LTC1516 [Linear]
Micropower, Regulated 5V Charge Pump DC/DC Converter; 微功耗， 5V稳压电荷泵DC / DC转换器
| 型号： | LTC1516 |
| 厂家： | 
Linear |
| 描述： | Micropower, Regulated 5V Charge Pump DC/DC Converter |
| 文件： | 总8页 (文件大小：109K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1516
Mic ro p o we r, Re g ula te d
5V Cha rg e Pum p
DC/ DC Co nve rte r
U
FEATURES
DESCRIPTION
The LTC®1516 is a micropower charge pump DC/DC
converter that produces a regulated 5V output from a 2V
to 5V supply. Extremely low supply current (12µA typical
with no load, <1µA in shutdown) and low external parts
count (two 0.22µF flying capacitors and two 10µF capaci-
■
Ultralow Power: Typical Operating ICC = 12µA
Short Circuit/Thermal Protection
Regulated 5V ±4% Output
2V to 5V Input Range
No Inductors
ICC in Shutdown: <1µA
■
■
■
■
■
tors at V and VOUT) make the LTC1516 ideally suited for
IN
■
Output Current:20mA (V > 2V)
small, light load battery-powered applications. Typical
IN
50mA (V > 3V)
Shutdown Disconnects Load from V
Internal Oscillator: 600kHz
Compact Application Circuit (0.1 in2)
8-Pin SO Package
efficiency (V = 3V) exceeds 70% with load currents
IN
IN
■
■
■
■
between50µAand50mA. ModulatingtheSHDNpinkeeps
the typical efficiency above 70% with load currents all the
way down to 10µA.
IN
The LTC1516 operates as either a doubler or a tripler
depending on V and output load conditions to improve
overall efficiency. The part has thermal shutdown and can
survive a continuous short from VOUT to GND. In shut-
U
IN
APPLICATIONS
■
2-Cell to 5V Conversion
Li-Ion Battery Backup Supplies
Local 3V to 5V Conversion
5V Flash Memory Programmer
down the load is disconnected from V .
IN
■
■
The LTC1516 is available in an 8-pin SO package in both
commercial and industrial temperature grades.
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
■
Smart Card Readers
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TYPICAL APPLICATION
Efficiency vs Output Current
0.22µF
90
V
IN
= 3V
1
2
3
4
8
7
6
5
+
–
C1
C1
80
70
60
50
V
SHDN
GND
ON/OFF
V
IN
= 2V TO 5V
IN
+
LOW I MODE
Q
(SEE FIGURE 3)
LTC1516
10µF
V
OUT
+
10µF
+
–
C2
C2
SHDN = 0V
0.22µF
V
= 5V ±4%
= 0mA TO 20mA, V ≥ 2V
= 0mA TO 50mA, V ≥ 3V
OUT
OUT
0.01
0.1
1
10
100
I
IN
IN
OUTPUT CURRENT (mA)
I
1516 • F01
OUT
1516 • TA01
Figure 1. Regulated 5V Output from a 2V to 5V Input
1
LTC1516
ABSOLUTE MAXIMUM RATINGS
W W
U W
U
W
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PACKAGE/ORDER INFORMATION
(Note 1)
ORDER PART
TOP VIEW
V to GND...................................................–0.3V to 6V
IN
NUMBER
+
–
V
OUT to GND ................................................–0.3V to 6V
SHDN to GND ..............................................–0.3V to 6V
OUT Short-Circuit Duration............................. Indefinite
C1
1
2
3
4
8
7
6
5
C1
LTC1516CS8
LTC1516IS8
V
SHDN
GND
IN
V
V
OUT
+
–
Operating Temperature Range
C2
C2
Commercial ............................................. 0°C to 70°C
Industrial ............................................ –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S8 PART MARKING
S8 PACKAGE
8-LEAD PLASTIC SO
1516
1516I
T
JMAX = 125°C, θJA = 150°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
V = 2V to 5V, C1 = C2 = 0.22µF, CIN = COUT = 10µF, TMIN to TMAX unless otherwise specified (Note 3).
