1
LTC1754-3.3/LTC1754-5
Micropower, Regulated
3.3V/5V Charge Pump with
Shutdown in SOT-23
s
Ultralow Power: I
IN
= 13
µ
A
s
Regulated Output Voltage: 3.3V
±
4%, 5V
±
4%
s
5V Output Current: 50mA (V
IN
3.0V)
s
3.3V Output Current: 40mA (V
IN
2.5V)
s
No Inductors Needed
s
Very Low Shutdown Current: <1
µ
A
s
Shutdown Disconnects Load from V
IN
s
Internal Oscillator: 600kHz
s
Short-Circuit and Overtemperature Protected
s
Ultrasmall Application Circuit: (0.052 Inch
2
)
s
6-Pin SOT-23 Package
s
SIM Interface Supplies for GSM Cellular Telephones
s
White LED Power Supplies
s
Li-Ion Battery Backup Supplies
s
Handheld Computers
s
Smart Card Readers
s
PCMCIA Local 5V Supplies
The LTC
®
1754 is a micropower charge pump DC/DC
converter that produces a regulated output. The input
voltage range is 2V to 4.4V for 3.3V output and 2.7V to
5.5V for 5V output. Extremely low operating current and a
low external parts count (one flying capacitor and two
small bypass capacitors at V
IN
and V
OUT
) make the LTC1754
ideally suited for small, battery-powered applications. The
total component area of the application circuit shown
below is only 0.052 inch
2
.
The LTC1754 operates as a Burst Mode
TM
switched capaci-
tor voltage doubler to produce a regulated output. It has
thermal shutdown capability and can survive a continuous
short circuit from V
OUT
to GND.
The LTC1754 is available in a 6-pin SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
LTC1754-5
Output Voltage vs Supply Voltage
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
SUPPLY VOLTAGE (V)
2.5
4.85
OUTPUT VOLTAGE (V)
4.90
4.95
5.00
5.05
5.15
3.0
3.5
4.0
4.5
1574 TA03
5.0
5.5
5.10
T
A
= 40
°
C
T
A
= 85
°
C
I
OUT
= 25mA
C
OUT
= 10
µ
F
C
FLY
= 1
µ
F
T
A
= 25
°
C
SUPPLY VOLTAGE (V)
2.0
OUTPUT VOLTAGE (V)
3.30
3.35
4.0
1754 TA02
3.25
3.20
2.5
3.0
3.5
4.5
3.40
I
OUT
= 20mA
C
OUT
= 10
µ
f
C
FLY
= 1
µ
F
T
A
= 85
°
C
T
A
= 25
°
C
T
A
= 40
°
C
LTC1754-3.3
Output Voltage vs Supply Voltage
1
LTC1754-X
Regulated 3.3V Output from 2V to 4.4V Input
Regulated 5V Output from 2.7V to 5.5V Input
2
3
6
5
4
ON/OFF
V
OUT
1754 TA01
V
IN
V
OUT
V
OUT
= 5V
±
4%
I
OUT
= 0mA TO 25mA, V
IN
> 2.7V
I
OUT
= 0mA TO 50mA, V
IN
> 3.0V
10
µ
F
1
µ
F
10
µ
F
GND
SHDN
C
+
V
IN
C
V
OUT
= 3.3V
±
4%
I
OUT
= 0mA TO 20mA, V
IN
> 2.0V
I
OUT
= 0mA TO 40mA, V
IN
> 2.5V
2
LTC1754-3.3/LTC1754-5
ORDER PART
NUMBER
Consult factory for Industrial and Military grade parts.
