LTC3261
1
3261fb
For more information www.linear.com/3261
Typical applicaTion
FeaTures DescripTion
High Voltage,
Low Quiescent Current
Inverting Charge Pump
The LT C
®
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.
applicaTions
n 4.5V to 32V VIN Range
n Inverting Charge Pump Generates –VIN
n 60µA Quiescent Current in Burst Mode
®
Operation
n Charge Pump Output Current Up to 100mA
n 50kHz to 500kHz Programmable Oscillator
Frequency
n Short-Circuit/Thermal Protection
n Low Profile Thermally Enhanced 12-Pin MSOP
Package
n Bipolar/Inverting Supplies
n Industrial/Instrumentation Bias Generators
n Portable Medical Equipment
n Portable Instruments
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.
15V to –15V Inverter
10µF10µF
–15V
3261 TA01
VOUT
15V
LTC3261
GND
VIN
MODE
C–
RT
EN
C+
1µF
VOUT Ripple
100µs/DIV
VOUT
10mV/DIV
AC-COUPLED
VOUT = –14.8V
VOUT = –14.1V
MODE = L
MODE = H
VOUT
200mV/DIV
AC-COUPLED
3261 TA01a
VIN = 15V
fOSC = 500kHz
IOUT = 5mA
LTC3261
2
3261fb
For more information www.linear.com/3261
absoluTe MaxiMuM raTings
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
(Notes 1, 3)
1
2
3
4
5
6
NC
RT
NC
VOUT
C–
NC
12
11
10
9
8
7
NC
MODE
EN
VIN
C+
NC
TOP VIEW
MSE PACKAGE
12-LEAD PLASTIC MSOP
13
GND
TJMAX = 150°C, θJA = 40°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
pin conFiguraTion
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/
LTC3261
3
3261fb
For more information www.linear.com/3261
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 l4.5 32 V
VUVLO VIN Undervoltage Lockout Threshold VIN Rising
VIN Falling
l
l
3.4
3.8
3.6
4 V
V
IVIN VIN Quiescent Current Shutdown, = EN = 0V
MODE = VIN, IVOUT = 0mA
MODE = 0V, IVOUT = 0mA
2
60
3.5
5
120
5.5
µA
µA
mA
VRT RT Regulation Voltage 1.200 V
VOUT VOUT Regulation Voltage MODE = 12V
MODE = 0V
–0.94 • VIN
–VIN
V
V
fOSC Oscillator Frequency RT = GND 450 500 550 KHz
ROUT Charge Pump Output Impedance MODE = 0V, RT = GND 32 Ω
ISHORT_CKT Max IVOUT Short-Circuit Current VOUT = GND, RT = GND l100 160 250 mA
VMODE(H) MODE Threshold Rising l1.1 2 V
VMODE(L) MODE Threshold Falling l0.4 1.0 V
IMODE MODE Pin Internal Pull-Down Current VIN = MODE = 32V 0.7 µA
VEN(H) EN Threshold Rising l1.1 2 V
VEN(L) EN Threshold Falling l0.4 1.0 V
IEN EN Pin Internal Pull-Down Current VIN = EN = 32V 0.7 µA
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
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.
LTC3261
4
3261fb
For more information www.linear.com/3261
Typical perForMance characTerisTics
Oscillator Frequency
vs Supply Voltage
Effective Open-Loop Resistance
vs Temperature
Quiescent Current
vs Supply Voltage
(Constant Frequency Mode)
Quiescent Current vs Temperature
(Constant Frequency Mode)
Oscillator Frequency vs RT
VOUT Short-Circuit Current
vs Supply Voltage
VOUT Short Circuit Current
vs Temperature
Shutdown Current vs Temperature
Quiescent Current vs Temperature
(Burst Mode Operation)
(TA = 25°C, CF LY = 1µF, CIN = COUT = 10µF unless otherwise noted)
SUPPLY VOLTAGE (V)
0
0
500
600
400
300
200
100
20 25 3010 155 35
3261 G01
RT = GND
RT = 200kΩ
OSCILLATOR FREQUENCY (kHz)
RT (kΩ)
1
0
500
600
400
300
200
100
100 100010 10000
3261 G02
OSCILLATOR FREQUENCY (kHz)
TEMPERATURE (°C)
–50
0
25
20
15
10
5
5025 100750–25 150125
3261 G03
SHUTDOWN CURRENT (µA)
VIN = 5V
VIN = 12V
VIN = 32V
TEMPERATURE (°C)
–50
0
140
100
120
60
80
40
20
5025 100750–25 150125
3261 G04
QUIESCENT CURRENT (µA)
RT = GND
VIN = 32V
VIN = 12V
VIN = 5V
SUPPLY VOLTAGE (V)
0
0
14
10
12
6
8
4
2
1510 25205 3530
3261 G05
QUIESCENT CURRENT (mA)
fOSC = 50kHz
fOSC = 200kHz
fOSC = 500kHz
TEMPERATURE (°C)
–50
0
9
7
8
5
6
4
3
2
1
50250 10075–25 150125
3261 G06
QUIESCENT CURRENT (mA)
fOSC = 50kHz
fOSC = 200kHz
fOSC = 500kHz
VIN = 12V
TEMPERATURE (°C)
–50
20
60
50
55
40
45
35
30
25
50250 10075–25 150125
3261 G07
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
VIN = 12V
VIN = 25V
VIN = 32V fOSC = 500kHz
SUPPLY VOLTAGE (V)
0
0
250
150
200
50
100
15105 2520 3530
3261 G08
V
OUT
SHORT CIRCUIT CURRENT (mA)
fOSC = 500kHz
fOSC = 200kHz
TEMPERATURE (°C)
–50
100
200
180
160
140
120
–25 0 25 50 12575 100
