LTC3260
Low Noise Dual Supply
Inverting Charge Pump
FeaTures
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DescripTion
The LTC
®
3260 is a low noise dual polarity output power
supply that includes an inverting charge pump with both
positive and negative LDO regulators. The charge pump
operates over a wide 4.5V to 32V input range and can deliver
up to 100mA of output current. Each LDO regulator can
provide up to 50mA of output current. The negative LDO
post regulator is powered from the charge pump output.
The LDO output voltages can be adjusted using external
resistor dividers.
The charge pump employs either low quiescent current
Burst Mode operation or low noise constant frequency
mode. In Burst Mode operation the charge pump V
OUT
regulates to
–0.94 •
V
IN
, and the LTC3260 draws only
100µA of quiescent current with both LDO regulators on.
In constant frequency mode the charge pump produces
an output equal to –V
IN
and operates at a fixed 500kHz
or to a programmed value between 50kHz to 500kHz us-
ing an external resistor. The LTC3260 is available in low
profile (0.75mm) 3mm x 4mm 14-pin DFN and thermally
enhanced 16-pin MSOP packages.
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.
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V
IN
Range: 4.5V to 32V
Inverting Charge Pump Generates –V
IN
Charge Pump Output Current Up to 100mA
Low Noise Negative LDO Post Regulator
(I
LDO–
= 50mA Max)
Low Noise Independent Positive LDO Regulator
(I
LDO+
= 50mA Max)
100µA Quiescent Current in Burst Mode
®
Operation
with Both LDO Regulators On
50kHz to 500kHz Programmable Oscillator Frequency
Stable with Ceramic Capacitors
Short-Circuit/Thermal Protection
Low Profile 3mm
×
4mm 14-Pin DFN and Thermally
Enhanced 16-Pin MSOP Packages
applicaTions
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Low Noise Bipolar/Inverting Supplies
Industrial/Instrumentation Low Noise Bias
Generators
Portable Medical Equipment
Portable Instruments
Typical applicaTion
±12V Outputs from a Single 15V Input
15V
V
IN
EN
+
LDO Rejection of V
OUT
Ripple
10µF
LDO
+
LTC3260
ADJ
+
BYP
+
GND
BYP
–
ADJ
–
10µF
12V
909k
100k
100k
909k
V
LDO+
10mV/DIV
AC-COUPLED
V
LDO–
10mV/DIV
AC-COUPLED
V
OUT
10mV/DIV
AC-COUPLED
V
IN
= 15V
V
LDO+
= 12V
V
LDO–
= –12V
f
OSC
= 500kHz
I
LDO+
= 50mA
I
LDO–
–50mA
1µs/DIV
3260 TA01b
EN
–
MODE
1µF
C
+
C
–
V
OUT
RT
10nF
10nF
–15V
10µF
LDO
–
10µF
3260 TA01a
–12V
200k
3260fa
1
LTC3260
absoluTe MaxiMuM raTings
(Notes 1, 3)
V
IN
, EN
+
, EN
–
, MODE.. ............................... –0.3V to 36V
LDO
+
...........................................................–16V to 36V
V
OUT
, LDO
–
............................................... –36V to 0.3V
RT, ADJ
+
...................................................... –0.3V to 6V
BYP
+
......................................................... –0.3V to 2.5V
ADJ
–
............................................................ –6V to 0.3V
BYP
–
......................................................... –2.5V to 0.3V
V
OUT
, LDO
+
, LDO
–
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)
MSE Only .......................................................... 300°C
pin conFiguraTion
TOP VIEW
EN
+
RT
BYP
–
ADJ
–
LDO
–
V
OUT
C
–
1
2
3
4
5
6
7
15
GND
14 BYP
+
13 ADJ
+
12 MODE
11 EN
–
10 LDO
+
9 V
IN
8 C
+
TOP VIEW
RT
BYP
–
ADJ
–
LDO
–
V
OUT
C
–
NC
EN
+
1
2
3
4
5
6
7
8
17
GND
16
15
14
13
12
11
10
9
BYP
+
ADJ
+
MODE
EN
–
LDO
+
V
IN
C
+
NC
DE PACKAGE
14-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB
MSE PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3260EDE#PBF
LTC3260IDE#PBF
LTC3260EMSE#PBF
LTC3260IMSE#PBF
LTC3260HMSE#PBF
LTC3260MPMSE#PBF
TAPE AND REEL
LTC3260EDE#TRPBF
LTC3260IDE#TRPBF
LTC3260EMSE#TRPBF
LTC3260IMSE#TRPBF
LTC3260HMSE#TRPBF
LTC3260MPMSE#TRPBF
PART MARKING*
3260
3260
3260
3260
3260
3260
PACKAGE DESCRIPTION
14-Lead (4mm
×
3mm) Plastic DFN
14-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping
container.Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3260fa
2
LTC3260
elecTrical characTerisTics
SYMBOL
Charge Pump
V
IN
V
UVLO
I
VIN
Input Voltage Range
V
IN
Undervoltage Lockout Threshold
V
IN
Quiescent Current
V
IN
Rising
V
IN
Falling
Shutdown, EN
+
= EN
–
= 0V
EN
–
= 0V, I
LDO+
= 0mA
MODE = V
IN
, EN
+
= 0V, I
VOUT
= I
LDO–
= 0mA
MODE = V
IN
, I
VOUT
= I
LDO+
= I
LDO–
= 0mA
MODE = 0V, I
VOUT
= 0mA
MODE = 12V
MODE = 0V
RT = GND
MODE = 0V, RT = GND
V
OUT
= GND
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= EN
+
= EN
–
= 12V, MODE = 0V, RT = 200kΩ.