(Note 1)
V
IN
to GND .................................................. 0.3V to 6V
V
OUT
to GND ............................................... 0.3V to 6V
SHDN to GND .............................................. 0.3V to 6V
I
OUT
(Note 4) ......................................................... 75mA
V
OUT
Short-Circuit Duration ............................ Indefinite
Operating Temperature Range (Note 3) ... 40
°
C to 85
°
C
Storage Temperature Range .................. 65
°
C to 150
°
C
Lead Temperature (Soldering, 10 sec)................... 300
°
C
LTC1754ES6-3.3
LTC1754ES6-5
T
JMAX
= 150
°
C,
JA
= 230
°
C/ W
S6 PART MARKING
LTGK
LTLW
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. C
FLY
= 1
µ
F (Note 2), C
IN
= 10
µ
F, C
OUT
= 10
µ
F.
V
OUT
1
GND 2
SHDN 3
6 C
+
5 V
IN
4 C
TOP VIEW
S6 PACKAGE
6-LEAD PLASTIC SOT-23
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
Note 2: 0.6
µ
F is the minimum required C
FLY
capacitance for rated output
current capability. Depending on the choice of capacitor material, a
somewhat higher value of capacitor may be required to attain 0.6
µ
F over
temperature.
Note 3: The LTC1754ES6-X is guaranteed to meet performance
specifications from 0
°
C to 70
°
C. Specifications over the 40
°
C to 85
°
C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 4: Based on long term current density limitations.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
LTC1754-3.3
V
IN
Input Supply Voltage
q
2.0
4.4
V
V
OUT
Output Voltage
2.0V
V
IN
4.4V, I
OUT
20mA
q
3.17
3.30
3.43
V
2.5V
V
IN
4.4V, I
OUT
40mA
q
3.17
3.30
3.43
V
I
CC
Operating Supply Current
2.0V
V
IN
4.4V, I
OUT
= 0mA, SHDN = V
IN
q
11
30
µ
A
V
R
Output Ripple
V
IN
= 2.5V, I
OUT
= 40mA
23
mV
P-P
Efficiency
V
IN
= 2.0V, I
OUT
= 20mA
82
%
f
OSC
Switching Frequency
Oscillator Free Running
600
kHz
t
ON
V
OUT
Turn-On Time
V
IN
= 2.0V, I
OUT
= 0mA
0.8
ms
I
SC
Output Short-Circuit Current
V
IN
= 2.5V, V
OUT
= 0V, SHDN = 2.5V
118
mA
LTC1754-5
V
IN
Input Supply Voltage
q
2.7
5.5
V
V
OUT
Output Voltage
2.7V
V
IN
5.5V, I
OUT
25mA
q
4.8
5.0
5.2
V
3.0V
V
IN
5.5V, I
OUT
50mA
q
4.8
5.0
5.2
V
I
CC
Operating Supply Current
2.7V
V
IN
5.5V, I
OUT
= 0mA, SHDN = V
IN
q
13
30
µ
A
V
R
Output Ripple
V
IN
= 3V, I
OUT
= 50mA
65
mV
P-P
Efficiency
V
IN
= 3V, I
OUT
= 50mA
82.7
%
f
OSC
Switching Frequency
Oscillator Free Running
700
kHz
t
ON
V
OUT
Turn-On Time
V
IN
= 3V, I
OUT
= 0mA
0.4
ms
I
SC
Output Short-Circuit Current
V
IN
= 3V, V
OUT
= 0V, SHDN = 3V
150
mA
LTC1754-3.3/LTC1754-5
I
SHDN
Shutdown Supply Current
V
IN
3.6V, I
OUT
= 0mA, V
SHDN
= 0V
q
0.01
1
µ
A
3.6V < V
IN
, I
OUT
= 0mA, V
SHDN
= 0V
q
2.5
µ
A
V
IH
SHDN Input Threshold (High)
q
1.4
V
V
IL
SHDN Input Threshold (Low)
q
0.3
V
I
IH
SHDN Input Current (High)
SHDN = V
IN
q
1
1
µ
A
I
IL
SHDN Input Current (Low)
SHDN = 0V
q
1
1
µ
A
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
ELECTRICAL CHARACTERISTICS
3
LTC1754-3.3/LTC1754-5
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
LTC1754-3.3, T
A
= 25
°
C unless otherwise noted.
