LTC1555L SIM Power Supply and Level Translator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®1555L provides power conversion and level shifting needed for low voltage GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). The part contains a patented buck/boost charge pump DC/DC converter* that delivers a regulated VCC supply voltage to the SIM card. Input voltage may range from 2.6V to 6V allowing direct connection to the battery. The output voltage may be programmed to 3V, 5V or direct connection to the VIN pin. Buck/Boost Charge Pump Generates 3V or 5V Input Voltage Range: 2.6V to 6V Controller VCC Range: 1.425V to 4.4V >10kV ESD on All SIM Contact Pins Short-Circuit and Overtemperature Protected 3V to 5V Signal Level Translators Very Low Operating Current: 40µA Very Low Shutdown Current: <1µA Soft-Start Limits Inrush Current at Turn-On 1MHz Switching Frequency Available in 16-Pin Narrow SSOP Package Internal level translators allow controllers operating with supplies as low as 1.425V to interface with 3V and 5V SIMs. A soft-start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low-power DC/DC converter. Battery life is maximized by 40µA operating current, and 1µA shutdown current. Board area is minimized by the miniature 16-pin narrow SSOP packages and the need for only three small external capacitors. U APPLICATIO S ■ ■ SIM Interface in GSM Cellular Telephones Smart Card Readers , LTC and LT are registered trademarks of Linear Technology Corporation. *U.S. Patent No.: 5,973,944 U TYPICAL APPLICATIO GSM Cellular Telephone SIM Interface GSM CONTROLLER 1.425V TO 4.4V 1 2 3 4 VCC 5 6 7 8 VIN 2.6V TO 6V LTC1555L CIN RIN CLK RST SIM 16 CLK 15 RST 14 DATA I/O DDRV VCC DVCC VIN N/C C1 + 11 M1 C1 – 10 M0 GND I/O 13 VCC IVCC = 10mA 12 9 2.2µF 0.1µF 1µF GND OUTPUT VOLTAGE MODES VCC = 3V VCC = 5V VCC* = VIN *ACTUAL VCC WILL DEPEND ON OUTPUT CURRENT IN THIS MODE 1555L TA01 1 LTC1555L U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Note 1) VIN, DVCC to GND ..................................... –0.3V to 6.5V VCC to GND ...............................................– 0.3V to 6.5V Digital Inputs to GND ................................– 0.3V to 6.5V CLK, RST, I/O to GND ..................... – 0.3V to VCC + 0.3V VCC 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 ORDER PART NUMBER TOP VIEW CIN 1 16 CLK RIN 2 15 RST DATA 3 14 I/0 DDRV 4 13 VCC DVCC 5 12 VIN N/C 6 11 C1+ M1 7 10 C1– M0 8 9 LTC1555LEGN GN PART MARKING GND 1555L GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 150°C/W Consult factory for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (VIN = 2.6V to 6V, DVCC = 1.425V to 4.4V, controller digital pins tied to DVCC, SIM digital pins floating, C1 = 0.1µF, COUT = 2.2µF unless otherwise noted) PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Operating Voltage ● 2.6 6 V DVCC Operating Voltage ● 1.425 4.4 V DVCC Undervoltage Lockout 1.2 VIN Operating Current VCC = 5V, IVCC = 0V ● VIN Shutdown Current M0, M1 = 0V ● DVCC Operating Current M0, M1, DATA = DVCC, CIN = 1MHz ● DVCC Shutdown Current M0, M1 = 0V, DATA, CIN = DVCC ● VCC Output Voltage 0 < IVCC < 10mA M0, M1 = DVCC, 2.6V < VIN < 6V M0, M1 = DVCC, 2.7V < VIN < 6V M0 = DVCC, M1 = 0 M0 = 0, M1 = DVCC ● 4.55 ● 4.75 ● 2.8 ● VIN – 0.2 VCC Shorted to GND ● VCC Short-Circuit Current Charge Pump fOSC 2 35 V 65 µA 1 µA 30 µA 1 µA 5 5 3 5.25 5.25 3.2 VIN V V V V 50 150 5 1 mA MHz LTC1555L ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (VIN = 2.6V to 6V, DVCC = 1.425V to 4.4V, controller digital pins tied to DVCC, SIM digital pins floating, C1 = 0.1µF, COUT = 2.2µF unless otherwise noted) PARAMETER CONDITIONS MIN TYP MAX UNITS 100 nA Controller Inputs/Outputs (DVCC = 3V) Input Current (IIH /IIL) M0, M1, M2, RIN, CIN ● –100 Input Current (IIH /IIL) DDRV ● –5 5 µA High Level Input Current (IIH) DATA ● –20 20 µA Low Level Input Current (IIL) DATA ● 1 mA High Input Voltage Threshold (VIH) M0, M1, M2, RIN, CIN, DDRV DATA ● ● 0.7 × DVCC DVCC – 0.6 Low Input Voltage Threshold (VIL) M0, M1, M2, RIN, CIN, DDRV DATA ● ● 0.2 × DVCC 0.4 V V High Level Output Voltage (VOH) DATA Source Current = 20µA I/O = VCC ● 0.7 × DVCC V Low Level Output Voltage (VOL) DATA Sink Current = –200µA I/O = 0V (Note 3) ● DATA Pull-Up Resistance Between DATA and DVCC ● DATA Output Rise/Fall Time DATA Loaded with 30pF ● I/O High Input Voltage Threshold (VIH) IIH(MAX) = ±20µA ● I/O Low Input Voltage Threshold (VIL) IIL(MAX) = 1mA ● 0.4 V High Level Output Voltage (VOH) I/O, Source Current = 20µA DATA or DDRV = DVCC ● 0.8 × VCC V Low Level Output Voltage (VOL) I/O, Sink Current = –1mA DATA or DDRV = 0V (Note 3) ● High Level Output Voltage (VOH) RST, CLK Source Current = 20µA ● Low Level Output Voltage (VOL) RST, CLK Sink Current = –200µA ● I/O Pull-Up Resistance Between I/O and VCC ● CLK Rise/Fall Time CLK Loaded with 30pF, VCC = 3V, or 5V RST, I/O Rise/Fall Time CLK Frequency VCC Turn-On Time COUT = 2.2µF, IVCC = 0 0.5 ms VCC Discharge Time to 1V IVCC = 0, VCC = 5V, COUT = 2.2µF 0.5 ms 13 V V 0.4 V 20 30 kΩ 1.3 2 µs 0.7 × VCC V SIM Inputs/Outputs (VCC = 3V or 5V) 0.4 V 0.9 × VCC V 0.4 V 14 kΩ ● 18 ns RST, I/O Loaded with 30pF ● 1 µs CLK Loaded with 30pF ● 5 MHz 6.5 10 SIM Timing Parameters (DVCC = 3V, VCC = 5V) Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1555LEGN 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. Note 3: The DATA and I/O pull-down drivers must also sink current sourced by the internal pull-up resistor. 3 LTC1555L U W TYPICAL PERFOR A CE CHARACTERISTICS IVIN vs Temperature IVIN vs VIN 50 50 IVCC = 0mA TA = 25°C IDVCC vs VDVCC 20 VIN = 3.6V IVCC = 0mA FCLK = 1MHz VCC = 5V 40 15 30 IVIN (µA) IVIN (µA) VCC = 5V VCC = 3V TA = 85°C VCC = 3V IDVCC (µA) 40 30 10 TA = –40°C TA = 25°C 20 20 10 2 4 3 5 5 10 –40 6 40 0 80 1555L • G02 VCC vs VIN 4 5 1555L • G03 VCC vs VIN 3.6 VCC = 5V IVCC = 10mA VCC = 3V IVCC = 10mA 3.3 5.5 TA = 85°C VCC (V) VCC (V) 3 2 VDVCC (V) 1555L • G01 5.0 TA = 25°C TA = –40°C TA = 85°C 3.0 TA = 25°C TA = –40°C 2.7 4.5 4.0 1 TEMPERATURE (°C) VIN (V) 6.0 0 120 2 3 4 2.4 5 6 2 3 4 5 6 VIN (V) VIN (V) 1555L • G04 1555L • G05 U U U PIN FUNCTIONS CIN (Pin 1): Clock Input Pin from Controller. RIN (Pin 2): Reset Input Pin from Controller. DATA (Pin 3): Controller Side Data Input/Output Pin. Can be used for single pin bidirectional data transfer between the controller and the SIM card as long as the controller data pin is open drain. The controller output must be able to sink 1mA max when driving the DATA pin low due to the internal pull-up resistors on the DATA and I/O pins. If the controller data output is not open drain, then the DDRV pin should be used for sending data to the SIM card and the DATA pin used for receiving data from the SIM card. 4 DDRV (Pin 4): Optional Data Input Pin for Sending Data to the SIM Card. When not needed, the DDRV pin should either be left floating or tied to DVCC (an internal 1µA current source will pull the DDRV pin up to DVCC if left floating). DVCC (Pin 5): Supply Voltage for Controller Side Digital Input/Output Pins (typically 3V). May be between 1.425V and 4.4V. The DVCC supply may be powered-down in shutdown for further reduction in battery current. When DVCC drops below 1.2V, the charge pump is disabled and the LTC1555L goes into shutdown mode regardless of the signals on the M0-M1 pins. LTC1555L U U U PIN FUNCTIONS N/C (Pin 6): No Internal Connection. VIN (Pin 12): Charge Pump Input Pin. May be between 2.6V and 6V. There is no power-up sequencing requirement for VIN with respect to DVCC. M1 (Pin 7): Mode Control Bit 1 (see Table 1). M0 (Pin 8): Mode Control Bit 0 (see Table 1). GND (Pin 9): Ground for Both the SIM and the Controller. Should be connected to the SIM GND contact as well as to the VIN/controller GND. Proper grounding and supply bypassing is required to meet 15kV ESD specifications. C1– (Pin 10): Charge Pump Flying Capacitor Negative␣ Input. C1+ (Pin 11): Charge Pump Flying Capacitor Positive␣ Input. Table 1. Truth Table M0 M1 OPERATING MODE 0V 0V Shutdown (VCC = 0V) 