LTC3413
3A, 2MHz Monolithic
Synchronous Regulator for
DDR/QDR Memory Termination
FEATURES
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DESCRIPTION
The LTC
®
3413 is a high efficiency monolithic synchro-
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 equal to (0.5)V
REF
while sourcing
or sinking up to 3A of output current. An internal voltage
divider reduces component count and eliminates the need
for external resistors by dividing the reference voltage in
half. The internal synchronous power switch with 85mΩ
on-resistance increases efficiency and eliminates the need
for an external Schottky diode. Switching frequencies up
to 2MHz are set by an external resistor.
Forced-continuous operation in the LTC3413 reduces
noise and RF interference. Fault protection is provided
by an overcurrent comparator that limits output current
during both sourcing and sinking operations. Adjustable
compensation allows the transient response to be optimized
over a wide range of loads and output capacitors.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178.
High Efficiency: Up to 90%
±3A Output Current
Symmetrical Source and Sink Output Current Limit
Low R
DS(ON)
Internal Switch: 85mΩ
No Schottky Diode Required
2.25V to 5.5V Input Voltage Range
V
OUT
= V
REF
/2
±1% Output Voltage Accuracy
Programmable Switching Frequency: Up to 2MHz
Power Good Output Voltage Monitor
Overtemperature Protected
Available in 16-Lead TSSOP Exposed Pad Package
APPLICATIONS
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Bus Termination: DDR and QDR™ Memory,
SSTL, HSTL, ...
Notebook Computers
Distributed Power Systems
TYPICAL APPLICATION
V
IN
2.5V
100
22μF
SV
IN
V
REF
4.7M
330pF
LTC3413
RUN/SS
5.11k
I
TH
2200pF
R
T
309k
V
FB
3413 F01a
90
80
V
OUT
1.25V
±3A
EFFICIENCY (%)
V
IN
= 2.5V
f = 1MHz
PV
IN
PGOOD
SW
PGND
SGND
L1
0.47μH
C
OUT
100μF
2
70
60
50
40
30
20
10
0
0.01
0.1
1
LOAD CURRENT (A)
10
3413 F01b
L1: VISHAY DALE IHLP-2525CZ-01 0.47
C
OUT
: TDK C4532X5R0J107M
Figure 1a. High Efficiency Bus Termination Supply
Figure 1b. Efficiency vs Load Current
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LTC3413
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
SV
IN
PGOOD
I
TH
V
FB
R
T
V
REF
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
SV
IN
, PV
IN
Supply Voltages ......................... –0.3V to 6V
I
TH
, RUN/SS, V
FB
, PGOOD Voltages ............ –0.3V to V
IN
V
REF
Voltage................................................ –0.3V to V
IN
SW Voltage ................................... –0.3V to (V
IN
+ 0.3V)
Operating Ambient Temperature Range
(Note 2) ................................................... –40°C to 85°C
Junction Temperature (Notes 5, 8)....................... 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................ 300°C
FE PACKAGE
16-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 38°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 17) MUST BE SOLDERED TO PGND
ORDER INFORMATION
LEAD FREE FINISH
LTC3413EFE#PBF
LTC3413IFE#PBF
LEAD BASED FINISH
LTC3413EFE
LTC3413IFE
TAPE AND REEL
LTC3413EFE#TRPBF
LTC3413IFE#TRPBF
TAPE AND REEL
LTC3413EFE#TR
LTC3413IFE#TR
PART MARKING
3413EFE
3413IFE
PART MARKING
3413EFE
3413IFE
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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
l
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 noted.
SYMBOL
V
IN
V
FB
I
FB
I
RUN
ΔV
FB
V
LOADREG
ΔV
PGOOD
R
PGOOD
I
Q
PARAMETER
Input Voltage Range
Feedback Voltage Accuracy
Voltage Feedback Leakage Current
RUN/SS Leakage Current
Feedback Voltage Line Regulation
Feedback Voltage Load Regulation
Power Good Range
Power Good Pull-Down Resistance
Input DC Bias Current
Active Current
Shutdown
(Note 4)
V
FB
= 1.5V, V
ITH
= 1.4V, V
REF
= 2.5V
V
RUN
= 0V (Note 7)
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
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ELECTRICAL CHARACTERISTICS
CONDITIONS
(Note 3)
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MIN
2.25
TYP
MAX
5.5
±1
0.4
1
UNITS
V
%
μA
μA
%/V
%
%
%
Ω
μA
μA
0.04
0.02
–0.02
±10
120
250
0.02
0.2
0.2
–0.2
±12
200
330
1
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LTC3413
ELECTRICAL CHARACTERISTICS
SYMBOL
f
OSC
R
PFET
R
NFET
I
LIMIT
V
UVLO
I
LSW
V
RUN
PARAMETER
Switching Frequency
Switching Frequency 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
V
RUN
= 0V, V
IN
= 5.5V (Note 7)
0.5
The
l
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 noted.
CONDITIONS
R
OSC
= 309k
(Note 6)
I
SW
= 300mA
I
SW
= 300mA
3.8
1.75
MIN
0.88
0.30
TYP
1.00
85
65
5.4
2
0.1
0.65
2.25
1
0.8
MAX
1.12
2.00
110
90
UNITS
MHz
MHz
mΩ
mΩ
A
V
μA
V
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 LTC3413E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. LTC3413I is guaranteed to meet specified
performance from –40°C to 85°C.
Note 3:
The LTC3413 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 TA and power
dissipation P
D
as follows: LTC3413E: T
J
= T
A
+ (P
D
• 38°C/W)
Note 6:
2MHz operation is guaranteed by design and not production tested.
