ltc1555l 1 applicatio s u features descriptio u typical applicatio u the ltc ? 1555l provides power conversion and level shifting needed for low voltage gsm cellular telephones tointerface 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 v cc supply voltage to the sim card. input voltage may rangefrom 2.6v to 6v allowing direct connection to the battery. the output voltage may be programmed to 3v, 5v or direct connection to the v in pin. internal level translators allow controllers operating withsupplies 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 40 m a operating current, and 1 m a shutdown current. board area is minimized by the miniature 16-pin narrow ssop packages and the need foronly three small external capacitors. sim interface in gsm cellular telephones smart card readers , ltc and lt are registered trademarks of linear technology corporation. sim power supply and level translator buck/boost charge pump generates 3v or 5v input voltage range: 2.6v to 6v controller v cc 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: 40 m a very low shutdown current: <1 m a soft-start limits inrush current at turn-on 1mhz switching frequency available in 16-pin narrow ssop package gsm cellular telephone sim interface 12 3 4 5 6 7 8 1615 14 13 12 11 10 9 cinrin data ddrv dv cc n/cm1 m0 clkrst i/o v cc i vcc = 10ma gnd clk rst i/o v cc v in c1 + c1 C gnd 0.1 m f 1 m f ltc1555l gsm controller sim v in 2.6v to 6v 1.425v to 4.4v 2.2 m f 1555l ta01 v cc v cc = 3v v cc = 5v v cc * = v in output voltage modes actual v cc will depend on outputcurrent in this mode * *u.s. patent no.: 5,973,944 downloaded from: http:///
ltc1555l 2 v in , dv cc to gnd ..................................... C0.3v to 6.5v v cc to gnd ............................................... C 0.3v to 6.5v digital inputs to gnd ................................C 0.3v to 6.5v clk, rst, i/o to gnd ..................... C 0.3v to v cc + 0.3v v cc short-circuit duration ............................... indefinite operating temperature range (note 2) .. C 40 c to 85 c storage temperature range ................. C 65 c to 150 c lead temperature (soldering,10 sec)................... 300 c order part number t jmax = 125 c, q ja = 150 c/w consult factory for parts specified with wider operating temperature ranges. ltc1555legn absolute axi u rati gs w ww u package/order i for atio uu w (note 1) electrical characteristics the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. (v in = 2.6v to 6v, dv cc = 1.425v to 4.4v, controller digital pins tied to dv cc , sim digital pins floating, c1 = 0.1 m f, c out = 2.2 m f unless otherwise noted) parameter conditions min typ max units v in operating voltage 2.6 6 v dv cc operating voltage 1.425 4.4 v dv cc undervoltage lockout 1.2 v v in operating current v cc = 5v, i vcc = 0v 35 65 m a v in shutdown current m0, m1 = 0v 1 m a dv cc operating current m0, m1, data = dv cc , c in = 1mhz 53 0 m a dv cc shutdown current m0, m1 = 0v, data, c in = dv cc 1 m a v cc output voltage 0 < i vcc < 10ma m0, m1 = dv cc , 2.6v < v in < 6v 4.55 5 5.25 v m0, m1 = dv cc , 2.7v < v in < 6v 4.75 5 5.25 v m0 = dv cc , m1 = 0 2.8 3 3.2 v m0 = 0, m1 = dv cc v in C 0.2 v in v v cc short-circuit current v cc shorted to gnd 50 150 ma charge pump f osc 1 mhz top view gn package 16-lead plastic ssop 12 3 4 5 6 7 8 1615 14 13 12 11 10 9 cin rin data ddrv dv cc n/c m1m0 clkrst i/0 v cc v in c1 + c1 C gnd gn part marking 1555l downloaded from: http:///
ltc1555l 3 parameter conditions min typ max units controller inputs/outputs (dv cc = 3v) input current (i ih /i il ) m0, m1, m2, rin, cin C100 100 na input current (i ih /i il ) ddrv C5 5 m a high level input current (i ih ) data C20 20 m a low level input current (i il ) data 1m a high input voltage threshold (v ih ) m0, m1, m2, rin, cin, ddrv 0.7 dv cc v data dv cc C 0.6 v low input voltage threshold (v il ) m0, m1, m2, rin, cin, ddrv 0.2 dv cc v data 0.4 v high level output voltage (v oh ) data source current = 20 m a i/o = v cc 0.7 dv cc v low level output voltage (v ol ) data sink current = C200 m a i/o = 0v (note 3) 0.4 v data pull-up resistance between data and dv cc 13 20 30 k w data output rise/fall time data loaded with 30pf 1.3 2 m s sim inputs/outputs (v cc = 3v or 5v) i/o high input voltage threshold (v ih )i ih(max) = 20 m a 0.7 v cc v i/o low input voltage threshold (v il )i il(max) = 1ma 0.4 v high level output voltage (v oh ) i/o, source current = 20 m a data