LINER LTC3588EDD

LTC3588-1
Piezoelectric Energy
Harvesting Power Supply
FEATURES
DESCRIPTION
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The LTC®3588-1 integrates a low-loss full-wave bridge
rectifier with a high efficiency buck converter to form a
complete energy harvesting solution optimized for high
output impedance energy sources such as piezoelectric
transducers. An ultralow quiescent current undervoltage
lockout (UVLO) mode with a wide hysteresis window allows
charge to accumulate on an input capacitor until the buck
converter can efficiently transfer a portion of the stored
charge to the output. In regulation, the LTC3588-1 enters
a sleep state in which both input and output quiescent
currents are minimal. The buck converter turns on and
off as needed to maintain regulation.
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950nA Input Quiescent Current (Output in
Regulation – No Load)
450nA Input Quiescent Current in UVLO
2.7V to 20V Input Operating Range
Integrated Low-Loss Full-Wave Bridge Rectifier
Up to 100mA of Output Current
Selectable Output Voltages of 1.8V, 2.5V, 3.3V, 3.6V
High Efficiency Integrated Hysteretic Buck DC/DC
Input Protective Shunt – Up to 25mA Pull-Down at
VIN ≥ 20V
Wide Input Undervoltage Lockout (UVLO) Range
Available in 10-Lead MSE and 3mm × 3mm DFN
Packages
APPLICATIONS
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Piezoelectric Energy Harvesting
Electro-Mechanical Energy Harvesting
Wireless HVAC Sensors
Mobile Asset Tracking
Tire Pressure Sensors
Battery Replacement for Industrial Sensors
Remote Light Switches
Standalone Nanopower Buck Regulator
Four output voltages, 1.8V, 2.5V, 3.3V and 3.6V, are pin
selectable with up to 100mA of continuous output current;
however, the output capacitor may be sized to service a
higher output current burst. An input protective shunt set
at 20V enables greater energy storage for a given amount
of input capacitance.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
100mA Piezoelectric Energy Harvesting Power Supply
LTC3588-1 3.3V Regulator Start-Up Profile
22
CSTORAGE = 22μF, COUT = 47μF
20 NO LOAD, IVIN = 2μA
18
ADVANCED CERAMETRICS PFC-W14
1μF
6V
CSTORAGE
25V
4.7μF
6V
PZ2
VIN
SW
LTC3588-1
10μH
VOUT
47μF
6V
VOUT
CAP
PGOOD
VIN2
D0, D1
GND
35881 TA01
2
OUTPUT
VOLTAGE
SELECT
VOLTAGE (V)
16
PZ1
14
VIN
12
10
8
6
VOUT
4
2
0
PGOOD = LOGIC 1
0
200
400
TIME (s)
600
35881 TA01b
35881f
1
LTC3588-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN
Low Impedance Source ....................... –0.3V to 18V*
Current Fed, ISW = 0A ...................................... 25mA†
PZ1, PZ2 ...........................................................0V to VIN
D0, D1.............. –0.3V to [Lesser of (VIN2 + 0.3V) or 6V]
CAP ......................[Higher of –0.3V or (VIN – 6V)] to VIN
VIN2 ....................–0.3V to [Lesser of (VIN + 0.3V) or 6V]
* VIN has an internal 20V clamp
† For t < 1ms and Duty Cycle < 1%,
Absolute Maximum Continuous Current = 5mA
VOUT ....................–0.3V to Lesser of (VIN2 + 0.3V) or 6V
PGOOD...............–0.3V to Lesser of (VOUT + 0.3V) or 6V
IPZ1, IPZ2 ..............................................................±50mA
ISW .......................................................................350mA
Operating Junction Temperature Range
(Notes 2, 3) ................................................–40 to 125°C
Storage Temperature Range.......................–65 to 125°C
Lead Temperature (Soldering, 10 sec)
MSE Only .......................................................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
10 PGOOD
PZ1
1
PZ2
2
CAP
3
VIN
4
7 VIN2
SW
5
6 VOUT
11
GND
PZ1
PZ2
CAP
VIN
SW
9 D0
8 D1
1
2
3
4
5
11
GND
10
9
8
7
6
PGOOD
D0
D1
VIN2
VOUT
MSE PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm s 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 43°C/W, θJC = 7.5°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
TJMAX = 125°C, θJA = 45°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3588EDD-1#PBF
LTC3588EDD-1#TRPBF
LFKY
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC3588IDD-1#PBF
LTC3588IDD-1#TRPBF
LFKY
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC3588EMSE-1#PBF
LTC3588EMSE-1#TRPBF
LTFKX
10-Lead Plastic MSOP
–40°C to 85°C
LTC3588IMSE-1#PBF
LTC3588IMSE-1#TRPBF
LTFKX
10-Lead Plastic MSOP
–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.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