No Load Supply Current
vs Supply Voltage
Output Voltage vs Output Current
Supply Current vs V
SHDN
OUTPUT CURRENT (mA)
0
OUTPUT VOLTAGE (V)
3.30
3.35
80
1754 G01
3.25
3.20
20
40
60
100
3.40
T
A
= 25
°
C
C
OUT
= 10
µ
F
C
FLY
= 1
µ
F
V
IN
= 2.5V
V
IN
= 2V
SUPPLY VOLTAGE (V)
2.0
5
SUPPLY CURRENT (
µ
A)
10
15
20
2.5
3.0
3.5
4.0
1754 G02
4.5
I
OUT
= 0
µ
A
C
FLY
= 1
µ
F
V
SHDN
= V
IN
T
A
= 85
°
C
T
A
= 25
°
C
T
A
= 40
°
C
V
SHDN
CONTROL VOLTAGE (V)
1
SUPPLY CURRENT (
µ
A)
10
15
5
1754 G03
5
0
2
3
4
20
T
A
= 25
°
C
I
OUT
= 0
µ
A
V
IN
= 4.5V
V
IN
= 2.5V
V
IN
= 2V
Efficiency vs Load Current
V
OUT
Short-Circuit Current
vs Supply Voltage
SUPPLY VOLTAGE (V)
2.0
60
V
OUT
SHORT-CIRCUIT CURRENT (mA)
80
100
120
140
160
180
2.5
3.0
3.5
4.0
1735 G04
4.5
T
A
= 25
°
C
C
FLY
= 1
µ
F
LOAD CURRENT (mA)
0.001
40
EFFICIENCY (%)
50
60
70
80
0.01
0.1
1
10
100
1754 G05
30
20
10
0
90
100
T
A
= 25
°
C
V
IN
= 2V
C
FLY
= 1
µ
F
Output Ripple
Load Transient Response
Start-Up Time
I
OUT
0mA to 20mA
10mA/DIV
V
OUT
AC COUPLED
20mV/DIV
V
IN
= 2V
50
µ
s/DIV
1754 G07
C
OUT
= 10
µ
F
V
OUT
AC COUPLED
20mV/DIV
V
IN
= 2V
5
µ
s/DIV
1754 G08
C
OUT
= 10
µ
F
I
OUT
= 20mA
SHDN
1V/DIV
V
OUT
1V/DIV
V
IN
= 2V
200
µ
s/DIV
1754 G9
C
OUT
= 10
µ
F
4
LTC1754-3.3/LTC1754-5
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
LTC1754-5, T
A
= 25
°
C unless otherwise noted.
No Load Supply Current
vs Supply Voltage
Output Voltage vs Output Current
Supply Current vs V
SHDN
Efficiency vs Load Current
V
OUT
Short-Circuit Current
vs Supply Voltage
Output Ripple
Load Transient Response
Start-Up Time
I
OUT
0mA to 50mA
25mA/DIV
V
OUT
AC COUPLED
50mV/DIV
V
IN
= 3V
50
µ
s/DIV
1754 G16
C
OUT
= 10
µ
F
V
OUT
AC COUPLED
20mV/DIV
V
IN
= 3V
5
µ
s/DIV
1754 G17
C
OUT
= 10
µ
F
I
OUT
= 50mA
SHDN
5V/DIV
V
OUT
1V/DIV
V
IN
= 3V
100
µ
s/DIV
1754 G18
C
OUT
= 10
µ
F
OUTPUT CURRENT (mA)
0
4.85
OUTPUT VOLTAGE (V)
4.90
4.95
5.00
5.05
5.10
5.15
20
40
60
80
1574-5 G02
100
T
A
= 25
°
C
C
OUT
= 10
µ
F
C
FLY
= 1
µ
F
V
IN
= 3V
V
IN
= 2.7V
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
µ
A)
4.0
4.5
1754 G11
2.5
3.0
3.5
5.0
5.5
20
15
10
5
I
OUT
= 0
µ
A
C
FLY
= 1
µ
F
V
SHDN
= V
IN
T
A
= 85
°
C
T
A
= 40
°
C
T
A
= 25
°
C
V
SHDN
CONTROL VOLTAGE (V)
1
SUPPLY CURRENT (
µ
A)
15
20
25
5