3261 G8b
V
OUT
SHORT CIRCUIT CURRENT (mA)
VIN = 12V
RT = GND
LTC3261
5
3261fb
For more information www.linear.com/3261
Typical perForMance characTerisTics
Voltage Loss (VIN – |VOUT|)
vs Output Current
(Constant Frequency Mode)
(TA = 25°C, CF LY = 1µF, CIN = COUT = 10µF unless otherwise noted)
Effective Open-Loop Resistance
vs Supply Voltage
Average Input Current
vs Output Current
VOUT Load Transient Burst Mode
Operation (MODE = H)
VOUT Ripple
VOUT Transient
(MODE = Low to High)
OUTPUT CURRENT (mA)
0.1
0.0
3.0
2.0
2.5
1.0
0.5
1.5
1 10010
3261 G09
VOLTAGE LOSS (V)
fOSC = 500kHz
fOSC = 200kHz
fOSC = 50kHz VIN = 12V
SUPPLY VOLTAGE (V)
0
0
90
70
80
50
40
30
20
10
60
5 10 15 20 3525 30
3261 G10
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
fOSC = 200kHz
fOSC = 500kHz
VOUT
500mV/DIV
AC-COUPLED
2ms/DIV 3261 G11
VIN = 12V
fOSC = 500kHz
–5mA
IOUT
–50mA
VOUT
500mV/DIV
AC-COUPLED
2ms/DIV 3261 G12
VIN = 12V
fOSC = 500kHz
IOUT = –5mA
MODE
OUTPUT CURRENT (mA)
0.1
0.1
100
10
1
1 10010
3261 G13
AVERAGE INPUT CURRENT (mA)
MODE = L
MODE = H
VIN = 12V
fOSC = 500kHz
100µs/DIV
VOUT
10mV/DIV
AC-COUPLED
VOUT
200mV/DIV
AC-COUPLED
3261 G14
VIN = 15V
fOSC = 500kHz
IOUT = 5mA
MODE = L
MODE = H
LTC3261
6
3261fb
For more information www.linear.com/3261
block DiagraM
CHARGE
PUMP
AND
INPUT
LOGIC
50kHz
TO
500kHz
OSC
VIN VOUT
S1 S4
S3
2
13 GND
3261 BD
5
C+C–
8
9 4
10 EN
MODE
RT
11
S2
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.
RT (Pin 2): Input Connection for Programming the Switch-
ing 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.
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.
C+ (Pin 8): Flying Capacitor Positive Connection.
VIN (Pin 9): Input Voltage for the Charge Pump. VIN should
be bypassed with a low impedance ceramic capacitor.
EN (Pin 10): Logic Input. A logic “high” on the EN pin
enables the inverting charge pump.
MODE (Pin 11): Logic Input. The MODE pin deter-
mines the charge pump operating mode. A logic “high”
on the MODE pin forces the charge pump into Burst
Mode operation regulating VOUT to approximately
–0.94 • VIN with hysteretic control. A logic “low” on the
MODE pin forces the charge pump to operate as an open-
loop 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.
GND (Exposed Pad Pin 13): Ground. The exposed pack-
age pad is ground and must be soldered to the PC board
ground plane for proper functionality and for rated thermal
performance.
LTC3261
7
3261fb
For more information www.linear.com/3261
operaTion
(Refer to the Block Diagram)
The LTC3261 is a high voltage inverting charge pump. It
supports a wide input power supply range from 4.5V to 32V.
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 opera-
tion 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.
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 ex-
ceeds 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 mo-
mentary overload conditions outside normal operation.
Continuous operation above the specified maximum op-
erating junction temperature may impair device reliability.
RT (kΩ)
1
0
500
600
400
300
200
100
100 100010 10000
3261 F01
OSCILLATOR FREQUENCY (kHz)
LTC3261
8
3261fb
For more information www.linear.com/3261
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 (CF LY ), 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
Figure 2. Typical ROL vs Temperature
VRIPPLE(P-P) ≈IOUT
COUT
•1
fOSC
– tON
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
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 open-
loop 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 capaci-
tance 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 ap-
propriate 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
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:
TEMPERATURE (°C)
–50
20
60
50
55
40
45
35
30
25
50250 10075–25 150125
3261 F02
EFFECTIVE OPEN LOOP RESISTANCE (Ω)
VIN = 12V
VIN = 25V
VIN = 32V fOSC = 500kHz
LTC3261
9
3261fb
For more information www.linear.com/3261
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 condi-
tions. Figure 3 shows an example layout for the LTC3261.
