LTC1754-5_15 [Linear]
Micropower, Regulated 3.3V/5V Charge Pump with Shutdown in SOT-23;
| 型号： | LTC1754-5_15 |
| 厂家： | 
Linear |
| 描述： | Micropower, Regulated 3.3V/5V Charge Pump with Shutdown in SOT-23 |
| 文件： | 总12页 (文件大小：216K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1754-3.3/LTC1754-5
Micropower, Regulated
3.3V/5V Charge Pump with
Shutdown in SOT-23
U
FEATURES
DESCRIPTIO
■
Ultralow Power: IIN = 13
µA
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
smallbypasscapacitorsatVINandVOUT)maketheLTC1754
ideally suited for small, battery-powered applications. The
total component area of the application circuit shown
below is only 0.052 inch2.
TheLTC1754operatesasaBurstModeTM switchedcapaci-
tor voltage doubler to produce a regulated output. It has
thermalshutdowncapabilityandcansurviveacontinuous
short circuit from VOUT to GND.
■
Regulated Output Voltage: 3.3V
±
4%, 5V
3.0V)
2.5V)
±4%
■
■
■
■
■
■
■
■
■
5V Output Current: 50mA (VIN
≥
3.3V Output Current: 40mA (VIN
≥
No Inductors Needed
Very Low Shutdown Current: <1µA
Shutdown Disconnects Load from VIN
Internal Oscillator: 600kHz
Short-Circuit and Overtemperature Protected
Ultrasmall Application Circuit: (0.052 Inch2)
6-Pin SOT-23 Package
U
APPLICATIO S
The LTC1754 is available in a 6-pin SOT-23 package.
■
SIM Interface Supplies for GSM Cellular Telephones
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
White LED Power Supplies
Burst Mode is a trademark of Linear Technology Corporation.
■
Li-Ion Battery Backup Supplies
■
Handheld Computers
Smart Card Readers
PCMCIA Local 5V Supplies
■
■
U
TYPICAL APPLICATIO
LTC1754-3.3
Output Voltage vs Supply Voltage
LTC1754-5
Output Voltage vs Supply Voltage
1
2
3
6
5
4
+
V
OUT
V
C
OUT
LTC1754-X
3.40
3.35
3.30
3.25
3.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
1µF
10µF
I
C
C
= 20mA
= 10µf
= 1µF
OUT
OUT
FLY
I
C
C
= 25mA
= 10µF
= 1µF
OUT
OUT
FLY
V
GND
V
IN
IN
10µF
–
ON/OFF
SHDN
C
1754 TA01
T
= 85°C
= 25°C
A
A
T
A
= 85°C
T
= 25°C
A
Regulated 3.3V Output from 2V to 4.4V Input
T
V
= 3.3V ±4%
OUT
T
= –40°C
T
A
= –40°C
A
I
I
= 0mA TO 20mA, V > 2.0V
IN
= 0mA TO 40mA, V > 2.5V
OUT
OUT
IN
Regulated 5V Output from 2.7V to 5.5V Input
V
= 5V ±4%
OUT
I
I
= 0mA TO 25mA, V > 2.7V
IN
= 0mA TO 50mA, V > 3.0V
IN
OUT
OUT
2.0
2.5
3.0
3.5
4.0
4.5
2.5
3.5
4.0
4.5
5.0
5.5
3.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
1754 TA02
1574 TA03
1
LTC1754-3.3/LTC1754-5
W W U W
U W
U
ABSOLUTE AXI U RATI GS
(Note 1)
PACKAGE/ORDER I FOR ATIO
ORDER PART
VIN to GND .................................................. –0.3V to 6V
VOUT to GND ............................................... –0.3V to 6V
SHDN to GND.............................................. –0.3V to 6V
TOP VIEW
NUMBER
+
V
1
6 C
5 V
4 C
OUT
LTC1754ES6-3.3
LTC1754ES6-5
GND 2
IN
–
I
OUT (Note 4) ......................................................... 75mA
SHDN 3
VOUT 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
S6 PART MARKING
S6 PACKAGE
6-LEAD PLASTIC SOT-23
TJMAX = 150°C, θJA = 230°C/ W
LTGK
LTLW
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. CFLY = 1µF (Note 2), CIN = 10µF, COUT = 10µF.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