1574 G12
10
5
0
2
3
4
6
T
A
= 25
°
C
I
OUT
= 0
µ
A
V
IN
= 5.5V
V
IN
= 3.3V
V
IN
= 2.7V
SUPPLY VOLTAGE (V)
V
OUT
SHORT-CIRCUIT CURRENT (mA)
4.0
4.5
1754 G13
2.5
3.0
3.5
5.0
5.5
220
180
140
200
160
120
100
T
A
= 25
°
C
C
FLY
= 1
µ
F
LOAD CURRENT (mA)
0.001
40
EFFICIENCY (%)
50
60
70
80
0.01
0.1
1
10
100
1754-5 G05
30
20
10
0
90
100
V
IN
= 3V
T
A
= 25
°
C
C
FLY
= 1
µ
F
5
LTC1754-3.3/LTC1754-5
V
OUT
(Pin 1): Regulated Output Voltage. For best perfor-
mance, V
OUT
should be bypassed with a 6.8
µ
F (min) low
ESR capacitor as close as possible to the pin.
GND (Pin 2): Ground. Should be tied to a ground plane for
best performance.
SHDN (Pin 3): Active Low Shutdown Input. A low on
SHDN disables the LTC1754. SHDN must not be allowed
to float.
C
(Pin 4): Flying Capacitor Negative Terminal.
V
IN
(Pin 5): Input Supply Voltage. V
IN
should be bypassed
with a 6.8
µ
F (min) low ESR capacitor.
C
+
(Pin 6): Flying Capacitor Positive Terminal.
SI PLIFIED
W
BLOCK DIAGRA
W
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
LTC1754-3.3. LTC1754-5, T
A
= 25
°
C unless otherwise noted.
Oscillator Frequency
vs Supply Voltage
Efficiency vs Supply Voltage
SUPPLY VOLTAGE (V)
2.0
70
80
100
3.5
4.5
1754 G19
60
50
2.5
3.0
4.0
5.0
5.5
40
30
90
EFFICIENCY (%)
T
A
= 25
°
C
C
FLY
= 1
µ
F
LTC1754-5
I
OUT
= 25mA
LTC1754-3.3
I
OUT
= 20mA
SUPPLY VOLTAGE (V)
2.0
OSCILLATOR FREQUENCY (kHz)
800
3.5
1754 G20
650
550
2.5
3.0
4.0
500
450
850
750
700
600
4.5
5.0
5.5
T
A
= 85
°
C
T
A
= 25
°
C
T
A
= 40
°
C
SUPPLY VOLTAGE (V)
2.0
THRESHOLD VOLTAGE (V)
0.85
0.90
0.95
3.5
4.5
1754 G21
0.80
0.75
2.5
3.0
4.0
5.0
5.5
0.70
0.65
T
A
= 40
°
C
T
A
= 25
°
C
T
A
= 85
°
C
+
COMP1
2
*
C
+
C
FLY
1
µ
F
C
*CHARGE PUMP SHOWN IN PHASE 1, THE CHARGING PHASE.
PHASE 1 IS ALSO THE SHUTDOWN PHASE
1
1
2
CONTROL
V
REF
C
OUT
10
µ
F
C
IN
10
µ
F
V
IN
1754 BD
V
OUT
SHDN
V
SHDN
Threshold Voltage
vs Supply Voltage
U
U
U
PI FU CTIO S
6
LTC1754-3.3/LTC1754-5
Operation (Refer To Block Diagram)
The LTC1754 uses a switched-capacitor charge pump to
boost V
IN
to a regulated output voltage. Regulation is
achieved by sensing the output voltage through an internal
resistor divider and enabling the charge pump when the
divided output drops below the lower trip point of COMP1.