PARAMETER
CONDITIONS
MIN
4.5
3.4
3.8
3.6
2
30
80
100
3.5
1.200
–0.94 •
V
IN
–V
IN
450
100
0.4
500
32
160
1.1
1.0
0.7
l
l
+
= 1.2V
TYP
MAX
32
4
5
50
160
200
5.5
UNITS
V
V
V
µA
µA
µA
µA
mA
V
V
V
V
RT
V
OUT
f
OSC
R
OUT
I
SHORT_CKT
V
MODE(H)
V
MODE(L)
I
MODE
RT Regulation Voltage
V
OUT
Regulation Voltage
Oscillator Frequency
Charge Pump Output Impedance
Max I
VOUT
Short-Circuit Current
MODE Threshold Rising
MODE Threshold Falling
MODE Pin Internal Pull-Down Current
LDO
+
Output Voltage Range
V
IN
= MODE = 32V
1.2
1.176
–50
l
550
250
2.0
kHz
Ω
mA
V
V
µA
50mA Positive Regulator
32
1.200
100
0.04
0.03
I
LDO+
= 50mA
C
BYP+
= 10nF
l
l
V
V
nA
mA
mV/V
mV/mA
V
ADJ
I
ADJ
+
ADJ
+
Reference Voltage
ADJ+ Input Current
LDO
+
Short-Circuit Current
Line Regulation
Load Regulation
V
ADJ
1.224
50
+
I
LDO+(SC)
50
V
DROPOUT+
V
EN+(H)
V
EN+(L)
I
EN+
LDO
+
Dropout Voltage
Output Voltage Noise
EN
+
Threshold Rising
EN
+
Threshold Falling
EN
+
Pin Internal Pull-Down Current
LDO
–
Output Voltage Range
400
100
1.1
0.4
1.0
0.7
l
l
800
2.0
mV
µV
RMS
V
V
µA
V
IN
= EN
+
= 32V
–32
–1.224
–50
l
50mA Negative Regulator
–1.2
–1.200
100
0.002
0.02
I
LDO–
= 50mA
C
BYP–
= 10nF
l
l
V
V
nA
mA
mV/V
mV/mA
V
ADJ–
I
ADJ–
I
LDO–(SC)
ADJ
–
Reference Voltage
ADJ
–
Input Current
LDO
–
Short-Circuit Current
Line Regulation
Load Regulation
V
ADJ–
= –1.2V
–1.176
50
50
V
DROPOUT–
V
EN(H)
V
EN(L)
I
EN–
LDO
–
Dropout Voltage
Output Voltage Noise
EN
–
Threshold Rising
EN
–
Threshold Falling
EN
–
Pin Internal Pull-Down Current
200
100
1.1
0.4
1.0
1.4
500
2.0
mV
µV
RMS
V
V
µA
V
IN
= EN
–
= 32V
3260fa
3
LTC3260
elecTrical characTerisTics
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 LTC3260 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3260E 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
LTC3260I is guaranteed over the –40°C to 125°C operating junction
temperature range, the LTC3260H is guaranteed over the –40°C to 150°C
operating junction temperature range and the LTC3260MP is tested and
guaranteed over the full –55°C to 150°C operating junction temperature
range. 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 (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
θ
JA
),
where
θ
JA
= 43°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.
