LTC3261
High Voltage,
Low Quiescent Current
Inverting Charge Pump
Description
Features
n
n
n
n
4.5V to 32V VIN Range
Inverting Charge Pump Generates –VIN
60µA Quiescent Current in Burst Mode® Operation
Charge Pump Output Current Up to 100mA
50kHz to 500kHz Programmable Oscillator
Frequency
n Short-Circuit/Thermal Protection
n Low Profile Thermally Enhanced 12-Pin MSOP
Package
n
Applications
n
n
n
n
Bipolar/Inverting Supplies
Industrial/Instrumentation Bias Generators
Portable Medical Equipment
Portable Instruments
The LTC®3261 is a high voltage inverting charge pump
that operates over a wide 4.5V to 32V input range and
is capable of delivering up to 100mA of output current.
The charge pump employs either low quiescent current
Burst Mode operation or low noise constant frequency
mode. In Burst Mode operation the charge pump VOUT
regulates to –0.94 • VIN and the LTC3261 draws only 60µA
of quiescent current. In constant frequency mode the charge
pump produces an output equal to –VIN and operates at
a fixed 500kHz or to a programmed frequency between
50kHz to 500kHz using an external resistor. The LTC3261
is available in a thermally enhanced 12-pin MSOP package.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Typical Application
15V to –15V Inverter
1µF
VOUT Ripple
C+
15V
C–
–15V
VOUT
VIN
10µF
10µF
VOUT
10mV/DIV
AC-COUPLED
MODE = L
VOUT
200mV/DIV
AC-COUPLED
MODE = H
VOUT = –14.8V
LTC3261
EN
MODE
RT
VOUT = –14.1V
GND
100µs/DIV
3261 TA01a
VIN = 15V
fOSC = 500kHz
IOUT = 5mA
3261 TA01
3261fb
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1
LTC3261
Absolute Maximum Ratings
Pin Configuration
(Notes 1, 3)
VIN, EN, MODE............................................ –0.3V to 36V
VOUT............................................................ –36V to 0.3V
RT................................................................. –0.3V to 6V
VOUT Short-Circuit Duration.............................. Indefinite
Operating Junction Temperature Range
(Note 2)................................................... –55°C to 150°C
Storage Temperature Range.................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................... 300°C
TOP VIEW
NC 1
RT 2
NC 3
VOUT 4
C– 5
NC 6
13
GND
12
11
10
9
8
7
NC
MODE
EN
VIN
C+
NC
MSE PACKAGE
12-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 40°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3261EMSE#PBF
LTC3261EMSE#TRPBF
3261
12-Lead Plastic MSOP
–40°C to 125°C
LTC3261IMSE#PBF
LTC3261IMSE#TRPBF
3261
12-Lead Plastic MSOP
–40°C to 125°C
LTC3261HMSE#PBF
LTC3261HMSE#TRPBF
3261
12-Lead Plastic MSOP
–40°C to 150°C
LTC3261MPMSE#PBF
LTC3261MPMSE#TRPBF
3261
12-Lead Plastic MSOP
–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/
3261fb
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LTC3261
Electrical
Characteristics
The
l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = EN = 12V, MODE = 0V, RT = 200kΩ.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Charge Pump
VIN
Input Voltage Range
VUVLO
VIN Undervoltage Lockout Threshold
VIN Rising
VIN Falling
IVIN
VIN Quiescent Current
Shutdown, = EN = 0V
MODE = VIN, IVOUT = 0mA
MODE = 0V, IVOUT = 0mA
VRT
RT Regulation Voltage
VOUT
VOUT Regulation Voltage
MODE = 12V
MODE = 0V
fOSC
Oscillator Frequency
RT = GND
ROUT
Charge Pump Output Impedance
MODE = 0V, RT = GND
ISHORT_CKT
Max IVOUT Short-Circuit Current
VOUT = GND, RT = GND
l
l
l
4.5
3.4
450
V
4
V
V
2
60
3.5
5
120
5.5
l
VMODE(H)
MODE Threshold Rising
VMODE(L)
MODE Threshold Falling
l
IMODE
MODE Pin Internal Pull-Down Current
VEN(H)
EN Threshold Rising
l
VEN(L)
EN Threshold Falling
l
IEN
EN Pin Internal Pull-Down Current
100
0.4
VIN = MODE = 32V
V
–0.94 • VIN
–VIN
V
V
500
550
VIN = EN = 32V
KHz
Ω
160
250
1.1
2
mA
V
1.0
V
0.7
1.1
0.4
µA
µA
mA
1.200
32
l
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 LTC3261 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC3261E 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 assured by design,
characterization and correlation with statistical process controls. The
LTC3261I is guaranteed over the –40°C to 125°C operating junction
temperature range, the LTC3261H is guaranteed over the –40°C to 150°C
operating junction temperature range and the LTC3261MP is tested and
guaranteed over the full –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
32
3.8
3.6
µA
2
V
1.0
V
0.7
µA
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.