When the charge pump is enabled, a two-phase
nonoverlapping clock activates the charge pump switches.
The flying capacitor is charged to V
IN
on phase one of the
clock. On phase two of the clock it is stacked in series with
V
IN
and connected to V
OUT
. This sequence of charging and
discharging the flying capacitor continues at a free run-
ning frequency of 600kHz (typ). Once the attenuated
output voltage reaches the upper trip point of COMP1, the
charge pump is disabled. When the charge pump is
disabled the LTC1754 draws only 13
µ
A from V
IN
thus
providing high efficiency under low load conditions.
In shutdown mode all circuitry is turned off and the
LTC1754 draws only leakage current from the V
IN
supply.
Furthermore, V
OUT
is disconnected from V
IN
. The SHDN
pin is a CMOS input with a threshold voltage of approxi-
mately 0.8V, but may be driven to a logic level that exceeds
V
IN
. The LTC1754 is in shutdown when a logic low is
applied to the SHDN pin. Since the SHDN pin is a high
impedance CMOS input, it should never be allowed to
float. To ensure that its state is defined, it must always be
driven with a valid logic level.
Power Efficiency
The efficiency (
) of the LTC1754 is similar to that of a
linear regulator with an effective input voltage of twice the
actual input voltage. This results because the input current
for a voltage doubling charge pump is approximately twice
the output current. In an ideal voltage doubling regulator
the power efficiency would be given by:
=
=
( )( )
( )( )
=
P
P
V
I
V
I
V
V
OUT
IN
OUT
OUT
IN
OUT
OUT
IN
2
2
At moderate-to-high output power, the switching losses and
quiescent current of the LTC1754 are negligible and the
expression above is valid. For example, an LTC1754-5 with
V
IN
= 3V, I
OUT
= 25mA and V
OUT
regulating to 5V, has a
measured efficiency of 82.7%, which is in close agreement
with the theoretical 83.3% calculation. The LTC1754 con-
tinues to maintain good efficiency even at fairly light loads
because of its inherently low power design.
Short-Circuit/Thermal Protection
During short-circuit conditions, the LTC1754 will draw
between 100mA and 400mA from V
IN
causing a rise in the
junction temperature. On-chip thermal shutdown circuitry
disables the charge pump once the junction temperature
exceeds approximately 150
°
C and reenables the charge
pump once the junction temperature drops back to ap-
proximately 140
°
C. The LTC1754 will cycle in and out of
thermal shutdown indefinitely without latchup or damage
until the short circuit on V
OUT
is removed.
Capacitor Selection
The style and value of capacitors used with the
LTC1754 determine several important parameters such as
output ripple, charge pump strength and turn-on time.
To reduce noise and ripple, it is recommended that low
ESR (< 0.1
) capacitors be used for both C
IN
and C
OUT
.
These capacitors should be either ceramic or tantalum and
be 6.8
µ
F or greater. Aluminum capacitors are not recom-
mended because of their high ESR. If the source imped-
ance to V
IN
is very low up to several megahertz, C
IN
may
not be needed.
A ceramic capacitor is recommended for the flying capaci-
tor with a value in the range of 1
µ
F to 2.2
µ
F. Note that a
large value flying capacitor (> 2.2
µ
F) will increase output
ripple unless C
OUT
is also increased. For very low load
applications, C
FLY
may be reduced to 0.01
µ
F to 0.047
µ
F.
This will reduce output ripple at the expense of maximum
output current and efficiency.
In order to achieve the rated output current it is necessary
to have at least 0.6
µ
F of capacitance for the flying capaci-
tor. Capacitors of different material lose their capacitance
over temperature at different rates. For example, a ceramic
capacitor made of X7R material will retain most of its
capacitance from 40
°
C to 85
°
C, whereas a Z5U or Y5V
style capacitor will lose considerable capacitance over that
APPLICATIO S I FOR ATIO
W
U
U
U
7
LTC1754-3.3/LTC1754-5
range. The capacitor manufacturer's data sheet should be
consulted to determine what style and value of capacitor
is needed to ensure 0.6
µ
F at all temperatures.
