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
V
IN
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: I
Q
= 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 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
OUT
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.
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
I
OUT
= 30mA
2.7V TO 4.5V
Li-Ion OR
3-CELL NiMH
1µF
V
IN
C
–
C
V
OUT
+
3.3V
I
OUT
= 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
U
3240fb
1
LTC3240-3.3/LTC3240-2.5
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
GND 1
V
IN
2
V
OUT
3
7
6 SHDN
5 C
–
4 C
+
V
IN
to GND ................................................... –0.3V to 6V
V
OUT
to GND ............................................. –0.3V to 5.5V
⎯
S
⎯
H
⎯
D
⎯
N to GND................................ –0.3V to (V
IN
+ 0.3V)
V
OUT
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
DC PACKAGE
6-LEAD (2mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 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.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
V
OUT
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
V
IH
V
IL
I
IH
I
IL
I
LIM
t
ON
⎯
S
⎯
H
⎯
D
⎯
N Input High Voltage
⎯
S
⎯
H
⎯
D
⎯
N Input Low Voltage
⎯
S
⎯
H
⎯
D
⎯
N Input Current
⎯
S
⎯
H
⎯
D
⎯
N Input Current
Output Current Limit
V
OUT
Turn-On Time
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C,
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
, C
FLY
= 1µF, C
IN
= 1µF, C
OUT
= 4.7µF unless otherwise noted.
CONDITIONS
●
MIN
●
●
●
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
%
%
%
%
1.8V ≤ V
IN
≤ 2.5V, I
OUT
< 40mA
2.5V ≤ V
IN
≤ 5.5V, I
OUT
< 150mA
1.8V ≤ V
IN
≤ 5.5V, I
OUT
< 60mA
I
OUT
= 0, 1.8V ≤ V
IN
≤ 5.5V
⎯
S
⎯
H
⎯
D
⎯
N = 0V, V
OUT
= 0V
V
IN
= 2.5V, I
OUT
= 100mA
V
IN
= 3.7V, I
OUT
= 100mA
V
IN
= 2V, I
OUT
= 50mA
V
IN
= 3V, I
OUT
= 50mA
1.8V ≤ V
IN
≤ 5.5V
1.8V ≤ V
IN
≤ 5.5V
V
⎯
S
⎯
H
⎯
D
⎯
N
= V
IN
= 5.5V
V
⎯
S
⎯
H
⎯
D
⎯
N
= 0V
V
IN
= 3.7V, V
OUT
= 0V Step-Down Mode
V
IN
= 2.4V, V
OUT
= 0V Step-Up Mode
From the Rising Edge of
⎯
S
⎯
H
⎯
D
⎯
N to 90% of V
OUT
V
IN
= 2.5V, R
LOAD
= 66Ω
V
IN
= 3.7V, R
LOAD
= 66Ω
1.8
3.168
3.168
2.4
I
IN
I
⎯
S
⎯
H
⎯
D
⎯
N
η
●
●
●
●
1.2
–1
–1
450
270
0.5
0.4
15
20
1.2
20
0.4
1
1
Step-Up Mode
I
BURST
Burst Mode Threshold
V
IN
= 2.4V
V
RIPPLE
Output Ripple
I
OUT
= 100mA, V
OUT
= 2.5V or 3.3V
f
OSC
Switching Frequency
V
IN
= 2.4V
®
V
RIPPLE(BURST)
Burst Mode Output Ripple
V
IN
= 2.4V
Burst Mode is a registered trademark of Linear Technology Corporation.
●
0.6
1.8
mA
mV
P-P
MHz
mV
P-P
3240fb
2
U
V
V
µA
µA
mA
mA
ms
ms
W
U
U
W W
W
LTC3240-3.3/LTC3240-2.5
ELECTRICAL CHARACTERISTICS
SYMBOL
R
OL
PARAMETER
Effective Open-Loop
Output Resistance
LTC3240-3.3
LTC3240-2.5
(Note 3)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C,
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
, C
FLY
= 1µF, C
IN
= 1µF, C
OUT
= 4.7µF unless otherwise noted.