IN
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Voltage
●
2
5
V
V
OUT
Output Voltage
2V
3V
3.6V
≤
≤
V
≤
≤
5V, I
3.6V, I
≤
20mA
●
●
4.8
4.8
4.8
5.2
5.2
5.2
V
V
V
IN
OUT
V
≤
50mA
IN
OUT
OUT
≤
V
≤
5V, I
≤
50mA, T = 25°C (Note 2)
A
IN
I
CC
Supply Current
2V
2V
≤
≤
V
V
IN
≤
≤
5V, I
5V, I
= 0mA, SHDN = 0V
●
●
12
0.005
20
1
µA
µA
IN
OUT
= 0mA, SHDN = V
OUT
IN
Output Ripple
Full Load
= 3V, I
100
82
mV
%
Efficiency
V
= 20mA
OUT
IN
f
Switching Frequency
SHDN Input Threshold
Full Load
600
kHz
V
OSC
V
●
●
●
●
(0.7)(V )
IH
IN
V
0.4
1
V
IL
I
IH
SHDN Input Current
V
SHDN
= V
–1
–1
µA
µA
µs
IN
I
IL
V
SHDN
= 0V
1
t
V
OUT
Turn-On Time
V
IN
= 3V, I = 0mA (Note 3)
OUT
500
ON
Note 2: At input voltages >3.6V and ambient temperatures >70°C,
continuous power dissipation must be derated to maintain junction
temperatures below 125°C. Derate 6mW/°C above 70°C in SO-8.
The
● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired
Note 3: The LTC1516 is tested with the capacitors shown in Figure 1.
2
LTC1516
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
No Load Supply Current vs
Input Voltage
Efficiency vs Input Voltage
Output Current vs Input Voltage
120
90
80
70
20
15
10
5
C
= 10µF
I
= 10mA
OUT
OUT
T = 25°C
A
100
80
60
40
20
0
C1 = C2
= 0.22µF
C1 = C2
= 0.1µF
C1 = C2
= 0.047µF
C1 = C2
= 0.022µF
60
50
C1 = C2 = 0.01µF
2
3
4
5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
2
3
4
5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1516 • G03
1516 • G01
1516 • G02
Output Voltage vs Input Voltage
Output Voltage vs Output Current
Load Transient Response, V = 3V
IN
5.10
5.05
5.00
4.95
4.90
5.10
5.05
5.00
4.95
4.90
V
IN
= 3V
I
= 20mA
OUT
IOUT
0mA TO 25mA,
,
10mA/DIV
VOUT
AC COUPLED,
100mV/DIV
,
1516 • G04
1
2
3
4
5
6
0.01
0.1
1
10
100
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
1516 • G04
1516 • G05
U
U
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PIN FUNCTIONS
C1+ (Pin 1): Flying Capacitor 1, Positive Terminal.
GND (Pin 6): Ground.
V (Pin 2): Input Supply Voltage.
IN
SHDN (Pin 7): Active High CMOS Logic-Level Shutdown
Input.
VOUT (Pin 3): 5V Output Voltage (VOUT = 0V in Shutdown).
C1– (Pin 8): Flying Capacitor 1, Negative Terminal.
C2+ (Pin 4): Flying Capacitor 2, Positive Terminal.
C2– (Pin 5): Flying Capacitor 2, Negative Terminal.
3
LTC1516
W
BLOCK DIAGRAM
V
IN
SHDN
+
10µF
S2A
S2B
V
OUT
S1A
+
+
–
C2
C2
10µF
0.22µF
COMP1
S1B
S1C
S1D
CLOCK 1
CLOCK 2
COMP2
COMP3
CONTROL
LOGIC
+
–
C1
C1
0.22µF
S2C
V
OS
S3
V
REF
CHARGE PUMP
LTC1516 • BD
CHARGE PUMP SHOWN IN TRIPLER MODE, DISCHARGE CYCLE
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APPLICATIONS INFORMATION
Operation
depending on V and output load conditions. COMP1 and
IN
COMP2 determine whether the charge pump is in doubler
mode or tripler mode. COMP1 forces the part into tripler
The LTC1516 uses a switched capacitor charge pump to
boost V from 2V to 5V to a regulated 5V ±4% output
IN
modeifV is <2.55V, regardless ofoutputload. WhenV
IN
IN
voltage. Regulation is achieved by sensing the output
voltage through an internal resistor divider and enabling
the charge pump when the output voltage droops below
the lower trip point of COMP2. When the charge pump is
enabled, a 2-phase, nonoverlapping clock controls the
charge pump switches. Clock 1 closes the S1 switches
which enable the flying capacitors, C1 and C2, to charge
is >2.55V, the part will be in doubler mode using only C2
as aflyingcapacitor. Indoublermode, iftheoutputdroops
by 50mV under heavy loads, COMP3 will force the charge
pump into tripler mode until VOUT climbs above the upper
trip point of COMP3. Under these V and load conditions,
IN
the nominal VOUT will be approximately 50mV lower than
the no load nominal VOUT. This method of sensing V and
IN
uptotheV voltage.Clock2closes theS2switches which
IN
output load results in efficiency greater than 80% with V
IN
stack C1 and C2 in series with V and connect the top
IN
between 2.5V and 3V.