Output Ripple
Low frequency
regulation mode ripple exists due to the
hysteresis in the sense comparator and propagation delay
in the charge pump control circuit. The amplitude and
frequency of this ripple are heavily dependent on the load
current, the input voltage and the output capacitor size.
For large V
IN
the ripple voltage can become substantial
because the increased strength of the charge pump causes
fast edges that may outpace the regulation circuitry.
Generally the regulation ripple has a sawtooth shape
associated with it.
A high frequency ripple component may also be present
on the output capacitor due to the charge transfer action
of the charge pump. In this case the output can display a
voltage pulse during the charging phase. This pulse
results from the product of the charging current and the
ESR of the output capacitor. It is proportional to the input
voltage, the value of the flying capacitor and the ESR of the
output capacitor.
Typical combined output ripple for the LTC1754-5 with
V
IN
= 3V under maximum load is 65mV
P-P
using a low ESR
10
µ
F output capacitor. A smaller output capacitor and/or
larger output current load will result in higher ripple due to
higher output voltage slew rates.
There are several ways to reduce output voltage ripple. For
applications requiring higher V
IN
or lower peak-to-peak
ripple, a larger C
OUT
capacitor (22
µ
F or greater) is recom-
mended. A larger capacitor will reduce both the low and
high frequency ripple due to the lower charging and
discharging slew rates, as well as the lower ESR typically
found with higher value (larger case size) capacitors. A low
ESR ceramic output capacitor will minimize the high
frequency ripple, but will not reduce the low frequency
ripple unless a high capacitance value is used. To reduce
both the low and high frequency ripple, a reasonable
compromise is to use a 10
µ
F to 22
µ
F tantalum capacitor
in parallel with a 1
µ
F to 3.3
µ
F ceramic capacitor on V
OUT
.
An R-C filter may also be used to reduce high frequency
voltage spikes (see Figure 1).
Figure 1. Output Ripple Reduction Techniques
In low load or high V
IN
applications, smaller values for the
flying capacitor may be used to reduce output ripple. A
smaller flying capacitor (0.01
µ
F to 0.47
µ
F) delivers less
charge per clock cycle to the output capacitor resulting in
lower output ripple. However, with a smaller flying capaci-
tor, the maximum available output current will be reduced
along with the efficiency.
Note that when using a larger output capacitor the turn on
time of the device will increase.
Inrush Currents
During normal operation V
IN
will experience current tran-
sients in the 50mA to 100mA range whenever the charge
pump is enabled. However during start-up, inrush cur-
rents may approach 250mA. For this reason it is important
to minimize the source impedance between the input
supply and the V
IN
pin. Too much source impedance may
result in regulation problems or prevent start-up.
Ultralow Quiescent Current Regulated Supply
The LTC1754 contains an internal resistor divider (refer to
the Simplified Block Diagram) that typically draws 1.5
µ
A
from V
OUT
. During no-load conditions, this internal load
causes a droop rate of only 150mV per second on V
OUT
with C
OUT
= 10
µ
F. Applying a 2Hz to 100Hz, 2% to 5% duty
cycle signal to the SHDN pin ensures that the circuit of
Figure 2 comes out of shutdown frequently enough to
maintain regulation. Since the LTC1754 spends nearly the
entire time in shutdown, the no-load quiescent current is
approximately (V
OUT
)(1.5
µ
A)/(
V
IN
).
