LTC3113 - 3A Low Noise Buck-Boost DC/DC Converter

LTC3113
3A Low Noise Buck-Boost
DC/DC Converter
FEATURES
DESCRIPTION
n
The LTC®3113 is a wide VIN range, highly efficient, fixed
frequency, buck-boost DC/DC converter that operates
from input voltages above, below or equal to the output
voltage. The topology incorporated in the IC provides low
noise operation, making it well suited for RF and precision
measurement applications.
n
n
n
n
n
n
n
n
n
n
n
n
Regulated Output with Input Voltage Above, Below
or Equal to the Output Voltage
1.8V to 5.5V Input and Output Voltage Range
3A Continuous Output Current VIN > 3.0V, VOUT = 3.8V
1.5A Continuous Output Current for VIN ≥ 1.8V,
VOUT = 3.3V
Single Inductor
Low Noise Buck-Boost Architecture
Up to 96% Efficiency
Programmable Frequency from 300kHz to 2MHz
Selectable Burst Mode® Operation
Output Disconnect in Shutdown
Shutdown Current: <1μA
Internal Soft-Start
Small, Thermally Enhanced 16-Lead
(4mm × 5mm × 0.75mm) DFN Package
and 20-Lead TSSOP Package
APPLICATIONS
n
n
n
n
n
The LTC3113 can deliver up to 3A of continuous output
current to satisfy the most demanding applications.
Higher output current is possible in stepdown (buck)
mode. Integrated low RDS(ON) power MOSFETs and a
programmable switching frequency up to 2MHz result
in a compact solution footprint. Selectable Burst Mode
operation improves efficiency at light loads.
Other features include <1μA shutdown current, integrated
soft-start, short-circuit protection, current limit and thermal overload protection. The LTC3113 is housed in the
thermally enhanced 16-lead (4mm × 5mm × 0.75mm)
DFN and 20-lead TSSOP packages.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and No RSENSE, PowerPath are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Wireless Modems
Backup Power Systems
Portable Inventory Terminals
Portable Barcode Readers
Portable Instrumentation
TYPICAL APPLICATION
Efficiency vs Input Voltage
100
Li-Ion to 3.8V/3A
95
2.2μH
VIN
3V TO 4.2V
SW2
VIN
47μF
OFF ON
PWM BURST
VOUT
845k
LTC3113
RUN
FB
BURST
VC
6.49k
47pF
49.9k
RT
SGND
ILOAD = 1A
90
680pF
158k
VOUT
3.8V
100μF 3A
EFFICIENCY (%)
SW1
VOUT = 3.8V
85
ILOAD = 3A
80
75
70
65
60
55
PGND
3113 TA01a
90.9k
12pF
50
1.5
2.0
2.5 3.0 3.5 4.0 4.5
INPUT VOLTAGE (V)
5.0
5.5
3113 TA01b
3113f
1
LTC3113
ABSOLUTE MAXIMUM RATINGS (Notes 1, 3)
VIN, VOUT, SW1, SW2 Voltage (DC).............. –0.3V to 6V
SW1, SW2 Voltage, Pulsed (<100ns) (Note 4)............7V
VC, RUN, BURST Voltage ............................. –0.3V to 6V
FB ................................................................–0.3V to VIN
RT Voltage.................................................... –0.3V to 1V
Operating Junction Temperature Range
(Notes 2, 5) ............................................ –40°C to 125°C
Maximum Junction Temperature........................... 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSSOP .............................................................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
PGND
1
20 PGND
VOUT
1
16 SW2
VOUT
2
19 SW2
VOUT
2
15 SW2
VOUT
3
18 SW2
VIN
3
14 SW1
VIN
4
VIN
4
13 SW1
VIN
5
VIN
5
12 SW1
VIN
6
SGND
6
11 RUN
SGND
7
14 RUN
BURST
7
10 FB
BURST
8
13 FB
RT
8
9
RT
9
12 VC
17
PGND
VC
17 SW1
21
PGND
PGND 10
DHD PACKAGE
16-LEAD (5mm s 4mm) PLASTIC DFN
TJMAX = 125°C, θJA = 36.5°C/W, θJC = 3.6°C/W
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
16 SW1
15 SW1
11 PGND
FE PACKAGE
20-LEAD PLASTIC TSSOP
TJMAX = 125°C, θJA = 31.5°C/W, θJC = 4.1°C/W
EXPOSED PAD (PIN 21) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3113EDHD#PBF
LTC3113EDHD#TRPBF
3113
16-Lead (5mm × 4mm) Plastic DFN
–40°C to 125°C
LTC3113IDHD#PBF
LTC3113IDHD#TRPBF
3113
16-Lead (5mm × 4mm) Plastic DFN
–40°C to 125°C
LTC3113EFE#PBF
LTC3113EFE#TRPBF
LTC3113FE
20-Lead Plastic TSSOP
–40°C to 125°C
LTC3113IFE#PBF
LTC3113IFE#TRPBF
LTC3113FE
20-Lead Plastic TSSOP
–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/
3113f
2
LTC3113
ELECTRICAL CHARACTERISTICS
The l denotes specifications which apply over the full junction temperature
range, otherwise specifications are at TA = 25°C (Note 2). VIN = 3.3V, VOUT = 3.8V unless otherwise noted.
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
Input Operating Range
l
1.8
5.5
V
Output Voltage Adjust Range
l
1.8
5.5
V
l
588
600
612
mV
Feedback Voltage
VBURST = 0V
Feedback Input Current
VFB = 0.7V
0
50
nA
Quiescent Current–Burst Mode Operation
VBURST = 3.3V
40
55
μA
Quiescent Current–Shutdown
VOUT = 0V, VRUN = 0V, Not Including Switch Leakage
0.1
1
μA
Quiescent Current–Active
VFB = 0.7V, VBURST = 0V, RT = 90.9k
300
500
μA
5.8
7.8
9.8
A
Peak Current Limit
6.5
11.1
16.0
A
Burst Mode Peak Current Limit
0.9
1.9
2.9
A
Reverse Current Limit
–1.6
–1
–0.4
A
l
Input Current Limit
NMOS Switch Leakage
Switch B, SW1 = 5.5V, VIN = 5.5V, VOUT = 5.5V
Switch C, SW2 = 5.5V, VIN = 5.5V, VOUT = 5.5V
0.01
0.01
10
10
μA
μA
PMOS Switch Leakage
Switch A, VIN = 5.5V, VOUT = 5.5V, SW1 = 0V
Switch D, VIN = 5.5V, VOUT = 5.5V, SW2 = 0V
0.01
0.01
20
20
μA
μA
NMOS Switch On-Resistance
Switch B, VOUT = 3.8V
Switch C, VOUT = 3.8V
25
35
mΩ
mΩ
PMOS Switch On-Resistance
Switch A, VIN = 3.3V
Switch D, VOUT = 3.8V
30
40
mΩ
mΩ
Maximum Duty Cycle
Boost (% Switch C On)
Buck (% Switch A On)
90
%
%
80
100
l
Minimum Duty Cycle
Frequency Accuracy
l
l
RT = 90.9k
l
0
0.8
Error Amp AVOL
Error Amp Source Current
VC = 0V, VFB = 0V
Error Amp Sink Current
VC = 1.2V, VFB = 0.7V
BURST Input Logic Threshold
BURST Input Current
RUN Input Current
VRUN = 5.5V
Soft-Start Time
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 LTC3113 is tested under pulsed load conditions such that
TJ ≈ TA . The LTC3113E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the
–40°C to 125°C operating temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3113I is guaranteed to meet performance specifications over the
–40°C to 125°C operating junction temperature range.
