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LTC1517-5 Micropower, Regulated 5V Charge Pump in a 5-Pin SOT-23 Package
FEATURES
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DESCRIPTION
The LTC(R)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 6A with no load) and low external parts count (one 0.1F 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.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation.
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Ultralow Power: ICC = 6A 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
APPLICATIONS
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Cellular Telephones Battery-Operated Equipment Local Power Supplies Handheld Instruments PCMCIA Supplies
TYPICAL APPLICATION
Typical Output Voltage vs Output Current
5.2
0.1F 5 C1 - LTC1517-5 VIN VIN 2.7V TO 5V 3.3F 1 GND 2 VOUT 3 6.8F VOUT = 5V 4% IOUT = 10mA (VIN 2.7V) IOUT = 20mA (VIN 3V)
1517 TA01
C1 +
OUTPUT VOLTAGE (V)
4
5.1
TA = 25C C1 = 0.1F COUT = 6.8F
5.0
4.9 VIN = 2.7V VIN = 3V VIN = 3.3V 4.8
0
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40 60 20 OUTPUT CURRENT (mA)
80
1517 TA02
1
LTC1517-5
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW VIN GND VOUT 1 2 3 4 C1 + 5 C1 -
VIN to GND ...................................................- 0.3V to 6V VOUT to GND ................................................- 0.3V to 6V VOUT Short-Circuit Duration ............................. Indefinite Operating Temperature Range: Commercial (Note 2) .............................. 0C to 70C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LTC1517CS5-5 S5 PART MARKING LTCJ
S5 PACKAGE 5-LEAD PLASTIC SOT-23
TJMAX = 125C, JA = 256C/ 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 = 0.1F, CIN = 3.3F, COUT = 6.8F, TMIN to TMAX, unless otherwise noted.
SYMBOL VIN VOUT ICC fOSC tON PARAMETER Operating Input Voltage Output Voltage Input Supply Current VOUT Ripple Oscillator Frequency VOUT Turn-On Time VIN = 3V 2.7V VIN 5V, IOUT 10mA 3V VIN 5V, IOUT 20mA 2.7V VIN 5V, IOUT = 0 VIN = 3V, IOUT = 20mA, COUT = 6.8F CONDITIONS
q q q q
MIN 2.7 4.8 4.8
TYP 5.0 5.0 6 75 800 1
MAX 5 5.2 5.2 15
UNITS V V V A mVP-P kHz ms
The q 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.
Note 2: Commercial grade parts are designed to operate over the temperature range of - 40C to 85C but are neither tested nor guaranteed beyond 0C to 70C.
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LTC1517-5 TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Input Voltage
5.15 IOUT = 10mA COUT = 10F 5.10 80 90 IOUT = 10mA TA = 25C 200
OUTPUT VOLTAGE (V)
VRIPPLE P-P (mV)
EFFICIENCY (%)
5.05 TA = 70C 5.00 TA = 25C 4.95 TA = 0C
4.90 2.5
3.0
4.0 4.5 3.5 INPUT VOLTAGE (V)
No Load Input Current vs Input Voltage
9 IOUT = 0mA 8
INPUT CURRENT (A)
7
TA = 25C
EFFICIENCY (%)
TA = 70C
6
TA = 0C
5
4 2.5
3.0
4.0 4.5 3.5 INPUT VOLTAGE (V)
UW
1517-5 G01
1517-5 G04
Efficiency vs Input Voltage
250
Output Ripple vs Input Voltage
IOUT = 10mA C1 = 0.1F TA = 25C COUT = 3.3F 150 COUT = 6.8F 100 COUT = 10F 50 COUT = 22F
70
60
50
5.0
40 2.5
3.0
4.0 4.5 3.5 INPUT VOLTAGE (V)
5.0
1517-5 G02
0 2.5
3.0
4.0 4.5 3.5 INPUT VOLTAGE (V)
5.0
1517-5 G03
Efficiency vs Output Current
90 VIN = 3V SHDN = 0V TA = 25C 80
Load Transient Response
IOUT 0mA to 10mA 10mA/DIV VOUT AC COUPLED 50mV/DIV
70
60
VIN = 3V COUT = 6.8F
5.0
500s/DIV
1517-5 G06
50 0.01
0.1 1 10 OUTPUT CURRENT (mA)
100
1517-5 G05
3
LTC1517-5
PIN FUNCTIONS
VIN (Pin 1): Charge Pump Input Voltage. May be between 2.7V and 5V. VIN should be bypassed with a 3.3F 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 3.3F 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.