Note 7:
Shutdown current and SW leakage current are only tested during
wafer sort.
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.
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current
100
V
OUT
= 1.25V
90 T
A
= 25°C
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
LOAD CURRENT (A)
10
3413 G01
Efficiency vs Input Voltage
100
V
OUT
= 1.25V
90 T
A
= 25°C
80
0
LOAD = 1A
–0.05
LOAD = 3A
ΔV
OUT
/V
OUT
(%)
–0.10
–0.15
–0.20
–0.25
–0.30
5.0
5.5
3413 G02
Load Regulation
T
A
= 25°C
V
IN
= 2.5V
V
IN
= 3.3V
EFFICIENCY (%)
70
LOAD = 100mA
60
50
40
30
20
2.5
3.0
4.5
4.0
INPUT VOLTAGE (V)
3.5
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
3413 G03
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LTC3413
TYPICAL PERFORMANCE CHARACTERISTICS
Switch On-Resistance
vs Temperature
120
100
ON-RESISTANCE (mΩ)
80
60
40
20
0
–40 –20
NFET
ON-RESISTANCE
V
IN
= 3.3V
PFET
ON-RESISTANCE
120
100
80
60
NFET ON-RESISTANCE
40
20
0
100 120
3413 G04
Switch On-Resistance
vs Input Voltage
T
A
= 25°C
PFET ON-RESISTANCE
2.5
Switch Leakage vs Input Voltage
T
A
= 25°C
LEAKAGE CURRENT (nA)
2.0
ON-RESISTANCE (mΩ)
1.5
PFET
1.0
NFET
0.5
0
20 40 60 80
TEMPERATURE (°C)
0
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
3413 G05
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
5.5
3413 G06
Frequency vs R
OSC
4500
4000
3500
FREQUENCY (kHz)
FREQUENCY (kHz)
3000
2500
2000
1500
1000
1000
500
0
54 154 254 354 454 554 654 754 854 954
R
OSC
(kΩ)
3413 G07
Frequency vs Input Voltage
1050
1040
1030
1020
1010
FREQUENCY (kHz)
T
A
= 25°C
1010
1008
1006
1004
1002
1000
998
996
994
992
990
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
5.5
3213 G08
Frequency vs Temperature
V
IN
= 3.3V
V
IN
= 3.3V
T
A
= 25°C
990
–40 –20
0
20 40 60 80
TEMPERATURE (°C)
100 120
3413 G09
Quiescent Current vs Input Voltage
350
300
QUIESCENT CURRENT (μA)
250
200
150
100
50
0
2.0
INDUCTOR
CURRENT
1A/DIV
T
A
= 25°C
OUTPUT
VOLTAGE
100mV/DIV
Load Step Transient
V
IN
= 2.5V
20μs/DIV
V
OUT
= 1.25V
LOAD STEP = 0A to 3A
2.5
4.5
3.0 3.5 4.0
INPUT VOLTAGE (V)
5.0
5.5
3413 G11
3413 G10
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LTC3413
TYPICAL PERFORMANCE CHARACTERISTICS
Load Step Transient
OUTPUT
VOLTAGE
100mV/DIV
OUTPUT
VOLTAGE
500mV/DIV
INDUCTOR
CURRENT
1A/DIV
INDUCTOR
CURRENT
1A/DIV
Start-Up
V
IN
= 2.5V
20μs/DIV
V
OUT
= 1.25V
LOAD STEP = 0A TO –3A
3413 G12
V
IN
= 2.5V
V
OUT
= 1.25V
LOAD = 0.4Ω
1ms/DIV
3413 G13
PIN FUNCTIONS
SV
IN
(Pin 1):
Signal Input Supply. Decouple this pin to
SGND with a capacitor. SV
IN
must be greater or equal to
PV
IN
, however, the difference between SV
IN
and PV
IN
must
be less than 0.5V.
PGOOD (Pin 2):
Power Good Output. Open-drain logic
output that is pulled to ground when the output voltage
is not within ±10% of regulation point.
I
TH
(Pin 3):
Error Amplifier Compensation Point. The
current comparator threshold increases with this control
voltage. Nominal voltage range for this pin is from 0.2V
to 1.4V with 0.6V corresponding to the zero-sense voltage
(zero current).
V
FB
(Pin 4):
Feedback Pin. Receives the feedback voltage
from the output.
R
T
(Pin 5):
Oscillator Resistor Input. Connecting a resistor
to ground from this pin sets the switching frequency.
V
REF
(Pin 6):
Reference Voltage Input. The positive input
of the internal error amplifier senses one-half of the volt-
age at this pin through a resistor divider.
RUN/SS (Pin 7):
Run Control and Soft-Start Input. Forcing
this pin below 0.5V shuts down the LTC3413. In shutdown
all functions are disabled drawing < 1μA of supply current.
A capacitor to ground from this pin sets the ramp time to
full output current.
SGND (Pin 8):
Signal Ground. All small-signal components
and compensation components should connect to this
ground, which in turn connects to PGND at one point.
PV
IN
(Pins 9, 16):
Power Input Supply. Decouple this pin
to PGND with a capacitor.
SW (Pins 10, 11, 14, 15):
Switch Node Connection to
Inductor. This pin connects to the drains of the internal
main and synchronous power MOSFET switches.
PGND (Pins 12, 13):
Power Ground. Connect this pin
closely to the (–) terminal of C
IN
and C
OUT
.
Exposed Pad (Pin 17):
Should be connected to PCB
ground.
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