Linear Technology LTC 3115-1 User manual

LTC3115-1
1
Rev. C
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TYPICAL APPLICATION
FEATURES DESCRIPTION
40V, 2A Synchronous
Buck-Boost DC/DC
Converter
The LTC
®
3115-1is a high voltage monolithic synchronous
buck-boost DC/DC converter. Its wide 2.7V to 40V input
and output voltage ranges make it well suited to a wide
variety of automotive and industrial applications. A propri-
etary low noise switching algorithm optimizes efficiency
with input voltages that are above, below or even equal
to the output voltage and ensures seamless transitions
between operational modes.
Programmable frequency PWM mode operation pro-
vides low noise, high efficiency operation and the ability
to synchronize switching to an external clock. Switching
frequencies up to 2MHz are supported to allow use of
small value inductors for miniaturization of the appli-
cation circuit. Pin selectable Burst Mode operation
reduces standby current and improves light load effi-
ciency which, combined with a 3µA shutdown current,
make the LTC3115-1 ideally suited for battery-powered
applications. Additional features include output discon-
nect in shutdown, short-circuit protection and inter-
nal soft-start. The LTC3115-1 is available in thermally
enhanced 16-lead 4mm ×5mm ×0.75mm DFN and
20-lead TSSOP packages.
Efficiency vs VIN
APPLICATIONS
n Wide VIN Range: 2.7V to 40V
n Wide VOUT Range: 2.7V to 40V
n 1A Output Current for VIN ≥ 3.6V, VOUT = 5V
n 2A Output Current in Step-Down Operation
for VIN ≥ 6V
n Programmable Frequency: 100kHz to 2MHz
n Synchronizable Up to 2MHz with an External Clock
n Up to 95% Efficiency
n 30µA No-Load Quiescent Current in Burst Mode
®
Operation
n Ultralow Noise Buck-Boost PWM
n Internal Soft-Start
n 3µA Supply Current in Shutdown
n Programmable Input Undervoltage Lockout
n Small 4mm ×5mm ×0.75mm DFN Package
n Thermally Enhanced 20-Lead TSSOP Package
n AEC-Q100 Qualified for Automotive Applications
n 24V/28V Industrial Applications
n Automotive Power Systems
n Telecom, Servers and Networking Equipment
n FireWire Regulator
n Multiple Power Source Supplies
BST1 BST2
PVIN
VIN
VC
PVOUT
PWM/SYNC
FBRUN
PVCC
VCC RT
SW1 SW2
GND PGND
LTC3115-1
10µH
0.1µF
BURST PWM
2.7V TO
40V
0.1µF
33pF
(OPTIONAL)
5V
1A VIN > 3.6V
2A VIN ≥ 6V
4.7µF 47µF
1M
249k
4.7µF
3115 TA01a
47.5k
15k
60.4k3300pF
OFF ON
INPUT VOLTAGE (V)
EFFICIENCY (%)
95
90
85
31151 TA01b
70
80
75
40
2 10
ILOAD = 0.5A
ILOAD = 1A
VOUT = 5V
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents including 6404251, 6166527 and others pending.