The junction temperature (TJ, in °C) is calculated from the ambient
temperature (TA, in °C) and power dissipation (PD, in Watts) according to
the formula:
TJ = TA + (PD • θJA),
where θJA = 40°C/W is the package thermal impedance.
Note 3: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperatures will exceed 150°C when overtemperature protection is
active. Continuous operation above the specified maximum operating
junction temperature may result in device degradation or failure.
3261fb
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LTC3261
Typical Performance Characteristics
(TA = 25°C, CFLY = 1µF, CIN = COUT = 10µF unless otherwise noted)
600
400
300
RT = 200kΩ
200
100
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
30
500
400
300
200
100
0
35
1
10
100
RT (kΩ)
1000
3261 G01
14
80
VIN = 12V
60
VIN = 5V
40
20
0
6
4
40
35
30
25
20
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3261 G07
fOSC = 500kHz
fOSC = 200kHz
fOSC = 50kHz
6
5
4
3
2
1
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
30
0
–50 –25
35
0
25 50 75 100 125 150
TEMPERATURE (°C)
3261 G06
VOUT Short Circuit Current
vs Temperature
250
VOUT SHORT CIRCUIT CURRENT (mA)
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
45
7
VOUT Short-Circuit Current
vs Supply Voltage
fOSC = 500kHz
50
VIN = 12V
3261 G05
Effective Open-Loop Resistance
vs Temperature
55
25 50 75 100 125 150
TEMPERATURE (°C)
8
8
0
25 50 75 100 125 150
TEMPERATURE (°C)
VIN = 32V
VIN = 25V
VIN = 12V
0
9
10
3261 G04
60
5
3261 G03
2
0
–50 –25
10
Quiescent Current vs Temperature
(Constant Frequency Mode)
fOSC = 500kHz
fOSC = 200kHz
fOSC = 50kHz
12
QUIESCENT CURRENT (mA)
QUIESCENT CURRENT (µA)
120
VIN = 32V
15
3261 G02
RT = GND
100
VIN = 32V
VIN = 12V
VIN = 5V
20
Quiescent Current
vs Supply Voltage
(Constant Frequency Mode)
Quiescent Current vs Temperature
(Burst Mode Operation)
140
Shutdown Current vs Temperature
0
–50 –25
10000
200
200
VOUT SHORT CIRCUIT CURRENT (mA)
0
25
QUIESCENT CURRENT (mA)
500
Oscillator Frequency vs RT
SHUTDOWN CURRENT (µA)
RT = GND
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (kHz)
600
Oscillator Frequency
vs Supply Voltage
fOSC = 500kHz
150
100
fOSC = 200kHz
50
0
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
30
35
3261 G08
VIN = 12V
RT = GND
180
160
140
120
100
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
3261 G8b
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LTC3261
Typical Performance Characteristics
(TA = 25°C, CFLY = 1µF, CIN = COUT = 10µF unless otherwise noted)
Voltage Loss (VIN – |VOUT|)
vs Output Current
(Constant Frequency Mode)
fOSC = 50kHz
fOSC = 200kHz
fOSC = 500kHz
VOLTAGE LOSS (V)
2.5
VIN = 12V
2.0
1.5
1.0
0.5
0.0
0.1
1
10
OUTPUT CURRENT (mA)
80
VOUT
500mV/DIV
AC-COUPLED
fOSC = 200kHz
70
60
50
–5mA
IOUT
–50mA
fOSC = 500kHz
40
30
20
VIN = 12V
fOSC = 500kHz
10
0
100
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
VOUT Transient
(MODE = Low to High)
VIN = 12V
fOSC = 500kHz