35881f
2
LTC3588-1
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TJ = 25°C. VIN = 5.5V unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
VIN
Input Voltage Range
Low Impedance Source on VIN
IVIN
VIN Quiescent Current
UVLO
Buck Enabled, Sleeping
Buck Enabled, Sleeping
Buck Enabled, Not Sleeping
VIN = 2.5V, Not PGOOD
VIN = 4.5V
VIN = 18V
ISW = 0A (Note 4)
VUVLO
VIN Undervoltage Lockout Threshold
MIN
MAX
UNITS
18.0
V
450
950
1.7
150
700
1500
2.5
250
nA
nA
μA
μA
VIN Rising
1.8V Output Selected; D1 = 0, D0 = 0
2.5V Output Selected; D1 = 0, D0 = 1
3.3V Output Selected; D1 = 1, D0 = 0
3.6V Output Selected; D1 = 1, D0 = 1
l
l
l
l
3.77
3.77
4.73
4.73
4.04
4.04
5.05
5.05
4.30
4.30
5.37
5.37
V
V
V
V
VIN Falling
1.8V Output Selected; D1 = 0, D0 = 0
2.5V Output Selected; D1 = 0, D0 = 1
3.3V Output Selected; D1 = 1, D0 = 0
3.6V Output Selected; D1 = 1, D0 = 1
l
l
l
l
2.66
2.66
3.42
3.75
2.87
2.87
3.67
4.02
3.08
3.08
3.91
4.28
V
V
V
V
19.0
20.0
21.0
V
VSHUNT
VIN Shunt Regulator Voltage
IVIN = 1mA
ISHUNT
Maximum Protective Shunt Current
1ms Duration
25
Internal Bridge Rectifier Loss
(|VPZ1 – VPZ2| – VIN)
IBRIDGE = 10μA
350
Internal Bridge Rectifier Reverse
Leakage Current
VREVERSE = 18V
Internal Bridge Rectifier Reverse
Breakdown Voltage
IREVERSE = 1μA
Regulated Output Voltage
1.8V Output Selected
Sleep Threshold
Wake-Up Threshold
2.5V Output Selected
Sleep Threshold
Wake-Up Threshold
3.3V Output Selected
Sleep Threshold
Wake-Up Threshold
3.6V Output Selected
Sleep Threshold
Wake-Up Threshold
VOUT
TYP
l
PGOOD Falling Threshold
As a Percentage of the Selected VOUT
IVOUT
Output Quiescent Current
VOUT = 3.6V
mA
400
450
mV
20
nA
VSHUNT
30
V
l
l
1.812
1.788
1.890
1.710
V
V
l
l
2.512
2.488
2.575
2.425
V
V
l
l
3.312
3.288
3.399
3.201
V
V
l
l
3.612
3.588
3.708
3.492
V
V
83
92
%
89
150
nA
260
350
mA
IPEAK
Buck Peak Switch Current
200
ILOAD
Available Buck Output Current
100
RP
Buck PMOS Switch On-Resistance
1.1
Ω
RN
Buck NMOS Switch On-Resistance
1.3
Ω
Max Buck Duty Cycle
l
100
VIH(D0, D1)
D0/D1 Input High Voltage
l
1.2
VIL(D0, D1)
D0/D1 Input Low Voltage
l
IIH(D0, D1)
IIL(D0, D1)
mA
%
V
0.4
V
D0/D1 Input High Current
10
nA
D0/D1 Input Low Current
10
nA
35881f
3
LTC3588-1
ELECTRICAL CHARACTERISTICS
Note that the maximum ambient temperature is determined by specific
operating conditions in conjunction with board layout, the rated package
thermal resistance and other environmental factors.
Note 3: TJ is calculated from the ambient TA and power dissipation PD
according to the following formula: TJ = TA + (PD • θJA).
Note 4: Dynamic supply current is higher due to gate charge being
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 LTC3588E-1 is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
junction temperature range are assured by design, characterization, and
correlation with statistical process controls. The LTC3588I-1 is guaranteed
over the full –40°C to 125°C operating junction temperature range.
TYPICAL PERFORMANCE CHARACTERISTICS
IVIN in UVLO vs VIN
IVIN in Sleep vs VIN
2400
D1 = D0 = 1
900
600
–40°C
500
85°C
1800
25°C
IVIN (nA)
400
1600
25°C
1400
1200
300
1000
200
800
–40°C
400
0
1
2
3
VIN (V)
4
5
6
2
4
6
8
10 12
VIN (V)
14
D1 = D0 = 1
4.0
3.6
3.4
Total Bridge Rectifier Drop
vs Bridge Current
21.0
1800
20.8
1600
20.6
1400
20.2
20.0
ISHUNT = 25mA
ISHUNT = 1mA
19.8
D1 = D0 = 0
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G04
–40°C
1200
85°C
1000
800
19.4
400
19.2
200
19.0
–55 –35 –15
|VPZ1 – VPZ2| – VIN
25°C
600
19.6
3.2
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G03
20.4
D1 = 1, D0 = 0
VSHUNT (V)
UVLO FALLING (V)
3.8
–55 –35 –15
18
VSHUNT vs Temperature
4.2
2.8
–55 –35 –15
16
35881 G02
UVLO Falling vs Temperature
3.0
4.4
D1 = D0 = 0
35881 G01
3.8
4.6
4.0
600
100
4.8
4.2
VBRIDGE (mV)
IVIN (nA)
D1 = D0 = 1
5.0
2000
800
0
D1 = D0 = 0
2200
85°C
700
UVLO Rising vs Temperature
5.2
UVLO RISING (V)
1000
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G05
0
1μ
10μ
100μ
1m
BRIDGE CURRENT (A)
10m
35881 G06
35881f
4
LTC3588-1
TYPICAL PERFORMANCE CHARACTERISTICS
Bridge Leakage vs Temperature
16
1.6
14
1.4
12
1.2
10
0.8
6
0.6
4
0.4
2
0.2
–10
35
80
125
TEMPERATURE (°C)
0
170
SLEEP THRESHOLD
1.80
WAKE-UP THRESHOLD
1.0
8
0
–55
1.8V Output vs Temperature
1.85
4VP-P APPLIED TO PZ1/PZ2 INPUT
1.8 MEASURED IN UVLO
VIN = 18V, LEAKAGE AT PZ1 OR PZ2
VIN (V)
BRIDGE LEAKAGE (nA)
18
Bridge Frequency Response
2.0
VOUT (V)
20
PGOOD FALLING
