LTC1517-5 - Micropower, Regulated 5V Charge Pump in a 5-Pin SOT-23 Package

LTC1517-5
Micropower, Regulated
5V Charge Pump in a
5-Pin SOT-23 Package
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DESCRIPTION
FEATURES
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Ultralow Power: ICC = 6µA Typ
Short-Circuit/Thermal Protected
5V ±4% Regulated Output
VIN Range: 2.7V to 5V
Output Current: 10mA (VIN ≥ 2.7V)
20mA (VIN ≥ 3V)
No Inductors
Ultrasmall Application Circuit (0.045in2)
800kHz Switching Frequency
Available in 5-Pin SOT-23
The LTC®1517-5 is a micropower charge pump DC/DC
converter that produces a regulated 5V output. The input
voltage range is 2.7V to 5V. Extremely low operating current
(typically 6µA with no load) and low external parts count (one
0.1µF flying capacitor and two small bypass capacitors at VIN
and VOUT) make the part ideally suited for small, light load
battery-powered applications. The total printed circuit board
area of the application circuit shown below is only 0.045in2.
The part operates as a Burst ModeTM switched-capacitor
voltage doubler to produce a regulated output. The part has
thermal shutdown capability and can survive a continuous
short circuit from VOUT to GND. The device is available in a
5-pin SOT-23 package.
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APPLICATIONS
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Cellular Telephones
Battery-Operated Equipment
Local Power Supplies
Handheld Instruments
PCMCIA Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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TYPICAL APPLICATION
Typical Output Voltage vs Output Current
5.2
5
4
C1 –
C1 +
LTC1517-5
VIN
2.7V TO 5V
3.3µF
VIN
GND
VOUT
1
2
3
6.8µF
VOUT = 5V ± 4%
IOUT = 10mA (VIN ≥ 2.7V)
IOUT = 20mA (VIN ≥ 3V)
OUTPUT VOLTAGE (V)
0.1µF
TA = 25°C
C1 = 0.1µF
COUT = 6.8µF
5.1
5.0
4.9
VIN = 2.7V VIN = 3V VIN = 3.3V
1517 TA01
4.8
0
40
60
20
OUTPUT CURRENT (mA)
80
1517 TA02
1
LTC1517-5
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
VIN to GND ...................................................– 0.3V to 6V
VOUT to GND ................................................– 0.3V to 6V
VOUT Short-Circuit Duration ............................. Indefinite
Operating Temperature Range:
Commercial ............................................ 0°C to 70°C
Extended (Note 2).............................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
TOP VIEW
VIN
1
GND
2
VOUT
3
5
C1 –
4
C1 +
LTC1517CS5-5
LTC1517ES5-5
S5 PART MARKING
S5 PACKAGE
5-LEAD PLASTIC SOT-23
LTCX
LTTF
TJMAX = 125°C, θJA = 256°C/ W
Consult factory for Industrial and Military grade parts and for -3 and -3.3
version availability.
ELECTRICAL CHARACTERISTICS
VIN = 2.7V to 5V, C1 = 0.1µF, CIN = 3.3µF, COUT = 6.8µF, TMIN to TMAX, unless otherwise noted.
SYMBOL
PARAMETER
VIN
Operating Input Voltage
VOUT
Output Voltage
ICC
CONDITIONS
●
2.7
2.7V ≤ VIN ≤ 5V, IOUT ≤ 10mA
3V ≤ VIN ≤ 5V, IOUT ≤ 20mA
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●
4.8
4.8
Input Supply Current
2.7V ≤ VIN ≤ 5V, IOUT = 0
●
VOUT Ripple
VIN = 3V, IOUT = 20mA, COUT = 6.8µF
fOSC
Oscillator Frequency
tON
VOUT Turn-On Time
VIN = 3V
The ● denotes specifications that 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.
2
MIN
TYP
MAX
UNITS
5
V
5.0
5.0
5.2
5.2
V
V
6
15
µA
75
mVP-P
800
kHz
1
ms
Note 2: Extended grade parts are 100% tested at TA = 25°C. Performance
at – 40°C and 85°C is assured by design, characterization and correlation
with statistical process controls.