LTC3115-1
2
Rev. C
For more information www.analog.com
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
VIN, PVIN, PVOUT........................................ –0.3V to 45V
VSW1
DC........................................... –0.3V to (PVIN + 0.3V)
Pulsed (<100ns)......................–1.5V to (PVIN + 1.5V)
VSW2
DC.........................................–0.3V to (PVOUT + 0.3V)
Pulsed (<100ns).................... –1.5V to (PVOUT + 1.5V)
VRUN ............................................. –0.3V to (VIN + 0.3V)
VBST1 .....................................VSW1 – 0.3V to VSW1 + 6V
VBST2 .....................................VSW2 – 0.3V to VSW2 + 6V
(Note 1)
VPWM/SYNC................................................... –0.3V to 6V
Voltage, All Other Pins ................................. –0.3V to 6V
Operating Junction Temperature Range (Notes 2, 4)
LTC3115E-1/LTC3115I-1 ..................... –40°C to 125°C
LTC3115H-1 ....................................... –40°C to 150°C
LTC3115MP-1..................................... –55°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
FE......................................................................300°C
16
15
14
13
12
11
10
9
PGND
17
1
2
3
4
5
6
7
8
PWM/SYNC
SW1
PVIN
BST1
BST2
PVCC
VIN
VCC
RUN
SW2
PVOUT
GND
GND
VC
FB
RT
TOP VIEW
DHD PACKAGE
16-LEAD (5mm ×4mm) PLASTIC DFN
TJMAX = 125°C, θJA = 43°C/W, θJC = 4.3°C/W
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
FE PACKAGE
20-LEAD PLASTIC TSSOP
TJMAX = 150°C, θJA = 38°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 21) IS PGND, MUST BE SOLDERED
TO PCB FOR RATED THERMAL PERFORMANCE
1
2
3
4
5
6
7
8
9
10
TOP VIEW
20
19
18
17
16
15
14
13
12
11
PGND
RUN
SW2
PVOUT
GND
GND
VC
FB
RT
PGND
PGND
PWM/SYNC
SW1
PVIN
BST1
BST2
PVCC
VIN
VCC
PGND
21
PGND

LTC3115-1
3
Rev. C
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ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL
PART
MARKING* PACKAGE DESCRIPTION
TEMPERATURE
RANGE
LTC3115EDHD-1#PBF LTC3115EDHD-1#TRPBF 31151 16-Lead (5mm ×4mm) Plastic DFN –40°C to 125°C
LTC3115IDHD-1#PBF LTC3115IDHD-1#TRPBF 31151 16-Lead (5mm ×4mm) Plastic DFN –40°C to 125°C
LTC3115EFE-1#PBF LTC3115EFE-1#TRPBF LTC3115FE-1 20-Lead Plastic TSSOP –40°C to 125°C
LTC3115IFE-1#PBF LTC3115IFE-1#TRPBF LTC3115FE-1 20-Lead Plastic TSSOP –40°C to 125°C
LTC3115HFE-1#PBF LTC3115HFE-1#TRPBF LTC3115FE-1 20-Lead Plastic TSSOP –40°C to 150°C
LTC3115MPFE-1#PBF LTC3115MPFE-1#TRPBF LTC3115FE-1 20-Lead Plastic TSSOP –55°C to 150°C
AUTOMOTIVE PRODUCTS**
LEAD FREE FINISH TAPE AND REEL TAPE AND REEL MINI
PART
MARKING* PACKAGE DESCRIPTION
TEMPERATURE
RANGE
LTC3115EDHD-1#WPBF LTC3115EDHD-1#WTRPBF LTC3115EDHD-1#WTRMPBF 31151 16-Lead (5mm ×4mm) Plastic DFN –40°C to 125°C
LTC3115IDHD-1#WPBF LTC3115IDHD-1#WTRPBF LTC3115IDHD-1#WTRMPBF 31151 16-Lead (5mm ×4mm) Plastic DFN –40°C to 125°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
**Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These
models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your
local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for
thesemodels.
The ldenotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are for TA= 25°C (Note 2). PVIN = VIN = 24V, PVOUT = 5V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Operating Voltage l2.7 40 V
Output Operating Voltage l2.7 40 V
Input Undervoltage Lockout Threshold VIN Falling
VIN Rising
VIN Rising (0°C to 125°C)
l
l
2.4
2.6 2.7 2.8
2.725
V
V
V
Input Undervoltage Lockout Hysteresis 100 mV
VCC Undervoltage Lockout Threshold VCC Falling l2.4 2.6 V
VCC Undervoltage Lockout Hysteresis 200 mV
Input Current in Shutdown VRUN = 0V 3 10 µA
Input Quiescent Current in Burst Mode Operation VFB = 1.1V (Not Switching), VPWM/SYNC = Low 50 µA
Oscillator Frequency RT = 35.7k, VPWM/SYNC = High l900 1000 1100 kHz
Oscillator Operating Frequency VPWM/SYNC = High l100 2000 kHz
PWM/SYNC Clock Input Frequency l100 2000 kHz
PWM/SYNC Input Logic Threshold l0.5 1.0 1.5 V
Soft-Start Duration 9 ms
Feedback Voltage l977 1000 1017 mV
Feedback Voltage Line Regulation VIN = 2.7V to 40V 0.1 %
Feedback Pin Input Current 1 50 nA
RUN Pin Input Logic Threshold l0.3 0.8 1.1 V
RUN Pin Comparator Threshold VRUN Rising l1.16 1.21 1.26 V

RUN Pin Hysteresis Current 500 nA
RUN Pin Hysteresis Voltage 100 mV
Inductor Current Limit (Note 3) l2.4 3.0 3.7 A
Reverse Inductor Current Limit Current into PVOUT (Note 3) 1.5 A
Burst Mode Inductor Current Limit (Note 3) 0.65 1.0 1.35 A
Maximum Duty Cycle Percentage of Period SW2 is Low in Boost Mode,
RT= 35.7k (Note 5)
l90 95 %
Minimum Duty Cycle Percentage of Period SW1 is High in Buck Mode,
RT= 35.7k (Note 5)
l0 %
SW1, SW2 Minimum Low Time RT= 35.7k (Note 5) 100 ns
N-Channel Switch Resistance Switch A (From PVIN to SW1)
Switch B (From SW1 to PGND)
Switch C (From SW2 to PGND)
Switch D (From PVOUT to SW2)
150
150
150
150
mΩ
mΩ
mΩ
mΩ
N-Channel Switch Leakage PVIN = PVOUT = 40V 0.1 10 µA
PVCC/VCC External Forcing Voltage 4.58 5.5 V
VCC Regulation Voltage IVCC = 1mA 4.33 4.45 4.58 V
VCC Load Regulation IVCC = 1mA to 20mA 1.2 %
VCC Line Regulation IVCC = 1mA, VIN = 5V to 40V 0.5 %
VCC Current Limit VCC = 2.5V 50 110 mA
VCC Dropout Voltage IVCC = 5mA, VIN = 2.7V 50 mV
VCC Reverse Current VCC = 5V, VIN = 3.6V 10 µA
LTC3115-1
4
Rev. C
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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 LTC3115-1 is tested under pulsed load conditions such
that TJ≈ TA. The LTC3115E-1 is guaranteed to meet specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are ensured by design,
characterization and correlation with statistical process controls. The
LTC3115I-1 specifications are guaranteed over the –40°C to 125°C
operating junction temperature range. The LTC3115H-1 specifications are
guaranteed over the –40°C to 150°C operating junction temperature range.
The LTC3115MP-1 specifications are guaranteed over the –55°C to 150°C
operating junction temperature range. High junction temperatures degrade
operating lifetime;operating lifetime is derated for junction temperatures
greater than 125°C. The maximum ambient temperature consistent with
these specifications is determined by specific operating conditions in
conjunction with board layout, the rated package thermal resistance and
other environmental factors.
The junction temperature (TJin °C) is calculated from the ambient
temperature (TAin °C) and power dissipation (PDin Watts) according to
the following formula:
TJ= TA+ (PD• θJA)
where θJA is the thermal impedance of the package.
Note 3: Current measurements are performed when the LTC3115-1 is
not switching. The current limit values measured in operation will be
somewhat higher due to the propagation delay of the comparators.
Note 4: 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 this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 5: Switch timing measurements are made in an open-loop test
configuration. Timing in the application may vary somewhat from these
values due to differences in the switch pin voltage during the non-overlap
durations when switch pin voltage is influenced by the magnitude and
direction of the inductor current.
The ldenotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are for TA= 25°C (Note 2). PVIN = VIN = 24V, PVOUT = 5V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS

LTC3115-1
5
Rev. C
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
PWM Mode Efficiency, VOUT = 5V,
fSW = 1MHz, Non-Bootstrapped
PWM Mode Efficiency,
VOUT = 12V, fSW = 1MHz
PWM Mode Efficiency,
VOUT = 24V, fSW = 1MHz
PWM Mode Efficiency, VOUT = 5V,
fSW = 500kHz, Non-Bootstrapped
PWM Mode Efficiency,
VOUT = 12V, fSW = 500kHz
PWM Mode Efficiency,
VOUT = 24V, fSW = 500kHz
(TA= 25°C unless otherwise specified)
LOAD CURRENT (A)
0.01
60
EFFICIENCY (%)
80
100
0.10 1
31151 G01
40
50
70
90
30
20
VIN = 3.6V
VIN = 5V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (A)
0.01
70
EFFICIENCY (%)
80
90
100
0.1 1
31151 G02
60
50
40
30
VIN = 5V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (A)
0.01
70
EFFICIENCY (%)
80
90
0.1 1
31151 G03
60
30
50
40
100
VIN = 12V
VIN = 18V
VIN = 24V
VIN = 36V
LOAD CURRENT (A)
0.01
60
EFFICIENCY (%)
80
100
0.1 1
31151 G04
40
50
70
90
30
20
VIN = 3.6V
VIN = 5V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (A)
0.01
70
EFFICIENCY (%)
80
90
100
0.1 1
31151 G05
60
50
40
30
VIN = 5V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (A)
0.01
70
EFFICIENCY (%)
80
90
0.1 1
31151 G06
60
30
40
50
100
VIN = 12V
VIN = 18V
VIN = 24V
VIN = 36V

LTC3115-1
6
Rev. C
For more information www.analog.com
Burst Mode Efficiency, VOUT = 5V,
L = 15µH, Non-Bootstrapped
Burst Mode Efficiency,
VOUT = 12V, L = 15µH
Burst Mode Efficiency,
VOUT = 24V, L = 15µH
TYPICAL PERFORMANCE CHARACTERISTICS
(TA= 25°C unless otherwise specified)
Maximum Load Current
vs VIN, Burst Mode Operation
Burst Mode No-Load Input
Current vs VIN
PWM Mode No-Load Input
Current vs VIN
Maximum Load Current
vs VIN, PWM Mode
Maximum Load Current
vs VIN, PWM Mode
Maximum Load Current
vs VIN, PWM Mode
LOAD CURRENT (mA)
0.1
70
EFFICIENCY (%)
80
90
1 10 100
31151 G07
60
65
75
85
55
50
VIN = 3.6V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (mA)
0.1
70
EFFICIENCY (%)
80
95
90
1 10 100
31151 G08
60
65
75
85
55
50
VIN = 5V
VIN = 12V
VIN = 24V
VIN = 36V
LOAD CURRENT (mA)
0.1
70
EFFICIENCY (%)
80
90
1 10 100
31151 G09
60
65
75
85
55
50
VIN = 12V
VIN = 18V
VIN = 24V
VIN = 36V
INPUT VOLTAGE (V)
2
0
INPUT CURRENT (µA)
100
200
400
10 40
31151 G10
300
50