LTC1754-3.3
V
V
Input Supply Voltage
Output Voltage
●
2.0
4.4
V
IN
2.0V ≤ V ≤ 4.4V, I
≤ 20mA
≤ 40mA
●
●
3.17
3.17
3.30
3.30
3.43
3.43
V
V
OUT
IN
OUT
OUT
2.5V ≤ V ≤ 4.4V, I
IN
I
Operating Supply Current
Output Ripple
2.0V ≤ V ≤ 4.4V, I
= 0mA, SHDN = V
IN
●
11
23
30
µA
CC
IN
OUT
V
V
V
= 2.5V, I
= 2.0V, I
= 40mA
= 20mA
mV
P-P
R
IN
IN
OUT
OUT
η
Efficiency
82
%
f
t
I
Switching Frequency
Oscillator Free Running
600
0.8
118
kHz
ms
mA
OSC
ON
V
Turn-On Time
V
V
= 2.0V, I = 0mA
OUT
OUT
IN
IN
Output Short-Circuit Current
= 2.5V, V
= 0V, SHDN = 2.5V
SC
OUT
LTC1754-5
V
V
Input Supply Voltage
Output Voltage
●
2.7
5.5
V
IN
2.7V ≤ V ≤ 5.5V, I
≤ 25mA
≤ 50mA
●
●
4.8
4.8
5.0
5.0
5.2
5.2
V
V
OUT
IN
OUT
OUT
3.0V ≤ V ≤ 5.5V, I
IN
I
Operating Supply Current
Output Ripple
2.7V ≤ V ≤ 5.5V, I
= 0mA, SHDN = V
IN
●
13
65
30
µA
CC
IN
OUT
V
V
V
= 3V, I
= 3V, I
= 50mA
= 50mA
mV
P-P
R
IN
IN
OUT
OUT
η
Efficiency
82.7
700
0.4
%
f
t
I
Switching Frequency
Oscillator Free Running
kHz
ms
mA
OSC
ON
V
Turn-On Time
V
V
= 3V, I
= 0mA
OUT
IN
IN
OUT
Output Short-Circuit Current
= 3V, V
= 0V, SHDN = 3V
OUT
150
SC
LTC1754-3.3/LTC1754-5
I
Shutdown Supply Current
V
≤ 3.6V, I
= 0mA, V
= 0mA, V
= 0V
= 0V
●
●
0.01
1
2.5
µA
µA
SHDN
IN
OUT
SHDN
SHDN
3.6V < V , I
IN OUT
V
V
SHDN Input Threshold (High)
SHDN Input Threshold (Low)
SHDN Input Current (High)
SHDN Input Current (Low)
●
●
●
●
1.4
V
V
IH
IL
0.3
1
I
I
SHDN = V
–1
–1
µA
µA
IH
IL
IN
SHDN = 0V
1
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
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 2: 0.6µF is the minimum required C capacitance for rated output
FLY
current capability. Depending on the choice of capacitor material, a
somewhat higher value of capacitor may be required to attain 0.6µF over
temperature.
Note 4: Based on long term current density limitations.
2
LTC1754-3.3/LTC1754-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS LTC1754-3.3, TA = 25°C unless otherwise noted.
No Load Supply Current
vs Supply Voltage
Output Voltage vs Output Current
Supply Current vs VSHDN
20
15
10
5
20
15
10
5
3.40
3.35
3.30
3.25
3.20
I
C
V
= 0µA
= 1µF
= V
T
I
= 25°C
= 0µA
T
C
C
= 25°C
OUT
FLY
SHDN
A
OUT
A
= 10µF
OUT
FLY
= 1µF
IN
V
IN
= 4.5V
T
T
= 85°C
= 25°C
V
IN
= 2.5V
A
V
= 2.5V
IN
V
= 2V
IN
A
V
= 2V
IN
T
A
= –40°C
0
2.0
2.5
3.0
3.5
4.0
4.5
3
4
1
5
0
20
40
60
80
100
2
SUPPLY VOLTAGE (V)
V
SHDN
CONTROL VOLTAGE (V)
OUTPUT CURRENT (mA)
1754 G02
1754 G03
1754 G01
VOUT Short-Circuit Current
vs Supply Voltage
Efficiency vs Load Current
100
180
160
T
A
= 25°C
= 1µF
T
V
C
= 25°C
A
90
80
70
C
= 2V
FLY
IN
= 1µF
FLY
140
120
60
50
40
30
20
10
0
100
80
60
2.0
2.5
3.0
3.5
4.0
4.5
0.001
0.01
0.1
1
10
100
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
1754 G05
1735 G04
Load Transient Response
Output Ripple
Start-Up Time
IOUT
0mA to 20mA
10mA/DIV
SHDN
1V/DIV
VOUT
AC COUPLED
20mV/DIV
VOUT
1V/DIV
VOUT
AC COUPLED
20mV/DIV
VIN = 2V
COUT = 10µF
200µs/DIV
1754 G9
VIN = 2V
COUT = 10µF
50µs/DIV
1754 G07
VIN = 2V
COUT = 10µF
IOUT = 20mA
5µs/DIV
1754 G08
3
LTC1754-3.3/LTC1754-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS LTC1754-5, TA = 25°C unless otherwise noted.