IOUT = –5mA
2ms/DIV
3261 G12
AVERAGE INPUT CURRENT (mA)
100
MODE
30
2ms/DIV
3261 G11
35
3261 G10
3261 G09
VOUT
500mV/DIV
AC-COUPLED
VOUT Load Transient Burst Mode
Operation (MODE = H)
90
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
3.0
Effective Open-Loop Resistance
vs Supply Voltage
Average Input Current
vs Output Current
10
VOUT Ripple
MODE = L
MODE = H
1
0.1
0.1
VIN = 12V
fOSC = 500kHz
1
10
OUTPUT CURRENT (mA)
100
VOUT
10mV/DIV
AC-COUPLED
MODE = L
VOUT
200mV/DIV
AC-COUPLED
MODE = H
100µs/DIV
3261 G14
VIN = 15V
fOSC = 500kHz
IOUT = 5mA
3261 G13
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LTC3261
Pin Functions
NC (Pins 1, 3, 6, 7,12): No Connect Pins. These pins are
not connected to the LTC3261 die. These pins should be
left floating or connected to ground. Pins 6 and 7 can also
be shorted to adjacent pins.
VIN (Pin 9): Input Voltage for the Charge Pump. VIN should
be bypassed with a low impedance ceramic capacitor.
RT (Pin 2): Input Connection for Programming the Switching Frequency. The RT pin servos to a fixed 1.2V when
the EN pin is driven to a logic “high”. A resistor from RT
to GND sets the charge pump switching frequency. If the
RT pin is tied to GND, the switching frequency defaults
to a fixed 500kHz.
MODE (Pin 11): Logic Input. The MODE pin determines the charge pump operating mode. A logic “high”
on the MODE pin forces the charge pump into Burst
Mode operation regulating V OUT to approximately
–0.94 • VIN with hysteretic control. A logic “low” on the
MODE pin forces the charge pump to operate as an openloop inverter with a constant switching frequency. The
switching frequency in both modes is determined by an
external resistor from the RT pin to GND. In Burst Mode,
this represents the frequency of the burst cycles before
the part enters the low quiescent current sleep state.
EN (Pin 10): Logic Input. A logic “high” on the EN pin
enables the inverting charge pump.
VOUT (Pin 4): Charge Pump Output Voltage. In constant
frequency mode (MODE = low) this pin is driven to –VIN.
In Burst Mode operation, (MODE = high) this pin voltage is
regulated to –0.94 • VIN using an internal burst comparator
with hysteretic control.
C– (Pin 5): Flying Capacitor Negative Connection.
GND (Exposed Pad Pin 13): Ground. The exposed package pad is ground and must be soldered to the PC board
ground plane for proper functionality and for rated thermal
performance.
C+ (Pin 8): Flying Capacitor Positive Connection.
Block Diagram
8
5
C+
9
VIN
C–
S1
S4
11
EN
MODE
4
S2
S3
10
VOUT
CHARGE
PUMP
AND
INPUT
LOGIC
50kHz
TO
500kHz
OSC
13
RT
2
GND
3261 BD
3261fb
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LTC3261
Operation (Refer to the Block Diagram)
Shutdown Mode
In shutdown mode, all circuitry except the internal bias is
turned off. The LTC3261 is in shutdown when a logic low is
applied to the enable input (EN). The LTC3261 only draws
2µA (typical) from the VIN supply in shutdown.