1.2
MHz
100
dB
500
μA
160
l
0.3
0.7
l
0.3
0
VBURST = 5.5V
RUN Input Logic Threshold
1
%
μA
1.2
V
0
1
μA
0.7
1.2
V
1
μA
2
ms
Note 3: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when the protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4: Voltage transients on the switch pins beyond the DC limit specified
in the absolute maximum ratings are non-disruptive to normal operation
when using good layout practices, as shown on the demo board or
described in the data sheet and application notes.
Note 5: The junction temperature (TJ in °C) is calculated from the ambient
temperature (TA in °C) and the power dissipation (PD in Watts) as follows:
TJ = TA + (PD) • (θJA°C/W)
3113f
3
LTC3113
TYPICAL PERFORMANCE CHARACTERISTICS
(TA = 25°C, VIN = 3.3V, VOUT = 3.8V unless otherwise specified)
Efficiency 3.3V ±10% to 3.8V
Burst Mode No-Load Input
Current vs VIN
Efficiency 1.8V, 3.6V, 5.5V to 3.8V
100
100
100
90
VIN = 2.97V
VIN = 3.3V
VIN = 3.63V
VIN = 2.97V BURST
VIN = 3.3V BURST
VIN = 3.63V BURST
60
50
0.001
0.01
0.1
1
LOAD CURRENT (A)
70
VIN = 1.8V
VIN = 3.6V
VIN = 5.5V
VIN = 1.8V BURST
VIN = 3.6V BURST
VIN = 5.5V BURST
60
50
0.001
10
0.01
0.1
1
LOAD CURRENT (A)
60
60
50
50
20
VOUT = 5.5V
40
30
VOUT = 3.8V
20
10
10
VOUT = 1.8V
0
–45 –25 –5
15 35 55 75
TEMPERATURE (°C)
0
1.5
95 115
2.0
2.5
3.0
3.5 4.0
VIN (V)
4.5
30
10
0
1.5 2.0
2.5 3.0
4.5
3.5 4.0
VIN (V)
5.0
5.0
1.4
Normalized P-Channel Switch
Resistance vs VIN
1.3
T = 125°C
1.2
1.1
T = 25°C
1.0
T = –40°C
0.9
0.8
0.7
1 1.5 2
5.5
2.5 3 3.5 4
VIN (V)
4.5 5
1.6
5.5
6
3113 G06
Feedback Voltage
vs Temperature
Normalized N-Channel Switch
Resistance vs VIN
5.5
3113 G03
3113 G05
3113 G04
Maximum Load Current in PWM
Mode vs VIN (Input Current limit 5.8A)
6
0.601
1.5
1.3
T = 125°C
1.2
1.1
T = 25°C
1.0
0.9
T = –40°C
0.8
MAXIMUM LOAD CURRENT (A)
0.600
1.4
FEEDBACK VOLTAGE (V)
NORMALIZED N-CHANNEL SWITCH RESISTANCE
VOUT = 1.8V
40
10
PWM Mode No-Load Input
Current vs VIN
INPUT CURRENT (mA)
INPUT CURRENT (μA)
Burst Mode No-Load Input
Current vs Temperature
30
50
3113 G02
3113 G01
40
70 V
OUT = 3.8V
60
20
NORMALIZED P-CHANNEL SWITCH RESISTANCE
70
80
INPUT CURRENT (μA)
EFFICIENCY (%)
EFFICIENCY (%)
80
VOUT = 5.5V
80
90
90
0.599
0.598
0.597
0.596
5
4
3
2
0.7
0.6
1 1.5 2
2.5
3 3.5 4
VIN (V)
4.5 5
5.5
6
3113 G07
0.595
–45 –25 –5 15 35 55 75
TEMPERATATURE (°C)
95 115
3113 G08
1
1.5
2.0
2.5
3.0
3.5 4.0
VIN (V)
4.5
5.0
5.5
3113 G09
3113f
4
LTC3113
TYPICAL PERFORMANCE CHARACTERISTICS
(TA = 25°C, VIN = 3.3V, VOUT = 3.8V unless otherwise specified)
Maximum Load Current in Burst
Mode Operation vs VIN (Burst
Mode Peak Current Limit 0.9A)
Output Voltage Regulation
vs Load Current
OUTPUT VOLTAGE REGULATION (%)
MAXIMUM LOAD CURRENT (mA)
300
250
200
150
100
50
0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0
VOUT
200mV/DIV
Burst Mode
OPERATION
–0.2
ILOAD
2A/DIV
–0.4
–0.6
–0.8
0.001
VIN (V)
0.01
0.1
LOAD CURRENT (A)
1
10
3113 G11
3113 G10
Output Voltage Ripple in Burst
Mode Operation
Output Voltage Ripple in
PWM Mode
Burst to PWM Mode Transient
VOUT
20mV/DIV
VOUT
20mV/DIV
VOUT
50mV/DIV
VIN = 3.3V
VOUT
20mV/DIV
VIN = 4V
VOUT
20mV/DIV
INDUCTOR
CURRENT
1A/DIV
BURST
2V/DIV
VIN = 4.55V
20μs/DIV
ILOAD = 50mA
FRONT PAGE TYPICAL APPLICATION
3113 G14
ILOAD = 1A
3113 G14
1μs/DIV
Normalized Peak Current Limit
vs Temperature (11.1A Typical)
500μs/DIV
3113 G16
1.10
NORMALIZED PEAK CURRENT LIMIT
VIN = 3.3V
VOUT = 3.8V
COUT = 100μF
NORMALIZED INPUT CURRENT LIMIT
1.10
RUN
5V/DIV
1.05
1.00
0.95
0.90
–45 –25 –5
3113 G15
ILOAD = 50mA
500μs/DIV
FRONT PAGE TYPICAL APPLICATION
Normalized Input Current Limit
vs Temperature (7.8A Typical)
Soft-Start
VOUT
2V/DIV
3113 G12
100μs/DIV
BACK PAGE TYPICAL APPLICATION
–1.0
0.0001
5.5
5.0
Load Step, 0A to 3A
PWM MODE
15 35 55 75
TEMPERATURE (°C)
95 115
3113 G17
1.05
1.00
0.95
0.90
–45 –25 –5
15 35 55 75
TEMPERATURE (°C)
95 115
3113 G18
3113f
5
LTC3113
TYPICAL PERFORMANCE CHARACTERISTICS
(TA = 25°C, VIN = 3.3V, VOUT = 3.8V unless otherwise specified)
Minimum Start-Up Voltage
vs Temperature
Negative Inductor Current
vs Oscillator Frequency
