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LTC1986 3V/5V SIM Power Supply in ThinSOT
FEATURES
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DESCRIPTIO
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VIN Range: 2.6V to 4.4V Ultralow Power Operating Current: 14A Shutdown Current: <1A No Inductors Short-Circuit/Thermal Protected Ultrasmall Application Circuit (< 0.045in2) Low Profile (1mm) ThinSOTTM Step-Up Charge Pump Generates 5V Output Current: 10mA VIN to VOUT Direct Connection for 3V SIMs Switching Frequency: 900kHz Soft-Start Limits Inrush Current at Turn-On Output Driven to Ground During Shutdown
The LTC(R)1986 is a micropower charge pump DC/DC converter that provides power for either 3V or 5V GSM SIM cards. It operates in one of three modes: VOUT = 5V (5V mode), VOUT = VIN (3V mode) or shutdown. The input voltage range is 2.6V to 4.4V and the part can provide 10mA of output current. The LTC1986 allows VIN to drop as low as 2.6V by providing a boost feature in 3V mode. In 3V mode, VOUT is connected directly to VIN through a 2.5 switch until VIN drops below 2.85V. When VIN is below 2.85V, the part automatically boosts VOUT to maintain a regulated 2.9V output, thereby ensuring VOUT stays within the 3V SIM VCC specification. Extremely low operating current (14A typical with no load) and low external parts count make the part ideally suited for small, light load battery-powered applications. The total PCB area of the application circuit shown below is less than 0.045in2. Protection features include inrush current limiting, undervoltage lockout, short circuit and thermal overload protection. The LTC1986 is available in a low profile (1mm) SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation.
APPLICATIO S
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GSM Cellular Telephones PCS/DCS Cellular Telephones Portable POS Terminals
TYPICAL APPLICATIO
VOUT = 5V OR VIN GSM CONTROLLER 3/5 1M 3 750k SHDN 2.2F
3V/5V SIM Power Supply
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VIN = 2.6V TO 4.4V LTC1986 VOUT GND VIN C1+ 6 5 4 0.047F
Output Voltage vs Input Voltage
TA = 25C IOUT = 10mA
OUTPUT VOLTAGE (V)
1 2
0.1F
5
4
MODE C1-
3
SHDN 3/5 MODE 0 0 SHUTDOWN 0 1 SHUTDOWN 1 0 VOUT = 5V VOUT = VIN 1 1
2 2.5
1986 TA01
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5V MODE 3V MODE (VOUT = VIN) 3.0 3.5 INPUT VOLTAGE (V)
1986 TA02
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4.0
4.5
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LTC1986
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW VOUT 1 GND 2 MODE 3 6 VIN 5 C1+ 4 C1-
VIN, VOUT to GND .........................................- 0.3V to 6V All Other Pins to GND ..................................- 0.3V to 6V VOUT Short-Circuit Duration ............................. Indefinite Operating Temperature Range (Note 2) .................................................. - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LTC1986ES6 S6 PART MARKING LTKX
S6 PACKAGE 6-LEAD PLASTIC SOT-23
TJMAX = 125C, JA = 230C/ W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. VIN = VMIN to VMAX, MODE = VIN, C1 = 0.047F, COUT = 2.2F, unless otherwise specified.
PARAMETER VIN Operating Voltage VOUT Output Voltage CONDITIONS
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MIN 2.6
TYP 0 VIN - 0.025 2.9 5 5 0.001 10 14 2.5 100 70 900
MAX 4.4
UNITS V V V V V V A A A mA kHz V V V A V
Shutdown Mode 3V Mode. VIN = 2.85V to 4.4V, IOUT 10mA 3V Mode, VIN < 2.85V, IOUT < 10mA 5V Mode, VIN < 2.7V, IOUT 10mA 5V Mode, VIN = 2.7V to 4.4V, IOUT 10mA Shutdown Mode, VMODE = 0V 3V Mode, IOUT = 0mA 5V Mode, IOUT = 0mA 3V Mode, VIN = 3V 3V or 5V Mode, VOUT = 0V VIN = 3V Oscillator Free-Running Shutdown Mode 5V Mode 3V Mode
q q q q q q q q q
2.75 4.55 4.75
3.05 5.25 5.25 1 25 30 5 200 200
VIN Operating Current
VIN-to-VOUT ON Resistance VOUT Short-Circuit Current VOUT Discharge Resistance Switching Frequency MODE Input Ranges
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0 VIN/2 + 0.1 VIN - 0.25 -1 1.4
VIN/2 - 0.1 VIN - 1.0 VIN 1
MODE Input Current Undervoltage Lockout Threshold Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2: The LTC1986E is guaranteed to meet performance specifications from 0C to 70C. Specifications over the - 40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls.