plate of C2 to the output capacitor at VOUT. This sequence
of charging and discharging continues at a free-running
frequency of 600kHz (typ) until the output has risen to the
upper trip point of COMP2 and the charge pump is
disabled.Whenthechargepumpis disabled,theLTC1516
In shutdown mode, all circuitry is turned off and the part
draws only leakage current (<1µA) from the V supply.
IN
V
OUT is also disconnected from V . The SHDN pin is a
IN
CMOS input with a threshold of approximately V /2;
IN
draws only 8µA (typ) from V which provides high
IN
however, the SHDN pin can be driven by logic levels that
efficiency at low load conditions.
exceed the V voltage. The part enters shutdown mode
IN
whenalogichighis appliedtotheSHDNpin.TheSHDNpin
cannot float; it must be driven with a logic high or low.
To achieve the highest efficiencyoverthe entire V range,
the LTC1516 operates as either a doubler or a tripler
IN
4
LTC1516
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APPLICATIONS INFORMATION
Short-Circuit/Thermal Protection
higher ripple due to higher output voltage dV/dt. High ESR
capacitors (ESR > 0.5Ω) on the output pin cause high
frequency voltage spikes on VOUT with every clock cycle.
During short-circuit conditions, the LTC1516 will draw
between 200mA and 400mA from V causing a rise in
IN
the junction temperature. On-chip thermal shutdown
circuitry disables the charge pump once the junction
temperature exceeds 135°C, and reenables the charge
pump once the junction temperature falls back to 115°C.
The LTC1516 will cycle in and out of thermal shutdown
indefinitelywithoutlatchupordamageuntiltheVOUT short
is removed.
There are several ways to reduce the output voltage ripple.
A larger COUT capacitor (22µF or greater) will reduce both
the low and high frequency ripple due to the lower COUT
charging and discharging dV/dt and the lower ESR typi-
cally 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
rippleunless ahighcapacitancevalueis chosen.Areason-
able compromise is to use a 10µF to 22µF tantalum
capacitor in parallel with a 1µF to 3.3µF ceramic capacitor
on VOUT to reduce both the low and high frequency ripple.
An RC filter may also be used to reduce high frequency
voltage spikes (see Figure 2).
Capacitor Selection
For best performance, it is recommended that low ESR
capacitors be used for both C and COUT to reduce noise
IN
and ripple. The C and COUT capacitors should be either
IN
ceramic or tantalum and should be 10µF or greater. If the
input source impedance is very low, C may not be
needed. Increasing the size of COUT to 22µF or greater will
reduce output voltage ripple.
IN
In low load or high V applications, smaller values for C1
IN
and C2 may be used to reduce output ripple. The smaller
C1andC2flyingcapacitors (0.022µFto0.1µF)deliverless
charge per clock cycle to the output capacitor resulting in
loweroutputripple.However,thesmallervalueflyingcaps
also reduce the maximum IOUT capability as well as
efficiency.
Ceramic or tantalum capacitors are recommended for the
flying caps C1 and C2 with values in the range of 0.1µF to
1µF. Note that large value flying caps (> 0.22µF) will
increase output ripple unless COUT is also increased. For
very low load applications, C1 and C2 may be reduced to
0.01µF to 0.047µF. This will reduce output ripple at the
expense of efficiency and maximum output current.