0V DVCC VCC* = VIN DVCC 0V VCC = 3V DVCC DVCC VCC = 5V VCC (Pin 13): SIM Card VCC Output. Should be connected to the SIM VCC contact. The VCC output voltage is determined by the M0-M1 pins (see Table 1). VCC is discharged to GND during shutdown (M0, M1 = 0V). A 2.2µF low ESR ouptut capacitor should connect close to the VCC pin. I/O (Pin 14): SIM Side I/O Pin. The pin is an open drain output with a nominal pull-up resistance of 10kΩ and should be connected to the SIM I/O contact. The SIM card must sink up to 1mA max when driving the I/O pin low due to the internal pull-up resistors on the I/O and DATA pins. The I/O pin is held active low during shutdown. RST (Pin 15): Level Shifted Reset Output Pin. Should be connected to the SIM RST contact. CLK (Pin 16): Level Shifted Clock Output Pin. Should be connected to the SIM CLK contact. Careful trace routing is recommended due to fast rise and fall edge speeds. *Actual VCC will depend on the output current in this mode. W BLOCK DIAGRA VBATT 0.1µF CIN 1µF C1+ C1– LTC1555L VIN VCC M0 M1 VCC COUT 2.2µF STEP-UP/ STEP-DOWN CHARGE PUMP DC/DC CONVERTER 1.8V UVLO DVCC VCC CONTROLLER RIN RST CIN CLK RST SIM 20k DATA CLK 10k I/O I/O 1µA OPTIONAL DDRV GND GND 1555L BD 5 LTC1555L U W U U APPLICATIO S I FOR ATIO The LTC1555L performs the two primary functions necessary for low voltage controllers (e.g., GSM cellular telephone controllers, smart card readers, etc.) to communicate with 5V SIMs or smart cards. The part produces a regulated 3V or 5V VCC supply for the SIM, and also provides level translators for communication between the SIM and the controller. If the input source impedance is very low (< 0.5Ω), CIN may not be needed. Increasing the size of COUT to 2.2µF or greater will reduce output voltage ripple—particularly with high VIN voltages (4V or greater). A ceramic X5R or X7R type capacitor is recommended for the flying capacitor C1 with a value of 0.1µF or 0.22µF. Output Ripple VCC Voltage Regulator The regulator section of the LTC1555L (refer to Block Diagram) consists of a buck/boost charge pump DC/DC converter. The charge pump can operate over a wide input voltage range (2.6V to 6V) while maintaining a regulated VCC output. The wide VIN range enables the part to be powered directly from a battery (if desired) rather than from a DC/DC converter output. When VIN is less than the selected VCC voltage, the part operates as a switched capacitor voltage doubler. When VIN is greater than VCC, the part operates as gated switch step-down converter. In either case, voltage conversion requires only one small flying capacitor and output capacitor. The VCC output can be programmed via the M0-M1 pins to either 3V, 5V or direct connection to VIN. This flexibility is useful in applications where multiple voltage SIMs may be used. When the charge pump is put into shutdown (M0, M1 = 0), VCC is pulled to GND via an internal switch to aid in proper system supply sequencing. An internal soft-start feature helps to limit inrush currents upon start-up or when coming out of shutdown mode. Inrush current limiting is especially useful when powering the LTC1555L from a DC/DC output since the unlimited inrush current may approach 300mA and cause voltage transients on the 3V supply. The part is fully short-circuit and over temperature protected, and can survive an indefinite short from VCC to GND. Capacitor Selection For best performance, it is recommended that low ESR (< 0.5Ω) 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 1µF or greater (ceramic capacitors will produce the smallest output ripple). 