LTC3639
High Efficiency, 150V
100mA Synchronous
Step-Down Regulator
FEATURES
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DESCRIPTION
The
LTC
®
3639
is a high efficiency step-down DC/DC
regulator with internal high side and synchronous power
switches that draws only 12μA typical DC supply current
while maintaining a regulated output voltage at no load.
The LTC3639 can supply up to 100mA load current and
features a programmable peak current limit that provides
a simple method for optimizing efficiency and for reduc-
ing output ripple and component size. The LTC3639’s
combination of Burst Mode
®
operation, integrated power
switches, low quiescent current, and programmable peak
current limit provides high efficiency over a broad range
of load currents.
With its wide input range of 4V to 150V and programmable
overvoltage lockout, the LTC3639 is a robust regulator
suited for regulating from a wide variety of power sources.
Additionally, the LTC3639 includes a precise run threshold
and soft-start feature to guarantee that the power system
start-up is well-controlled in any environment.
The LTC3639 is available in a thermally enhanced high
voltage-capable 16-lead MSE package with four missing pins.
L,
LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
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Wide Operating Input Voltage Range: 4V to 150V
Synchronous Operation for Highest Efficiency
Internal High Side and Low Side Power MOSFETs
No Compensation Required
Adjustable 10mA to 100mA Maximum Output
Current
Low Dropout Operation: 100% Duty Cycle
Low Quiescent Current: 12µA
Wide Output Range: 0.8V to V
IN
0.8V ±1% Feedback Voltage Reference
Precise RUN Pin Threshold
Internal or External Soft-Start
Programmable 1.8V, 3.3V, 5V or Adjustable Output
Few External Components Required
Programmable Input Overvoltage Lockout
Thermally Enhanced High Voltage MSOP Package
APPLICATIONS
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Industrial Control Supplies
Medical Devices
Distributed Power Systems
Portable Instruments
Battery-Operated Devices
Automotive
Avionics
TYPICAL APPLICATION
5V to 150V Input to 5V Output, 100mA Step-Down Regulator
1µF
200V
V
IN
SW
470µH
LTC3639
RUN
V
FB
OVLO
V
PRG2
SS
V
PRG1
3639 TA01a
Efficiency and Power Loss vs Load Current
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.1
1
10
LOAD CURRENT (mA)
1
100
3639 TA01b
V
OUT
= 5V
EFFICIENCY
V
IN
5V TO 150V
V
OUT
5V
10µF 100mA
V
IN
= 12V
V
IN
= 36V
V
IN
= 72V
V
IN
= 150V
POWER LOSS
1000
POWER LOSS (mW)
100
10
GND
3639fc
For more information
www.linear.com/LTC3639
1
LTC3639
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
SW 1
V
IN
3
FBO
V
PRG2
V
PRG1
GND
5
6
7
8
17
GND
16 GND
14 RUN
12
11
10
9
OVLO
I
SET
SS
V
FB
V
IN
Supply Voltage ................................... –0.3V to 150V
RUN Voltage............................................. –0.3V to 150V
SS, FBO, OVLO, I
SET
Voltages ...................... –0.3V to 6V
V
FB
, V
PRG1
, V
PRG2
Voltages ......................... –0.3V to 6V
Operating Junction Temperature Range (Notes 2, 3)
LTC3639E, LTC3639I ......................... –40°C to 125°C
LTC3639H .......................................... –40°C to 150°C
LTC3639MP ....................................... –55°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
MSE PACKAGE
VARIATION: MSE16 (12)
16-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 40°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3639EMSE#PBF
LTC3639IMSE#PBF
LTC3639HMSE#PBF
LTC3639MPMSE#PBF
TAPE AND REEL
LTC3639EMSE#TRPBF
LTC3639IMSE#TRPBF
LTC3639HMSE#TRPBF
LTC3639MPMSE#TRPBF
PART MARKING*
3639
3639
3639
3639
PACKAGE DESCRIPTION
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°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/
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, unless otherwise noted.