Oscillator Frequency vs RT
2.5
1.705
0
VOUT PULLED UP TO 5.5V
L = 2.2μH
START-UP VOLTAGE (V)
1.701
1.699
1.697
1.695
1.693
1.691
1.689
2.0
REVERVE CURRENT LIMIT (A)
OSCILLATOR FREQUENCY (MHz)
1.703
1.5
1.0
0.5
–1
–2
–3
–4
–5
1.687
1.685
–45 –25 –5
0
15 35 55 75
TEMPERATURE (°C)
0
95 115
50
100
150 200
RT (kΩ)
250
300
3113 G20
3113 G19
Junction Temperature Rise
vs Continuous Load Current for
VOUT = 1.8V
60
50
40
30
20
VIN = 1.8V
VIN = 2.4V
VIN = 3.3V
VIN = 5.5V
10
0
0.5
1
1.5 2 2.5 3 3.5
LOAD CURRENT (A)
4
JUNCTION TEMPERATURE RISE (°C)
JUNCTION TEMPERATURE RISE (°C)
3113 G21
Junction Temperature Rise
vs Continuous Load Current for
VOUT = 3.3V
60
0
–6
0.25 0.45 0.65 0.85 1.05 1.25 1.45 1.65 1.85
OSCILLATOR FREQUENCY (MHz)
350
50
40
30
20
0
4.5
VIN = 1.8V
VIN = 2.4V
VIN = 3.3V
VIN = 5.5V
10
0
0.5
1
1.5 2 2.5 3 3.5
LOAD CURRENT (A)
4
3113 G22
3113 G23
Junction Temperature Rise
vs Continuous Load Current for
VOUT = 5.5V
Junction Temperature Rise
vs Continuous Load Current for
VOUT = 3.8V
60
50
40
30
20
VIN = 1.8V
VIN = 2.4V
VIN = 3.3V
VIN = 5.5V
10
0
0.5
1
1.5 2 2.5 3 3.5
LOAD CURRENT (A)
4
4.5
3113 G24
JUNCTION TEMPERATURE RISE (°C)
JUNCTION TEMPERATURE RISE (°C)
60
0
4.5
50
40
30
20
VIN = 1.8V
VIN = 2.4V
VIN = 3.3V
VIN = 5.5V
10
0
0
0.5
1
1.5
2
2.5
LOAD CURRENT (A)
3
3.5
3113 G25
3113f
6
LTC3113
PIN FUNCTIONS
(DFN/TSSOP)
VOUT (Pins 1, 2/Pins 2, 3): Buck-Boost Output Voltage. A
low ESR capacitor should be placed from VOUT to PGND.
The capacitor should be placed as close to the IC as possible and have a short return path to ground.
VIN (Pins 3, 4, 5/Pins 4, 5, 6): Power Input for the
Converter. A 47μF or larger bypass capacitor should be
connected between VIN and PGND. The bypass capacitor
should located as close to VIN and PGND as possible and
should via directly to the ground plane.
SGND (Pin 6/Pin 7): Signal Ground. Terminate the frequency setting resistor and output voltage divider to SGND.
BURST (Pin 7/Pin 8): Pulse Width Modulation/Burst Mode
Selection Input. Forcing this pin low causes the switching
converter to operate in low noise fixed frequency PWM
mode. Forcing this pin high enables constant Burst Mode
operation for the converter. During Burst Mode operation,
the converter can only support a reduced maximum load
current.
RT (Pin 8/Pin 9): Programs the Frequency of the Internal
Oscillator. Connect a resistor from RT to ground (SGND).
The RT resistor value for a given frequency is given by the
following equation.
RT ≅
90
(kΩ)
f (MHz )
VC (Pin 9/Pin 12): Error Amp Output. An R-C network is
connected from this pin to FB for loop compensation. Refer
to the Closing the Feedback Loop section for component
selection guidelines.
FB (Pin 10/Pin 13): Feedback Voltage for the Buck-Boost
Converter Derived from a Resistor Divider on the BuckBoost Output Voltage. The buck-boost output voltage is
given by the following equation:
⎛ R2 ⎞
VOUT = 0.600 ⎜ 1+ ⎟ ( V )
⎝
R1⎠
where R1 is a resistor connected between FB and SGND,
and R2 is a resistor connected between FB and VOUT . The
buck-boost output voltage can be adjusted from 1.8V to
5.5V.
RUN (Pin 11/Pin 14): Active High Converter Enable Input. Applying a voltage <0.3V to this pin shuts down the
LTC3113. Applying a voltage >1.2V to this pin enables
the LTC3113.
SW1 (Pins 12, 13, 14/Pins 15, 16, 17): Switch Pin Where
Internal Switches A and B are Connected. Connect the
inductor from SW1 to SW2. Minimize trace length to
reduce EMI.
SW2 (Pins 15, 16/Pins 18, 19): Switch Pin Where Internal
Switches C and D are Connected. Connect the inductor
from SW1 to SW2. Minimize trace length to reduce EMI.
PGND (Exposed Pad Pin 17/Pins 1, 10, 11, 20, Exposed
Pad Pin 21): The exposed pad must be soldered to the
PCB and electrically connected to ground through the
shortest and lowest impedance connection possible.
In most applications the bulk of the heat flow out of the
LTC3113 is through this pad, so printed circuit board
design has an impact on the thermal performance of the
part. See the PCB Layout and Thermal Considerations
section for more details.