No Load Supply Current
vs Supply Voltage
Output Voltage vs Output Current
Supply Current vs VSHDN
5.15
5.10
20
15
10
5
25
20
15
10
5
T
C
C
= 25°C
A
T
I
= 25°C
= 0µA
I
C
V
= 0µA
= 1µF
A
OUT
FLY
= 10µF
OUT
FLY
OUT
V
V
= 5.5V
= 1µF
IN
= V
SHDN
IN
T
= 85°C
= 25°C
A
= 3.3V
= 2.7V
IN
5.05
5.00
V
= 3V
IN
V
IN
T
V
= 2.7V
A
IN
4.95
4.90
4.85
T
= –40°C
A
0
0
20
40
60
80
100
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1
2
3
4
5
6
OUTPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
V
CONTROL VOLTAGE (V)
SHDN
1574-5 G02
1754 G11
1574 G12
VOUT Short-Circuit Current
vs Supply Voltage
Efficiency vs Load Current
100
220
200
180
160
140
120
100
V
T
= 3V
= 25°C
= 1µF
T
= 25°C
= 1µF
IN
A
90
80
70
C
A
FLY
C
FLY
60
50
40
30
20
10
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.001
0.01
0.1
1
10
100
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
1754-5 G05
1754 G13
Load Transient Response
Output Ripple
Start-Up Time
IOUT
0mA to 50mA
25mA/DIV
SHDN
5V/DIV
VOUT
AC COUPLED
20mV/DIV
VOUT
1V/DIV
VOUT
AC COUPLED
50mV/DIV
V
IN = 3V
100µs/DIV
1754 G18
V
IN = 3V
50µs/DIV
1754 G16
VIN = 3V
COUT = 10µF
IOUT = 50mA
5µs/DIV
1754 G17
COUT = 10µF
COUT = 10µF
4
LTC1754-3.3/LTC1754-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1754-3.3. LTC1754-5, TA = 25°C unless otherwise noted.
Oscillator Frequency
vs Supply Voltage
VSHDN Threshold Voltage
vs Supply Voltage
Efficiency vs Supply Voltage
850
100
90
0.95
0.90
T
= 25°C
FLY
A
C
= 1µF
800
750
T
= 85°C
= 25°C
A
A
T
= –40°C
= 25°C
A
80
70
60
50
40
LTC1754-5
= 25mA
0.85
0.80
700
650
600
550
500
I
T
OUT
A
T
T
= 85°C
A
0.75
0.70
0.65
LTC1754-3.3
= 20mA
T
= –40°C
A
I
OUT
450
30
2.5
3.0
4.0 4.5 5.0 5.5
2.0
3.5
4.0
5.0 5.5
4.0
5.0 5.5
2.0 2.5
3.0 3.5
4.5
2.0 2.5 3.0 3.5
4.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
1754 G20
1754 G19
1754 G21
U
U
U
PI FU CTIO S
C– (Pin 4): Flying Capacitor Negative Terminal.
VOUT (Pin 1): Regulated Output Voltage. For best perfor-
mance, VOUT should be bypassed with a 6.8µF (min) low
ESR capacitor as close as possible to the pin.
VIN (Pin 5): Input Supply Voltage. VIN should be bypassed
with a 6.8µF (min) low ESR capacitor.
C+ (Pin 6): Flying Capacitor Positive Terminal.
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.
W
W
SI PLIFIED BLOCK DIAGRA
*
+
C
V
OUT
2
C
OUT
10µF
C
FLY
1µF
1
V
IN
C
IN
10µF
+
COMP1
CONTROL
2
–
–
C
1
V
REF
SHDN
1754 BD
*CHARGE PUMP SHOWN IN PHASE 1, THE CHARGING PHASE.