10
100
1k
10k 100k 1M
FREQUENCY (Hz)
1.60
–55 –35 –15
10M 100M
2.5V Output vs Temperature
35881 G09
3.6V Output vs Temperature
3.3V Output vs Temperature
3.35
3.65
SLEEP THRESHOLD
SLEEP THRESHOLD
SLEEP THRESHOLD
3.60
3.30
2.50
WAKE-UP THRESHOLD
WAKE-UP THRESHOLD
WAKE-UP THRESHOLD
3.55
3.25
3.20
VOUT (V)
VOUT (V)
VOUT (V)
2.45
2.40
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G08
2.55
3.15
3.50
3.45
3.40
2.35
3.10
PGOOD FALLING
2.30
2.25
–55 –35 –15
3.35
3.05
3.00
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
PGOOD FALLING
PGOOD FALLING
3.30
3.25
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
VOUT Load Regulation
35881 G12
VOUT Line Regulation
2.56
2.54
2.52
2.52
VOUT (V)
2.54
IVOUT vs Temperature
120
L = 10μH, ILOAD = 100mA, D1 = 0, D0 = 1
110
90
2.50
2.48
2.48
2.46
2.46
VOUT = 3.6V
100
IVOUT (nA)
VIN = 5V, L = 10μH, D1 = 0, D0 = 1
2.50
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G11
35881 G10
VOUT (V)
1.70
1.65
35881 G07
2.56
1.75
80
VOUT = 3.3V
70
60
50
40
VOUT = 2.5V
VOUT = 1.8V
30
2.44
1μ
10μ
100μ
1m
10m
LOAD CURRENT (A)
100m
35881 G13
2.44
4
6
8
10
12
VIN (V)
14
16
18
35881 G14
20
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G15
35881f
5
LTC3588-1
TYPICAL PERFORMANCE CHARACTERISTICS
RDS(ON) of PMOS/NMOS
vs Temperature
IPEAK vs Temperature
Operating Waveforms
2.0
300
OUTPUT
VOLTAGE
50mV/DIV
AC-COUPLED
290
1.8
280
NMOS
1.6
RDS(ON) (Ω)
IPEAK (mA)
270
260
250
240
SWITCH
VOLTAGE
2V/DIV
1.4
PMOS
0V
INDUCTOR
CURRENT
200mA/DIV
0mA
1.2
230
220
1.0
210
200
–55 –35 –15
0.8
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
5 25 45 65 85 105 125
TEMPERATURE (°C)
35881 G17
35881 G16
Efficiency vs VIN for
ILOAD = 100mA, L = 10μH
Efficiency vs ILOAD, L = 10μH
90
VIN = 5V
80
EFFICIENCY (%)
EFFICIENCY (%)
70
60
50
40
30
VOUT = 3.6V
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
20
10
0
1μ
10μ
100μ
1m
10m
LOAD CURRENT (A)
100
95
90
85
80
75
70
60
VOUT = 3.6V
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
50
40
100m
2
4
6
8
10 12
VIN (V)
14
EFFICIENCY (%)
EFFICIENCY (%)
80
70
60
50
40
30
VOUT = 3.6V
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
10
0
1μ
10μ
100μ
1m
10m
LOAD CURRENT (A)
100m
35881 G22
ILOAD = 100mA
ILOAD = 1mA
ILOAD = 100μA
ILOAD = 50μA
ILOAD = 10μA
45
35
18
4
6
8
10
12
VIN (V)
14
95
90
85
80
75
70
60
40
VOUT = 3.6V
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
2
4
6
8
10 12
VIN (V)
14
18
Efficiency vs VIN for
VOUT = 3.3V, L = 100μH
100
50
16
35881 G21
EFFICIENCY (%)
VIN = 5V
20
55
Efficiency vs VIN for
ILOAD = 100mA, L = 100μH
Efficiency vs ILOAD, L = 100μH
90
16
65
35881 G20
35881 G19
100
Efficiency vs VIN for
VOUT = 3.3V, L = 10μH
EFFICIENCY (%)
100
35881 G18
5μs/DIV
VIN = 5V, VOUT = 3.3V
ILOAD = 1mA
L = 10μH, COUT = 47μF
16
18
35881 G23
65
55
ILOAD = 100mA
ILOAD = 100μA
ILOAD = 50μA
ILOAD = 30μA
ILOAD = 10μA
45
35
4
6
8
10
12
VIN (V)
14
16
18
35881 G24
35881f
6
LTC3588-1
PIN FUNCTIONS
PZ1 (Pin 1): Input connection for piezoelectric element or
other AC source (used in conjunction with PZ2).
PZ2 (Pin 2): Input connection for piezoelectric element or
other AC source (used in conjunction with PZ1).
CAP (Pin 3): Internal rail referenced to VIN to serve as gate
drive for buck PMOS switch. A 1μF capacitor should be
connected between CAP and VIN. This pin is not intended
for use as an external system rail.
VIN (Pin 4): Rectified Input Voltage. A capacitor on this
pin serves as an energy reservoir and input supply for the
buck regulator. The VIN voltage is internally clamped to a
maximum of 20V (typical).
SW (Pin 5): Switch Pin for the Buck Switching Regulator.
A 10μH or larger inductor should be connected from SW
to VOUT.
VOUT (Pin 6): Sense pin used to monitor the output voltage and adjust it through internal feedback.
VIN2 (Pin 7): Internal low voltage rail to serve as gate drive
for buck NMOS switch. Also serves as a logic high rail for
output voltage select bits D0 and D1. A 4.7μF capacitor
should be connected from VIN2 to GND. This pin is not
intended for use as an external system rail.
D1 (Pin 8): Output Voltage Select Bit. D1 should be tied
high to VIN2 or low to GND to select desired VOUT (see
Table 1).
D0 (Pin 9): Output Voltage Select Bit. D0 should be tied
high to VIN2 or low to GND to select desired VOUT (see
Table 1).
PGOOD (Pin 10): Power good output is logic high when
VOUT is above 92% of the target value. The logic high is
referenced to the VOUT rail.
