
0.8
0.04
0.02
300
0.816
0.2
0.2
2
LTC3411A
ELECTRICAL CHARACTERISTICS
SYMBOL
I
S
PARAMETER
Input DC Supply Current (Note 4)
Active Mode
Sleep Mode
Shutdown
Shutdown Threshold High Active
Oscillator Resistor
Oscillator Frequency
Synchronization Frequency
Peak Switch Current Limit
Top Switch On-Resistance
Bottom Switch On-Resistance
I
SW(LKG)
V
UVLO
PGOOD
Switch Leakage Current
Undervoltage Lockout Threshold
Power Good Threshold
Power Bad Threshold
R
PGOOD
PGOOD Blanking
V
SYNC-MODE
t
SOFT-START
Pulse Skip
Force Continous
Burst
10% to 90% of Regulation
Power Good Pull-Down On-Resistance
V
FB
Step from 0V to 0.8V
V
FB
Step from 0.8V to 0V
0.93
V
IN
– 0.75
0.5
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 3.6V, R
T
= 125k unless otherwise specified. (Note 2)
CONDITIONS
V
SYNC/MODE
= 3.6V, V
FB
= 0.75V
V
SYNC/MODE
= 3.6V, V
FB
= 0.84V
V
SHDN/RT
= 3.6V
MIN
TYP
330
40
0.1
V
IN
– 0.6
125k
2.5
MAX
450
60
1
V
IN
– 0.4
1M
2.8
4
4
2.6
0.18
0.16
1
2.4
UNITS
μA
μA
μA
V
Ω
MHz
MHz
MHz
A
Ω
Ω
Ω
Ω
μA
V
%
%
%
%
Ω
μs
μs
V
V
V
ms
V
SHDN/RT
f
OSC
f
SYNC
I
LIM
R
DS(ON)
R
T
= 125k
(Note 7)
(Note 7)
V
FB
= 0.5V
MS Package
DD Package (Note 6)
MS Package
DD Package (Note 6)
V
IN
= 5.5V, V
SHDN/RT
= 5.5V, V
SW
= 0V
or 5.5V
V
IN
Ramping Down
V
FB
Ramping Up from 0.68V to 0.8V
V
FB
Ramping Down from 0.92V to 0.8V
V
FB
Ramping Down from 0.8V to 0.68V
V
FB
Ramping Up from 0.8V to 0.9V
2.25
0.4
1.6
2.1
0.15
0.15
0.13
0.13
0.01
1.8
–5
5
2.1
–7
7
–10
10
15
40
105
–12
12
30
0.63
V
IN
– 1.05
0.8
1.0
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC3411AE is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3411AI is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3:
The LTC3411A is tested in a feedback loop which servos V
FB
to
the midpoint for the error amplifier (V
ITH
= 0.7V).
Note 4:
Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 5:
T
J
is calculated from the ambient T
A
and power dissipation P
D
according to the following formulas:
LTC3411AEDD: T
J
= T
A
+ (P
D
• 43°C/W)
LTC3411AEMS: T
J
= T
A
+ (P
D
• 120°C/W)
Note 6:
For the DD package, switch on-resistance is sampled at wafer
level measurements and assured by design, characterization and
correlation with statistical process controls.
Note 7:
4MHz operation is guaranteed by design but not production
tested and is subject to duty cycle limitations (see Applications
Information).
Note 8:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is
active. Continuous operation above the specified maximum operating
junction temperature may impair device reliability.
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