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 .
Thermal Management
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.
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.
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 ther-
mal 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 re-
gion 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 tempera-
ture, typically around 165°C, the output is re-enabled and
the part resumes normal operation.
Figure 3. Recommended Layout
Figure 4. Maximum Power Dissipation vs Ambient Temperature
GND
GND 3261 F03
CF LY
RT
VIN VOUT
EN
MODE
AMBIENT TEMPERATURE (°C)
–50
0
6
4
5
2
3
1
7550250 125100–25 175150
3261 F04
MAXIMUM POWER DISSIPATION (W)
θJA = 40°C/W
RECOMMENDED
OPERATION
TJ = 150°C
LTC3261
10
3261fb
For more information www.linear.com/3261
Typical applicaTions
3261 TA06
4.5V TO 32V
NOTE: I2VIN • 2 + I–2VIN • 2 + IOUT < = 100mA
~ 2VIN
~ –2VIN
–VIN
C1
4.7µF
50V
C2
1µF
50V
C3
1µF
50V
C4
1µF
50V
C7
4.7µF
50V
D3
1N4148
C6
4.7µF
100V
MODE
RT
C+
VIN
C–
VOUT
EN
GND
LTC3261
C5
4.7µF
100V
D1
1N4148
D2
1N4148
D4
1N4148
High Input Divide by 2 Voltage Divider
Inverting Charge Pump with Bipolar Doubler
C3
4.7µF
25V
C2
1µF
50V
9V TO 32V
VIN/2
C1
4.7µF
50V
VIN VOUT
MODE RT
EN
C+
GND
3261 TA04
C–
LTC3261
NOTE: MINIMUM LOAD OF
120µA IS REQUIRED TO
ASSURE START-UP
LTC3261
12
3261fb
For more information www.linear.com/3261
package DescripTion
MSOP (MSE12) 0911 REV F
0.53 ± 0.152
(.021 ± .006)
SEATING
PLANE
0.18
(.007)
1.10
(.043)
MAX
0.22 –0.38
(.009 – .015)
TYP
0.86
(.034)
REF
0.650
(.0256)
BSC
12
12 11 10 9 8 7
7
DETAIL “B”
16
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.
0.254
(.010) 0° – 6° TYP
DETAIL “A”
DETAIL “A”
GAUGE PLANE
RECOMMENDED SOLDER PAD LAYOUT
BOTTOM VIEW OF
EXPOSED PAD OPTION
2.845 ± 0.102
(.112 ± .004)
2.845 ± 0.102
(.112 ± .004)
4.039 ± 0.102
(.159 ± .004)
(NOTE 3)
1.651 ± 0.102
(.065 ± .004)
1.651 ± 0.102
(.065 ± .004)
0.1016 ± 0.0508
(.004 ± .002)
1 2 3 4 5 6
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
0.406 ± 0.076
(.016 ± .003)
REF
4.90 ± 0.152
(.193 ± .006)
DETAIL “B”
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
NO MEASUREMENT PURPOSE
0.12 REF
0.35
REF
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
0.889 ± 0.127
(.035 ± .005)
0.42 ± 0.038
(.0165 ± .0015)
TYP
0.65
(.0256)
BSC
MSE Package
12-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1666 Rev F)
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LTC3261
13
3261fb
For more information www.linear.com/3261
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
A 9/12 Changed the Operating Junction Temperature to –55°C to 150°C in the Absolute Maximum section
Added LTC3261HMSE and LTC3261MPMSE to Order Information table
Added the word junction to the heading for Electric Characteristics
Added LTC3261H and LTC3261MP guarantees into Note 2 following LTC3261I sentence
Deleted Thermal Shutdown curve from Figure 4
Changed two paragraphs with respect to operation at 150°C and thermal shutdown
Updated Related Parts list
2
2
3
3
9
9
14
B 1/13 Corrected pin number on MODE pin in Pin Functions page 6
LTC3261
14
3261fb
For more information www.linear.com/3261
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
LINEAR TECHNOLOGY CORPORATION 2012
LT 0113 REV B • PRINTED IN USA
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/3261
relaTeD parTs
Typical applicaTion
24V to –24V Inverter
C3
10µF
C1
10µF
–24V
3261 TA03
VOUT
9
8 5
10
11
13
2
4
24V
LTC3261
GND
VIN
MODE
C–
RT
EN
C+
C2
1µF
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/
LTC3250-1.5
Inductorless Step-Down DC/DC Converters VIN: 3.1V to 5.5V, VOUT = 1.2V, 1.5V, IQ = 35µA,
ThinSOT Package
LTC3251 500mA Spread Spectrum Inductorless Step-Down DC/DC
Converter
VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, 1.2V, 1.5V, IQ = 9µA, MS10E
Package
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