Constant Frequency Operation
The LTC3261 provides low noise constant frequency operation when a logic low is applied to the MODE pin. The charge
pump and oscillator circuit are enabled using the EN pin. At
the beginning of a clock cycle, switches S1 and S2 are closed.
The external flying capacitor across the C+ and C– pins is
charged to the VIN supply. In the second phase of the clock
cycle, switches S1 and S2 are opened, while switches S3
and S4 are closed. In this configuration the C+ side of the
flying capacitor is grounded and charge is delivered through
the C– pin to VOUT. In steady state the VOUT pin regulates at
–VIN less any voltage drop due to the load current on VOUT.
The charge transfer frequency can be adjusted between
50kHz and 500kHz using an external resistor on the RT
pin. At slower frequencies the effective open-loop output
resistance (ROL) of the charge pump is larger and it is able
to provide smaller average output current. Figure 1 can
be used to determine a suitable value of RT to achieve a
required oscillator frequency. If the RT pin is grounded,
the part operates at a constant frequency of 500kHz.
Burst Mode Operation
The LTC3261 provides low power Burst Mode operation
when a logic high is applied to the MODE pin. In Burst
Mode operation, the charge pump charges the VOUT pin to
–0.94 • VIN (typical). The part then shuts down the internal
oscillator to reduce switching losses and goes into a low
current state. This state is referred to as the sleep state in
which the IC consumes only about 60µA. When the output
voltage droops enough to overcome the burst comparator
hysteresis, the part wakes up and commences charge pump
cycles until output voltage exceeds –0.94 • VIN (typical).
This mode provides lower operating current at the cost of
higher output ripple and is ideal for light load operation.
The frequency of charging cycles is set by the external resistor
on the RT pin. The charge pump has a lower ROL at higher
frequencies. For Burst Mode operation it is recommended that
the RT pin be tied to GND. This minimizes the charge pump
ROL, quickly charges the output up to the burst threshold
and optimizes the duration of the low current sleep state.
600
OSCILLATOR FREQUENCY (kHz)
The LTC3261 is a high voltage inverting charge pump. It
supports a wide input power supply range from 4.5V to 32V.
500
400
300
200
100
0
1
10
100
RT (kΩ)
1000
10000
3261 F01
Figure 1. Oscillator Frequency vs RT
Soft-Start
The LTC3261 has built in soft-start circuitry to prevent
excessive current flow during start-up. The soft-start is
achieved by internal circuitry that slowly ramps the amount
of current available at the output storage capacitor. The
soft-start circuitry is reset in the event of a commanded
shutdown or thermal shutdown.
Short-Circuit/Thermal Protection
The LTC3261 has built-in short-circuit current limit as
well as overtemperature protection. During a short-circuit
condition, the part automatically limits its output current
to approximately 160mA. If the junction temperature exceeds approximately 175°C the thermal shutdown circuitry
disables current delivery to the output. Once the junction
temperature drops back to approximately 165°C current
delivery to the output is resumed. When thermal protection
is active the junction temperature is beyond the specified
operating range. Thermal protection is intended for momentary overload conditions outside normal operation.
Continuous operation above the specified maximum operating junction temperature may impair device reliability.
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LTC3261
Applications Information
Effective Open-Loop Output Resistance
The effective open-loop output resistance (ROL) of a charge
pump is a very important parameter which determines the
strength of the charge pump. The value of this parameter
depends on many factors such as the oscillator frequency
(fOSC), value of the flying capacitor (CFLY), the nonoverlap
time, the internal switch resistances (RS) and the ESR of
the external capacitors.
Typical ROL values as a function of temperature are shown
in Figure 2
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
60
55
VIN = 32V
VIN = 25V
VIN = 12V
fOSC = 500kHz
50
45
40
35
30
IOUT 1
•
– tON
COUT fOSC
where fOSC is the oscillator frequency tON is the on-time
of the oscillator (1µs) typical and COUT is the value of the
output capacitor.