SYMBOL
V
IN
V
OUT
UVLO
PARAMETER
Input Voltage Operating Range
Output Voltage Operating Range
V
IN
Undervoltage Lockout
DC Supply Current (Note 4)
Active Mode
Sleep Mode
Shutdown Mode
RUN Pin Threshold
V
IN
Rising
V
IN
Falling
Hysteresis
l
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
4
0.8
3.5
3.3
TYP
MAX
150
V
IN
UNITS
V
V
V
V
mV
µA
µA
µA
V
V
mV
nA
V
V
mV
3639fc
Input Supply (V
IN
)
3.75
3.5
250
150
12
1.4
4.0
3.8
I
Q
No Load
V
RUN
= 0V
RUN Rising
RUN Falling
Hysteresis
RUN = 1.3V
OVLO Rising
OVLO Falling
Hysteresis
1.17
1.06
–10
1.17
1.06
350
22
6
1.25
1.14
10
1.25
1.14
V
RUN
I
RUN
V
OVLO
1.21
1.10
110
0
1.21
1.10
110
RUN Pin Leakage Current
OVLO Pin Threshold
2
For more information
www.linear.com/LTC3639
LTC3639
ELECTRICAL CHARACTERISTICS
SYMBOL
V
FB(ADJ)
V
FBH
I
FB
V
FB(FIXED)
PARAMETER
Feedback Comparator Threshold
(Adjustable Output)
Feedback Comparator Hysteresis
(Adjustable Output)
Feedback Pin Current
Feedback Comparator Thresholds
(Fixed Output)
Output Supply (V
FB
)
V
FB
Rising, V
PRG1
= V
PRG2
= 0V
LTC3639E, LTC3639I
LTC3639H, LTC3639MP
V
FB
Falling, V
PRG1
= V
PRG2
= 0V
V
FB
= 1V, V
PRG1
= V
PRG2
= 0V
V
FB
Rising, V
PRG1
= SS, V
PRG2
= 0V
V
FB
Falling, V
PRG1
= SS, V
PRG2
= 0V
V
FB
Rising, V
PRG1
= 0V, V
PRG2
= SS
V
FB
Falling, V
PRG1
= 0V, V
PRG2
= SS
V
FB
Rising, V
PRG1
= V
PRG2
= SS
V
FB
Falling, V
PRG1
= V
PRG2
= SS
Operation
I
PEAK
R
ON
I
LSW
I
SS
t
INT(SS)
Peak Current Comparator Threshold
I
SET
Floating
100k Resistor from I
SET
to GND
I
SET
Shorted to GND
I
SW
= –50mA
I
SW
= 50mA
V
IN
= 150V, SW = 0V
V
SS
< 2.5V
SS Pin Floating
4
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The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
0.792
0.788
3
–10
4.94
4.91
3.26
3.24
1.78
1.77
200
100
17
0.800
0.800
5
0
5.015
4.985
3.31
3.29
1.81
1.80
230
120
25
4.2
2.2
0.1
5
1
0.808
0.812
9
10
5.09
5.06
3.36
3.34
1.84
1.83
260
140
30
V
V
mV
nA
V
V
V
V
V
V
mA
mA
mA
Ω
Ω
Power Switch On-Resistance
Top Switch
Bottom Switch
Switch Pin Leakage Current
Soft-Start Pin Pull-Up Current
Internal Soft-Start Time
1
6
μA
μA
ms
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 LTC3639 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3639E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3639I is guaranteed
over the –40°C to 125°C operating junction temperature range, the
LTC3639H is guaranteed over the –40°C to 150°C operating junction
temperature range and the LTC3639MP is tested and guaranteed over the
–55°C to 150°C operating junction temperature range.
High junction temperatures degrade operating lifetimes; operating lifetime
is derated for junction temperatures greater than 125°C. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors.
Note 3:
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
θ
JA
)
where
θ
JA
is 40°C/W for the MSOP package.
Note that the maximum ambient temperature consistent with these
specifications is determined by specific operating conditions in
conjunction with board layout, the rated package thermal impedance and
other environmental factors.