LTC1516
3
V
5V
OUT
V
OUT
+
+
15µF
TANTALUM
1µF
CERAMIC
Output Ripple
NormalLTC1516operationproduces voltagerippleonthe
LTC1516
2Ω
3
V
OUT
5V
VOUT pin.Outputvoltagerippleis requiredfortheLTC1516
V
OUT
+
to regulate. Low frequency ripple exists due to the hyster-
esis inthesensecomparatorandpropagationdelays inthe
chargepumpenable/disablecircuits.Highfrequencyripple
is also present mainly due to ESR (Equivalent Series
Resistance) in the output capacitor. Typical output ripple
10µF
10µF
1516 F02
Figure 2. Output Ripple Reduction Techniques
under maximum load is 100mVP-P with a low ESR 10µF Inrush Currents
output capacitor.
During normal operation, V will experience current tran-
IN
The magnitude of the ripple voltage depends on several sients in the 100mA to 200mA range whenever the charge
factors.Highinputvoltages (V >3.3V)increasetheoutput
pump is enabled. During start-up, these inrush currents
may approach 500mA. For this reason, it is important to
minimize the source resistance between the input supply
IN
ripple since more charge is delivered to COUT per clock
cycle. Large C1 and C2 flying capacitors (>0.22µF) also
increase ripple for the same reason. Large output current
load and/or a small output capacitor (<10µF) results in
and the V pin to prevent start-up problems and large
IN
input voltage transients.
5
LTC1516
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APPLICATIONS INFORMATION
Ultralow Quiescent Current (IQ < 5µA) Regulated
Supply
The LTC1516 must be out of shutdown for a minimum
durationof200µs toallowenoughtimetosensetheoutput
and keep it in regulation. As the VOUT load current
increases, the frequency with which the part is taken out
of shutdown must also be increased to prevent VOUT
from drooping below 4.8V during the OFF phase (see
Figure 4b). A 100Hz 98% duty cycle signal on the SHDN
pin ensures proper regulation with load currents as high
as 100µA. When load current greater than 100µA is
needed, the SHDN pin must be forced low as in normal
operation. The typical no-load supply current for this
The LTC1516 contains an internal resistor divider (refer to
Block Diagram) which draws only 1.5µA (typ) from VOUT
During no-load conditions, the internal load causes a
droop rate of only 150mV per second on V with
.
OUT
COUT = 10µF. Applying a 5Hz to 100Hz, 95% to 98% duty
cycle signal to the SHDN pin ensures that the circuit of
Figure 3 comes out of shutdown frequently enough to
maintain regulation during no-load or low-load condi-
tions. Since the part spends nearly all of its time in
shutdown, theno-loadquiescentcurrent(seeFigure4a)is
circuit with V = 3V is only 3.2µA.
IN
approximately equal to (VOUT)(1.5µA)/(V )(Efficiency).
IN
0.22µF
1
2
3
4
8
7
6
5
+
–
C1
C1
V
SHDN
GND
FROM MPU
SHDN PIN WAVEFORMS:
V
IN
= 2V TO 5V
IN
+
LTC1516
10µF
V
OUT
+
10µF
+
–
C2
C2
LOW I MODE (5Hz TO 100Hz, 95% TO 98% DUTY CYCLE)
V
OUT
LOAD ENABLE MODE
Q
I
≤ 100µA
(I
OUT
= 100µA TO 50mA)
OUT
0.22µF
1516 • F03
V
OUT
= 5V ±4%
Figure 3. Ultralow Quiescent Current (<5µA) Regulated Supply
6.0
1000
SHDN ON PULSE WIDTH = 200µs
= 10µF
C
OUT
4.0
2.0
0.0
100
10
1
2.0
3.0
4.0
5.0
1
10
100
1000
INPUT VOLTAGE (V)
1516 • F04a
OUTPUT CURRENT (µA)
1516 • F04b
Figure 4b. Maximum SHDN OFF Time vs Output Load Current for
Ultralow IQ Operation
Figure 4a. No Load ICC vs Input Voltage for Circuit in Figure 3
6
LTC1516
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APPLICATIONS INFORMATION
Paralleling Devices
General Layout Considerations
Two or more LTC1516’s may be connected in parallel to
Due to the high switching frequency and high transient
currents producedbytheLTC1516, carefulboardlayoutis
a must. A clean board layout using a ground plane and
short connections to all capacitors will improve perfor-
mance and ensure proper regulation under all conditions
(refer to Figure 6).