150
350
250
VOUT = 24V
VOUT = 15V
VOUT = 5V
VOUT = 5V, BOOTSTRAPPED
INPUT VOLTAGE (V)
2
0
INPUT CURRENT (mA)
10
20
30
40
10 40
31151 G11
50
5
15
25
35
45 VOUT = 24V
VOUT = 12V
VOUT = 5V
fSW = 1MHz
INPUT VOLTAGE (V)
LOAD CURRENT (A)
2.5
2.0
1.5
31151 G12
0
1.0
0.5
40
2 10
L = 22µH
fSW = 500kHz
VOUT = 24V
VOUT = 12V
VOUT = 5V
INPUT VOLTAGE (V)
2 10
10
LOAD CURRENT (mA)
100
1000
40
31151 G13
L = 22µH
VOUT = 32V
VOUT = 12V
VOUT = 5V
INPUT VOLTAGE (V)
LOAD CURRENT (A)
2.5
2.0
1.5
31151 G47
0
1.0
0.5
40
2 10
L = 15µH
fSW = 1MHz
VOUT = 24V
VOUT = 12V
VOUT = 5V
INPUT VOLTAGE (V)
LOAD CURRENT (A)
2.5
2.0
1.5
31151 G48
0
1.0
0.5
40
2 10
L = 5.2µH
fSW = 2MHz
VOUT = 12V
VOUT = 5V

LTC3115-1
7
Rev. C
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
Combined VCC/PVCC Supply
Current vs VCC
Combined VCC/PVCC Supply
Current vs Temperature Output Voltage Load Regulation
VCC Regulator Load Regulation
(TA= 25°C unless otherwise specified)
VCC Regulator Line Regulation
Output Voltage Line Regulation
VCC Voltage vs Temperature
VCC (V)
2.5
VCC/PVCC CURRENT (mA)
6
8
10
45
31151 G16
4
2
03 3.5 4.5
12
14
16
5.5
fSW = 1MHz
fSW = 500kHz
TEMPERATURE (°C)
–50
11.0
VCC/PVCC CURRENT (mA)
11.1
11.3
11.4
11.5
12.0
11.7
050
31151 G17
11.2
11.8
11.9
11.6
100 150
VIN = 6V
VOUT = 5V
fSW = 1MHz
INPUT VOLTAGE (V)
0
–0.5
CHANGE IN OUTPUT VOLTAGE FROM VIN = 20V (%)
–0.4
–0.2
–0.1
0
0.5
0.2
10 20
31151 G19
–0.3
0.3
0.4
0.1
30 40
TEMPERATURE (°C)
–50
–1.0
CHANGE FROM 25°C (%)
–0.8
–0.4
–0.2
0
1.0
0.4
050
31151 G20
–0.6
0.6
0.8
0.2
100 150
INPUT VOLTAGE (V)
0
–1.0
CHANGE FROM V
IN
= 24V (%)
–0.8
–0.4
–0.2
0
1.0
0.4
10 20
31151 G22
–0.6
0.6
0.8
0.2
30 40
LOAD CURRENT (A)
0
–0.5
CHANGE IN VOLTAGE FROM ZERO LOAD (%)
–0.4
–0.2
–0.1
0
0.5
0.2
0.5 1
31151 G18
–0.3
0.3
0.4
0.1
1.5 2
ICC (mA)
0
CHANGE IN VOLTAGE FROM I
CC
= 0mA (%)
–1.0
–0.5
0
40
31151 G21
–1.5
–2.0
–2.5 10 20 30 50
Efficiency vs Switching Frequency
Combined VCC/PVCC Supply
Current vs Switching Frequency
SWITCHING FREQUENCY (kHz)
0
EFFICIENCY (%)
80
85
2000
31151 G14
75
70 500 1000 1500
95
90
BOOTSTRAPPED
PWM MODE
L = 47µH
VIN = 24V
VOUT = 5V
ILOAD = 0.5A
NON-BOOTSTRAPPED
SWITCHING FREQUENCY (kHz)
0
20
25
35
1500
31151 G15
15
10
500 1000 2000
5
0
30
VCC/PVCC CURRENT (mA)
VIN = 36V
VOUT = 24V
VIN = 12V
VOUT = 5V

LTC3115-1
8
Rev. C
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