GND (Exposed Pad Pin 11): Ground. The Exposed Pad
should be connected to a continuous ground plane on the
second layer of the printed circuit board by several vias
directly under the LTC3588-1.
35881f
7
LTC3588-1
BLOCK DIAGRAM
VIN 4
20V
INTERNAL RAIL
GENERATION
3
CAP
5
SW
7
VIN2
PZ1 1
PZ2 2
BUCK
CONTROL
UVLO
11 GND
SLEEP
BANDGAP
REFERENCE
8, 9
D1, D0
6
VOUT
2
PGOOD
COMPARATOR
10 PGOOD
35881 BD
35881f
8
LTC3588-1
OPERATION
Internal Bridge Rectifier
The LTC3588-1 has an internal full-wave bridge rectifier
accessible via the differential PZ1 and PZ2 inputs that
rectifies AC inputs such as those from a piezoelectric
element. The rectified output is stored on a capacitor at
the VIN pin and can be used as an energy reservoir for the
buck converter. The low-loss bridge rectifier has a total
drop of about 400mV with typical piezo generated currents
(~10μA). The bridge is capable of carrying up to 50mA.
One side of the bridge can be operated as a single-ended
DC input. PZ1 and PZ2 should never be shorted together
when the bridge is in use.
Internal Rail Generation
Two internal rails, CAP and VIN2, are generated from VIN and
are used to drive the high side PMOS and low side NMOS
of the buck converter, respectively. Additionally the VIN2
rail serves as logic high for output voltage select bits D0
and D1. The VIN2 rail is regulated at 4.8V above GND while
the CAP rail is regulated at 4.8V below VIN. These are not
intended to be used as external rails. Bypass capacitors
are connected to the CAP and VIN2 pins to serve as energy
reservoirs for driving the buck switches. When VIN is below
4.8V, VIN2 is equal to VIN and CAP is held at GND. Figure 1
shows the ideal VIN, VIN2 and CAP relationship.
18
16
14
VOLTAGE (V)
The LTC3588-1 is an ultralow quiescent current power
supply designed specifically for energy harvesting and/or
low current step-down applications. The part is designed to
interface directly to a piezoelectric or alternative A/C power
source, rectify a voltage waveform and store harvested
energy on an external capacitor, bleed off any excess power
via an internal shunt regulator, and maintain a regulated
output voltage by means of a nanopower high efficiency
synchronous buck regulator.
10
8
6
When the voltage on VIN rises above the UVLO rising
threshold the buck converter is enabled and charge is
transferred from the input capacitor to the output capacitor. A wide (~1V) UVLO hysteresis window is employed
with a lower threshold approximately 300mV above the
selected regulated output voltage to prevent short cycling
during buck power-up. When the input capacitor voltage
is depleted below the UVLO falling threshold the buck
converter is disabled. Extremely low quiescent current
(450nA typical) in UVLO allows energy to accumulate on
the input capacitor in situations where energy must be
harvested from low power sources.
VIN2
4
CAP
2
0
Undervoltage Lockout (UVLO)
VIN
12
0
5
10
15
VIN (V)
35881 F01
Figure 1. Ideal VIN, VIN2 and CAP Relationship
Buck Operation
The buck regulator uses a hysteretic voltage algorithm
to control the output through internal feedback from the
VOUT sense pin. The buck converter charges an output
capacitor through an inductor to a value slightly higher
than the regulation point. It does this by ramping the
inductor current up to 260mA through an internal PMOS
switch and then ramping it down to 0mA through an internal NMOS switch. This efficiently delivers energy to the
output capacitor. The ramp rate is determined by VIN, VOUT,
and the inductor value. If the input voltage falls below the
35881f
9
LTC3588-1
OPERATION
When the sleep comparator signals that the output has
reached the sleep threshold the buck converter may be
in the middle of a cycle with current still flowing through
the inductor. Normally both synchronous switches would
turn off and the current in the inductor would freewheel
to zero through the NMOS body diode. The LTC3588-1
keeps the NMOS switch on during this time to prevent the
conduction loss that would occur in the diode if the NMOS
were off. If the PMOS is on when the sleep comparator
trips the NMOS will turn on immediately in order to ramp
down the current. If the NMOS is on it will be kept on until
the current reaches zero.
Though the quiescent current when the buck is switching
is much greater than the sleep quiescent current, it is still
a small percentage of the average inductor current which
results in high efficiency over most load conditions. The
buck operates only when sufficient energy has been accumulated in the input capacitor and the length of time the
converter needs to transfer energy to the output is much
less than the time it takes to accumulate energy. Thus, the
buck operating quiescent current is averaged over a long
period of time so that the total average quiescent current
is low. This feature accommodates sources that harvest
small amounts of ambient energy.
Four selectable voltages are available by tying the output
select bits, D0 and D1, to GND or VIN2. Table 1 shows
the four D0/D1 codes and their corresponding output
voltages.
Table 1. Output Voltage Selection
D1
D0
VOUT
0
0
1.8V
44nA
0
1
2.5V
62nA
1
0
3.3V
81nA
1
1
3.6V
89nA
VOUT QUIESCENT CURRENT (IVOUT)
The internal feedback network draws a small amount of
current from VOUT as listed in Table 1.
Power Good Comparator
A power good comparator produces a logic high referenced
to VOUT on the PGOOD pin the first time the converter
reaches the sleep threshold of the programmed VOUT,
signaling that the output is in regulation. The PGOOD pin
will remain high until VOUT falls to 92% of the desired
regulation voltage. Several sleep cycles may occur during
this time. Additionally, if PGOOD is high and VIN falls below
the UVLO falling threshold, PGOOD will remain high until
VOUT falls to 92% of the desired regulation point. This
allows output energy to be used even if the input is lost.
