ltc3240-3.3 Linear Technology Corporation, ltc3240-3.3 Datasheet

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ltc3240-3.3

Manufacturer Part Number
ltc3240-3.3
Description
3.3v/2.5v Step-up/ Step-down Charge Pump Dc/dc Converter
Manufacturer
Linear Technology Corporation
Datasheet
APPLICATIO S
FEATURES
TYPICAL APPLICATIO
2.7V TO 4.5V
Step-Up/Step-Down Charge Pumps Generate Fixed
3.3V or 2.5V Outputs
V
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: I
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
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
3-CELL NiMH
IN
Li-Ion OR
Range: 1.8V to 5.5V
Li-Ion to 3.3V at Up to 150mA
1µF
OFF ON
U
V
GND
SHDN
LTC3240-3.3
IN
C
1µF
V
C
OUT
U
+
Q
3240 TA01a
= 65µA
4.7µF
3.3V
I
OUT
= 150mA
DESCRIPTIO
The LTC
charge pump DC/DC converters that produce a fi xed
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 operat-
ing current (65µA typical) and ultralow operating current
in shutdown (<1µA). Built-in soft-start circuitry prevents
excessive inrush current during start-up. Thermal shut-
down and current-limit circuitry allow the parts to survive
a continuous short-circuit from V
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.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6411531.
Step-Down Charge Pump
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
LTC3240-3.3/LTC3240-2.5
®
Output Voltage vs Input Voltage (Full Range)
3240-3.3/LTC3240-2.5 are step-up/step-down
3.50
3.45
3.40
3.35
3.30
3.25
3.20
3.15
3.10
1.7
I
OUT
3.3V/2.5V Step-Up/
2.2
= 30mA
DC/DC Converter
U
2.7
INPUT VOLTAGE (V)
3.2
3.7
4.2
OUT
4.7
to GND.
3240 TA01b
5.2
5.7
3240fb
1

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ltc3240-3.3 Summary of contents

Page 1

... V 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. ...

Page 2

... LTC3240-3.3 LTC3240-2 Load Input Current IN I Shutdown Current ⎯ S ⎯ H ⎯ D ⎯ N η Effi ciency LTC3240-3.3 LTC3240-2.5 ⎯ S ⎯ H ⎯ D ⎯ N Input High Voltage V IH ⎯ S ⎯ H ⎯ D ⎯ N Input Low Voltage V IL ⎯ S ⎯ H ⎯ D ⎯ N Input Current I IH ⎯ ...

Page 3

... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3240-3.3/LTC3240-2.5 are guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the W ...

Page 4

... I (mA) LOAD 3240 G10 V Soft-Start (LTC3240-3.3) OUT V OUT 2V/DIV SHDN 2V/DIV V = 2.4V 200µs/DIV 66Ω LOAD 4 No-Load Input Current vs Supply Voltage (LTC3240-3.3) 100 1.7 2.2 2.7 3.2 3.7 4.2 4.7 85 SUPPLY VOLTAGE (V) Mode Switch Threshold vs Load Current (LTC3240-2.5) 2.95 2.90 DOUBLER TO LDO 2 ...

Page 5

... Flying Capacitor Negative Terminal. ⎯ S ⎯ H ⎯ D ⎯ N (Pin 6): Active Low Shutdown Input. A low on ⎯ S ⎯ H ⎯ D ⎯ N should be bypassed disables the LTC3240-3.3/LTC3240-2.5. This pin is a high IN impedance CMOS input pin which must be driven with valid logic levels. This pin must not be allowed to fl oat. ...

Page 6

... LTC3240-3.3/LTC3240-2.5 W BLOCK DIAGRA V 3 OUT SWITCH CONTROL OSCILLATOR – + – 100mV OUT CHARGE PUMP 1, 7 GND SOFT-START 6 SHDN AND 1.2MHz + 4 C – 3204 BD 3240fb ...

Page 7

... The LTC3240 provides automatic Burst Mode operation while operating as a charge pump, to increase effi ciency of the power converter at light loads. Burst Mode operation LTC3240-3.3/LTC3240-2.5 is initiated if the output load current falls below an inter- by about 100mV it nally programmed threshold. Once Burst Mode operation ...

Page 8

... IN At moderate to high output power, the switching losses and the quiescent current of the LTC3240 are negligible and the expression above is valid. For example, the mea- sured effi ciency of LTC3240-3.3 with V 100mA and V regulating to 3.3V is 64% which is in OUT close agreement with the theoretical value of 66%. ...

Page 9

... The fl ying capacitor controls the strength of the charge pump. A 1µF or greater ceramic capacitor is suggested for the fl ying capacitor. For the LTC3240-3.3 operating at an input voltage in the range 1.8V ≤ V necessary to have at least 0.5µF of capacitance for the fl ...

Page 10

... LTC3240-3.3/LTC3240-2 APPLICATIO S I FOR ATIO to additional switch resistance. However, for very light load applications, the above expression can be used as a guideline in determining a starting capacitor value. Ceramic Capacitors Ceramic capacitors of different materials lose their ca- pacitance with higher temperature and voltage at differ- ent rates. For example, a capacitor made of X5R or X7R material will retain most of its capacitance from – ...

Page 11

... 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC3240-3.3/LTC3240-2 This derating curve assumes a maximum thermal resis- tance, θ ...

Page 12

... LTC3240-3.3/LTC3240-2.5 U TYPICAL APPLICATIO RELATED PARTS PART NUMBER DESCRIPTION LTC1751-3.3/LTC1751-5 100mA, 800kHz Regulated Doubler LTC1983-3/LTC1983-5 100mA, 900kHz Regulated Inverter LTC3200-5 100mA, 2MHz Low Noise, Doubler/White LED Driver LTC3202 125mA, 1.5MHz Low Noise, Fractional White LED Driver LTC3204-3.3 Low Noise, Regulated Charge Pumps in (2mm × ...

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