provide higher output currents. The V , VOUT, GND and
IN
SHDN pins may be tied together, but the C1 and C2 pins
must be kept separate (see Figure 5). Separate C and
IN
COUT capacitors may be required to reduce output noise
and ripple if the paralleled devices cannot be kept close
together. Otherwise, single C and COUT capacitors may
IN
be used with each being 2× (or 3× if three parts are
paralleled, etc.) in value.
C1
0.22µF
C
IN
1
8
+
+
V
IN
2
3
7
6
SHDN
1
2
3
4
8
7
6
5
+
–
C1
C1
LTC1516
V
OUT
V
SHDN
GND
IN
GND
C
LTC1516
OUT
4
5
V
OUT
+
–
C2
C2
C2
0.22µF
0.22µF
1516 • F06
Figure 6. Suggested Component Placement for LTC1516
1
2
3
4
8
7
6
5
+
–
C1
C1
V
= 2V
TO 5V
IN
V
SHDN
GND
ON/OFF
IN
+
LTC1516
22µF
V
OUT
+
22µF
+
–
C2
C2
0.22µF
V
OUT
= 5V ±4%
I
= 0mA TO 40mA, V ≥ 2V
OUT
IN
I
= 0mA TO 100mA, V ≥ 3V
IN
OUT
1516 • F05
Figure 5. Paralleling Devices
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-
tationthattheinterconnectionofits circuits as describedhereinwillnotinfringeonexistingpatentrights.
7
LTC1516
U
TYPICAL APPLICATIONS N
Fault-Protected SIM Interface Supply for
GSM Cellular Phones
Generating 5V and a Negative Supply
0.1µF
0.1µF
3V
V
= 5V ±4%
OUT
1
2
7
8
3
6
1
7
8
+
–
+
–
I
= 20mA,V ≥ 2V
C1
V
C1
C1
C1
OUT
IN
I
= 50mA, V ≥ 3V
OUT
IN
3
V
ON/OFF
SHDN
LTC1516
V
IN
OUT
OUT
V
= 5V ±4%
= 40mA
240Ω 8.2k
OUT
LTC1516
SHDN
+
I
2.2µF
2
4
6
5
OUT
V
IN
2V TO 5V
10µF
GND
V
GND
IN
+
+
4
5
+
–
Q1
**
Q2
10µF
+
–
C2
C2
C2
C2
10µF
3.3k
0.1µF
0.1µF
0.22µF
–V
–I
OUT
= –1.4V TO –3V
OUT
= 5mA
GSM
CONTROLLER
10µF
*
+
V
CC
RST
CLK
*CENTRAL SEMICONDUCTOR CMPSH-35 DUAL SCHOTTKY
**OPTIONAL CIRCUITRY FOR MAINTAINING –V AT LOW V
Q1, Q2: 2N3904
LEVEL SHIFT
1516 • TA03
LOADS
OUT OUT
SIM CARD
I/O
GND
1516 • TA02
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
0.010 – 0.020
(0.254 – 0.508)
7
5
8
6
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.016 – 0.050
0.406 – 1.270
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
SO8 0695
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1
3
4
2
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
®
LT 1054
100mA Switched Capacitor Converter
20mA Switched Capacitor Converter for Up to 20V Inputs
Includes Reference and Amplifier for Regulation
LTC1144
LTC1261
LTC1262
LTC1550/51
Includes Micropower Shutdown (8µA)
Positive to Negative Regulated Switched Capacitor Converter Low Noise (5mV) Output for Up to 10mA Loads
5V to 12V Regulated Switched Capacitor Converter
Low Noise Switched Capacitor Regulated Converter
Up to 30mA at Regulated Output
Provides –4.1V at 20mA with <1mV Ripple
LT/GP 0796 7K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
8
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LINEAR TECHNOLOGY CORPORATION 1996
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