allows the transient response to be optimized over a wide
range of loads and output capacitors.
The LTC3412 can be configured for either Burst Mode
®
operation or forced continuous operation. Forced con-
tinuous operation reduces noise and RF interference
while Burst Mode operation provides high efficiency by
reducing gate charge losses at light loads. In Burst Mode
operation, external control of the burst clamp level allows
the output voltage ripple to be adjusted according to the
requirements of the application. To further maximize bat-
tery life, the P-channel MOSFET is turned on continuously
in dropout (100% duty cycle).
L,
LT, LTC, LTM, Burst Mode, OPTI-LOOP Linear Technology and the Linear logo are registered
,
trademarks and ThinSOT is a trademark of Analog Devices, Inc. All other trademarks are the
property of their respective owners.
■
■
■
■
■
High Efficiency: Up to 95%
2.5A Output Current
Low Quiescent Current: 62µA
Low R
DS(ON)
Internal Switches: 85mΩ
Programmable Frequency: 300kHz to 4MHz
No Schottky Diode Required
± 2% Output Voltage Accuracy
0.8V Reference Allows Low Output Voltage
Selectable Forced Continuous/Burst Mode Operation
with Adjustable Burst Clamp
Synchronizable Switching Frequency
Low Dropout Operation: 100% Duty Cycle
Power Good Output Voltage Monitor
Overtemperature Protection
Available in 16-Lead Thermally Enhanced TSSOP
and QFN Packages
APPLICATIONS
■
■
■
■
■
■
Portable Instruments
Battery-Powered Equipment
Notebook Computers
Distributed Power Systems
Cellular Telephones
Digital Cameras
TYPICAL APPLICATION
V
IN
2.7V TO 5.5V
SV
IN
R
T
4.7M
309k
LTC3412
RUN/SS
470pF
15k
1000pF
PGND
SGND
I
TH
SYNC/MODE V
FB
100pF
110k
75k
392k
3412 F01
Efficiency vs Load Current
PV
IN
PGOOD
SW
100µF
1µH
22µF
V
OUT
2.5V
2.5A
100
80
EFFICIENCY (%)
Burst Mode OPERATION
60
FORCED CONTINUOUS
40
20
V
IN
= 3.3V
V
OUT
= 2.5V
0.01
0.1
1
LOAD CURRENT (A)
10
3412 G01
0
0.001
Figure 1. 2.5V, 2.5A Step-Down Regulator
3412fc
For more information
www.linear.com/LTC3412
1
LTC3412
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage .................................... – 0.3V to 6V
I
TH
, RUN, V
FB
Voltages ............................... –0.3V to V
IN
SYNC/MODE Voltages................................. –0.3V to V
IN
SW Voltage ................................... –0.3V to (V
IN
+ 0.3V)
Peak SW Sink and Source Current ..........................6.5A
Operating Temperature Range (Note 2)....–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Junction Temperature (Note 5) ............................. 125°C
Lead Temperature (Soldering, 10 sec) TSSOP ...... 300°C
PIN CONFIGURATION
SV
IN
PGOOD
I
TH
V
FB
R
T
SYNC/MODE
RUN/SS
SGND
1
2
3
4
5
6
7
8
17
16 PV
IN
15 SW
14 SW
13 PGND
12 PGND
11 SW
10 SW
9
PV
IN
RUN/SS 1
SGND 2
PV
IN
3
SW 4
5
SW
6
PGND
7
PGND
8
SW
17
SYNC/MODE
TOP VIEW
TOP VIEW
V
FB
16 15 14 13
12 PGOOD
11 SV
IN
10 PV
IN
9
SW
FE PACKAGE
16-LEAD PLASTIC TSSOP
EXPOSED PAD (PIN 17) IS SGND, MUST BE SOLDERED TO PCB
T
JMAX
= 125°C,
θ
JA
= 37.6°C/W,
θ
JC
= 10°C/W
UF PACKAGE
16-LEAD (4mm
×
4mm) PLASTIC QFN
EXPOSED PAD (PIN 17) IS SGND, MUST BE SOLDERED TO PCB
T
JMAX
= 125°C,
θ
JA
= 34°C/W,
θ
JC
= 1°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3412EFE#PBF
LTC3412IFE#PBF
LTC3412EUF#PBF
LEAD BASED FINISH
LTC3412EFE
LTC3412IFE
LTC3412EUF
TAPE AND REEL
LTC3412EFE#TRPBF
LTC3412IFE#TRPBF
LTC3412EUF#TRPBF
TAPE AND REEL
LTC3412EFE#TR
LTC3412IFE#TR
LTC3412EUF#TR
http://www.linear.com/product/LTC3412#orderinfo
PART MARKING*
3412EFE
3412IFE
3412
PART MARKING*
3412EFE
3412IFE
3412
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
16-Lead (4mm
×
4mm) Plastic QFN
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
16-Lead (4mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–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. *The temperature grade is identified by a label on the shipping container.
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
I
TH
R
T
2
3412fc
For more information
www.linear.com/LTC3412
LTC3412
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V unless otherwise specified.
SYMBOL PARAMETER
SV
IN
V
FB
I
FB
∆V
FB
Signal Input Voltage Range
Regulated Feedback Voltage
Voltage Feedback Leakage Current
Reference Voltage Line Regulation
V
IN
= 2.7V to 5.5V (Note 3)
Measured in Servo Loop, V
ITH
= 0.36V
Measured in Servo Loop, V
ITH
= 0.84V
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
(Note 3)
l
MIN
2.625
0.784
TYP
0.800
0.1
0.04
0.02
– 0.02
±7.5
120
MAX
5.5
0.816
0.4
0.2
0.2
–0.2
±9
200
330
80
1
1.1
4
4
110
90
2.625
1
0.8
1
UNITS
V
V
µA
%V
%
%
%
Ω
µA
µA
µA
MHz
MHz
MHz
mΩ
mΩ
A
V
µA
V
µA
V
LOADREG
Output Voltage Load Regulation
∆V
PGOOD
R
PGOOD
I
Q
Power Good Range
Power Good Pull-Down Resistance
Input DC Bias Current
Active Current
Sleep
Shutdown
Switching Frequency
Switching Frequency Range
SYNC Capture Range
R
DS(ON)
of P-Channel FET
R
DS(ON)
of N-Channel FET
Peak Current Limit
Undervoltage Lockout Threshold
SW Leakage Current
RUN Threshold
RUN/SS Leakage Current
(Note 4)
V
FB
= 0.78V, V
ITH
= 1V
V
FB
= 1V, V
ITH
= 0V
V
RUN
= 0V, V
MODE
= 0V
R
OSC
= 309kΩ
(Note 6)
(Note 6)
I
SW
= 1A (Note 7)
I
SW
= –1A (Note 7)
4
2.375
V
RUN
= 0V, V
IN
= 5.5V
0.5
0.88
0.3
0.3
250
62
0.02
0.95
f
OSC
f
SYNC
R
PFET
R
NFET
I
LIMIT
V
UVLO
I
LSW
V
RUN
I
RUN
85
65
5.4
2.500
0.1
0.65
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 LTC3412E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3412I is guaranteed to meet
specified performance over the –40°C to 85°C temperature range.
Note 3:
The LTC3412 is tested in a feedback loop that adjusts V
FB
to
achieve a specified error amplifier output voltage (I
TH
).
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 temperature T
A
and power
dissipation as follows: LTC3412: T
J
= T
A
+ P
D
(37.6°C/W).
Note 6:
4MHz operation is guaranteed by design and not production tested.
Note 7:
Switch on resistance is guaranteed by design and test correlation
in the UF package and by production test in the FE package.
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