LTC1986 3V/5V SIM Power Supply in SOT-23 U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®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 2.5Ω 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. VIN Range: 2.6V to 4.4V Step-Up Charge Pump Generates 5V Output Current: 10mA VIN to VOUT Direct Connection for 3V SIMs Ultralow Power Operating Current: 14µA Shutdown Current: <1µA No Inductors Short-Circuit/Thermal Protected Switching Frequency: 900kHz Soft-Start Limits Inrush Current at Turn-On Output Driven to Ground During Shutdown Ultrasmall Application Circuit (< 0.045in2) 6-Lead SOT-23 Package Extremely low operating current (14µA 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 6-lead SOT-23 package. U APPLICATIO S ■ ■ ■ GSM Cellular Telephones PCS/DCS Cellular Telephones Portable POS Terminals , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATIO Output Voltage vs Input Voltage 3V/5V SIM Power Supply VOUT = 5V OR VIN 1 2.2µF 3/5 2 1M 3 LTC1986 VOUT VIN GND C1+ MODE C1– 6 0.1µF 5 4 0.047µF 750k SHDN SHDN 3/5 MODE 0 0 SHUTDOWN 0 1 SHUTDOWN 1 0 VOUT = 5V VOUT = VIN 1 1 TA = 25°C IOUT = 10mA OUTPUT VOLTAGE (V) GSM CONTROLLER 6 VIN = 2.6V TO 4.4V 3V MODE (VOUT = VIN) 4 3 2 2.5 1986 TA01 5V MODE 5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 1986 TA02 1 LTC1986 W U U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) ORDER PART NUMBER TOP VIEW 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) .................................................. – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C VOUT 1 6 VIN GND 2 5 C1+ MODE 3 4 C1– LTC1986ES6 S6 PACKAGE 6-LEAD PLASTIC SOT-23 S6 PART MARKING TJMAX = 125°C, θJA = 230°C/ W LTKX Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. VIN = VMIN to VMAX, MODE = VIN, C1 = 0.047µF, COUT = 2.2µF, unless otherwise specified. PARAMETER VIN Operating Voltage CONDITIONS MAX 4.4 UNITS V VOUT Output Voltage 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 0 VIN – 0.025 2.9 5 5 3.05 5.25 5.25 V V V V V ● ● ● VIN Operating Current Shutdown Mode, VMODE = 0V 3V Mode, IOUT = 0mA 5V Mode, IOUT = 0mA ● ● ● 0.001 10 14 1 25 30 µA µA µA VIN-to-VOUT ON Resistance 3V Mode, VIN = 3V ● 2.5 5 Ω VOUT Short-Circuit Current 3V or 5V Mode, VOUT = 0V ● 100 200 mA 70 200 ● VOUT Discharge Resistance 2.75 4.55 4.75 TYP 20 ● Switching Frequency Oscillator Free-Running MODE Input Ranges Shutdown Mode 5V Mode 3V Mode MODE Input Current Undervoltage Lockout Threshold Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. 2 MIN 2.6 900 ● ● ● 0 VIN/2 + 0.1 VIN – 0.25 ● –1 1.4 Ω kHz VIN/2 – 0.1 VIN – 1.0 VIN V V V 1 µA V Note 2: The LTC1986 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. LTC1986 U W TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage vs Output Current (3V Mode) Efficiency vs Input Voltage 100 3.10 IOUT = 10mA VOUT = 5V TA = 25°C 80 3.05 EFFICIENCY (%) OUTPUT VOLTAGE (V) VIN = VMODE = 3V TA = 25°C 3.00 60 40 2.95 2.90 0.001 0.1 1 0.01 OUTPUT CURRENT (mA) 20 2.5 10 3.0 3.5 4.0 1986 G02 1986 G01 Positive Supply Current vs Input Voltage Efficiency vs Output Current 40 POSITIVE SUPPLY CURRENT (mA ) 100 80 EFFICIENCY (%) 4.5 INPUT VOLTAGE (V) 60 40 20 VIN = 3V 5V MODE (VMODE = 0.6VIN) TA = 25°C 0 0.001 0.1 0.01 1 OUTPUT CURRENT (mA) IOUT = 0mA TA = 25°C 30 20 5V MODE (VMODE = 0.6VIN) 10 3V MODE (VMODE = VIN) 0 2.5 10 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 1986 G04 1986 G03 Output Voltage vs VMODE Waveforms Output Voltage Ripple (5V Mode) 5V VOUT 2V/DIV VOUT 50mV/DIV AC COUPLED 0V 4V VMODE 2V/DIV 0V 5ms/DIV VIN = 3V IOUT = 10mA TA = 25°C 2ms/DIV VIN = 4V TA = 25°C 1986 G06 1986 G05 3 LTC1986 U U U 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 ≥ 2.2µF low ESR capacitor to ground. 