The LTC1754 must be out of shutdown for a minimum
duration of 200
µ
s to allow enough time to sense the output
voltage and keep it in regulation. A 2Hz, 2% duty cycle
LTC1754-X
15
µ
F
TANTALUM
V
OUT
V
OUT
V
OUT
1
µ
F
CERAMIC
LTC1754-X
2
10
µ
F
TANTALUM
10
µ
F
TANTALUM
V
OUT
1754 F01
+
+
+
APPLICATIO S I FOR ATIO
W
U
U
U
8
LTC1754-3.3/LTC1754-5
Layout Considerations
Due to high switching frequency and high transient cur-
rents produced by the LTC1754, careful board layout is
necessary. A true ground plane and short connections to
all capacitors will improve performance and ensure proper
regulation under all conditions. Figure 4 shows the recom-
mended layout configuration
Figure 4. Recommended Layout
signal will keep V
OUT
in regulation under no-load condi-
tions. As the V
OUT
load current increases, the frequency
with which the LTC1754 is taken out of shutdown must
also be increased.
Figure 2. Ultralow Quiescent Current Regulated Supply
Figure 3. No-Load Supply Current vs Supply Voltage
for the Circuit Shown in Figure 2
SUPPLY VOLTAGE (V)
2.0
SUPPLY CURRENT (
µ
A)
4
5
6
3.5
4.5
1754 F03
3
2
2.5
3.0
4.0
5.0
5.5
1
0
T
A
= 25
°
C
I
OUT
= 0
µ
A
C
FLY
= 1
µ
F
LTC1754-5
LTC1754-3.3
LTC1754-X
V
IN
V
OUT
GND
1754-5 F04
SHDN
10
µ
F
10
µ
F
1
µ
F
C
+
1
2
3
6
5
4
LTC1754-X
V
IN
C
V
OUT
1754 F02
V
IN
V
OUT
LOW I
Q
MODE (2Hz TO 100Hz, 2% TO 5% DUTY CYCLE)
10
µ
F
1
µ
F
10
µ
F
SHDN PIN
WAVEFORM
GND
SHDN
Thermal Management
For higher input voltages and maximum output current,
there can be substaintial power dissipation in the LTC1754.
If the junction temperature increases above approximately
150
°
C, the thermal shutdown circuitry will automatically
deactivate the output. To reduce the maximum junction
temperature, a good thermal connection to the PC board
is recommended. Connecting the GND pin (Pin 2) to a
ground plane and maintaining a solid ground plane under
the device on at least two layers of the PC board can reduce
the thermal resistance of the package and PC board
system to about 150
°
C/W.
APPLICATIO S I FOR ATIO
W
U
U
U
9
LTC1754-3.3/LTC1754-5
TYPICAL APPLICATIO S
U
Low Power Battery Backup with Autoswitchover and No Reverse Current
C
1
µ
F
C
+
V
IN
4
6
1
3
2
1
5
+
4
3
6
10k
1.2M
5
2
175433 TA03
1
8
HIGH = BACKUP MODE
3
2
7
10
µ
F
V
OUT
= 3.3V
I
OUT
300mA
I
OUT
20mA BACKUP
V
OUT
LTC1754-3.3
LTC1540
SHDN
GND
10
µ
F
2-CELL
NiCd
BATTERY
10
µ
F
75k
1N4148
V
IN
5V
475k
1M
LTC1521-3.3
5
4
6
LTC1754-5
1
µ
F
3
1
2
1754 TA06
10
µ
F
10
µ
F
V
OUT
5V
±
4%
50mA
USB Port to Regulated 5V Power Supply
10
LTC1754-3.3/LTC1754-5
5V, 100mA Step-Up Generator from 3V
TYPICAL APPLICATIO S
U
C
C
+
V
IN
4
6
V
OUT
LTC1754-5
GND
SHDN
1
2
5
V
IN
3V
V
OUT
5V
100mA
ON/OFF
1
µ
F
3
10
µ
F
C
C
+
V
IN
4
6
V
OUT
LTC1754-5
GND
SHDN
1
2
5
1
µ
F
3
10
µ
F
1754 TA07
Lithium-Ion Battery to 5V White or Blue LED Driver
ON/OFF
3V TO 4.4V
Li-Ion
BATTERY
C
C
+
V
IN
4
6
V
OUT
LTC1754-5
GND
SHDN
1
2
5
1
µ
F
3
100
1754 TA08
10
µ
F
10
µ
F
100
100
3.3V and 5V Step-Up Generator from 2V
ON/OFF
V
IN
2V
C
C
+
V
IN
4
6
V
OUT
LTC1754-3.3
GND
SHDN
1
2
5
1
µ
F
1
µ
F
3
1754 TA09
10
µ
F
10
µ
F
C
C
+
V
IN
4
6
V
OUT
LTC1754-5
GND
SHDN
1
2
5
3
10
µ
F
V
OUT1
3.3V
I
3.3
+ 2I
5
20mA
V
OUT2
5V
3.3I
3.3
+ 5I
5
V
IN
(2I
3.3
+ 4I
5
)
11
LTC1754-3.3/LTC1754-5
PACKAGE DESCRIPTIO
N
U
Dimensions in inches (millimeters), unless otherwise noted.