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LTC1986 TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Output Current (3V Mode)
3.10 VIN = VMODE = 3V TA = 25C 100 IOUT = 10mA VOUT = 5V TA = 25C
OUTPUT VOLTAGE (V)
3.05
EFFICIENCY (%)
3.00
2.95
2.90 0.001
0.1 1 0.01 OUTPUT CURRENT (mA)
Efficiency vs Output Current
100
POSITIVE SUPPLY CURRENT (mA )
40
80
EFFICIENCY (%)
60
40
20
0 0.001
0.1 0.01 1 OUTPUT CURRENT (mA)
Output Voltage Ripple (5V Mode)
VOUT 50mV/DIV AC COUPLED
VIN = 3V IOUT = 10mA TA = 25C
UW
Efficiency vs Input Voltage
80
60
40
10
1986 G01
20 2.5
3.0
3.5 INPUT VOLTAGE (V)
4.0
4.5
1986 G02
Positive Supply Current vs Input Voltage
IOUT = 0mA TA = 25C 30
20 5V MODE (VMODE = 0.6VIN) 10 3V MODE (VMODE = VIN) 0 2.5
VIN = 3V 5V MODE (VMODE = 0.6VIN) TA = 25C 10
1986 G03
3.0
3.5 INPUT VOLTAGE (V)
4.0
4.5
1986 G04
Output Voltage vs VMODE Waveforms
5V VOUT 2V/DIV 0V 4V VMODE 2V/DIV 0V
5ms/DIV VIN = 4V TA = 25C
1986 G05
2ms/DIV
1986 G06
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LTC1986
PIN FUNCTIONS
VOUT (Pin 1): Charge Pump Output. The VOUT voltage will depend on the MODE pin input voltage. VOUT = 0V in shutdown mode, VOUT = VIN in 3V mode and VOUT = 5V in 5V mode. The LTC1986 provides a 2.9V regulated output when the part is in 3V mode and the VIN voltage is below 2.85V. This feature allows the input voltage to be below the minimum voltage specification for 3V SIM cards without violating the SIM VCC specification. Bypass the VOUT pin with a 2.2F low ESR capacitor to ground. GND (Pin 2): Ground. Connect to a ground plane for best performance. MODE (Pin 3): MODE Input Pin. The voltage on this pin determines the operating mode of the LTC1986. It operates in either shutdown mode, 3V mode or 5V mode depending on the MODE pin voltage with respect to VIN. The three different modes can be realized by using two external resistors as shown in the typical application circuit. If VMODE < VIN/2 - 0.1V, the part is in shutdown mode.If VIN/2 + 0.1V < VMODE < VIN - 1V, the part is in 5V mode. If VIN - 0.25V < VMODE, the part is in 3V mode. To achieve the lowest possible shutdown current, the MODE pin should be pulled to 0V, i.e., both the SHDN and 3/5 signals from the controller should be pulled low. C1- (Pin 4): Charge Pump Flying Capacitor Negative Terminal. C1+ (Pin 5): Charge Pump Flying Capacitor Positive Terminal. VIN (Pin 6): Input Supply Voltage. Bypass VIN with a 0.1F low ESR capacitor to ground.
SI PLIFIED BLOCK DIAGRA
50 2.5
VIN 6
SOFT START - 1.25V + 900kHz OSC 2.9V BOOST
VIN - 0.6V MODE 3 VIN/2
3V LOGIC 5V SHDN
UVLO/ THERMAL SHDN
1.25V REF SHDN
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+
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C1 -
4 5
C1 +
LTC1986
5V MODE
CHARGE PUMP
3V MODE
1 VOUT
2
GND
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LTC1986
APPLICATIONS INFORMATION
Operation The LTC1986 is a charge pump DC/DC converter designed specifically to supply VCC power for either 3V or 5V SIM cards. The part can operate in one of three modes: a low power shutdown mode which disconnects VIN from VOUT and actively pulls down the VOUT supply, 3V mode which provides a direct connection between VIN and VOUT for powering 3V SIM cards, and 5V mode which provides a regulated 5V output for powering 5V SIM cards. In 5V mode, regulation is achieved by sensing the output voltage through a resistor divider and enabling the charge pump as needed to maintain regulation. 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 900kHz (typ) and continues until the divided output voltage reaches the upper trip point of the comparator. Once the output is in regulation, the charge pump is disabled. This method of bursting the charge pump on and off enables the LTC1986 to achieve high efficiency at extremely low output loads. Mode Selection The operating mode is determined by the voltage applied to the MODE pin. The MODE pin has three voltage thresholds--all of which are referenced to VIN: Shutdown Mode VMODE < VIN/2 - 0.1V 5V Mode VIN/2 + 0.1V < VMODE < VIN - 1V 3V Mode VIN - 0.25V < VMODE For example, if VIN = 3V, then the following table applies:
VMODE 0V to 1.4V 1.6V to 2V 2.75V to 3V OPERATING MODE Shutdown Mode 5V Mode 3V Mode (VOUT = VIN)
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The three modes can be selected using two totem pole digital outputs and two external resistors as shown in Figure 1. Shutdown mode disconnects VIN from VOUT and enables an internal pull-down device which forces VOUT to GND. To achieve the lowest possible quiescent current in shutdown mode, the voltage on the MODE pin should be pulled below 0.4V. 3V mode connects VOUT to VIN through a 2.5 internal switch. The LTC1986 has the additional capability of boosting VOUT to a regulated 2.9V in 3V mode when the input voltage drops below 2.85V. This ensures that the 3V SIM VCC specification is not violated if VIN drops below 2.7V during transients or low battery conditions.