SI PLIFIED BLOCK DIAGRA
VIN CIN
C1 -
CHARGE PUMP 3.75M
800kHz OSC
LTC1517-5
1517 BD
4
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C1 0.1F
C1 + VOUT COUT
+ -
THERMAL SHDN 1.25V REF 1.25M
LTC1517-5
APPLICATIONS INFORMATION
Operation 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. 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 3.3F or greater. Ceramic capacitors will provide the smallest size and lowest ESR for a given capacitance. If the input source impedance is very low (< 0.5), CIN may not be needed. Ceramic capacitors are recommended for the flying capacitor C1 with values of 0.1F or 0.22F. Smaller value flying capacitors may be used in low IOUT applications. Output Ripple 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 (< 0.5) 3.3F output capacitor (minimum recommended COUT). For applications requiring VIN to exceed 3.3V or for applications requiring < 100mV of peak-to-peak ripple, a 6.8F to 10F COUT capacitor is recommended. Slight further decreases in output ripple can be achieved by using COUT capacitors larger than 10F. 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 160C. The charge pump is reenabled once the junction temperature drops to approximately 145C. 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
TYPICAL APPLICATIONS
0.1F 5 C1 - LTC1517-5 VIN VIN 3.3V TO 5V 1 1F 470 Q2 Q1, Q2: 2N3904 3.3F 1F 1F
1517 TA04a
4 C1 +
GND 2
VOUT 3 470 Q1 B 1F A
VIN 2.7V TO 5V
3.3F
6
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Low Noise Boosted 5V Supply
A
50mV/DIV AC COUPLED
B
VOUT = 5V IOUT = 1mA (VIN 3.3V) IOUT = 10mA (VIN 3.6V) VRIPPLE < 2mVP-P
VOUT 2mV/DIV AC COUPLED
VIN = 3.3V IOUT = 1mA
50s/DIV
1517-5 TA04b
Generating 5V and a Negative Supply
0.1F 5 C1 - LTC1517-5 VIN 1 GND 2 VOUT 3 3.3F 470 8.2k VOUT = 5V 4% IOUT = 10mA (2.7V VIN 5V) IOUT = 20mA (3V VIN 5V) 4 C1 +
Q1 0.1F
Q2 3.3k
**
1517 TA05
3.3F * *CENTRAL SEMICONDUCTOR CMPSH-35 DUAL SCHOTTKY **OPTIONAL CIRCUITRY FOR MAINTAINING - VOUT WITH LOW VOUT LOADS Q1, Q2: 2N3904
- VOUT = - 1.4V TO - 3.5V - IOUT = 0mA to 5mA
LTC1517-5
PACKAGE DESCRIPTION
0.10 - 0.60 (0.004 - 0.024) REF
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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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)
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)
0.09 - 0.20 (0.004 - 0.008) (NOTE 2)
0.35 - 0.50 0.90 - 1.30 (0.014 - 0.020) (0.035 - 0.051) FIVE PLACES (NOTE 2) S5 SOT-23 0797
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LTC1517-5
TYPICAL APPLICATION
3.3V to 1.9V, 6A Power Supply
C1 Y5V CERAMIC 3.3F 1 2 3 C2 Y5V CERAMIC 10F 5V C4 0.1F D1 BAT54 1 2 3 4 5 6 7 8 LTC1517-5 4 5 C3 0.22F
C5 1F
ON
OFF R1 100
*AVX TPS TANTALUM
RELATED PARTS
PART NUMBER LTC1514-X LTC1515 Series LTC1516 LTC1522 DESCRIPTION Step-Up/Step-Down Switched-Capacitor DC/DC Converter with Low Battery Comparator Step-Up/Step-Down Switched-Capacitor DC/DC Converter with Reset Micropower Regulated 5V Charge Pump DC/DC Converter Micropower Regulated 5V Charge Pump DC/DC Converter COMMENTS 3.3V or 5V Output Up to 50mA Fixed or Adjustable Output Up to 50mA 20mA for VIN 2V, 50mA for VIN 3V Same as LTC1517-5 with Shutdown, Available in MSOP
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417 q (408) 432-1900 FAX: (408) 434-0507 q TELEX: 499-3977 q www.linear-tech.com
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VIN 3.3V
+
C6 TO C9* 330F 6.3V C10 x4 0.1F
R2 24k
C11 1F L1 2.4H, 8A SUMIDA CDRH127-2R4 D2 MBRS120 R5 4.99K 1% R6 10K 1%
Q1 Si4410
R3 1k LTC1430CS 16 G1 G2 15 PVCC1 PVCC2 14 PGND VCC 13 IFB GND 12 - IMAX SENSE 11 FB FREQSET 10 + SENSE COMP 9 SHDN SS C12 0.1F
Q2 Si4410
VOUT 1.9V 6A
C16 0.018F
+
C17 TO C21 * 330F 6.3V x5
R4 5.2k C14 0.012F
+
C13 390pF
C15 10F 10V
1517 TA03
15175f LT/TP 0298 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1997

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