Just as the value of COUT controls the amount of output
ripple, the value of CIN controls the amount of ripple present
at the input (VIN) pin. The amount of bypass capacitance
required at the input depends on the source impedance
driving VIN. For best results it is recommended that VIN
be bypassed with at least 2µF of low ESR capacitance. A
high ESR capacitor such as tantalum or aluminum will
have higher input noise than a low ESR ceramic capacitor.
Therefore, a ceramic capacitor is recommended as the
main bypass capacitance with a tantalum or aluminum
capacitor used in parallel if desired.
Flying Capacitor Selection
25
20
–50 –25
VRIPPLE(P-P) ≈
0
25 50 75 100 125 150
TEMPERATURE (°C)
3261 F02
Figure 2. Typical ROL vs Temperature
Input/Output Capacitor Selection
The style and value of capacitors used with the LTC3261
determine several important parameters such as regulator
control loop stability, output ripple, charge pump strength
and minimum turn-on time. To reduce noise and ripple, it is
recommended that low ESR ceramic capacitors be used for
the charge pump output. The charge pump output capacitor
should retain at least 2µF of capacitance over operating
temperature and bias voltage. Tantalum and aluminum
capacitors can be used in parallel with a ceramic capacitor
to increase the total capacitance but should not be used
alone because of their high ESR. In constant frequency
mode, the value of COUT directly controls the amount of
output ripple for a given load current. Increasing the size of
COUT will reduce the output ripple at the expense of higher
minimum turn-on time. The peak-to-peak output ripple at
the VOUT pin is approximately given by the expression:
The flying capacitor controls the strength of the charge
pump. A 1µF or greater ceramic capacitor is suggested
for the flying capacitor for applications requiring the full
rated output current of the charge pump.
For very light load applications, the flying capacitor may
be reduced to save space or cost. For example, a 0.2µF
capacitor might be sufficient for load currents up to 20mA.
A smaller flying capacitor leads to a larger effective openloop resistance (ROL) and thus limits the maximum load
current that can be delivered by the charge pump.
Ceramic Capacitors
Ceramic capacitors of different materials lose their capacitance with higher temperature and voltage at different rates.
For example, a capacitor made of X5R or X7R material will
retain most of its capacitance from –40°C to 85°C whereas a
Z5U or Y5V style capacitor will lose considerable capacitance
over that range. Z5U and Y5V capacitors may also have a
poor voltage coefficient causing them to lose 60% or more of
their capacitance when the rated voltage is applied. Therefore
when comparing different capacitors, it is often more appropriate to compare the amount of achievable capacitance
for a given case size rather than discussing the specified
capacitance value. The capacitor manufacture’s data sheet
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LTC3261
Applications Information
should be consulted to ensure the desired capacitance at
all temperatures and voltages. Table 1 is a list of ceramic
capacitor manufacturers and their websites.
Table 1
AVX
www.avxcorp.com
Kemet
www.kemet.com
Murata
www.murata.com
Taiyo Yuden
www.t-yuden.com
Vishay
www.vishay.com
TDK
www.component.tdk.com
Layout Considerations
Due to high switching frequency and high transient currents
produced by LTC3261, careful board layout is necessary
for optimum performance. A true ground plane and short
connections to all the external capacitors will improve
performance and ensure proper regulation under all conditions. Figure 3 shows an example layout for the LTC3261.
The power dissipated in the LTC3261 is:
PD = (VIN – |VOUT|) • (IOUT)
where IOUT denotes output current at the VOUT pin.
The derating curve in Figure 4 assumes a maximum thermal resistance, θJA, of 40°C/W for the package. This can
be achieved with a four layer PCB that includes 2oz Cu
traces and six vias from the exposed pad of the LTC3261
to the ground plane.
It is recommended that the LTC3261 be operated in the region corresponding to TJ ≤ 150°C for continuous operation
as shown in Figure 4. Operation beyond 150°C should be
avoided as it may degrade part performance and liftetime.