3113f
7
LTC3113
DETAILED BLOCK DIAGRAM
(DFN Package)
2.2μH
12
VIN
1.8V TO 5.5V
3
+
VIN
13
14
SW1
SW2
SWA
GATE
DRIVERS
AND
ANTICROSS
CONDUCTION
5
SWB
PEAK
CURRENT
LIMIT
11.1A
1.6V
RT
+
–
+
–
UVLO
+
–
PWM
LOGIC
AND
OUTPUT
PHASING
– +
7.8A
REVERSE
CURRENT
LIMIT
INPUT
CURRENT
+ LIMIT
RZ2
6.49k
CZ1
47pF
–
ERROR
AMP
+
+
–
SOFT-START
0.6V
+
–
FB
VC
10
CP1
RZ 680pF
49.9k
CL
100μF
9
CP2
12pF
SLEEP
7
PWM
COMPARATORS
R2
845k
2
–1.0A
SWC
1
OSC
RT
90.9k
1 = BURST
0 = PWM
VOUT
SWD
4
8
15 16
Burst Mode
CONTROL
R1
158k
BURST
PGND SGND
17
RUN
RUN LOGIC
RUN
11
1 = ON
0 = OFF
6
3113 BD
3113f
8
LTC3113
OPERATION
INTRODUCTION
The LTC3113 is a low noise, high power synchronous
buck-boost DC/DC converter optimized for demanding
applications. The LTC3113 utilizes a proprietary switching
algorithm, which allows its output voltage to be regulated
above, below or equal to the input voltage. The error amplifier output (VC) determines the output duty cycle of each
switch. The low RDS(ON), low gate charge, synchronous
power switches provide high frequency pulse width modulation control. High efficiency is achieved at light loads
when Burst Mode operation is commanded.
LOW NOISE FIXED FREQUENCY OPERATION
Oscillator
The frequency of operation can be programmed between
300kHz and 2MHz by an external resistor from the RT pin
to ground, according to the following equation:
RT ≅
90
(kΩ)
f (MHz )
Error Amplifier
The error amplifier is a high gain voltage mode amplifier. The loop compensation components are configured
around the amplifier (from FB to VC) to obtain stable
converter operation. For improved bandwidth, an additional RC feedforward network can be placed across the
upper feedback divider resistor. Refer to the Applications
Information section of this data sheet under Closing the
Feedback Loop for information on selecting compensation
type and components.
Current Limit Operation
The buck-boost converter has two current limit circuits.
The primary current limit is an average current limit circuit which sources current into FB to reduce the output
voltage, should the input current exceed 7.8A. Due to the
high gain of the feedback loop, the injected current forces
the error amplifier output to decrease until the average
current through switch A decreases approximately to the
current limit value. The average current limit utilizes the
error amplifier in an active state and thereby provides a
smooth recovery with little overshoot once the current
limit fault condition is removed. Since the current limit is
based on the average current through switch A, the peak
inductor current in current limit will have a dependency
on the duty cycle (i.e., on the input and output voltages)
in the overcurrent condition. For this current limit feature
to be most effective, the Thevenin resistance from FB to
ground should exceed 100k.
The speed of the average current limit circuit is limited
by the dynamics of the error amplifier. On a hard output
short, it is possible for the inductor current to increase
substantially beyond current limit before the average current limit circuit would react. For this reason, there is a
second current limit circuit which turns off switch A if the
current ever exceeds approximately 142% of the average
current limit value. This provides additional protection in
the case of an instantaneous hard output short.
Should the output voltage become less then 1.2V nominally, both the current limits are reduced compared to the
normal operating current limits.
Reverse Current Limit
During fixed frequency operation, a reverse-current comparator on switch D monitors the current entering VOUT .
When this current exceeds 1A (typical) switch D will be
turned off for the remainder of the switching cycle. This
feature protects the buck-boost converter from excessive
reverse current if the buck-boost output is held above the
regulation voltage by an external source.
In applications where the oscillator frequency is programmed above 1MHz and the output voltage is held above
its programmed regulation value, reverse currents greater
than 1A (typical) may be observed. In conjunction with
oscillator frequencies higher than 1MHz, higher output
voltages will also increase the magnitude of observed
reverse current. Refer to the Negative Inductor Current
vs Oscillator Frequency graph in the Typical Performance
Characteristics section for typical variations.
3113f
9
LTC3113
OPERATION
Internal Soft-Start
Inductor Damping
The LTC3113 buck-boost converter has an independent
internal soft-start circuit with a nominal duration of 2ms.
The converter remains in regulation during soft-start and
will therefore respond to output load transients which occur
during this time. In addition, the output voltage rise time
has minimal dependency on the size of the output capacitor or load current during start-up. During soft-start, the
buck-boost is forced into PWM mode operation regardless
of the state of the BURST pin.
When the LTC3113 is in burst operation and sleep mode,
active circuits “damp” the inductor voltage through 165Ω
(typical) impedance from both SW1 and SW2 to ground
minimizing EMI.
Thermal Shutdown
If the die temperature exceeds 155°C the LTC3113 buckboost converter will be disabled. All power devices are
turned off and the switch nodes will be forced into a high
impedance state. The soft-start circuit for the converter
is reset during thermal shutdown to provide a smooth
recovery once the overtemperature condition is eliminated.
When the die temperature drops to approximately 145°C
the LTC3113 will restart. For recommendations regarding
thermal design of the LTC3113 PCB, refer to the PCB Thermal Considerations section in Applications Information.
Undervoltage Lockout
If the supply voltage decreases below 1.6V (typical) then
the LTC3113 buck-boost converter will be disabled and
all power devices are turned off. The soft-start circuit is
reset during undervoltage lockout to provide a smooth
restart once the input voltage rises above 1.7V (typical)
the undervoltage lockout increasing threshold.
When operating the LTC3113 at low input voltages, care
must be taken under heavy loads to prevent the part from
cycling into and out of UVLO. When operating at low input
voltages the voltage drop created by the source resistance
can trigger the UVLO, resetting the part. Operation near the
undervoltage lockout is not recommended, but if requirements dictate, the source resistance should be less than
100mV/IIN(MAX) (where IIN(MAX) is the maximum input
current) to ensure proper operation.
PWM Mode Operation
When the BURST pin is held low, the LTC3113 buckboost converter operates in a fixed-frequency pulse width
modulation (PWM) mode using voltage mode control. Full
output current is only available in PWM mode. A proprietary
switching algorithm allows the converter to transition
between buck, buck-boost, and boost modes without
discontinuity in inductor current. The switch topology for
the buck-boost converter is shown in Figure 1.
VOUT
VIN
A
D
L
B
C
3113 F01
Figure 1. Buck-Boost Switch Topology
When the input voltage is significantly greater than the
output voltage, the buck-boost converter operates in
buck mode. Switch D turns on continuously and switch
C remains off. Switches A and B are pulse width modulated to produce the required duty cycle to support the
output regulation voltage. As the input voltage decreases,
switch A remains on for a larger portion of the switching
cycle. When the duty cycle reaches approximately 85%,
the switch pair AC begins turning on for a small fraction
of the switching period. As the input voltage decreases
further, the AC switch pair remains on for longer durations
and the duration of the BD phase decreases proportionally.
As the input voltage drops below the output voltage, the
3113f
10
LTC3113
OPERATION
AC phase will eventually increase to the point that there is
no longer any BD phase. At this point, switch A remains on
continuously while switch pair CD is pulse width modulated to obtain the desired output voltage. At this point,
the converter is operating solely in boost mode.