LTC1517-5
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TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Input Voltage
Efficiency vs Input Voltage
5.15
IOUT = 10mA
COUT = 10µF
5.05
TA = 70°C
5.00
TA = 0°C
TA = 25°C
4.95
VRIPPLE P-P (mV)
EFFICIENCY (%)
OUTPUT VOLTAGE (V)
200
80
70
60
3.0
4.0
4.5
3.5
INPUT VOLTAGE (V)
40
2.5
5.0
COUT = 3.3µF
150
COUT = 6.8µF
100
COUT = 10µF
COUT = 22µF
50
50
4.90
2.5
IOUT = 10mA
C1 = 0.1µF
TA = 25°C
IOUT = 10mA
TA = 25°C
5.10
3.0
4.0
4.5
3.5
INPUT VOLTAGE (V)
1517-5 G01
5.0
0
2.5
3.0
4.0
4.5
3.5
INPUT VOLTAGE (V)
5.0
1517-5 G03
1517-5 G02
No Load Input Current
vs Input Voltage
Load Transient Response
Efficiency vs Output Current
90
9
VIN = 3V
SHDN = 0V
TA = 25°C
IOUT = 0mA
8
IOUT
0mA to 10mA
10mA/DIV
80
TA = 70°C
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EFFICIENCY (%)
INPUT CURRENT (µA)
Output Ripple vs Input Voltage
250
90
TA = 25°C
TA = 0°C
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VOUT
AC COUPLED
50mV/DIV
70
60
5
VIN = 3V
COUT = 6.8µF
4
2.5
3.0
4.0
4.5
3.5
INPUT VOLTAGE (V)
5.0
1517-5 G04
50
0.01
0.1
1
10
OUTPUT CURRENT (mA)
500µs/DIV
1517-5 G06
100
1517-5 G05
3
LTC1517-5
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PIN FUNCTIONS
VIN (Pin 1): Charge Pump Input Voltage. May be between
2.7V and 5V. VIN should be bypassed with a ≥ 3.3µF low
ESR capacitor as close as possible to the pin for best
performance.
GND (Pin 2): Ground. Should be tied to a ground plane for
best performance.
VOUT (Pin 3): Regulated Output Voltage. VOUT should be
bypassed with a ≥ 3.3µF low ESR capacitor as close as
possible to the pin for best performance.
C1 + (Pin 4): Charge Pump Flying Capacitor Positive
Terminal.
C1 – (Pin 5): Charge Pump Flying Capacitor Negative
Terminal.
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SI PLIFIED BLOCK DIAGRA
C1
0.1µF
C1 –
VIN
C1 +
VOUT
CHARGE PUMP
CIN
3.75M
COUT
+
800kHz
OSC
–
THERMAL
SHDN
1.25M
1.25V
REF
LTC1517-5
1517 BD
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LTC1517-5
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APPLICATIONS INFORMATION
Operation
Output Ripple
The LTC1517-5 uses a switched-capacitor charge pump
to boost VIN to a 5V ±4% regulated output. The part
achieves regulation by sensing the output voltage through
an internal resistor divider and enabling the charge pump
when the divided output droops below the comparator’s
lower trip point (set by VREF). When the charge pump is
enabled, a 2-phase nonoverlapping clock controls the
internal charge pump switches. Flying capacitor C1 is
charged to VIN on phase one of the clock. On phase two of
the clock, C1 is stacked in series with VIN and connected
to VOUT through an internal switch. This sequence of
charging and discharging the flying capacitor occurs at a
free running frequency of 800kHz (typ) and continues until
the divided output voltage reaches the upper trip point of
the comparator. Once the output is back in regulation, the
charge pump is disabled. This method of bursting the
charge pump on and off enables the LTC1517-5 to achieve
high efficiency at extremely low output loads.
Normal LTC1517-5 operation produces voltage ripple on
the VOUT pin. Output voltage ripple is required for the part
to regulate. Low frequency ripple exists due to the hysteresis in the sense comparator and propagation delays in the
charge pump enable/disable circuits. High frequency ripple
is also present mainly from the ESR (equivalent series
resistance) in the output capacitor. Typical output ripple
with VIN = 3V under maximum load is 100mV peak-to-peak
with a low ESR (< 0.5Ω) 3.3µF output capacitor (minimum
recommended COUT). For applications requiring VIN to
exceed 3.3V or for applications requiring < 100mV of
peak-to-peak ripple, a 6.8µF to 10µF COUT capacitor is
recommended. Slight further decreases in output ripple
can be achieved by using COUT capacitors larger than
10µF.
Capacitor Selection
For best performance, it is recommended that low ESR
capacitors be used for both CIN and COUT to reduce noise
and ripple. The CIN and COUT capacitors should be either
ceramic or tantalum and should be 3.3µF or greater.
Ceramic capacitors will provide the smallest size and
lowest ESR for a given capacitance. If the input source
impedance is very low (< 0.5Ω), CIN may not be needed.
Ceramic capacitors are recommended for the flying capacitor C1 with values of 0.1µF or 0.22µF. Smaller value
flying capacitors may be used in low IOUT applications.