At high temperatures, typically around 175°C, the part is
placed in thermal shutdown and the output is disabled.
When the part cools back down to a low enough temperature, typically around 165°C, the output is re-enabled and
the part resumes normal operation.
The flying capacitor nodes C+ and C– switch large currents
at a high frequency. These nodes should not be routed
close to sensitive pins such as the RT pin .
GND
CFLY
Thermal Management
Derating Power at High Temperatures
To prevent an overtemperature condition in high power
applications, Figure 4 should be used to determine the
maximum combination of ambient temperature and power
dissipation.
The power dissipated in the LTC3261 should always fall
under the line shown for a given ambient temperature.
VIN
VOUT
EN
MODE
RT
GND
3261 F03
Figure 3. Recommended Layout
6
MAXIMUM POWER DISSIPATION (W)
At high input voltages and maximum output current, there
can be substantial power dissipation in the LTC3261. If
the junction temperature increases above approximately
175°C, the thermal shutdown circuitry will automatically
deactivate the output. To reduce the maximum junction
temperature, a good thermal connection to the PC board
ground plane is recommended. Connecting the exposed pad
of the package to a ground plane under the device on two
layers of the PC board can reduce the thermal resistance
of the package and PC board considerably.
θJA = 40°C/W
5
4
3
2
RECOMMENDED
OPERATION
1
0
–50 –25
TJ = 150°C
0 25 50 75 100 125 150 175
AMBIENT TEMPERATURE (°C)
3261 F04
Figure 4. Maximum Power Dissipation vs Ambient Temperature
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9
LTC3261
Typical Applications
High Input Divide by 2 Voltage Divider
C2
1µF
50V
9V TO 32V
C1
4.7µF
50V
VIN
C+
EN
C–
VOUT
LTC3261
MODE
RT
GND
3261 TA04
VIN/2
C3
4.7µF
25V
NOTE: MINIMUM LOAD OF
120µA IS REQUIRED TO
ASSURE START-UP
Inverting Charge Pump with Bipolar Doubler
D1
1N4148
4.5V TO 32V
C1
4.7µF
50V
C+
VIN
EN
LTC3261
C–
D4
1N4148
D3
1N4148
GND
VOUT
3261 TA06
~ 2VIN
C5
4.7µF
100V
C2
1µF
50V
C3
1µF
50V
C4
1µF
50V
MODE
RT
D2
1N4148
~ –2VIN
C6
4.7µF
100V
–VIN
C7
4.7µF
50V
NOTE: I2VIN • 2 + I–2VIN • 2 + IOUT < = 100mA
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LTC3261
Typical Applications
High Voltage to Inverted Low Voltage Charge Pump
4.5V TO 32V
C1
4.7µF
50V
D1
MBR0540
VIN
VOUT
VOUT
C4
4.7µF
50V
EN
C+
C2
1µF
50V
V –V – |I | •R
VOUT – IN f OUT OL –Vf
2
LTC3261
D2
MBR0540
C3
1µF
50V
D3
MBR0540
C–
MODE
GND
RT
3261 TA07
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11
LTC3261
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
MSE Package
12-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1666 Rev F)
BOTTOM VIEW OF
EXPOSED PAD OPTION
2.845 ± 0.102
(.112 ± .004)
5.23
(.206)
MIN
2.845 ± 0.102
(.112 ± .004)
0.889 ± 0.127
(.035 ± .005)
6
1
1.651 ± 0.102
(.065 ± .004)
1.651 ± 0.102 3.20 – 3.45
(.065 ± .004) (.126 – .136)
12
0.65
0.42 ± 0.038
(.0256)
(.0165 ± .0015)
BSC
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
0.35
REF
4.039 ± 0.102
(.159 ± .004)
(NOTE 3)
0.12 REF
DETAIL “B”
CORNER TAIL IS PART OF
DETAIL “B” THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
7
NO MEASUREMENT PURPOSE
0.406 ± 0.076
(.016 ± .003)
REF
12 11 10 9 8 7
DETAIL “A”
0° – 6° TYP
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
4.90 ± 0.152
(.193 ± .006)
GAUGE PLANE
0.53 ± 0.152
(.021 ± .006)
DETAIL “A”
1.10
(.043)
MAX
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
1 2 3 4 5 6
0.650
(.0256)
BSC
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
6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL
NOT EXCEED 0.254mm (.010") PER SIDE.