VIN
VIN 3/5 1M 3 750k SHDN LTC1986 MODE
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SHDN 3/5 MODE 0 0 SHUTDOWN (ICC < 1A) 0 1 SHUTDOWN (ICC = 10A) VOUT = 5V 1 0 VOUT = VIN 1 1
1986 F01
Figure 1
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. Ceramic capacitors will provide the smallest size for a given capacitance. If the input source impedance is very low (< 0.5), CIN may not be needed. For best performance, COUT should be 2.2F or greater. Ceramic capacitors are also recommended for the flying capacitor C1 with values between 0.047F and 0.22F. If a small value output capacitor (3.3F or less) is used, a small flying capacitor should also be used to prevent high output ripple in 5V mode. The recommended capacitor values to minimize board space and cost are: CIN = 0.1F, C1 = 0.047F and COUT = 2.2F (ceramic).
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LTC1986
APPLICATIONS INFORMATION
Output Ripple Normal 5V mode operation produces voltage ripple on the VOUT pin. Output voltage ripple is required for regulation. 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 75mVP-P with a low ESR 2.2F output capacitor and a 0.047F C1 capacitor. For applications requiring VIN to exceed 3.3V or for applications requiring < 75mV of peak-to-peak ripple, a 3.3F to 10F COUT capacitor is recommended. Slight further decreases in output ripple can be achieved by using COUT capacitors larger than 10F. Protection Features The LTC1986 provides several protection features. Undervoltage lockout prevents any current from flowing between V IN and V OUT until the V IN voltage exceeds 1.4V (typ). This prevents undesirable glitches during power-up. The parts also limit inrush current during power-up to under 200mA regardless of VIN voltage, operating mode and output load by disabling the main direct connect switch (3V mode) or the charge pump (5V mode) and enabling a 50 series switch between VIN and VOUT until VOUT reaches VIN/2. The parts are also short-circuit protected and can survive an indefinite short from VOUT to GND regardless of operating mode or input voltage. In the event of thermal overload, the parts will enter thermal shutdown if the junction temperature exceeds 165C and return to normal operation once the junction temperature drops to 150C.
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LTC1986
PACKAGE DESCRIPTION
0.62 MAX
0.95 REF
3.85 MAX 2.62 REF
RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR
0.20 BSC 1.00 MAX DATUM `A'
0.30 - 0.50 REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 0.09 - 0.20 (NOTE 3)
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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S6 Package 6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC (NOTE 4)
1.22 REF
1.4 MIN
2.80 BSC
1.50 - 1.75 (NOTE 4) PIN ONE ID
0.95 BSC
0.30 - 0.45 6 PLCS (NOTE 3)
0.80 - 0.90 0.01 - 0.10
1.90 BSC
S6 TSOT-23 0302
1986fa
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LTC1986
TYPICAL APPLICATION
3V/5V SIM Power Supply
VOUT = 5V OR VIN GSM CONTROLLER 3/5 1M 3 750k SHDN SHDN 3/5 MODE 0 0 SHUTDOWN 0 1 SHUTDOWN 1 0 VOUT = 5V VOUT = VIN 1 1 2.2F LTC1986 VOUT GND VIN C1+ 6 5 4 0.047F
RELATED PARTS
PART NUMBER LTC1503 LTC1517 LTC1555 LT1615 LT1682 LTC1754-5 LTC1754-3.3 LT1761 LTC1755 LTC1911-1.5/LTC1911-1.8 LTC3250-1.5 DESCRIPTION High Efficiency Step-Down Charge Pump Micropower Charge Pump in 5-Pin ThinSOT SIM Power Supply and Level Translator Micropower Step-Up DC/DC Converter in ThinSOT Charge Pump Plus Low Noise LDO Regulator in MS8 5V Charge Pump with Shutdown in ThinSOT 3.3V Charge Pump with Shutdown in ThinSOT Low Noise, 100mA Micropower LDO Regulator Smart Card Power Supply and Level Translator High Efficiency, Inductorless, Low Noise Step-Down DC/DC Converter High Efficiency, Inductorless, Low Noise Step-Down DC/DC Converter
TM
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
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VIN = 2.6V TO 4.4V
1 2
0.1F
MODE C1-
1986 TA01
COMMENTS VIN = 2.4V to 6V, 100mA Output Current ICC = 6A, Short-Circuit/Thermal Protected VIN = 2.7V to 10V, 10kV ESD on SIM Contact Pins VIN = 1.2V to 15V; 350mA, 36V Switch 50mA Output Current; 60VRMS Output Noise 50mA Output Current, ICC = 13A VIN = 2V to 4.4V; IOUT = 40mA; Ripple = 23mVP-P IQ = 20A, 20VRMS Noise, ThinSOT ISO 7816-3 and EMV Compliant Up to 85% Efficiency, 1.5MHz, VIN: 2.7V to 5.5V, IQ = 180A, MS8 Up to 90% Efficiency, 1.5MHz, VIN: 3.1V to 5.5V, IQ = 35A, ThinSOT
1986fa LT/TP 0902 1K REV A * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 1999

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