This switching algorithm provides a seamless transition
between operating modes and eliminates discontinuities
in average inductor current, inductor current ripple, and
loop transfer function throughout all three operational
modes. These advantages result in increased efficiency
and stability in comparison to the traditional four-switch
buck-boost converters.
Burst Mode Operation
With the BURST pin held high, the buck-boost converter
operates utilizing a variable frequency switching algorithm
designed to improve efficiency at light load and reduce
the standby current at zero load. In Burst Mode operation,
the inductor is charged with fixed peak amplitude current
pulses and as a result only a fraction of the maximum
output current can be delivered when in this mode.
These current pulses are repeated as often as necessary
to maintain the output regulation voltage. The maximum
output current, IMAX, which can be supplied in Burst Mode
operation is dependent upon the input and output voltage
as given by the following formula:
IMAX ≅
IPK
VIN
•
• η (A)
2 VIN + VOUT
where IPK is the Burst Mode peak current limit in amps
and is the η efficiency.
If the buck-boost load exceeds the maximum Burst Mode
current capability, the output rail will lose regulation. In
Burst Mode operation, the error amplifier is configured
in a low power mode of operation and used to hold the
compensation pin, VC, to reduce transients that may occur during transitions from Burst Mode to PWM mode
operation.
3113f
11
LTC3113
APPLICATIONS INFORMATION
The basic LTC3113 application circuit is shown as the
typical application on the front page of this data sheet.
The external component selection is dependent upon the
required performance of the IC in each particular application given considerations and trade-offs such as PCB
area, output voltage, output current, output ripple voltage
and efficiency. This section of the data sheet provides
some basic guidelines and considerations to aid in the
selection of external components and the design of the
application circuit.
OUTPUT VOLTAGE PROGRAMMING
The buck-boost output voltage is set via an external resistor
divider connected to the FB pin as shown in Figure 2.
1.8V ≤ VOUT ≤ 5.5V
R2
formulas, where f is the frequency in MHz and L is the
inductance in μH:
ΔIL,P-P,BUCK =
VOUT ⎛ VIN – VOUT ⎞
⎟⎠ ( A )
f • L ⎜⎝
VIN
ΔIL,P-P,BOOST =
VIN ⎛ VOUT – VIN ⎞
(A)
f • L ⎜⎝ VOUT ⎟⎠
To ensure operation without triggering the reverse current
comparator under no load conditions it is recommended
that the peak-to-peak inductor ripple not exceed 800mA
taking into account the maximum reverse current limit of
–0.4A specified in the Electrical Characteristics section.
Utilizing this recommendation for applications operating
at a switching frequency of 300kHz requires a minimum
inductance of 6.8μH, similarly an application operation at
a frequency of 2MHz would require a minimum of 1μH.
FB
LTC3113
R1
SGND
3113 F02
Figure 2. Setting the Output Voltage
The resistor divider values determine the buck-boost output
voltage according to the following formula:
⎛ R2 ⎞
VOUT = 0.600 ⎜ 1+ ⎟
⎝
R1⎠
(V)
As noted in the Current Limit Operation section: “for the
current limit feature to be most effected, the Thevenin resistance (R1||R2) from FB to ground should exceed 100k.”
INDUCTOR SELECTION
To achieve high efficiency, a low ESR inductor should be
selected for the buck-boost converter. In addition, the
inductor must have a saturation current rating that is
greater than the worst-case average inductor current plus
half the ripple current. The peak-to-peak inductor current
ripple will be larger in buck and boost mode than in the
buck-boost region. The peak-to-peak inductor current
ripple for each mode can be calculated from the following
In addition to affecting output current ripple, the value of
the inductor can also impact the stability of the feedback
loop. In boost and buck-boost mode, the converter transfer
function has a right half plane zero at a frequency that is
inversely proportional to the value of the inductor. As a
result, a large inductor can move this zero to a frequency
that is low enough to degrade the phase margin of the
feedback loop.
In addition to affecting the efficiency of the buck-boost
converter, the inductor DC resistance can also impact the
maximum output capability of the buck-boost converter
at low input voltage. In buck mode, the buck-boost output
current is limited only by the inductor current reaching the
current limit value. However, in boost mode, especially at
large step-up ratios, the output current capability can also
be limited by the total resistive losses in the power stage.
These include switch resistances, inductor resistance
and PCB trace resistance. Use of an inductor with high
DC resistance can degrade the output current capability
from that shown in the graph in the Typical Performance
Characteristics section of this data sheet.
Different inductor core materials and styles have an impact
on the size and price of an inductor at any given current
rating. Shielded construction is generally preferred as it
minimizes the chances of interference with other circuitry.
3113f
12
LTC3113
APPLICATIONS INFORMATION
The choice of inductor style depends upon the price, sizing,
and EMI requirements of a particular application. Table 1
provides a small sampling of inductors that are well suited
to many LTC3113 buck-boost converter applications. All
inductor specifications are listed at an inductance value
of 2.2μH for comparison purposes but other values within
these inductor families are generally well suited to this
application. Within each family (i.e. at a fixed size), the DC
resistance generally increases and the maximum current
generally decreases with increased inductance.
f is the frequency in MHz, COUT is the capacitance in μF, L
is the inductance in μH, VIN is the input voltage in volts,
VOUT is the output voltage in volts. ∆VP-P is the output
ripple in volts and ILOAD is the output current in amps.
Table 1. Representative Buck-Boost Surface Mount Inductors
Given that the output current is discontinuous in boost
mode, the ripple in this mode will generally be much larger
than the magnitude of the ripple in buck mode.
PART
NUMBER
VALUE
(μH)
DCR
(mΩ)
MAX DC
CURRENT (A)
SIZE (mm)
W×L×H
COUT ≥
COUT ≥
1
ΔVP-P,BUCK • 8 • L • f 2
•
ILOAD ( VOUT – VIN )
ΔVP-P,BOOST • VOUT • f
( VIN – VOUT ) • VOUT (µF )
V
IN
(µF )
CoilCraft (www.coilcraft.com)
MSS1048
2.2
7.2
8.4
10 × 10.3 × 4
MSS1260
2.2
12
13.9
12.3 × 12.3 × 6
SER1052
2.2
4
10
10.6 × 10.6 × 5.2
Toko (www.toko.com)
D106C
2.4
7.7
10
10.3 × 10.3 × 6.7
FDA1055
2.2
4.8
10.5
11.6 × 10.8 × 5.5
FDA1254
2.2
4.5
14.7
13.5 × 12.6 × 5.4
Cooper (www.cooperbussmann.com)
HCP0703
2.2
18
14
7 × 7.3 × 3
HCP0704
2.3
16.5
11.5
6.8 × 6.8 × 4.2
HC8
2.6
11.4
10
10.9 × 10.4 × 4
9.7 × 10 × 4
INPUT CAPACITOR SELECTION
It is recommended that a low ESR ceramic capacitor with a
value of at least 47μF be located as close to VIN as possible.