0.86
(.034)
REF
0.1016 ± 0.0508
(.004 ± .002)
MSOP (MSE12) 0911 REV F
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12
For more information www.linear.com/3261
LTC3261
Revision History
REV
DATE
DESCRIPTION
A
9/12
Changed the Operating Junction Temperature to –55°C to 150°C in the Absolute Maximum section
2
Added LTC3261HMSE and LTC3261MPMSE to Order Information table
2
Added the word junction to the heading for Electric Characteristics
3
Added LTC3261H and LTC3261MP guarantees into Note 2 following LTC3261I sentence
3
Deleted Thermal Shutdown curve from Figure 4
9
Changed two paragraphs with respect to operation at 150°C and thermal shutdown
9
Updated Related Parts list
14
Corrected pin number on MODE pin in Pin Functions page
6
B
1/13
PAGE NUMBER
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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
its circuits
as described
herein will not infringe on existing patent rights.
Forofmore
information
www.linear.com/3261
13
LTC3261
Typical Application
24V to –24V Inverter
C2
1µF
8
5
+
C–
C
9
24V
VOUT
VIN
C1
10µF
4
LTC3261
10
11
–24V
C3
10µF
EN
MODE
RT
2
GND
13
3261 TA03
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LT1054/LT1054L
Switched-Capacitor Voltage Converters with Regulator
VIN: 3.5V to 15V/7V, IOUT = 100mA/125mA, N8, S08,
SO16 Packages
LTC1144
Switched-Capacitor Wide Input Range Voltage Converter
with Shutdown
Wide Input Voltage Range: 2V to 18V, ISD < 8µA,
SO8 Package
LTC1514/LTC1515
Step-Up/Step-Down Switched-Capacitor DC/DC
Converters
VIN: 2V to 10V, VOUT: 3.3V to 5V, IQ = 60µA, SO8 Package
LT®1611
150mA Output, 1.4MHz Micropower Inverting Switching
Regulator
VIN: 0.9V to 10V, VOUT = ±34V, ThinSOT™ Package
LT1614
250mA Output, 600kHz Micropower Inverting Switching
Regulator
VIN: 0.9V to 6V, VOUT = ±30V, IQ = 1mA, MS8, SO8 Packages
LTC1911
250mA, 1.5MHz Inductorless Step-Down DC/DC
Converter
VIN: 2.7V to 5.5V, VOUT = 1.5V/1.8V, IQ = 180µA,
MS8 Package
LTC3250/LTC3250-1.2/ Inductorless Step-Down DC/DC Converters
LTC3250-1.5
VIN: 3.1V to 5.5V, VOUT = 1.2V, 1.5V, IQ = 35µA,
ThinSOT Package
LTC3251
500mA Spread Spectrum Inductorless Step-Down DC/DC VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, 1.2V, 1.5V, IQ = 9µA, MS10E
Package
Converter
LTC3252
Dual 250mA, Spread Spectrum Inductorless Step-Down
DC/DC Converter
VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, IQ = 50µA,
DFN12 Package
LTC3260
Low Noise Dual Supply Inverting Charge Pump
VIN: 4.5V to 32V, VOUT = –VIN, IOUT = 100mA, FOSC = 50kHz to
500kHz, VLDO+ = 1.2V to 32V, ILDO+ = 50mA, VLDO– = –1.2V to –32V,
ILDO– = 50mA, DE14 and MSE16 Packages
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14 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/3261
●
●
(408) 432-1900 FAX: (408) 434-0507
www.linear.com/3261
LT 0113 REV B • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2012
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