6 Normal LTC1555L operation produces voltage ripple on the VCC pin. Output voltage ripple is required for the parts 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 (VIN < 4V) under maximum load is 75mV peak-to-peak with a low ESR, 2.2µF output capacitor. (VCC = 5V) The magnitude of the ripple voltage depends on several factors. High input voltages increase the output ripple since more charge is delivered to COUT per charging cycle. A large C1 flying capacitor (> 0.22µF) also increases ripple in step-up mode for the same reason. Large output current load and/or a small output capacitor (< 1µF) results in 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. A 2.2µF ceramic capacitor on the VCC pin should produce acceptable levels of output voltage ripple in nearly all applications. Also, in order to keep noise down to a minimum all capacitors should be placed close to LTC1555L. Level Translators All SIMs and smart cards contain a clock input, a reset input, and a bidirectional data input/output. The LTC1555L provides level translators to allow controllers to communicate with the SIM. (See Figure 1a and 1b). The CLK and RST inputs to the SIM are level shifted from the controller supply rails (DVCC and GND) to the SIM supply rails (VCC and GND). The data input to the SIM may be provided two different ways. The first method is to use the DATA pin as a bidirectional level translator. This configuration is only allowed if the controller data output pin is LTC1555L U U W U APPLICATIO S I FOR ATIO open drain (all SIM I/O pins are open drain). Internal pull-up resistors are provided for both the DATA pin and the I/O pin on the SIM side. The second method is to use the DDRV pin to send data to the SIM and use the DATA pin to receive data from the SIM. When the DDRV pin is not used, it should either be left floating or tied to DVCC. Shutting Down the DVCC Supply To conserve power, the DVCC supply may be shut down while the VIN supply is still active. When the DVCC supply is forced below 1.2V, an undervoltage lockout circuit forces the LTC1555L into shutdown mode regardless of the status of the M0-M1 pins. 10kV ESD Protection All pins that connect to the SIM (CLK, RST, I/O, VCC, GND) withstand over 10kV of human body model ESD. In order to ensure proper ESD protection, careful board layout is required. The GND pin should be tied directly to a GND plane. The VCC capacitor should be located very close to the VCC pin and tied immediately to the GND plane. LTC1555L LTC1555L CLK TO SIM CIN CLK CLK TO SIM CIN CLK RST TO SIM RIN RST RST TO SIM RIN RST DATA I/O DATA FROM SIM DATA I/O DDRV VCC DATA TO SIM DDRV VCC DATA TO/FROM SIM CONTROLLER SIDE DVCC SIM SIDE CONTROLLER SIDE DVCC 1555L F01a Figure 1a. Level Translator Connections for Bidirectional Controller DATA Pin SIM SIDE 1555L F01b Figure 1b. Level Translator Connections for One-Directional Controller Side DATA Flow 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 LTC1555L U TYPICAL APPLICATIO GSM Cellular Telephone SIM Interface GSM CONTROLLER 1.425V TO 4.4V 1 2 3 4 5 VCC 6 7 8 VIN 2.6V TO 6V LTC1555L CIN CLK RIN RST SIM 16 CLK 15 RST 14 DATA I/O DDRV VCC DVCC VIN N/C C1 + 11 M1 C1 – 10 M0 GND I/O VCC = 3V, 5V or VIN IVCC = 10mA 13 12 2.2µF 0.1µF 1µF GND 9 1555L TA01a U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. GN Package 16-Lead Plastic SSOP (Narrow 0.150) (LTC DWG # 05-08-1641) 0.189 – 0.196* (4.801 – 4.978) 16 15 14 13 12 11 10 9 0.229 – 0.244 (5.817 – 6.198) 0.150 – 0.157** (3.810 – 3.988) 1 0.015 ± 0.004 × 45° (0.38 ± 0.10) 0.007 – 0.0098 (0.178 – 0.249) 0.009 (0.229) REF 2 3 4 5 6 7 0.053 – 0.068 (1.351 – 1.727) 8 0.004 – 0.0098 (0.102 – 0.249) 0° – 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.008 – 0.012 (0.203 – 0.305) 0.0250 (0.635) BSC * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE GN16 (SSOP) 1098 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1555L-1.8 SIM Power Supply and Level Translator VIN = 2.6V to 6V; Interface with 1.8V, 3V and 5V SIMs LTC1555/LTC1556 SIM Power Supply and Level Translator VIN = 2.7V to 10V; Step-Up/Step-Down Charge Pump; 3V and 5V VOUT LTC1755 Smart Card Interface VIN = 2.7V to 6V; 24-Pin SSOP Package; IQ = 60µA LTC1756 Smart Card Interface VIN = 2.7V to 6V; 16-Pin SSOP Package; IQ = 75µA LTC1986 3V/5V SIM Power Supply in SOT-23 VIN = 2.6V to 4.4V; IQ = 14µA 8 Linear Technology Corporation 1555lf LT/TP 0601 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 2000