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. GND (Pin 2): Ground. Connect to a ground plane for best performance. C1+ (Pin 5): Charge Pump Flying Capacitor Positive Terminal. 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. VIN (Pin 6): Input Supply Voltage. Bypass VIN with a ≥ 0.1µF low ESR capacitor to ground. W W SI PLIFIED BLOCK DIAGRA C1 – C1 + 4 5 LTC1986 50Ω 2.5Ω VIN 6 SOFT START – 2.9V BOOST + 900kHz OSC + 3V – MODE 3 + VIN/2 – VIN – 0.6V 1 VOUT + 1.25V 3V MODE CHARGE PUMP 5V MODE – LOGIC 5V UVLO/ THERMAL SHDN 1.25V REF SHDN SHDN 2 GND 1986 BD 4 LTC1986 U W U U 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. 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 2.5Ω 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 LTC1986 1M 3 MODE 750k SHDN SHDN 3/5 MODE 0 0 SHUTDOWN (ICC < 1µA) 0 1 SHUTDOWN (ICC = 10µA) VOUT = 5V 1 0 VOUT = VIN 1 1 1986 F01 Figure 1 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 6 OPERATING MODE 0V to 1.4V Shutdown Mode 1.6V to 2V 5V Mode 2.75V to 3V 3V Mode (VOUT = VIN) 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 (< 0.5Ω), CIN may not be needed. For best performance, COUT should be 2.2µF or greater. Ceramic capacitors are also recommended for the flying capacitor C1 with values between 0.047µF and 0.22µF. If a small value output capacitor (3.3µF 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 = 0.1µF, C1 = 0.047µF and COUT = 2.2µF (ceramic). 5 LTC1986 U W U U APPLICATIONS INFORMATION Output Ripple Protection Features 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 2.2µF output capacitor and a 0.047µF C1 capacitor. For applications requiring VIN to exceed 3.3V or for applications requiring < 75mV of peak-to-peak ripple, a 3.3µF to 10µF COUT capacitor is recommended. Slight further decreases in output ripple can be achieved by using COUT capacitors larger than 10µF. 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 50Ω 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 165°C and return to normal operation once the junction temperature drops to 150°C. 6 LTC1986 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) 1.90 (0.074) REF 2.6 – 3.0 (0.110 – 0.118) 1.50 – 1.75 (0.059 – 0.069) 0.35 – 0.55 (0.014 – 0.022) 0.00 – 0.15 (0.00 – 0.006) 0.09 – 0.20 (0.004 – 0.008) (NOTE 2) 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) SIX PLACES (NOTE 2) S6 SOT-23 0898 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. 7 LTC1986 U TYPICAL APPLICATION 3V/5V SIM Power Supply VOUT = 5V OR VIN GSM CONTROLLER VIN = 2.6V TO 4.4V 1 2.2µF 3/5 2 1M 3 LTC1986 6 VOUT VIN GND C1+ 5 MODE C1– 4 0.1µF 0.047µF 750k SHDN SHDN 3/5 MODE 0 0 SHUTDOWN 0 1 SHUTDOWN 1 0 VOUT = 5V VOUT = VIN 1 1 1986 TA01 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1503 High Efficiency Step-Down Charge Pump VIN = 2.4V to 6V, 100mA Output Current LTC1517 Micropower Charge Pump in 5-Pin SOT-23 ICC = 6µA, Short-Circuit/Thermal Protected LTC1555 SIM Power Supply and Level Translator VIN = 2.7V to 10V, 10kV ESD on SIM Contact Pins LT1615 Micropower Step-Up DC/DC Converter in SOT-23 VIN = 1.2V to 15V; 350mA, 36V Switch LT1682 Charge Pump Plus Low Noise LDO Regulator in MSOP 50mA Output Current; 60µVRMS Output Noise LTC1754-5 5V Charge Pump with Shutdown in SOT-23 50mA Output Current, ICC = 13µA LTC1754-3.3 3.3V Charge Pump with Shutdown in SOT-23 VIN = 2V to 4.4V; IOUT = 40mA; Ripple = 23mVP-P LT1761 Low Noise, 100mA Micropower LDO Regulator IQ = 20µA, 20µVRMS Noise, SOT-23 Package LTC1755 Smart Card Power Supply and Level Translator ISO 7816-3 and EMV Compliant 8 Linear Technology Corporation 1986f LT/TP 0100 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1999