In addition, the return trace from the pin to the ground
plane should be made as short as possible. It is important
to minimize any stray resistance from the converter to the
battery or other power sources. If cabling is required to
connect the LTC3113 to the battery or power supply, a higher
ESR capacitor or a series resistor with low ESR capacitor
in parallel with the low ESR capacitor may be needed to
damp out ringing caused by the cable inductance.
TDK (www.component.tdk.com)
VLF100040
2.2
7.9
8.2
RLF12560
2.7
4.5
12
13 × 13 × 6
VLF12060
2.7
6.4
10
11.7 × 12 × 6
Wurth (www.we-online.com)
744066
2.2
10.5
6.8
10 × 10 × 3.8
744355
2
8
13
13.2 × 12.8 × 6.2
744324
2.4
4.8
17
10.5 × 10.2 × 4.7
OUTPUT CAPACITOR SELECTION
A low ESR output capacitor should be utilized at the buckboost converter output in order to minimize output voltage
ripple. Multilayer ceramic capacitors are an excellent choice
as they have low ESR and are available in small footprints.
The capacitor should be chosen large enough to reduce the
output voltage ripple to acceptable levels. Neglecting the
capacitor ESR and ESL, the peak-to-peak output voltage
ripple can be calculated by the following formulas, where
CAPACITOR VENDOR INFORMATION
Both the input bypass capacitors and output capacitors
used with the LTC3113 must be low ESR and designed
to handle the large AC currents generated by switching
converters. This is important to maintain proper functioning
of the IC and to reduce output ripple. Many modern low
voltage ceramic capacitors experience significant loss in
capacitance from their rated value with increased DC bias
voltages. For example, it is not uncommon for a small
surface mount ceramic capacitor to lose 50% or more
of its rated capacitance when operated near its rated
voltage. As a result, it is sometimes necessary to use
a larger value capacitance or a capacitor with a higher
voltage rating than required in order to actually realize
the intended capacitance at the full operating voltage. For
details, consult the capacitor vendor’s curve of capacitance
versus DC bias voltage.
3113f
13
LTC3113
APPLICATIONS INFORMATION
The capacitors listed in Table 2 provide a sampling of small
surface mount ceramic capacitors that are well suited to
LTC3113 application circuits. All listed capacitors are either
X5R or X7R dielectric in order to ensure that capacitance
loss over temperature is minimized.
Table 2. Representative Buck-Boost Surface Input Mount Bypass
and Output Capacitors
VALUE
(μF)
VOLTAGE
(V)
SIZE (mm) W × L × H
(FOOTPRINT)
1812D476KAT2A
47
6.3
3.2 × 4.5 × 2.5 (1812)
18126D107KAT2A
100
6.3
3.2 × 4.5 × 2.8 (1812)
GRM43ER60J476ME01
47
6.3
3.2 × 4.5 × 2.5 (1812)
GRM43SR60J107ME20
100
6.3
3.2 × 4.5 × 2.8 (1812)
GRM55FR60J107KA01L
100
6.3
5 × 5.7 × 3.2 (2220)
PART NUMBER
AVX (www.avx.com)
Murata (www.murata.com)
Taiyo Yuden (www.t-yuden.com)
JMK432BJ476MM-T
47
6.3
3.2 × 4.5 × 2.5 (1812)
JMK432C107MM-T
100
6.3
3.2 × 4.5 × 2.8 (1812)
TDK (www.component.tdk.com)
C4532X5R0J476M
47
6.3
3.2 × 4.5 × 2.5 (1812)
C4532X5R0J107M
100
6.3
3.2 × 4.5 × 2.5 (1812)
C5750X5R1C476M
47
16
5 × 5.7 × 2.5 (2220)
C5750X5R1A686M
68
10
5 × 5.7 × 2.5 (2220)
C5750X5R0J107M
100
6.3
5 × 5.7 × 2.5 (2220)
PCB LAYOUT CONSIDERATIONS
The LTC3113 switches large currents at high frequencies.
Special attention should be paid to the PCB layout to ensure
a stable, noise-free and efficient application circuit. Figure
3 presents a representative 4-layer PCB layout to outline
some of the primary considerations. A few key guidelines
are outlined below:
1. All circulating high current paths should be kept as
short as possible. This can be accomplished by keeping
the routes to all highlighted components in Figure 3
as short and as wide as possible. Capacitor ground
connections should via down to the ground plane in
the shortest route possible. The bypass capacitors on
VIN should be placed as close to the IC as possible and
should have the shortest possible paths to ground.
2. The Exposed Pad is the power ground connection for
the LTC3113. Multiple vias should connect the backpad
directly to the ground plane. In addition maximization
of the metallization connected to the backpad will improve the thermal environment and improve the power
handling capabilities of the IC. Refer to Figure 3d bottom layer as an example of proper exposed pad power
ground and via layout to provide good thermal and
ground connection performance.
3. The components shown highlighted and their connections should all be placed over a complete ground plane
to minimize loop cross-sectional areas. This minimizes
EMI and reduces inductive drops.
4. Connections to all of the components shown highlighted
should be made as wide as possible to reduce the series
resistance. This will improve efficiency and maximize the
output current capability of the buck-boost converter.
5. To prevent large circulating currents from disrupting
the output voltage sensing, the ground for each resistor
divider should be returned to the ground plane using
a via placed close to the IC and away from the power
connections.
6. Keep the connection from the resistor dividers to the
feedback pins, FB, as short as possible and away from
the switch pin connections.
7. Crossover connections should be made on inner copper
layers if available. If it is necessary to place these on
the ground plane, make the trace on the ground plane
as short as possible to minimize the disruption to the
ground plane.