Note 4:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
3639fc
For more information
www.linear.com/LTC3639
3
LTC3639
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current,
V
OUT
= 5V
100
90
80
EFFICIENCY (%)
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.1
I
SET
OPEN
FIGURE 13 CIRCUIT
V
IN
= 12V
V
IN
= 36V
V
IN
= 72V
V
IN
= 150V
1
10
LOAD CURRENT (mA)
100
3639 G01
Efficiency vs Load Current,
V
OUT
= 3.3V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.1
I
SET
OPEN
FIGURE 13 CIRCUIT
V
IN
= 12V
V
IN
= 36V
V
IN
= 72V
V
IN
= 150V
1
10
LOAD CURRENT (mA)
100
3639 G02
Efficiency vs Load Current,
V
OUT
= 1.8V
100
90
80
70
60
50
40
30
20
10
0
0.1
I
SET
OPEN
FIGURE 13 CIRCUIT
V
IN
= 12V
V
IN
= 36V
V
IN
= 72V
V
IN
= 150V
1
10
LOAD CURRENT (mA)
100
3639 G03
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
Efficiency vs Input Voltage,
V
OUT
= 5V
I
SET
OPEN
FIGURE 13 CIRCUIT
THRESHOLD VOLTAGE (V)
Feedback Comparator Trip
Threshold vs Temperature
802
RUN OR OVLO THRESHOLD VOLTAGE (V)
1.24
1.22
1.20
1.18
1.16
1.14
1.12
1.10
1.08
RUN and OVLO Comparator
Threshold vs Temperature
RISING
801
800
799
FALLING
I
LOAD
= 100mA
I
LOAD
= 10mA
I
LOAD
= 1mA
0
25
75
50
100
V
IN
VOLTAGE (V)
125
150
3639 G04
798
–55
–25
95
5
35
65
TEMPERATURE (°C)
125
155
1.06
–55 –25
3639 G05
65
35
95
5
TEMPERATURE (°C)
125
155
3639 G06
Peak Current Trip Threshold
vs R
ISET
250
PEAK CURRENT TRIP THRESHOLD (mA)
200
PEAK CURRENT (mA)
150
100
50
0
300
250
200
150
100
50
Peak Current Trip Threshold
vs Temperature
300
I
SET
OPEN
PEAK CURRENT (mA)
250
200
150
100
50
0
Peak Current Trip Threshold
vs Input Voltage
I
SET
OPEN
R
ISET
= 100k
R
ISET
= 100k
I
SET
= GND
–25
65
95
5
35
TEMPERATURE (°C)
125
155
I
SET
= GND
0
30
60
90
120
150
3639 G09
0
25
50
75
100 125 150 175 200
R
ISET
(k )
3639 G07
0
–55
3639 G08
V
IN
VOLTAGE (V)
4
3639fc
For more information
www.linear.com/LTC3639
LTC3639
TYPICAL PERFORMANCE CHARACTERISTICS
Quiescent Supply Current
vs Input Voltage
15
30
25
V
IN
SUPPLY CURRENT (µA)
20
15
10
5
0
–55
SLEEP
Quiescent Supply Current
vs Temperature
V
IN
= 150V
SWITCH LEAKAGE CURRENT (µA)
8
7
6
5
4
3
2
1
0
–1
125
155
Switch Leakage Current
vs Temperature
V
IN
= 150V
V
IN
SUPPLY CURRENT (µA)
SLEEP
10
5
SHUTDOWN
0
0
30
60
90
V
IN
VOLTAGE (V)
150
3639 G10
SW = 150V
SHUTDOWN
–25
65
35
5
95
TEMPERATURE (°C)
SW = 0V
5
95
65
35
TEMPERATURE (°C)
125
155
120
–2
–55 –25
3639 G12
3639 G11
Switch On-Resistance
vs Input Voltage
7
6
5
TOP
4
3
BOTTOM
2
1
8
7
SWITCH ON-RESISTANCE ( )
6
5
4
Switch On-Resistance
vs Temperature
OUTPUT
VOLTAGE
50mV/DIV
TOP
LOAD
CURRENT
50mA/DIV
Load Step Transient Response
SWITCH ON-RESISTANCE ( )
BOTTOM
3
2
V
IN
= 48V
200µs/DIV
V
OUT
= 3.3V
1mA TO 100mA LOAD STEP
FIGURE 14 CIRCUIT
3639 G15
0
30
60
90
V
IN
VOLTAGE (V)
120
150
3639 G13
1
–55 –25
5
65
95
35
TEMPERATURE (°C)
125
155
3639 G14
Operating Waveforms, V
IN
= 48V
OUTPUT
VOLTAGE
50mV/DIV
SWITCH
VOLTAGE
20V/DIV
INDUCTOR
CURRENT
200mA/DIV
V
IN
= 48V
10µs/DIV
V
OUT
= 3.3V
I
OUT
= 100mA
FIGURE 14 CIRCUIT
3639 G16
Operating Waveforms, V
IN
= 150V
OUTPUT
VOLTAGE
50mV/DIV
SWITCH
VOLTAGE
50V/DIV
INDUCTOR
CURRENT
200mA/DIV
V
IN
= 150V
10µs/DIV
V
OUT
= 3.3V
I
OUT
= 50mA
FIGURE 14 CIRCUIT
3639 G17
Short-Circuit and Recovery
OUTPUT
VOLTAGE
1V/DIV
INDUCTOR
CURRENT
100mA/DIV
500µs/DIV
FIGURE 14 CIRCUIT
3639 G18
3639fc
For more information
www.linear.com/LTC3639
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