Figure 2 shows the behavior for VOUT = 3.6V and no load.
At t = 75s VIN becomes high impedance and is discharged
by the quiescent current of the LTC3588-1 and through
servicing VOUT which is discharged by its own leakage
current. VIN crosses UVLO falling but PGOOD remains high
until VOUT decreases to 92% of the desired regulation point.
The PGOOD pin is designed to drive a microprocessor or
other chip I/O and is not intended to drive higher current
loads such as an LED.
6
CVIN = CVOUT = 100μF
5
VOLTAGE (V)
UVLO falling threshold before the output voltage reaches
regulation, the buck converter will shut off and will not
be turned on until the input voltage again rises above the
UVLO rising threshold. During this time the output voltage
will be loaded by less than 100nA. When the buck brings
the output voltage into regulation the converter enters a
low quiescent current sleep state that monitors the output
voltage with a sleep comparator. During this operating mode
load current is provided by the buck output capacitor. When
the output voltage falls below the regulation point the buck
regulator wakes up and the cycle repeats. This hysteretic
method of providing a regulated output reduces losses
associated with FET switching and maintains an output
at light loads. The buck delivers a minimum of 100mA of
average load current when it is switching.
VIN
VIN = UVLO FALLING
4
VOUT
3
2
PGOOD
1
0
0
100
200
300
TIME (s)
35881 F02
Figure 2. PGOOD Operation During Transition to UVLO
35881f
10
LTC3588-1
OPERATION
The D0/D1 inputs can be switched while in regulation as
shown in Figure 3. If VOUT is programmed to a voltage with
a PGOOD falling threshold above the old VOUT, PGOOD will
transition low until the new regulation point is reached.
When VOUT is programmed to a lower voltage, PGOOD
will remain high through the transition.
5
COUT = 100μF, ILOAD = 100mA
D1=D0=0
VOUT VOLTAGE (V)
4
D1=D0=1
D1=D0=0
3
VOUT
2
1
0
PGOOD = LOGIC1
0
2
4
6
Energy Storage
Harvested energy can be stored on the input capacitor
or the output capacitor. The wide input range takes advantage of the fact that energy storage on a capacitor is
proportional to the square of the capacitor voltage. After
the output voltage is brought into regulation any excess
energy is stored on the input capacitor and its voltage
increases. When a load exists at the output the buck can
efficiently transfer energy stored at a high voltage to the
regulated output. While energy storage at the input utilizes
the high voltage at the input, the load current is limited
to what the buck converter can supply. If larger loads
need to be serviced the output capacitor can be sized to
support a larger current for some duration. For example,
a current burst could begin when PGOOD goes high and
would continuously deplete the output capacitor until
PGOOD went low.
8 10 12 14 16 18 20
TIME (ms)
35881 F03
Figure 3. PGOOD Operation During D0/D1 Transition
35881f
11
LTC3588-1
APPLICATIONS INFORMATION
Introduction
The LTC3588-1 harvests ambient vibrational energy
through a piezoelectric element in its primary application.
Common piezoelectric elements are PZT (lead zirconate
titanate) ceramics, PVDF (polyvinylidene fluoride) polymers, or other composites. Ceramic piezoelectric elements
exhibit a piezoelectric effect when the crystal structure
of the ceramic is compressed and internal dipole movement produces a voltage. Polymer elements comprised
of long-chain molecules produce a voltage when flexed
as molecules repel each other. Ceramics are often used
under direct pressure while a polymer can be flexed more
readily. A wide range of piezoelectric elements are available and produce a variety of open-circuit voltages and
short-circuit currents. Typically the open-circuit voltage
and short-circuit currents increase with available vibrational
energy as shown in Figure 4. Piezoelectric elements can
be placed in series or in parallel to achieve desired opencircuit voltages.
12
PIEZO VOLTAGE (V)
9
INCREASING
VIBRATION ENERGY
6
3
0
0
10
20
PIEZO CURRENT (μA)
30
The LTC3588-1 is well-suited to a piezoelectric energy
harvesting application. The 20V input protective shunt
can accommodate a variety of piezoelectric elements. The
low quiescent current of the LTC3588-1 enables efficient
energy accumulation from piezoelectric elements which
can have short-circuit currents on the order of tens of
microamps. Piezoelectric elements can be obtained from
manufacturers listed in Table 2.
Table 2. Piezoelectric Element Manufacturers
Advanced Cerametrics
www.advancedcerametrics.com
Piezo Systems
www.piezo.com
Measurement Specialties
www.meas-spec.com
PI (Physik Instrumente)
www.pi-usa.us
MIDE Technology Corporation
www.mide.com
Morgan Technical Ceramics
www.morganelectroceramics.com
The LTC3588-1 will gather energy and convert it to a useable output voltage to power microprocessors, wireless
sensors, and wireless transmission components. Such a
wireless sensor application may require much more peak
power than a piezoelectric element can produce. However,
the LTC3588-1 accumulates energy over a long period of
time to enable efficient use for short power bursts. For
continuous operation, these bursts must occur with a low
duty cycle such that the total output energy during the burst
does not exceed the average source power integrated over
an energy accumulation cycle. For piezoelectric inputs the
time between cycles could be minutes, hours, or longer
depending on the selected capacitor values and the nature
of the vibration source.