VCC Regulator Dropout Voltage
vs Temperature
RUN Pin Threshold
vs Temperature
RUN Pin Hysteresis Current
vs Temperature
Oscillator Frequency vs RT
Oscillator Frequency
vs Temperature
(TA= 25°C unless otherwise specified)
Power Switch Resistance
vs Temperature
Oscillator Frequency vs VIN
RUN Pin Current
vs RUN Pin Voltage
Shutdown Current on VIN/PVIN
vs Input Voltage
TEMPERATURE (°C)
–50
DROPOUT VOLTAGE (V)
0.10
0.15
150
31151 G23
0.05
0050 100
0.25
0.20
VIN = 4V
IVCC = 20mA
TEMPERATURE (°C)
–50
–1.0
CHANGE FROM 25°C (%)
–0.8
–0.4
–0.2
0
1.0
0.4
050
31151 G24
–0.6
0.6
0.8
0.2
100 150
TEMPERATURE (°C)
–50
CHANGE FROM 25°C (%)
0
0.5
1.0
150
31151 G25
–0.5
–1.0
–2.0 050 100
–1.5
2.0
1.5
RT(kΩ)
10
100
SWITCHING FREQUENCY (kHz)
1000
10000
100 1000
31151 G26
TEMPERATURE (°C)
–50
CHANGE FROM 25°C (%)
0
0.5
1.0
150
31151 G27
–0.5
–1.0
–2.0 050 100
–1.5
2.0
1.5
fSW = 1MHz
VIN (V)
2
–2.0
CHANGE FROM VIN = 24V (%)
–1.0
0
2.0
10 40
31151 G28
1.0
–1.5
–0.5
1.5
0.5
fSW = 1MHz
RUN PIN VOLTAGE (V)
0
CURRENT INTO RUN PIN (µA)
3
4
5
40
31151 G29
2
1
–1 10 20 30
0
7VIN = 40V
6
INPUT VOLTAGE (V)
0
0
COMBINED V
IN
/PV
IN
CURRENT (µA)
0.5
1.0
1.5
2.0
2.5
3.0
VRUN = 0V
10 20 30 40
31151 G30
TEMPERATURE (°C)
–50
0
POWER SWITCH (A-D) RESISTANCE (mΩ)
50
100
150
200
250
300
0 50 100 150
31151 G31

LTC3115-1
9
Rev. C
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
Inductor Current Limit Thresholds
vs Temperature
(TA= 25°C unless otherwise specified)
SW1, SW2 Minimum Low Time
vs VCC
SW1, SW2 Minimum Low Time
vs Switching Frequency
SW2 Maximum Duty Cycle
vs Switching Frequency
Die Temperature Rise vs Load
Current, VOUT = 5V, fSW = 750kHz
Die Temperature Rise vs Load
Current, VOUT = 5V, fSW = 1.5MHz
SW1, SW2 Minimum Low Time
vs Temperature
TEMPERATURE (°C)
–50
–5
CHANGE FROM 25°C (%)
–4
–2
–1
0
5
2
050
31151 G34
–3
3
4
1
100 150
SWA
CURRENT
LIMIT
SWB
CURRENT
LIMIT
TEMPERATURE (°C)
–50
90
MINIMUM LOW TIME (ns)
92
96
98
100
110
104
050
31151 G35
94
106
108
102
100 150
fSW = 1MHz
NO LOAD
VCC (V)
2.5
60
MINIMUM LOW TIME (ns)
80
100
120
140
180
33.5 4 4.5
31151 G36
5 5.5
160
fSW = 300kHz
fSW = 1MHz
fSW = 2MHz
SWITCHING FREQUENCY (kHz)
0
140
160
200
1500
31151 G37
120
100
500 1000 2000
80
60
180
MINIMUM LOW TIME (ns)
VCC = 2.7V
VCC = 4.4V
SWITCHING FREQUENCY (kHz)
0
MAXIMUM DUTY CYCLE (%)
92
93
2000
31151 G38
91