Thermal Considerations
The LTC3113 output current may need to be derated if
it is required to operate in a high ambient temperature
or delivering a large amount of continuous power. The
amount of current derating is dependent upon the input
voltage, output voltage and ambient temperature. The
temperature rise curves given in the Typical Performance
Characteristics section can be used as a guide. These curves
were generated by mounting the LTC3113 to a 4-layer
FR4 demo board shown in Figure 3. Boards of other sizes
and layer count can exhibit different thermal behavior, so
3113f
14
LTC3113
APPLICATIONS INFORMATION
L1
2.2μH
12
VIN E3
1.8V TO 5.5V
13
14
15
3
4
C5
1μF
5
11
C7
68μF
10V
VOUT
VIN
VIN
VIN
VOUT
R8
90.9k
1%
FB
VC
SGND
6
OFF
1
2
3
R2
715k
1%
VOUT
3.3V
E2
GND
10
9
C8
R5 680pF
10k
C9
10pF
17
E4
ON
1
2
PGND
R7
158k
1%
GND
GND
JP2
R3
10k
C3
1μF
6.3V
LTC3113EDHD
RUN
7
BURST
8
RT
R4
1M
C2
100μF
6.3V
C1
33pF
16
SW1 SW1 SW1 SW2 SW2
VIN
E1
VOUT
Burst Mode
OPERATION
FIXED
FREQUENCY
3113 F03a
JP1
PWM
1
2
3
R9
1.0M
VIN
Figure 3a
Figure 3b. Fabrication Layer of Example PCB
3113f
15
LTC3113
APPLICATIONS INFORMATION
THERMAL AND
PGND VIAS
Figure 3c. Top Layer of Example PCB
Figure 3d. Bottom Layer of Example PCB
it is incumbent upon the user to verify proper operation
over the intended system’s line, load and environmental
operating conditions.
Consequently, a poor printed circuit board design can cause
excessive heating, resulting in impaired performance or
reliability. Refer to the PCB Layout Considerations section
for printed circuit board design suggestions.
The junction-to-air (θJA) and junction-to-case (θJC) thermal
resistance given in the “Pin Configuration” diagram may
also be used to estimate the LTC3113 internal temperature.
These thermal coefficients are determined using a 4-layer
PCB. Bear in mind that the actual thermal resistance of
the LTC3113 to the printed circuit board depends upon
the design of the circuit board.
The die temperature of the LTC3113 must be lower than
the maximum rating of 125°C, so care should be taken in
the layout of the circuit board to ensure good heat sinking
of the LTC3113. The bulk of the heat flow is through the
bottom exposed pad of the part into the printed circuit board.
As described in the Thermal Shutdown section, the
LTC3113 is equipped with a thermal shutdown circuit that
will inhibit power switching at high junction temperatures.
The activation threshold of this function, however, is
above the 125°C rating to avoid interfering with normal
operation. Thus, it follows that prolonged or repetitive
operation under a condition in which the thermal shutdown
activates necessarily means that the die is subjected to
temperatures above the 125°C rating for prolonged or
repetitive intervals, which may damage or impair the
reliability of the device.
3113f
16
LTC3113
APPLICATIONS INFORMATION
CLOSING THE FEEDBACK LOOP
The LTC3113 incorporates voltage mode PWM control.
The control-to-output gain varies with the operation region
(buck, buck-boost, boost), but is usually no greater than
15. The output filter exhibits a double pole response, as
given by:
fFILTER _ POLE =
1
2π LCOUT
(Hz )
(In Buck Region)
fFILTER _ POLE =
1
2π LCOUT
VIN
(Hz )
VOUT
(In Boost Region)
where L is in Henries and COUT is in Farads. The output
filter zero is given by:
fFILTER _ ZERO =
1
2πRESRCOUT
(Hz )
where RESR is the equivalent series resistance out the
output capacitor in ohms.
A troublesome feature in the boost and buck-boost region
is the right-half plane (RHP) zero, given by:
fRHPZ
Most applications demand an improved transient response
to allow a smaller output capacitor. To achieve a higher
bandwidth, Type III compensation is required, providing
two zeros to compensate for the double-pole response of
the output filter. Referring to Figure 5, the location of the
poles and zeros are given by:
1
(Hz )
2π105 R2CP1
1
fZERO1 =
(Hz )
2πR Z CP1
1
fZERO2 =
(Hz )
2πR2CZ1
1
fPOLE2 =
(Hz )
2πR Z CP2
1
fPOLE3 =
(Hz )
2πRP C Z1
fPOLE1 =
where resistance is in Ohms and capacitance is in
Farads.
VOUT
A simple Type I compensation network can be incorporated
to stabilize the loop at the cost of reduced bandwidth and
slower transient response. To ensure proper phase margin
using Type I compensation, the loop must be crossed over
a decade before the LC double pole. Referring to Figure 4,
the unity-gain frequency of the error amplifier with the
Type I compensation is given by:
ERROR
AMP
FB
VIN2
=
(Hz )
2πIOUT LVOUT
The loop gain is typically rolled off before the RHP zero
frequency.
+
0.6V
R2
–
VC
CP1
R1
3113 F04
Figure 4. Error Amplifier with Type I Compensation
VOUT
0.6V
RP
CZ1
R2
FB
+
ERROR
AMP
VC
–
R1
CP1
RZ
CP2
3113 F05
1
fUG =
(Hz )
2πR2CP1
Figure 5. Error Amplifier with Type III Compensation
3113f
17
LTC3113
TYPICAL APPLICATIONS
Li-Ion to 3.3V/3A
2.2μH
VIN
2.5V TO 4.2V
Li-Ion
SW1
SW2
VIN
VOUT
47μF
825k
LTC3113
OFF ON
PWM BURST
RUN
FB
BURST
VC
47pF
49.9k
RT
SGND
6.49k
VOUT
3.3V
100μF 3A
680pF
PGND
182k
3113 TA02a
90.9k
12pF
Efficiency Li-Ion (3V, 3.7V, 4.2V) to 3.3V
100
EFFICIENCY (%)
90
80
VIN = 3V
VIN = 3.7V
VIN = 4.2V
VIN = 3V BURST
VIN = 3.7V BURST
VIN = 4.2V BURST
70
60
0.001
0.1
1
0.01