35881 F04
Figure 4. Typical Piezoelectric Load Lines
for Piezo Systems T220-A4-503X
35881f
12
LTC3588-1
APPLICATIONS INFORMATION
1μF
6V
10μF
25V
PZ1
PZ2
VIN
PGOOD
CAP LTC3588-1
VIN2
4.7μF
6V
SW
3.3V
MICROPROCESSOR
CORE
VOUT
D1
D0
TX
EN
10μH
GND
47μF
6V
OUTPUT
VOLTAGE
20mV/DIV
AC-COUPLED
LOAD
CURRENT
25mA/DIV
5mA
GND
35881 F05a
35881 F05b
250μs/DIV
VIN = 5V
L = 10μH, COUT = 47μF
LOAD STEP BETWEEN 5mA and 55mA
Figure 5. 3.3V Piezoelectric Energy Harvester Powering a Microprocessor
with a Wireless Transmitter and 50mA Load Step Response
PGOOD Signal
The PGOOD signal can be used to enable a sleeping
microprocessor or other circuitry when VOUT reaches
regulation, as shown in Figure 5. Typically VIN will be
somewhere between the UVLO thresholds at this time
and a load could only be supported by the output capacitor. Alternatively, waiting a period of time after PGOOD
goes high would let the input capacitor accumulate more
energy allowing load current to be maintained longer as
the buck efficiently transfers that energy to the output.
While active, a microprocessor may draw a small load
when operating sensors, and then draw a large load to
transmit data. Figure 5 shows the LTC3588-1 responding
smoothly to such a load step.
Input and Output Capacitor Selection
The input and output capacitors should be selected based
on the energy needs and load requirements of the application. In every case the VIN capacitor should be rated
to withstand the highest voltage ever present at VIN.
For 100mA or smaller loads, storing energy at the input
takes advantage of the high voltage input since the buck
can deliver 100mA average load current efficiently to the
output. The input capacitor should then be sized to store
enough energy to provide output power for the length of
time required. This may involve using a large capacitor,
letting VIN charge to a high voltage, or both. Enough energy
should be stored on the input so that the buck does not
reach the UVLO falling threshold which would halt energy
transfer to the output. In general:
(
1
PLOAD tLOAD = ηCIN VIN 2 − VUVLOFALLING 2
2
VUVLOFALLING ≤ VIN ≤ VSHUNT
)
The above equation can be used to size the input capacitor to meet the power requirements of the output for the
desired duration. Here η is the average efficiency of the
buck converter over the input range and VIN is the input
voltage when the buck begins to switch. This equation
may overestimate the input capacitor necessary since load
current can deplete the output capacitor all the way to the
lower PGOOD threshold. It also assumes that the input
source charging has a negligible effect during this time.
The duration for which the regulator sleeps depends on
the load current and the size of the output capacitor. The
sleep time decreases as the load current increases and/or
as the output capacitor decreases. The DC sleep hysteresis
window is ±12mV around the programmed output voltage. Ideally this means that the sleep time is determined
by the following equation:
t SLEEP = COUT
24mV
ILOAD
35881f
13
LTC3588-1
APPLICATIONS INFORMATION
This is true for output capacitors on the order of 100μF
or larger, but as the output capacitor decreases towards
10μF delays in the internal sleep comparator along with
the load current may result in the VOUT voltage slewing
past the ±12mV thresholds. This will lengthen the sleep
time and increase VOUT ripple. A capacitor less than 10μF
is not recommended as VOUT ripple could increase to an
undesirable level.
If transient load currents above 100mA are required then a
larger capacitor can be used at the output. This capacitor
will be continuously discharged during a load condition
and the capacitor can be sized for an acceptable drop in
VOUT:
I
−I
COUT = ( VOUT+ − VOUT– ) LOAD BUCK
tLOAD
Here VOUT+ is the value of VOUT when PGOOD goes high
and VOUT– is the desired lower limit of VOUT. IBUCK is the
average current being delivered from the buck converter,
typically IPEAK /2.
A standard surface mount ceramic capacitor can be used
for COUT, though some applications may be better suited
to a low leakage aluminum electrolytic capacitor or a
supercapacitor. These capacitors can be obtained from
manufacturers such as Vishay, Illinois Capacitor, AVX,
or CAP-XX.
Inductor
The buck is optimized to work with an inductor in the range
of 10μH to 22μH, although inductor values outside this
range may yield benefits in some applications. For typical
applications, a value of 10μH is recommended. A larger
inductor will benefit high voltage applications by increasing
the on-time of the PMOS switch and improving efficiency
by reducing gate charge loss. Choose an inductor with a
DC current rating greater than 350mA. The DCR of the
inductor can have an impact on efficiency as it is a source
of loss. Tradeoffs between price, size, and DCR should be
evaluated. Table 3 lists several inductors that work well
with the LTC3588-1.
Table 3. Recommended Inductors for LTC3588-1
INDUCTOR
TYPE
L
(μH)
MAX
IDC
(mA)
MAX
DCR
(Ω)
SIZE in mm
(L × W × H)
MANUFACTURER
CDRH2D18/LDNP
10
430
0.180
3×3×2
Sumida
107AS-100M
10
650
0.145
2.8 × 3 × 1.8
Toko
EPL3015-103ML
10
350
0.301
2.8 × 3 × 1.5
Coilcraft
MLP3225s100L
10
1000
0.130 3.2 × 2.5 × 1.0
TDK
XLP2010-163ML
10
490
0.611 2.0 × 1.9 × 1.0
Coilcraft
SLF7045T
100
500
0.250 7.0 × 7.0 × 4.5
TDK
VIN2 and CAP Capacitors
A 1μF capacitor should be connected between VIN and
CAP and a 4.7μF capacitor should be connected between
VIN2 and GND. These capacitors hold up the internal rails
during buck switching and compensate the internal rail
generation circuits. In applications where the input source
is limited to less than 6V, the CAP pin can be tied to GND
and the VIN2 pin can be tied to VIN as shown in Figure 6.
An optional 5.6V Zener diode can be connected to VIN to
clamp VIN in this scenario. The leakage of the Zener diode
below its Zener voltage should be considered as it may
be comparable to the quiescent current of the LTC3588-1.
This circuit does not require the capacitors on VIN2 and
CAP, saving components and allowing a lower voltage
rating for the single VIN capacitor.