PHASE 1 IS ALSO THE SHUTDOWN PHASE
5
LTC1754-3.3/LTC1754-5
W U U
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APPLICATIO S I FOR ATIO
Operation (Refer To Block Diagram)
VIN = 3V, IOUT = 25mA and VOUT regulating to 5V, has a
measuredefficiencyof82.7%,whichisincloseagreement
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.
The LTC1754 uses a switched-capacitor charge pump to
boost VIN to a regulated output voltage. Regulation is
achievedbysensingtheoutputvoltagethroughaninternal
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
nonoverlappingclockactivatesthechargepumpswitches.
The flying capacitor is charged to VIN on phase one of the
clock. On phase two of the clock it is stacked in series with
VIN andconnectedtoVOUT. Thissequenceofchargingand
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 13µA from VIN thus
providing high efficiency under low load conditions.
Short-Circuit/Thermal Protection
During short-circuit conditions, the LTC1754 will draw
between 100mA and 400mA from VIN causing a rise in the
junctiontemperature. On-chipthermalshutdowncircuitry
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 VOUT is removed.
Capacitor Selection
In shutdown mode all circuitry is turned off and the
LTC1754 draws only leakage current from the VIN supply.
Furthermore, VOUT is disconnected from VIN. The SHDN
pin is a CMOS input with a threshold voltage of approxi-
mately0.8V, butmaybedriventoalogiclevelthatexceeds
VIN. 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.
The style and value of capacitors used with the
LTC1754determineseveralimportantparameterssuchas
output ripple, charge pump strength and turn-on time.
To reduce noise and ripple, it is recommended that low
ESR (<0.1Ω) capacitors be used for both CIN and COUT
.
Thesecapacitorsshouldbeeitherceramicortantalumand
be 6.8µF or greater. Aluminum capacitors are not recom-
mended because of their high ESR. If the source imped-
ance to VIN is very low up to several megahertz, CIN may
not be needed.
Power Efficiency
Aceramiccapacitorisrecommendedfortheflyingcapaci-
tor with a value in the range of 1µF to 2.2µF. Note that a
large value flying capacitor (>2.2µF) will increase output
ripple unless COUT is also increased. For very low load
applications, CFLY may be reduced to 0.01µF to 0.047µF.
This will reduce output ripple at the expense of maximum
output current and efficiency.
The efficiency (η) of the LTC1754 is similar to that of a
linear regulator with an effective input voltage of twice the
actualinputvoltage.Thisresultsbecausetheinputcurrent
foravoltagedoublingchargepumpisapproximatelytwice
the output current. In an ideal voltage doubling regulator
the power efficiency would be given by:
In order to achieve the rated output current it is necessary
to have at least 0.6µF of capacitance for the flying capaci-
tor. Capacitors of different material lose their capacitance
overtemperatureatdifferentrates.Forexample,aceramic
capacitor made of X7R material will retain most of its
capacitance from –40°C to 85°C, whereas a Z5U or Y5V
stylecapacitorwillloseconsiderablecapacitanceoverthat
VOUT IOUT
(
)(
)
POUT
P
IN
VOUT
η =
=
=
2V
V
IN)(
2IOUT
IN
(
)
Atmoderate-to-highoutputpower,theswitchinglossesand
quiescent current of the LTC1754 are negligible and the
expressionaboveisvalid.Forexample,anLTC1754-5with
6
LTC1754-3.3/LTC1754-5
W U U
APPLICATIO S I FOR ATIO
range. The capacitor manufacturer’s data sheet should be
consulted to determine what style and value of capacitor
is needed to ensure 0.6µF at all temperatures.
U
V
V
OUT
OUT
+
+
15µF
1µF
LTC1754-X
TANTALUM
CERAMIC
2Ω
Output Ripple
V
V
OUT
OUT
+
10µF
TANTALUM
10µF
LTC1754-X
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 VIN the ripple voltage can become substantial
becausetheincreasedstrengthofthechargepumpcauses
fast edges that may outpace the regulation circuitry.
Generally the regulation ripple has a sawtooth shape
associated with it.
TANTALUM
1754 F01
Figure 1. Output Ripple Reduction Techniques
In low load or high VIN applications, smaller values for the
flying capacitor may be used to reduce output ripple. A
smaller flying capacitor (0.01µF to 0.47µF) 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.