or ddrv = dv cc 0.8 v cc v low level output voltage (v ol ) i/o, sink current = C1ma data or ddrv = 0v (note 3) 0.4 v high level output voltage (v oh ) rst, clk source current = 20 m a 0.9 v cc v low level output voltage (v ol ) rst, clk sink current = C200 m a 0.4 v i/o pull-up resistance between i/o and v cc 6.5 10 14 k w sim timing parameters (dv cc = 3v, v cc = 5v) clk rise/fall time clk loaded with 30pf, v cc = 3v, or 5v 18 ns rst, i/o rise/fall time rst, i/o loaded with 30pf 1 m s clk frequency clk loaded with 30pf 5 mhz v cc turn-on time c out = 2.2 m f, i vcc = 0 0.5 ms v cc discharge time to 1v i vcc = 0, v cc = 5v, c out = 2.2 m f 0.5 ms 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 C 40 c to 85 c operating temperature range are assured by design, characterization andcorrelation 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. the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. (v in = 2.6v to 6v, dv cc = 1.425v to 4.4v, controller digital pins tied to dv cc , sim digital pins floating, c1 = 0.1 m f, c out = 2.2 m f unless otherwise noted) electrical characteristics downloaded from: http:///
ltc1555l 4 v in (v) 2 v cc (v) 5.0 5.5 6 1555l ? g04 4.54.0 3 4 5 6.0 v cc = 5v i vcc = 10ma t a = C40 c t a = 25 c t a = 85 c v in (v) 2 v cc (v) 3.0 3.3 6 1555l ? g05 2.72.4 3 4 5 3.6 t a = C40 c t a = 85 c v cc = 3v i vcc = 10ma t a = 25 c v dvcc (v) 1 i dvcc ( a) 10 15 5 1555l ? g03 50 2 3 4 20 f clk = 1mhz t a = C40 c t a = 85 c t a = 25 c temperature ( c) C40 i vin ( a) 30 40 120 1555l ? g02 2010 0 40 80 50 v cc = 5v v cc = 3v v in = 3.6v i vcc = 0ma v in (v) 2 i vin ( a) 30 40 6 1555l ? g01 2010 3 4 5 50 v cc = 5v v cc = 3v i vcc = 0ma t a = 25 c pi n fu n ctio n s uuu 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 betweenthe 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. ddrv (pin 4): optional data input pin for sending data to the sim card. when not needed, the ddrv pin shouldeither be left floating or tied to dv cc (an internal 1 m a current source will pull the ddrv pin up to dv cc if left floating).dv cc (pin 5): supply voltage for controller side digital input/output pins (typically 3v). may be between 1.425vand 4.4v. the dv cc supply may be powered-down in shutdown for further reduction in battery current. whendv cc drops below 1.2v, the charge pump is disabled and the ltc1555l goes into shutdown mode regardless of thesignals on the m0-m1 pins. typical perfor a ce characteristics uw i vin vs v in v cc vs v in i vin vs temperature i dvcc vs v dvcc v cc vs v in downloaded from: http:///
ltc1555l 5 m0 m1 operating mode 0v 0v shutdown (v cc = 0v) 0v dv cc v cc * = v in dv cc 0v v cc = 3v dv cc dv cc v cc = 5v table 1. truth table *actual v cc will depend on the output current in this mode. n/c (pin 6): no internal connection. 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 tothe v in /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. pi n fu n ctio n s uuu v in (pin 12): charge pump input pin. may be between 2.6v and 6v. there is no power-up sequencing require-ment for v in with respect to dv cc . v cc (pin 13): sim card v cc output. should be connected to the sim v cc contact. the v cc output voltage is deter- mined by the m0-m1 pins (see table 1). v cc is discharged to gnd during shutdown (m0, m1 = 0v). a 2.2 m f low esr ouptut capacitor should connect close to the v cc pin. i/o (pin 14): sim side i/o pin. the pin is an open drain output with a nominal pull-up resistance of 10k w and should be connected to the sim i/o contact. the sim cardmust 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 isrecommended due to fast rise and fall edge speeds. block diagra w ddrv optional 1 m a i/o data 20k 10k clk cin rst dv cc 1.8v rin gnd m1 m0 v in v batt c in 1 m f v cc i/o clk rstgnd v cc c1 + 0.1 m f c1 C step-up/ step-down charge pump dc/dc converter sim controller v cc c out 2.2 m f uvlo ltc1555l 1555l bd downloaded from: http:///