S6 Package
6-Lead Plastic SOT-23
(LTC DWG # 05-08-1634)
0.95
(0.037)
REF
1.50 1.75
(0.059 0.069)
0.35 0.55
(0.014 0.022)
0.35 0.50
(0.014 0.020)
SIX PLACES (NOTE 2)
S6 SOT-23 0898
2.80 3.00
(0.110 0.118)
(NOTE 3)
1.90
(0.074)
REF
0.90 1.45
(0.035 0.057)
0.90 1.30
(0.035 0.051)
0.00 0.15
(0.00 0.006)
0.09 0.20
(0.004 0.008)
(NOTE 2)
2.6 3.0
(0.110 0.118)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DIMENSIONS ARE INCLUSIVE OF PLATING
3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
4. MOLD FLASH SHALL NOT EXCEED 0.254mm
5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)
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.
12
LTC1754-3.3/LTC1754-5
175435f LT/TP 0400 4K · PRINTED IN USA
©
LINEAR TECHNOLOGY CORPORATION 1999
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
q
FAX: (408) 434-0507
q
www.linear-tech.com
PART NUMBER
DESCRIPTION
COMMENTS
LT1054
High Power Doubler Charge Pump
Up to 100mA Output, V
IN
= 3.5V to 15V, SO-8 Package
LTC1144
Charge Pump Inverter with Shutdown
V
IN
= 2V to 18V, 15V to 15V Supply
LTC1262
12V, 30mA Flash Memory Prog. Supply
Regulated 12V
±
5% Output, I
Q
= 500
µ
A
LTC1514/LTC1515
Buck/Boost Charge Pumps with I
Q
= 60
µ
A
50mA Output at 3V, 3.3V or 5V; 2V to 10V Input
LTC1516
Micropower 5V Charge Pump
I
Q
= 12
µ
A, Up to 50mA Output, V
IN
= 2V to 5V
LTC1517-5/LTC1517-3.3
Micropower 5V/3.3V Doubler Charge Pumps
I
Q
= 6
µ
A, Up to 20mA Output
LTC1522
Micropower 5V Doubler Charge Pump
I
Q
= 6
µ
A, Up to 20mA Output
LT1615
Step-Up Switching Regulator in SOT-23
I
Q
= 20
µ
A, V
IN
= 1.2V to 15V, Up to 34V Output
LTC1682
Low Noise Doubler Charge Pump
Output Noise = 60
µ
V
RMS
, 2.5V to 5.5V Output
RELATED PARTS
Low Power Battery Backup with Autoswitchover and No Reverse Current
C
1
µ
F
Si4435DY
C
+
V
IN
4
6
1
5
+
4
3
6
10k
1.43M
5
2
1754 TA05
1
8
3
2
7
10
µ
F
V
OUT
= 5V
I
OUT
50mA
V
OUT
LTC1754-5
LTC1540
SHDN
GND
BAT54C
10
µ
F
3-CELL
NiCd
BATTERY
10
µ
F
75k
1N4148
V
IN
5V
475k
1M
TYPICAL APPLICATIO
U
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