PIEZO SYSTEMS T220-A4-503X
PZ1
PZ2
VIN
PGOOD
VIN2
5.6V
(OPTIONAL)
10μF
6V
10μH
LTC3588-1
CAP
PGOOD
VOUT
1.8V
SW
D1
VOUT
10μF
6V
D0
GND
35881 F06
Figure 6. Smallest Solution Size 1.8V Low Voltage Input
Piezoelectric Power Supply
35881f
14
LTC3588-1
APPLICATIONS INFORMATION
A piezo powered LTC3588-1 can also be used in concert
with a battery connected to VIN to supplement the system
if ambient vibrational energy ceases as shown in Figure 8.
A blocking diode placed in series with the battery to VIN
prevents reverse current in the battery if the piezo source
charges VIN past the battery voltage. A 9V battery is shown,
but any stack of batteries of a given chemistry can be used
as long as the battery stack voltage does not exceed 18V.
In this setup the presence of the piezo energy harvester
can greatly increase the life of the battery. If the piezo
source is removed the LTC3588-1 can serve as a standalone nanopower buck converter. In this case the bridge
is unused and the blocking diode is unnecessary.
Additional Applications with Piezo Inputs
The versatile LTC3588-1 can be used in a variety of configurations. Figure 7 shows a single piezo source powering
two LTC3588-1s simultaneously, providing capability for
multiple rail systems. This setup features automatic supply sequencing as the LTC3588-1 with the lower voltage
output (i.e. lower UVLO rising threshold) will come up first.
As the piezo provides input power both VIN rails will
initially come up together, but when one output starts
drawing power, only its corresponding VIN will fall as the
bridges of each LTC3588-1 provide isolation. Input piezo
energy will then be directed to this lower voltage capacitor
until both VIN rails are again equal. This configuration is
expandable to any number of LTC3588-1s powered by a
single piezo as long as the piezo can support the sum total
of the quiescent currents from each LTC3588-1.
PIEZO SYSTEMS T220-A4-503X
PGOOD1
PZ1
PZ2
PZ1
PZ2
PGOOD
VIN
VIN
PGOOD
10μH
3.6V
1μF
6V
LTC3588-1
SW
CAP
VOUT
VIN2
10μF
6V
10μF
25V
D1
PGOOD2
10μH
LTC3588-1
10μF
25V
4.7μF
6V
D0
GND
1μF
6V
CAP
SW
VIN2
VOUT
1.8V
10μF
6V
D1
4.7μF
6V
D0
GND
35881 F07
Figure 7. Dual Rail Power Supply with Single Piezo and
Automatic Supply Sequencing
PIEZO SYSTEMS T220-A4-503X
IR05H40CSPTR
PZ1
PZ2
VIN
PGOOD
1μF
6V
9V
BATTERY
100μF
16V
4.7μF
6V
10μH
LTC3588-1
CAP
SW
VIN2
VOUT
D1
D0
PGOOD
VOUT
3.3V
47μF
6V
PZ1
GND
PZ2
35881 F08
Figure 8. Piezo Energy Harvester with Battery Backup
35881f
15
LTC3588-1
APPLICATIONS INFORMATION
DANGER! HIGH VOLTAGE!
DANGEROUS AND LETHAL POTENTIALS ARE PRESENT IN OFFLINE CIRCUITS!
150k
150k
120VAC
60Hz 150k
150k
BEFORE PROCEEDING ANY FURTHER, THE READER IS WARNED THAT
CAUTION MUST BE USED IN THE CONSTRUCTION, TESTING AND USE OF
OFFLINE CIRCUITS. EXTREME CAUTION MUST BE USED IN WORKING WITH
PZ1
PZ2
VIN
PGOOD
1μF
6V
10μF
25V
4.7μF
6V
AND MAKING CONNECTIONS TO THESE CIRCUITS. REPEAT: OFFLINE
PGOOD
CIRCUITS CONTAIN DANGEROUS, AC LINE-CONNECTED HIGH VOLTAGE
POTENTIALS. USE CAUTION. ALL TESTING PERFORMED ON AN OFFLINE
10μH
LTC3588-1
CAP
SW
VIN2
VOUT
D1
D0
VOUT
3.6V
CIRCUIT MUST BE DONE WITH AN ISOLATION TRANSFORMER CONNECTED
100μF
6V
CONSTRUCTORS OF OFFLINE CIRCUITS MUST OBSERVE THIS PRECAUTION
GND
BETWEEN THE OFFLINE CIRCUIT’S INPUT AND THE AC LINE. USERS AND
WHEN CONNECTING TEST EQUIPMENT TO THE CIRCUIT TO AVOID ELECTRIC
SHOCK. REPEAT: AN ISOLATION TRANSFORMER MUST BE CONNECTED
BETWEEN THE CIRCUIT INPUT AND THE AC LINE IF ANY TEST EQUIPMENT IS
35881 F09
TO BE CONNECTED.
Figure 9. AC Line Powered 3.6V Buck Regulator with
Large Output Capacitor to Support Heavy Loads
COPPER PANEL
(12" s 24")
PANELS ARE PLACED 6"
FROM 2' s 4' FLUORESCENT
LIGHT FIXTURES
PZ1
PZ2
VIN
PGOOD
1μF
6V
10μF
25V
4.7μF
6V
COPPER PANEL
(12" s 24")
PGOOD
10μH
LTC3588-1
CAP
SW
VIN2
VOUT
3.3V
10μF
6V
D1
D0
GND
35881 F10
Figure 10. Electric Field Energy Harvester
Alternate Power Sources
The LTC3588-1 is not limited to use with piezoelectric elements but can accommodate a wide variety of input sources
depending on the type of ambient energy available. Figure 9
shows the LTC3588-1 internal bridge rectifier connected
to the AC line in series with four 150k current limiting
resistors. This is a high voltage application and minimum
spacing between the line, neutral, and any high voltage
components should be maintained per the applicable UL
specification. For general off-line applications refer to UL
regulation 1012.