(T
A
= 25°C, C
FLY
= 1µF, C
IN
= C
OUT
= C
LDO+
= C
LDO–
= 10µF unless otherwise noted)
Oscillator Frequency
vs Supply Voltage
600
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (kHz)
500
400
300
200
100
0
R
T
= 200k
R
T
= GND
600
500
400
300
200
100
0
SHUTDOWN CURRENT (µA)
Typical perForMance characTerisTics
Oscillator Frequency vs R
T
Shutdown Current vs Temperature
30
25
20
15
10
5
0
–50 –25
V
IN
= 32V
V
IN
= 12V
V
IN
= 5V
0
25 50 75 100 125 150
TEMPERATURE (°C)
3260 G03
0
5
20
15
25
10
SUPPLY VOLTAGE (V)
30
35
3260 G01
1
10
100
R
T
(k )
1000
10000
3260 G02
Quiescent Current vs Temperature
160
140
QUIESCENT CURRENT (µA)
120
100
80
60
40
20
0
–50 –25
0
POSITIVE LDO ON
25 50 75 100 125 150
TEMPERATURE (°C)
3260 G04
Quiescent Current vs Supply
Voltage (Constant Frequency Mode)
16
10
9
QUIESCENT CURRENT (mA)
8
7
6
5
4
3
2
1
30
35
3260 G05
Quiescent Current vs Temperature
(Constant Frequency Mode)
V
IN
= 12V
f
OSC
= 500kHz
V
IN
= 12V
QUIESCENT CURRENT (mA)
Burst Mode OPERATION
WITH BOTH LDOs ON
14
12
10
8
6
4
2
0
0
5
10
f
OSC
= 50kHz
25
20
15
SUPPLY VOLTAGE (V)
f
OSC
= 500kHz
f
OSC
= 200kHz
Burst Mode OPERATION
WITH NEGATIVE LDO ON
f
OSC
= 200kHz
f
OSC
= 50kHz
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3260 G06
3260fa
4
LTC3260
(T
A
= 25°C, C
FLY
= 1µF, C
IN
= C
OUT
= C
LDO
= C
LDO
= 10µF unless otherwise noted)
Effective Open-Loop Resistance
vs Temperature
60
EFFECTIVE OPEN-LOOP RESISTANCE ( )
50
40
30
20
10
0
–50 –25
V
IN
= 32V
V
IN
= 25V
V
IN
= 12V
0
25 50 75 100 125 150
TEMPERATURE (°C)
3620 G07
Typical perForMance characTerisTics
+
–
V
OUT
Short-Circuit Current
vs Supply Voltage
250
V
OUT
SHORT-CIRCUIT CURRENT (mA)
Voltage Loss (V
IN
– |V
OUT
|)
vs Output Current (Constant
Frequency Mode)
3.0
2.5
VOLTAGE LOSS (V)
2.0
f
OSC
= 50kHz
1.5
1.0
0.5
0
f
OSC
= 500kHz
0.1
1
10
OUTPUT CURRENT (mA)
100
3260 G09
f
OSC
= 500kHz
V
IN
= 12V
f
OSC
= 200kHz
200
R
T
= GND
150
100
R
T
= 200k
50
0
0
5
20
10
25
15
SUPPLY VOLTAGE (V)
30
35
3260 G08
Effective Open-Loop Resistance
vs Supply Voltage
90
EFFECTIVE OPEN-LOOP RESISTANCE ( )
80
ADJ
+
PIN VOLTAGE (V)
70
60
50
40
30
20
10
0
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
30
35
f
OSC
= 500kHz
f
OSC
= 200kHz
1.224
ADJ
+
Pin Voltage vs Temperature
800
LDO
+
DROPOUT VOLTAGE (mV)
700
600
500
400
300
200
100
1.176
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3260 G11
LDO
+
Dropout Voltage
vs Temperature
V
IN
= 12V
I
LDO+
= 50mA
1.212
1.200
1.188
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3260 G12
3260 G10
LDO
+
Supply Rejection
60
50
GND PIN CURRENT (mA)
40
30
20
10
V
IN
= 6.5V
V
LDO+
= 5V
I
LDO+
= 50mA
V
RIPPLE
= 50mV
RMS
C
LDO+
= 10µF
1
10
100
FREQUENCY (kHz)
1000
3260 G13
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
LDO
+
GND Pin Current vs I
LOAD
V
IN
= 12V
1.2006
1.2004
1.2002
V
LDO+
(V)
1.2000
1.1998
1.1996
1.1994
LDO
+
Load Regulation
V
IN
= 12V
UNITY GAIN
LDO
+
SUPPLY REJECTION (dB)
0
0.1
0
1
I
LOAD
(mA)
10
100
3260 G14
0.1
1
I
LDO+
(mA)
10
100
3260 G15
3260fa
5
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