CONDITIONS
Doubler Mode
V
IN
= 1.8V, V
OUT
= 3V
V
IN
= 1.8V, V
OUT
= 2.25V
MIN
TYP
MAX
UNITS
7.5
8.0
Ω
Ω
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 LTC3240-3.3/LTC3240-2.5 are guaranteed to meet
performance specifications from 0°C to 85°C. Specifications over the
–40°C to 85°C operating temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 3:
R
OL
≡
(2V
IN
– V
OUT
)/I
OUT
Note 4:
Failure to solder the exposed backside of the package to a PCB
ground plane will result in a thermal resistance much higher than 80°C/W.
TYPICAL PERFOR A CE CHARACTERISTICS
unless otherwise noted)
Oscillator Frequency vs Supply
Voltage (Doubler Mode)
1.8
OSCILLATOR FREQUENCY (MHz)
1.6
SHUTDOWN VOLTAGE (V)
1.4
25°C
1.2
85°C
1.0
0.8
0.6
1.8
2.2
2.6
3.0
3.4
SUPPLY VOLTAGE (V)
3.8
3240 G01
0.8
85°C
0.6
SHORT-CIRCUIT CURRENT (mA)
–40°C
Start-Up Time vs Supply Voltage
1000
900
OUTPUT VOLTAGE (V)
800
700
600
500
400
1.6 1.8 2
2.2 2.4 2.6 2.8
V
IN
(V)
3 3.2 3.4 3.6
3240 G04
I
LOAD
= 50mA
V
IN
= 3.7V
3.30
V
IN
= 2.5V
3.25
V
IN
= 1.8V
OUTPUT VOLTAGE (V)
START-UP TIME (µs)
U W
(T
A
= 25°C, C
FLY
= C
IN
= 1µF, C
OUT
= 4.7µF
⎯
SH
⎯
D
⎯
N Threshold Voltage
⎯
vs Supply Voltage
1.0
25°C
–40°C
600
500
400
300
200
100
700
Short-Circuit Current
vs Supply Voltage
0.4
0.2
SHUTDOWN
HYSTERESIS
0
1.80 2.30 2.80 3.30 3.80 4.30 4.80 5.30 5.80
SUPPLY VOLTAGE (V)
3240 G02
0
1.7
2.2
2.7
4.7
SUPPLY VOLTAGE (V)
3.2
3.7
4.2
5.2
5.7
3240 G03
Load Regulation (LTC3240-3.3)
3.40
2.60
Load Regulation (LTC3240-2.5)
3.35
2.55
V
IN
= 2.8V
2.50
V
IN
= 1.8V
V
IN
= 2.4V
2.45
3.20
0
30
90
120
60
LOAD CURRENT (mA)
150
3240 G05
2.40
0
30
90
120
60
LOAD CURRENT (mA)
150
3240 G06
3240fb
3
LTC3240-3.3/LTC3240-2.5
TYPICAL PERFOR A CE CHARACTERISTICS
unless otherwise noted)
Effective Open-Loop Resistance
vs Temperature (LTC3240-3.3)
10
EFFECTIVE OPEN-LOOP RESISTANCE (Ω)
100
V
IN
= 1.8V
V
OUT
= 3V
NO-LOAD INPUT CURRENT (µA)
90
80
70
60
50
40
30
20
10
5
–40
0
–15
35
10
TEMPERATURE (°C)
60
85
3240 G07
NO-LOAD INPUT CURRENT (µA)
5.2
9
8
7
6
Mode Switch Threshold
vs Load Current (LTC3240-3.3)
3.80
3.75
3.70
3.65
V
IN
(V)
V
IN
(V)
3.60
3.55
3.50
3.45
3.40
0
20
40
60 80 100 120 140 160
I
LOAD
(mA)
3240 G10
DOUBLER TO
LDO MODE
(V
IN
RISING)
EFFICIENCY (%)
LDO TO
DOUBLER MODE
(V
IN
FALLING)
V
OUT
Soft-Start (LTC3240-3.3)
V
OUT
2V/DIV
V
OUT
20mV/DIV
AC COUPLED
SHDN
2V/DIV
V
IN
= 2.4V
R
LOAD