Figure 10 shows an application where copper panels are
placed near a standard fluorescent room light to capacitively
harvest energy from the electric field around the light.
The frequency of the emission will be 120Hz for magnetic
ballasts but could be higher if the light uses electronic
ballast. The LTC3588-1 bridge rectifier can handle a wide
range of input frequencies.
The LTC3588-1 can also be configured for use with DC
sources such as a solar panel or thermal couple as shown
in Figures 11 and 12 by connecting them to one of the
PZ1/PZ2 inputs. Connecting the two sources in this way
prevents reverse current from flowing in each element.
Current limiting resistors should be used to protect the
PZ1 or PZ2 pins. This can be combined with a battery
backup connected to VIN with a blocking diode.
35881f
16
LTC3588-1
APPLICATIONS INFORMATION
300Ω
PZ1
PZ2
VIN
PGOOD
IR05H4OCSPTR
+
–
1μF
6V
5V TO 16V
SOLAR PANEL
9V
BATTERY
100μF
25V
4.7μF
6V
LTC3588-1
PGOOD
10μH
CAP
SW
VIN2
VOUT
VOUT
2.5V
+
D0
D1
10μF
6V
GND
3F
2.7V
NESS SUPER CAPACITOR
ESHSR-0003CO-002R7
35881 F11
Figure 11. 5V to 16V Solar-Powered 2.5V Supply with Supercapacitor for
Increased Output Energy Storage and Battery Backup
RS, 5.2Ω
100Ω
PG-1 THERMAL
GENERATOR
P/N G1-1.0-127-1.27
(TELLUREX)
1μF
6V
5.4V
1μF
16V
4.7μF
6V
PZ1
PZ2
VIN
PGOOD
LTC3588-1
PGOOD
10μH
CAP
SW
VIN2
VOUT
VOUT
2.5V
47μF
6V
D0
D1
GND
35881 F12
Figure 12. Thermoelectric Energy Harvester
35881f
17
LTC3588-1
PACKAGE DESCRIPTION
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699)
R = 0.115
TYP
6
0.38 ± 0.10
10
0.675 ±0.05
3.50 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
3.00 ±0.10
(4 SIDES)
PACKAGE
OUTLINE
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
(DD) DFN 1103
5
0.200 REF
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
1
0.25 ± 0.05
0.50 BSC
0.75 ±0.05
0.00 – 0.05
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
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
35881f
18
LTC3588-1
PACKAGE DESCRIPTION
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661 Rev E)
BOTTOM VIEW OF
EXPOSED PAD OPTION
2.794 p 0.102
(.110 p .004)
5.23
(.206)
MIN
0.889 p 0.127
(.035 p .005)
1
2.06 p 0.102
(.081 p .004)
1.83 p 0.102
(.072 p .004)
2.083 p 0.102 3.20 – 3.45
(.082 p .004) (.126 – .136)
10
0.50
0.305 p 0.038
(.0197)
(.0120 p .0015)
BSC
TYP
RECOMMENDED SOLDER PAD LAYOUT
3.00 p 0.102
(.118 p .004)
(NOTE 3)
10 9 8 7 6
3.00 p 0.102
(.118 p .004)
(NOTE 4)
4.90 p 0.152
(.193 p .006)
0.254
(.010)
DETAIL “A”
0o – 6o TYP
1 2 3 4 5
GAUGE PLANE
0.53 p 0.152
(.021 p .006)
DETAIL “A”
0.18
(.007)
0.497 p 0.076
(.0196 p .003)
REF
SEATING
PLANE
0.86
(.034)
REF
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
0.50
(.0197)
BSC
0.1016 p 0.0508
(.004 p .002)
MSOP (MSE) 0307 REV B
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
35881f
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.
19
LTC3588-1
TYPICAL APPLICATION
Peak-to-Peak Output Ripple vs COUT1
Piezoelectric 3.3V Power Supply with LDO
Post Regulator for Reduced Output Ripple
47μF
25V
PZ2
VIN
PGOOD
CAP LTC3588-1
VIN2
4.7μF
6V
SHDN
10μH
VOUT1
3.6V
SW
VOUT
OUT
GND
D1
D0
LT3009-3.3
IN
COUT1
10μF
6V
GND
VOUT2
3.3V
20mA
COUT2
1μF
6V
VOUT RIPPLE PEAK-TO-PEAK (mV)
1μF
6V
PZ1
120
100
VOUT1 (LTC3588-1)
80
60
40
VOUT2 (LT3009-3.3)
20
0
35881 TA02a
COUT2 = 1μF
10
100
COUT1 (μF)
35881 TA02b
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MPPT for Solar, 4.95V to 32V, Up to 2A Charge Current
LT3970
40V, 350mA Step-Down Regulator with 2.5μA IQ
Integrated Boost and Catch Diodes, 4.2V to 40V Operating Range
LT3971
38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA IQ
4.3V to 38V Operating Range, Low Ripple Burst Mode® Operation
LT3991
55V, 1.2A 2MHz Step-Down Regulator with 2.8μA IQ
4.3V to 55V Operating Range, Low Ripple Burst Mode Operation
LTC3631
45V, 100mA, Synchronous Step-Down Regulator with 12μA IQ
4.5V to 45V Operating Range, Overvoltage Lockout Up to 60V
LTC3642
45V, 50mA, Synchronous Step-Down Regulator with 12μA IQ
4.5V to 45V Operating Range, Overvoltage Lockout Up to 60V
35881f
20 Linear Technology Corporation
LT 0110 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
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www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2010