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, thevalueoftheflyingcapacitorandtheESRofthe
output capacitor.
Note that when using a larger output capacitor the turn on
time of the device will increase.
Inrush Currents
During normal operation VIN will experience current tran-
sients in the 50mA to 100mA range whenever the charge
pump is enabled. However during start-up, inrush cur-
rentsmayapproach250mA. Forthisreasonitisimportant
to minimize the source impedance between the input
supply and the VIN pin. Too much source impedance may
result in regulation problems or prevent start-up.
Typical combined output ripple for the LTC1754-5 with
VIN =3Vundermaximumloadis65mVP-P usingalowESR
10µF output capacitor. A smaller output capacitor and/or
larger output current load will result in higher ripple due to
higher output voltage slew rates.
Thereareseveralwaystoreduceoutputvoltageripple. For
applications requiring higher VIN or lower peak-to-peak
ripple, a larger COUT capacitor (22µF 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
foundwithhighervalue(largercasesize)capacitors.Alow
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 10µF to 22µF tantalum capacitor
Ultralow Quiescent Current Regulated Supply
The LTC1754 contains an internal resistor divider (refer to
the Simplified Block Diagram) that typically draws 1.5µA
from VOUT. During no-load conditions, this internal load
causes a droop rate of only 150mV per second on VOUT
withCOUT =10µF. Applyinga2Hzto100Hz, 2%to5%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 (VOUT)(1.5µA)/(ηVIN).
in parallel with a 1µF to 3.3µF ceramic capacitor on VOUT
.
The LTC1754 must be out of shutdown for a minimum
durationof200µstoallowenoughtimetosensetheoutput
voltage and keep it in regulation. A 2Hz, 2% duty cycle
An R-C filter may also be used to reduce high frequency
voltage spikes (see Figure 1).
7
LTC1754-3.3/LTC1754-5
W U U
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APPLICATIO S I FOR ATIO
Layout Considerations
signal will keep VOUT in regulation under no-load condi-
tions. As the VOUT load current increases, the frequency
with which the LTC1754 is taken out of shutdown must
also be increased.
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
allcapacitorswillimproveperformanceandensureproper
regulationunderallconditions.Figure4showstherecom-
mended layout configuration
1
2
3
6
5
4
+
V
V
C
OUT
OUT
1µF
10µF
LTC1754-X
V
IN
GND
V
IN
SHDN PIN
WAVEFORM
V
IN
10µF
–
SHDN
C
V
OUT
1µF
LOW I MODE (2Hz TO 100Hz, 2% TO 5% DUTY CYCLE) 1754 F02
Q
10µF
10µF
GND
Figure 2. Ultralow Quiescent Current Regulated Supply
LTC1754-X
SHDN
1754-5 F04
6
T
OUT
C
= 25°C
A
Figure 4. Recommended Layout
I
= 0µA
= 1µF
5
4
3
FLY
Thermal Management
LTC1754-5
For higher input voltages and maximum output current,
therecanbesubstaintialpowerdissipationintheLTC1754.
Ifthejunctiontemperatureincreasesaboveapproximately
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
thedeviceonatleasttwolayersofthePCboardcanreduce
the thermal resistance of the package and PC board
system to about 150°C/W.