= 66Ω
200µs/DIV
3240 G13
4
U W
(T
A
= 25°C, C
FLY
= C
IN
= 1µF, C
OUT
= 4.7µF
No-Load Input Current
vs Supply Voltage (LTC3240-3.3)
100
90
80
70
60
50
40
30
20
10
0
1.7 2.2
2.7 3.2 3.7 4.2 4.7
SUPPLY VOLTAGE (V)
5.7
No-Load Input Current
vs Supply Voltage (LTC3240-2.5)
1.7 2.2
2.7 3.2 3.7 4.2 4.7
SUPPLY VOLTAGE (V)
5.2
5.7
3240 G08
3240 G09
Mode Switch Threshold
vs Load Current (LTC3240-2.5)
2.95
2.90
2.85
2.80
2.75
2.70
2.65
0
20
40
LDO TO DOUBLER
MODE (V
IN
FALLING)
DOUBLER TO LDO
MODE (V
IN
RISING)
100
90
80
70
60
50
40
30
20
10
60 80 100 120 140 160
I
LOAD
(mA)
3240 G11
Efficiency vs Supply Voltage
(LTC3240-3.3)
LDO TO DOUBLER
MODE (V
IN
FALLING)
I
LOAD
= 40mA
I
LOAD
= 1mA
DOUBLER TO LDO
MODE (V
IN
RISING)
0
1.80 2.30 2.80 3.30 3.80 4.30 4.80 5.30 5.80
SUPPLY VOLTAGE (V)
3240 G12
Output Noise/Ripple
(LTC3240-3.3)
V
IN
= 2.4V
I
LOAD
= 100mA
500ns/DIV
3240 G14
3240fb
LTC3240-3.3/LTC3240-2.5
TYPICAL PERFOR A CE CHARACTERISTICS
unless otherwise noted)
Load Transient Response
(LTC3240-3.3)
V
OUT
20mV/DIV
AC COUPLED
LDO MODE
V
OUT
20mV/DIV
AC COUPLED
60mA
I
LOAD
10mA
V
IN
= 3.7V
10µs/DIV
I
LOAD
= 10mA TO 60mA
3240 G15
PI FU CTIO S
GND (Pin 1):
Ground. This pin should be tied to a ground
plane for best performance.
V
IN
(Pin 2):
Input Supply Voltage. V
IN
should be bypassed
with a 1μF or greater, low ESR ceramic capacitor.
V
OUT
(Pin 3):
Regulated Output Voltage. V
OUT
should be
bypassed with a 4.7μF or greater, low ESR ceramic capaci-
tor as close to the pin as possible for best performance.
C
+
(Pin 4):
Flying Capacitor Positive Terminal.
C
–
(Pin 5):
Flying Capacitor Negative Terminal.
⎯ ⎯ ⎯ ⎯
⎯ ⎯ ⎯ ⎯
SHDN (Pin 6):
Active Low Shutdown Input. A low on SHDN
disables the LTC3240-3.3/LTC3240-2.5. This pin is a high
impedance CMOS input pin which must be driven with valid
logic levels. This pin must not be allowed to float.
Exposed Pad (Pin 7):
Ground. The exposed pad must be
soldered to PCB ground to provide electrical contact and
optimum thermal performance.
U W
(T
A
= 25°C, C
FLY
= C
IN
= 1µF, C
OUT
= 4.7µF
Output Noise/Ripple
(LTC3240-2.5)
V
OUT
20mV/DIV
AC COUPLED
Load Transient Response
(LTC3240-2.5)
Burst Mode
OPERATION
CONST FREQUENCY
MODE
I
LOAD
50mA
10mA
V
IN
= 2.4V
10µs/DIV
I
LOAD
= 10mA TO 50mA
3240 G17
V
IN
= 2.4V
I
LOAD
= 100mA
500ns/DIV
3240 G16
U
U
U
3240fb
5
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