LOAD CURRENT (A)
10
3113 TA02b
Power Loss Li-Ion (3V, 3.7V, 4.2V) to 3.3V
10
PWM MODE
POWER LOSS (W)
1
0.1
0.01
Burst Mode
OPERATION
0.001
0.0001
0.001
VIN = 3V
VIN = 3.7V
VIN = 4.2V
0.1
1
0.01
LOAD CURRENT (A)
10
3113 TA02c
3113f
18
LTC3113
TYPICAL APPLICATIONS
Supercap Powered Backup Supply
2.2μH
SW1
VIN
1.8V TO 4.5V
SW2
VIN
30F
30F
0.1μF
VOUT
825k
LTC3113
OFF ON
PWM BURST
RUN
FB
BURST
VC
SGND
100μF
47pF
49.9k
RT
6.49k
VOUT
3.3V
680pF
PGND
182k
3113 TA03a
90.9k
12pF
Typical Output Response with 1.5A Load
VIN
2V/DIV
VOUT
2V/DIV
RUN
2V/DIV
5 SEC/DIV
3113 TA03b
3113f
19
LTC3113
TYPICAL APPLICATIONS
3.3V to 5V/2.5A Boost Converter with Output Disconnect
2.2μH
VIN
3.3V
±10%
SW2
SW1
VIN
VOUT
47μF
5V
887k
LTC3113
OFF ON
PWM BURST
RUN
FB
BURST
VC
SGND
100μF
47pF
49.9k
RT
6.49k
680pF
PGND
121k
3113 TA04a
90.9k
12pF
Efficiency vs Load Current
100
PWM MODE
EFFICIENCY (%)
90
Burst Mode
OPERATION
80
70
60
50
0.001
0.01
0.1
1
LOAD CURRENT (A)
10
3113 TA04b
Power Loss vs Load Current
10
PWM MODE
POWER LOSS (W)
1
0.1
Burst Mode
OPERATION
0.01
0.001
0.001
0.1
1
0.01
LOAD CURRENT (A)
10
3113 TA04c
3113f
20
LTC3113
TYPICAL APPLICATIONS
3.3V to 1.8V/5A Buck Converter
2.2μH
SW2
SW1
VIN
47μF
VOUT
665k
LTC3113
OFF ON
PWM BURST
RUN
FB
BURST
VC
SGND
6.49k
100μF
VOUT
1.8V
47pF
49.9k
RT
680pF
PGND
332k
3113 TA05a
90.9k
12pF
Efficiency vs Load Current
100
PWM MODE
EFFICIENCY (%)
90
Burst Mode
OPERATION
80
70
60
50
0.001
0.01
0.1
1
LOAD CURRENT (A)
10
3113 TA05b
Power Loss vs Load Current
10
1
PWM MODE
POWER LOSS (W)
VIN
3.3V
±10%
0.1
0.01
Burst Mode
OPERATION
0.001
0.0001
0.001
0.01
0.1
1
LOAD CURRENT (A)
10
3113 TA06
3113f
21
LTC3113
PACKAGE DESCRIPTION
DHD Package
16-Lead Plastic DFN (5mm × 4mm)
(Reference LTC DWG # 05-08-1707)
0.70 p0.05
4.50 p0.05
3.10 p0.05
2.44 p0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC
4.34 p0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
5.00 p0.10
(2 SIDES)
R = 0.20
TYP
4.00 p0.10
(2 SIDES)
9
0.40 p 0.10
16
2.44 p 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
PIN 1
NOTCH
(DHD16) DFN 0504
8
0.200 REF
1
0.25 p 0.05
0.50 BSC
0.75 p0.05
0.00 – 0.05
4.34 p0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJGD-2) IN JEDEC
PACKAGE OUTLINE MO-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
3113f
22
LTC3113
PACKAGE DESCRIPTION
FE Package
20-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation CA
6.40 – 6.60*
(.252 – .260)
4.95
(.195)
4.95
(.195)
20 1918 17 16 15 14 13 12 11
6.60 p0.10
2.74
(.108)
4.50 p0.10
6.40
2.74
(.252)
(.108)
BSC
SEE NOTE 4
0.45 p0.05
1.05 p0.10
0.65 BSC
1 2 3 4 5 6 7 8 9 10
RECOMMENDED SOLDER PAD LAYOUT
4.30 – 4.50*
(.169 – .177)
0.09 – 0.20
(.0035 – .0079)
0.25
REF
0.50 – 0.75
(.020 – .030)
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
3. DRAWING NOT TO SCALE
1.20
(.047)
MAX
0o – 8o
0.65
(.0256)
BSC
0.195 – 0.30
(.0077 – .0118)
TYP
0.05 – 0.15
(.002 – .006)
FE20 (CA) TSSOP 0204
4. RECOMMENDED MINIMUM PCB METAL SIZE
FOR EXPOSED PAD ATTACHMENT
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.150mm (.006") PER SIDE
3113f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
23
LTC3113
TYPICAL APPLICATION
Pulsed Load or Portable RF Power Amplifier Application
2.2μH
VIN
3.3V
±10%
SW1
Typical Output Response
SW2
VIN
VOUT
4.7μF
47μF
845k
LTC3113
OFF ON
PWM BURST
RUN
FB
BURST
VC
SGND
4.7μF
VOUT
200mV/DIV
33pF
68k
RT
10k
200μF
VOUT
3.8V
0A TO 3A
220pF
PGND
ILOAD
2A/DIV
158k
100μs/DIV
3113 TA06a
90.9k
3113 TA06b
10pF
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC3112
15V, 2.5A (IOUT) Synchronous Buck-Boost DC/DC Converter
VIN: 2.7V to 15V, VOUT: 2.5V to 14V, IQ = 50μA, ISD < 1μA,
DFN Package
LTC3127
1A Buck-Boost DC/DC Converter with Programmable Input
Current Limit
VIN: 1.8V to 5.5V, VOUT: 1.8V to 5.25V, IQ = 35μA, ISD < 1μA,
DFN Package
LTC3531
200mA Buck-Boost Synchronous DC/DC Converter
VIN: 1.8V to 5.5V, VOUT = 3.3V, IQ =16μA, ISD < 1μA, DFN Package
LTC3533
2A (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter
VIN: 1.8V to 5.5V, VOUT : 1.8V to 5.25V, IQ = 40μA, ISD < 1μA,
DFN Package
LTC3534
7V, 500mA Synchronous Buck-Boost DC/DC Converter
VIN: 2.4V to 7V, VOUT : 1.8V to 7V, IQ = 25μA, ISD < 1μA,
DFN Package
LTC3440
600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter
VIN: 2.5V to 5.5V, VOUT : 2.5V to 5.25V, IQ = 25μA, ISD < 1μA,
MSOP and DFN Packages
LTC3441
1.2A (IOUT), 1MHz Synchronous Buck-Boost DC/DC Converter
VIN: 2.4V to 5.5V, VOUT : 2.4V to 5.25V, IQ = 25μA, ISD < 1μA,
DFN Package
LTC3442
1.2A (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter
with Programmable Burst Mode Operation
VIN: 2.4V to 5.5V, VOUT : 2.4V to 5.25V, IQ = 35μA, ISD < 1μA,
DFN Package
LTC3785
10V, High Efficiency, Synchronous, No RSENSE™ Buck-Boost
Controller
VIN: 2.7V to 10V, VOUT : 2.7V to 10V, IQ = 86μA, ISD < 15μA,
QFN Package
LTC3101
Wide VIN, Multi-Output DC/DC Converter and PowerPath™
Controller
VIN: 1.8V to 5.5V, VOUT : 1.5V to 5.25V, IQ = 38μA, ISD < 15μA,
QFN Package
LTC3530
Wide Input Voltage Synchronous Buck-Boost DC/DC Converter
VIN: 1.8V to 5.5V, VOUT : 1.8V to 5.25V, IQ = 40μA, ISD < 1μA,
DFN Package
3113f
24 Linear Technology Corporation
LT 1110 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2010