90 500 1000 1500
95
94
Power Switch Resistance
vs VCC FB Voltage vs Temperature
VCC (V)
2.5
140
POWER SWITCH (A-D) RESISTANCE (mΩ)
145
150
155
160
170
33.5 4 4.5
31151 G32
5 5.5
165
TEMPERATURE (°C)
–50
–1.0
CHANGE FROM 25°C (%)
–0.8
–0.4
–0.2
0
1.0
0.4
050
31151 G33
–0.6
0.6
0.8
0.2
100 150
LOAD CURRENT (A)
0
0
DIE TEMPERATURE CHANGE FROM AMBIENT (°C)
10
20
30
40
50
60
0.5 1 1.5 2
31151 G49
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 6V
VIN = 3.6V
STANDARD DEMO PCB
L = 15µH MSS1048
LOAD CURRENT (A)
0
0
DIE TEMPERATURE CHANGE FROM AMBIENT (°C)
10
20
30
50
70
100
90
40
60
80
0.5 1 1.5
2
31151 G50
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 6V
VIN = 3.6V
STANDARD DEMO PCB
L = 15µH MSS1048

LTC3115-1
10
Rev. C
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
Die Temperature Rise vs Load
Current, VOUT = 12V, fSW = 750kHz
Load Transient (0A to 1A),
VIN = 24V, VOUT = 5V
Load Transient (0A to 1A),
VIN = 3.6V, VOUT = 5V
Output Voltage Ripple in
Burst Mode Operation,
VIN = 24V, VOUT = 5V
(TA= 25°C unless otherwise specified)
Phase-Locked Loop Acquisition,
VIN = 24V 1.2MHz Clock
Phase-Locked Loop Release,
VIN = 24V, 1.2MHz Clock
Soft-Start Waveforms
Burst Mode Operation to PWM
Mode Output Voltage Transient
Output Voltage Ripple in PWM
Mode, VIN = 24V, VOUT = 5V
VOUT
(200mV/DIV)
LOAD
CURRENT
(1A/DIV)
FRONT PAGE
APPLICATION 200µs/DIV 31151 G39
INDUCTOR
CURRENT
(1A/DIV)
VOUT
(200mV/DIV)
LOAD
CURRENT
(1A/DIV)
FRONT PAGE
APPLICATION 200µs/DIV 31151 G40
INDUCTOR
CURRENT
(2A/DIV)
VOUT
(50mV/DIV)
L = 15µH
COUT = 22µF
ILOAD = 25mA
20µs/DIV 31151 G41
INDUCTOR
CURRENT
(0.5A/DIV)
VOUT
(5mV/DIV)
L = 22µH
COUT = 22µF
ILOAD = 2A
fSW = 750kHz
1µs/DIV 31151 G43
INDUCTOR
CURRENT
(100mA/DIV)
VPWM/SYNC
(5V/DIV)
VOUT
(200mV/DIV)
FRONT PAGE
APPLICATION 50µs/DIV 31151 G45
INDUCTOR
CURRENT
(1A/DIV)
VPWM/SYNC
(5V/DIV)
VOUT
(200mV/DIV)
FRONT PAGE
APPLICATION 50µs/DIV 31151 G46
INDUCTOR
CURRENT
(1A/DIV)
VOUT
(2V/DIV)
VRUN
(5V/DIV)
VCC
(2V/DIV)
FRONT PAGE
APPLICATION
2ms/DIV
31151 G42
INDUCTOR
CURRENT
(1A/DIV)
VOUT
(200mV/DIV)
VPWM/SYNC
(5V/DIV)
FRONT PAGE
APPLICATION
500µs/DIV
31151 G44
INDUCTOR
CURRENT
(1A/DIV)
LOAD CURRENT (A)
0
0
DIE TEMPERATURE CHANGE FROM AMBIENT (°C)
10
20
30
50
70
80
40
60
0.5 1 1.5
2
31151 G51
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 6V
STANDARD DEMO PCB
L = 15µH MSS1048