nous, step-down DC/DC converter utilizing a constant
frequency, current mode architecture. It operates from
an input voltage range of 2.25V to 5.5V and provides a
regulated output voltage from 0.8V to 5V while deliver-
ing up to 3A of output current. The internal synchronous
power switch with 77mΩ on-resistance increases efficiency
and eliminates the need for an external Schottky diode.
Switching frequency is set by an external resistor or can
be synchronized to an external clock. 100% duty cycle
provides low dropout operation extending battery life in
portable systems. OPTI-LOOP
®
compensation allows the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3412A can be configured for either Burst Mode
operation or forced continuous operation. Forced continu-
ous 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 application
requirements.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP 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, 6304066, 6127815, 6498466,
6611131, 6724174.
APPLICATIO S
■
■
■
■
Point-of-Load Regulation
Notebook Computers
Portable Instruments
Distributed Power Systems
TYPICAL APPLICATIO
22μF
V
IN
3.3V
PV
IN
SV
IN
2.2M
294k
RT
Efficiency and Power Loss
100
95
EFFICIENCY
10000
100000
PGOOD
LTC3412A
SW
0.47μH
EFFICIENCY (%)
90
V
OUT
2.5V AT 3A
C
OUT
100μF
×2
85
80
75
70
65
60
POWER LOSS
10
100
1000
RUN/SS
1000pF
12.1k
I
TH
PGND
SGND
SYNC/MODE
V
FB
820pF
69.8k
115k
3412A F01a
392k
55
50
0.01
0.1
1
LOAD CURRENT (A)
1
10
3412A F01b
Figure 1. 2.5V/3A Step-Down Regulator
U
POWER LOSS (mW)
U
U
3412afc
1
LTC3412A
ABSOLUTE
(Note 1)
AXI U RATI GS
Operating Ambient Temperature Range
(Note 2) ...............................................– 40°C to 85°C
Junction Temperature (Note 5) ............................. 125°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
Input Supply Voltage .................................... –0.3V to 6V
I
TH
, RUN/SS, V
FB
, PGOOD,
SYNC/MODE Voltages ....................................–0.3 to V
IN
SW Voltages ..................................–0.3V to (V
IN
+ 0.3V)
PI CO FIGURATIO
TOP VIEW
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
SYNC/MODE
V
FB
16 15 14 13
12 PGOOD
17
11 SV
IN
10 PV
IN
9
5
SW
6
PGND
7
PGND
8
SW
SW
FE PACKAGE
16-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 38°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 17) IS SGND MUST BE SOLDERED TO PCB
UF PACKAGE
16-LEAD (4mm × 4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W,
JC
= 1°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE CONNECTED TO PCB
ORDER I FOR ATIO
LEAD FREE FINISH
LTC3412AEFE#PBF
LTC3412AIFE#PBF
LTC3412AEUF#PBF
LTC3412AIUF#PBF
LEAD BASED FINISH
LTC3412AEFE
LTC3412AIFE
LTC3412AEUF
LTC3412AIUF
TAPE AND REEL
PART MARKING*
3412AEFE
3412AIFE
3412A
3412A
PART MARKING*
3412AEFE
3412AIFE
3412A
3412A
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
16-Lead (4mm
×
4mm) Plastic QFN
16-Lead (4mm
×
4mm) Plastic QFN
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
16-Lead (4mm
×
4mm) Plastic QFN
16-Lead (4mm
×
4mm) Plastic QFN
I
TH
R
T
LTC3412AEFE#TRPBF
LTC3412AIFE#TRPBF
LTC3412AEUF#TRPBF
LTC3412AIUF#TRPBF
TAPE AND REEL
LTC3412AEFE#TR
LTC3412AIFE#TR
LTC3412AEUF#TR
LTC3412AIUF#TR
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/
2
U
U
W W
U
W
W
U
U
U
TOP VIEW
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
3412afc
LTC3412A
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
SV
IN
V
FB
I
FB
ΔV
FB
V
LOADREG
ΔV
PGOOD
R
PGOOD
I
Q
PARAMETER
Signal Input Voltage Range
Regulated Feedback Voltage
Voltage Feedback Leakage Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
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
V
RUN
= 0V, V
IN
= 5.5V
0.5
(Note 4)
V
FB
= 0.78V, V
ITH
= 1V
V
FB
= 1V, V
ITH
= 0V
V
RUN
= 0V, V
MODE
= 0V
R
OSC
= 294kΩ
(Note 6)
(Note 6)
I
SW
= 1A (Note 7)
I
SW
= –1A (Note 7)
4.5
1.75
0.88
0.3
0.3
77
65
6
2
0.1
0.65
2.25
1
0.8
1
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
●
●
●
(Note 3)
●
CONDITIONS
MIN
2.25
0.784
0.800
0.1
0.04
0.02
–0.02
±7.5
120
250
64
0.02
1
TYP
MAX
5.5
0.816
0.2
0.2
0.2
–0.2
±9
200
330
80
1
1.1
4
4
110
90
UNITS
V
V
μA
%V
%
%
%
Ω
μA
μA
μA
MHz
MHz
MHz
mΩ
mΩ
A
V
μA
V
μA
ELECTRICAL CHARACTERISTICS
f
OSC
f
SYNC
R
PFET
R
NFET
I
LIMIT
V
UVLO
I
LSW
V
RUN
I
RUN
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 LTC3412AE 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 LTC3412AI is guaranteed to
meet performance specifications over the full –40°C to 85°C operating
temperature range.
Note 3:
The LTC3412A 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: LTC3412AFE: T
J
= T
A
+ P
D
(38°C/W)
LTC3412AUF: T
J
= T
A
+ P
D
(34°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 condition in
the UF package and by final test correlation in the FE package.
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