LTC3260_15 Datasheet, PDF (1/18 Pages) Linear Technology – Low Noise Dual Supply Inverting Charge Pump

LTC3260
Low Noise Dual Supply
Inverting Charge Pump
Features
n _{VIN Range: 4.5V to 32V}
n _{Inverting Charge Pump Generates –VIN}
n _{Charge Pump Output Current Up to 100mA}
n _{Low Noise Negative LDO Post Regulator}
(I_LDO– = 50mA Max)
n _{Low Noise Independent Positive LDO Regulator}
(I_LDO+ = 50mA Max)
n _{100µA Quiescent Current in Burst Mode}^® _Operation
with Both LDO Regulators On
n _{50kHz to 500kHz Programmable Oscillator Frequency}
n _{Stable with Ceramic Capacitors}
n _{Short-Circuit/Thermal Protection}
n _{Low Profile 3mm × 4mm 14-Pin DFN and Thermally}
Enhanced 16-Pin MSOP Packages
Applications
n _{Low Noise Bipolar/Inverting Supplies}
n _{Industrial/Instrumentation Low Noise Bias}
Generators
n _{Portable Medical Equipment}
n _{Portable Instruments}
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.
Typical Application
±12V Outputs from a Single 15V Input
15V
–15V
10µF
V_IN
LDO⁺
LTC3260
EN⁺
ADJ⁺
EN^–
BYP⁺
MODE
C⁺
1µF _C–
GND
BYP^–
ADJ^–
V_OUT
LDO^–
10µF
RT
200k
12V
10µF _909k
100k
10nF
10nF
100k
10µF
3260 TA01a
909k
–12V
LDO Rejection of V_OUT Ripple
V_LDO+
10mV/DIV
AC-COUPLED
V_LDO–
10mV/DIV
AC-COUPLED
V_OUT
10mV/DIV
AC-COUPLED
VVV^{ILLNDDOO=+–1==5V1–21V2V}
f_OSC = 500kHz
II^{LLDDOO+–}
= 50mA
–50mA
1µs/DIV
3260 TA01b
3260fa
1