Document
LTC3240-3.3/LTC3240-2.5 3.3V/2.5V Step-Up/ Step-Down Charge Pump DC/DC Converter FEATURES
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DESCRIPTIO
Step-Up/Step-Down Charge Pumps Generate Fixed 3.3V or 2.5V Outputs VIN Range: 1.8V to 5.5V Output Current up to 150mA Automatic Mode Switching Constant Frequency (1.2MHz) Operation in Step-Up Mode Low Dropout Regulator Operation in Step-Down Mode Low No-Load Quiescent Current: IQ = 65µA Built-In Soft-Start Reduces Inrush Current Shutdown Disconnects Load from Input Shutdown Current < 1µA Short-Circuit/Thermal Protection Available in a 6-Lead (2mm × 2mm) DFN Package
The LTC®3240-3.3/LTC3240-2.5 are step-up/step-down charge pump DC/DC converters that produce a fixed regulated output voltage of 3.3V or 2.5V over a wide input voltage range (1.8V to 5.5V). With input voltages greater than the regulated output voltage the LTC3240 operates as a low dropout regulator. Once the input voltage drops within 100mV of the regulated output voltage the part automatically switches to step-up mode. In step-up mode the LTC3240 operates as a constant frequency (1.2MHz) doubling charge pump. The LTC3240-3.3/LTC3240-2.5 feature low no load operating current (65µA typical) and ultralow operating current in shutdown (<1µA). Built-in soft-start circuitry prevents excessive inrush current during start-up. Thermal shutdown and current-limit circuitry allow the parts to survive a continuous short-circuit from VOUT to GND. The LTC3240-3.3/LTC3240-2.5 require only three tiny external ceramic capacitors for an ultrasmall application footprint. The LTC3240-3.3/LTC3240-2.5 are available in a 6-pin (2mm × 2mm) DFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6411531.
U APPLICATIO S
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2 AA to 2.5V 2-3 AA/Li-Ion to 3.3V Low Power Supplies for Cameras, I/O Supplies, Audio, PC Cards, Misc. Logic, etc., in a Wide Variety of Handheld Products
TYPICAL APPLICATIO
1µF
Output Voltage vs Input Voltage (Full Range) Li-Ion to 3.3V at Up to 150mA
3.50 3.45 OUTPUT VOLTAGE (V) 3.40 3.35 3.30 3.25 3.20
3240 TA01a
IOUT = 30mA
2.7V TO 4.5V Li-Ion OR 3-CELL NiMH 1µF
VIN
C–
C+ VOUT
3.3V IOUT = 150mA 4.7µF
LTC3240-3.3 GND
OFF ON
SHDN
3.15 3.10 1.7 2.2 2.7 3.2 3.7 4.2 4.7 INPUT VOLTAGE (V) 5.2 5.7
U
3240 TA01b
U
3240fb
1
LTC3240-3.3/LTC3240-2.5
ABSOLUTE
(Note 1)
AXI U RATI GS
U W U PACKAGE/ORDER I FOR ATIO
TOP VIEW GND 1 VIN 2 VOUT 3 7 6 SHDN 5 C– 4 C+
VIN to GND ................................................... –0.3V to 6V VOUT to GND ............................................. –0.3V to 5.5V ⎯S⎯H⎯D⎯N to GND................................ –0.3V to (VIN + 0.3V) VOUT Short-Circuit Duration ............................. Indefinite Operating Temperature Range (Note 2) ...–40°C to 85°C Storage Temperature Range...................–65°C to 125°C Maximum Junction Temperature .......................... 125°C
ELECTRICAL CHARACTERISTICS
SYMBOL VIN VOUT PARAMETER Input Voltage Range Output Voltage Range LTC3240-3.3 LTC3240-2.5 No Load Input Current Shutdown Current Efficiency LTC3240-3.3 LTC3240-2.5 VIH VIL IIH IIL ILIM tON ⎯S⎯H⎯D⎯N Input High Voltage ⎯S⎯H⎯D⎯N Input Low Voltage ⎯SH ⎯ D ⎯ N ⎯ Input Current ⎯SH ⎯ D ⎯ N ⎯ Input Current Output Current Limit VOUT Turn-On Time
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, ⎯S⎯H⎯D⎯N = VIN, CFLY = 1µF, CIN = 1µF, COUT = 4.7µF unless otherwise noted.
CONDITIONS
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1.8V ≤ VIN ≤ 2.5V, IOUT < 40mA 2.5V ≤ VIN ≤ 5.5V, IOUT < 150mA 1.8V ≤ VIN ≤ 5.5V, IOUT < 60mA IOUT = 0, 1.8V ≤ VIN ≤ 5.5V ⎯S⎯H⎯D⎯N = 0V, VOUT = 0V VIN = 2.5V, IOUT = 100mA VIN = 3.7V, IOUT = 100mA VIN = 2V, IOUT = 50mA VIN = 3V, IOUT = 50mA 1.8V ≤ VIN ≤ 5.5V 1.8V ≤ VIN ≤ 5.5V V⎯S⎯H⎯D⎯N = VIN = 5.5V V⎯S⎯H⎯D⎯N = 0V VIN = 3.7V, VOUT = 0V Step-Down Mode VIN = 2.4V, VOUT = 0V Step-Up Mode From the Rising Edge of ⎯S⎯H⎯D⎯N to 90% of VOUT VIN = 2.5V, RLOAD = 66Ω VIN = 3.7V, RLOAD = 66Ω
IIN I⎯S⎯H⎯D⎯N η
Step-Up Mode IBURST Burst Mode Threshold VIN = 2.4V VRIPPLE Output Ripple IOUT = 100mA, VOUT = 2.5V or 3.3V fOSC Switching Frequency VIN = 2.4V VRIPPLE(BURST) Burst Mode® Output Ripple VIN = 2.4V Burst Mode is a registered trademark of Linear Technology Corporation.
2
U
W W
W
DC PACKAGE 6-LEAD (2mm × 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 80°C/W (NOTE 4) EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER LTC3240EDC-3.3 LTC3240EDC-2.5
DC PART MARKING LBXJ LCBP
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
MIN
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TYP 3.3 3.3 2.5 65 0.1 64 87 63 83
MAX 5.5 3.432 3.432 2.6 100 1
UNITS V V V V µA µA % % % % V V µA µA mA mA ms ms mA mVP-P MHz mVP-P
3240fb
1.8 3.168 3.168 2.4
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1.2 –1 –1 450.