LTC1754-3.3
2
1
0
4.0
2.0 2.5 3.0 3.5
SUPPLY VOLTAGE (V)
5.0 5.5
4.5
1754 F03
Figure 3. No-Load Supply Current vs Supply Voltage
for the Circuit Shown in Figure 2
8
LTC1754-3.3/LTC1754-5
U
TYPICAL APPLICATIO S
Low Power Battery Backup with Autoswitchover and No Reverse Current
3
1
LTC1521-3.3
2
1µF
4
6
–
+
C
C
1N4148
V
I
= 3.3V
75k
OUT
OUT
OUT
5
1
V
IN
≤ 300mA
V
V
OUT
IN
5V
I
≤ 20mA BACKUP
+
10µF
10µF
2-CELL
NiCd
BATTERY
LTC1754-3.3
SHDN
3
10µF
GND
2
7
1.2M
475k
4
3
6
8
HIGH = BACKUP MODE
LTC1540
10k
1M
5
175433 TA03
2
1
USB Port to Regulated 5V Power Supply
1µF
4
6
5
3
1
LTC1754-5
V
OUT
10µF
10µF
5V ±4%
50mA
2
1754 TA06
9
LTC1754-3.3/LTC1754-5
U
TYPICAL APPLICATIO S
5V, 100mA Step-Up Generator from 3V
1µF
4
6
–
+
C
C
V
OUT
5
3
1
2
V
IN
5V
V
V
OUT
LTC1754-5
IN
3V
100mA
10µF
SHDN
GND
1µF
4
–
6
+
C
C
5
3
1
2
V
V
OUT
LTC1754-5
IN
10µF
ON/OFF
SHDN
GND
1754 TA07
Lithium-Ion Battery to 5V White or Blue LED Driver
1µF
4
6
–
+
C
C
5
3
1
2
V
V
OUT
IN
3V TO 4.4V
Li-Ion
BATTERY
100Ω
100Ω
100Ω
10µF
10µF
LTC1754-5
ON/OFF
SHDN
GND
1754 TA08
3.3V and 5V Step-Up Generator from 2V
V
OUT1
3.3V
1µF
1µF
I
+ 2I ≤ 20mA
5
3.3
3.3I + 5I
(2I + 4I )
IN 3.3
3.3
5
η
4
–
6
+
4
–
6
+
V
5
C
C
V
C
C
V
5
3
1
2
5
3
1
2
V
V
OUT2
IN
V
V
IN
OUT
IN
OUT
5V
2V
10µF
LTC1754-3.3
LTC1754-5
10µF
10µF
ON/OFF
SHDN
GND
SHDN
GND
1754 TA09
10
LTC1754-3.3/LTC1754-5
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters), unless otherwise noted.
S6 Package
6-Lead Plastic SOT-23
(LTC DWG # 05-08-1634)
2.80 – 3.00
(0.110 – 0.118)
(NOTE 3)
0.95
(0.037)
REF
1.90
(0.074)
REF
2.6 – 3.0
(0.110 – 0.118)
1.50 – 1.75
(0.059 – 0.069)
0.00 – 0.15
(0.00 – 0.006)
0.90 – 1.45
(0.035 – 0.057)
0.35 – 0.55
(0.014 – 0.022)
0.35 – 0.50
(0.014 – 0.020)
SIX PLACES (NOTE 2)
0.90 – 1.30
(0.035 – 0.051)
S6 SOT-23 0898
0.09 – 0.20
(0.004 – 0.008)
(NOTE 2)
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-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LTC1754-3.3/LTC1754-5
U
TYPICAL APPLICATIO
Low Power Battery Backup with Autoswitchover and No Reverse Current
Si4435DY
1µF
4
6
–
+
C
C
1N4148
75k
5
1
3
V
V
I
= 5V
≤ 50mA
IN
OUT
OUT
V
V
OUT
IN
5V
+
10µF
10µF
3-CELL
NiCd
BATTERY
LTC1754-5
SHDN
10µF
GND
2
BAT54C
7
1.43M
475k
4
3
6
8
LTC1540
10k
1M
5
2
1
1754 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
Up to 100mA Output, V = 3.5V to 15V, SO-8 Package
LT1054
High Power Doubler Charge Pump
Charge Pump Inverter with Shutdown
IN
LTC1144
V = 2V to 18V, 15V to –15V Supply
IN
LTC1262
12V, 30mA Flash Memory Prog. Supply
Regulated 12V ±5% Output, I = 500µA
Q
LTC1514/LTC1515
LTC1516
Buck/Boost Charge Pumps with I = 60µA
50mA Output at 3V, 3.3V or 5V; 2V to 10V Input
Q
Micropower 5V Charge Pump
I = 12µA, Up to 50mA Output, V = 2V to 5V
Q IN
LTC1517-5/LTC1517-3.3 Micropower 5V/3.3V Doubler Charge Pumps
I = 6µA, Up to 20mA Output
Q
LTC1522
LT1615
Micropower 5V Doubler Charge Pump
Step-Up Switching Regulator in SOT-23
Low Noise Doubler Charge Pump
I = 6µA, Up to 20mA Output
Q
I = 20µA, V = 1.2V to 15V, Up to 34V Output
Q
IN
LTC1682
Output Noise = 60µV
, 2.5V to 5.5V Output
RMS
175435f LT/TP 0400 4K • PRINTED IN USA
12 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
LINEAR TECHNOLOGY CORPORATION 1999
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