Short-Circuit/Thermal Protection
During short-circuit conditions, the LTC1517-5 will draw
between 50mA and 200mA from VIN, causing a rise in
junction temperature. On-chip thermal shutdown circuitry
disables the charge pump once the junction temperature
exceeds approximately 160°C. The charge pump is
reenabled once the junction temperature drops to approximately 145°C. The LTC1517-5 will cycle in and out of
thermal shutdown indefinitely without latchup or damage
until the VOUT short is removed.
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LTC1517-5
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TYPICAL APPLICATIONS
Low Noise Boosted 5V Supply
0.1µF
5
4
C1 –
C1 +
LTC1517-5
VIN
3.3V TO 5V
VIN
GND
VOUT
1
2
3
50mV/DIV
AC COUPLED
B
VOUT
2mV/DIV
AC COUPLED
A
1µF
470Ω
Q1
3.3µF
470Ω
A
Q2
1µF
1µF
Q1, Q2: 2N3904
VOUT = 5V
IOUT = 1mA (VIN ≥ 3.3V)
IOUT = 10mA (VIN ≥ 3.6V)
B
1µF
VRIPPLE < 2mVP-P
1517 TA04a
VIN = 3.3V
IOUT = 1mA
50µs/DIV
Generating 5V and a Negative Supply
0.1µF
5
4
C1 –
C1 +
LTC1517-5
VIN
2.7V TO 5V
VIN
GND
VOUT
1
2
3
3.3µF
VOUT = 5V ± 4%
IOUT = 10mA (2.7V ≤ VIN ≤ 5V)
IOUT = 20mA (3V ≤ VIN ≤ 5V)
3.3µF
470Ω
Q1
8.2k
Q2
3.3k
0.1µF
**
1517 TA05
3.3µF
*
*CENTRAL SEMICONDUCTOR CMPSH-35 DUAL SCHOTTKY
**OPTIONAL CIRCUITRY FOR MAINTAINING – VOUT WITH LOW
VOUT LOADS
Q1, Q2: 2N3904
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– VOUT = – 1.4V TO – 3.5V
– IOUT = 0mA to 5mA
1517-5 TA04b
LTC1517-5
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S5 Package
5-Lead Plastic SOT-23
(LTC DWG # 05-08-1633)
2.80 – 3.00
(0.110 – 0.118)
(NOTE 3)
2.60 – 3.00
(0.102 – 0.118)
1.50 – 1.75
(0.059 – 0.069)
0.10 – 0.60
(0.004 – 0.024)
REF
0.09 – 0.20
(0.004 – 0.008)
(NOTE 2)
1.90
(0.074)
REF
0.00 – 0.15
(0.00 – 0.006)
0.95
(0.037)
REF
0.90 – 1.45
(0.035 – 0.057)
0.35 – 0.50
0.90 – 1.30
(0.014 – 0.020)
(0.035 – 0.051)
FIVE PLACES (NOTE 2)
S5 SOT-23 0797
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC1517-5
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TYPICAL APPLICATION
3.3V to 1.9V, 6A Power Supply
VIN
3.3V
C1
Y5V CERAMIC
3.3µF
2
+
5
1
LTC1517-5
3
4
C3
0.22µF
C6 TO C9*
330µF
6.3V
C10
×4
0.1µF
R2
24k
C2
Y5V CERAMIC
10µF
C11
1µF
L1
2.4µH, 8A
SUMIDA
CDRH127-2R4
Q1
Si4410
5V
D1
BAT54
C5
1µF
ON OFF
1
2
3
4
5
6
7
8
LTC1430CS
16
G2
G1
15
PVCC2
PVCC1
14
PGND
VCC
13
GND
IFB
12
–
IMAX
SENSE
11
FB
FREQSET
10
+
SENSE
COMP
9
SHDN
SS
C12
0.1µF
R1
100Ω
D2
MBRS120
Q2
Si4410
R3
1k
C4
0.1µF
C16
0.018µF
R5
4.99K
1%
VOUT
1.9V
6A
+
R6
10K
1%
C17 TO C21 *
330µF
6.3V
×5
R4
5.2k
C13
390pF
C14
0.012µF
+
C15
10µF
10V
1517 TA03
*AVX TPS TANTALUM
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1514-X
Step-Up/Step-Down Switched-Capacitor DC/DC Converter with
Low Battery Comparator
3.3V or 5V Output Up to 50mA
LTC1515 Series
Step-Up/Step-Down Switched-Capacitor DC/DC Converter with Reset
Fixed or Adjustable Output Up to 50mA
LTC1516
Micropower Regulated 5V Charge Pump DC/DC Converter
20mA for VIN ≥ 2V, 50mA for VIN ≥ 3V
LTC1522
Micropower Regulated 5V Charge Pump DC/DC Converter
Same as LTC1517-5 with Shutdown, Available in MSOP
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417● (408) 432-1900
FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com
15175fs, sn15175a LT/TP 0298 4K • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 1997