ltc1555l 6 applicatio s i for atio wu u u the ltc1555l performs the two primary functions nec-essary for low voltage controllers (e.g., gsm cellular telephone controllers, smart card readers, etc.) to com- municate with 5v sims or smart cards. the part produces a regulated 3v or 5v v cc supply for the sim, and also provides level translators for communication between thesim and the controller. v cc voltage regulator the regulator section of the ltc1555l (refer to blockdiagram) 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 v cc output. the wide v in range enables the part to be powered directly from a battery (if desired) rather thanfrom a dc/dc converter output. when v in is less than the selected v cc voltage, the part operates as a switched capacitor voltage doubler. when v in is greater than v cc , the part operates as gated switch step-down converter. ineither case, voltage conversion requires only one small flying capacitor and output capacitor. the v cc output can be programmed via the m0-m1 pins to either 3v, 5v or direct connection to v in . this flexibility is useful in applications where multiple voltage sims may beused. when the charge pump is put into shutdown (m0, m1 = 0), v cc 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 indefi- nite short from v cc to gnd. capacitor selectionfor best performance, it is recommended that low esr (< 0.5 w ) capacitors be used for both c in and c out to reduce noise and ripple. the c in and c out capacitors should be either ceramic or tantalum and should be 1 m f or greater (ceramic capacitors will produce the smallest output ripple). if the input source impedance is very low (< 0.5 w ), c in may not be needed. increasing the size of c out to 2.2 m f or greater will reduce output voltage rippleparticularly with high v in voltages (4v or greater). a ceramic x5r or x7r typecapacitor is recommended for the flying capacitor c1 with a value of 0.1 m f or 0.22 m f. output ripplenormal ltc1555l operation produces voltage ripple on the v cc pin. output voltage ripple is required for the parts to regulate. low frequency ripple exists due to the hyster-esis 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 (v in < 4v) under maximum load is 75mv peak-to-peak with a low esr, 2.2 m f output capacitor. (v cc = 5v) the magnitude of the ripple voltage depends on severalfactors. high input voltages increase the output ripple since more charge is delivered to c out per charging cycle. a large c1 flying capacitor (> 0.22 m f) also increases ripple in step-up mode for the same reason. large output currentload and/or a small output capacitor (< 1 m f) results in higher ripple due to higher output voltage dv/dt. high esrcapacitors (esr > 0.5 w ) on the output pin cause high frequency voltage spikes on v out with every clock cycle. a 2.2 m f ceramic capacitor on the v cc pin should produce acceptable levels of output voltage ripple in nearly allapplications. 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 (dv cc and gnd) to the sim supply rails (v cc and gnd). the data input to the sim may be provided two different ways. the first method is to use thedata pin as a bidirectional level translator. this configu- ration is only allowed if the controller data output pin is downloaded from: http:///
ltc1555l 7 applicatio s i for atio wu u u open drain (all sim i/o pins are open drain). internalpull-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 dv cc . shutting down the dv cc supply to conserve power, the dv cc supply may be shut down while the v in supply is still active. when the dv cc supply is forced below 1.2v, an undervoltage lockout circuit forces the ltc1555l into shutdown mode regardless ofthe status of the m0-m1 pins. 10kv esd protection all pins that connect to the sim (clk, rst, i/o, v cc , gnd) withstand over 10kv of human body model esd. in orderto ensure proper esd protection, careful board layout is required. the gnd pin should be tied directly to a gnd plane. the v cc capacitor should be located very close to the v cc pin and tied immediately to the gnd plane. 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 represen-tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. figure 1a. level translator connections forbidirectional controller data pin figure 1b. level translator connections forone-directional controller side data flow cinrin data ddrv dv cc clk rst i/o v cc clk to sim rst to sim data to/from sim ltc1555l controller side sim side 1555l f01a cinrin data ddrv dv cc clk rst i/o v cc clk to sim rst to sim data from sim data to sim ltc1555l controller side sim side 1555l f01b downloaded from: http:///
ltc1555l 8 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear-tech.com ? linear technology corporation 2000 1555lf lt/tp 0601 2k ? printed in usa related parts typical applicatio u part number description comments ltc1555l-1.8 sim power supply and level translator v in = 2.6v to 6v; interface with 1.8v, 3v and 5v sims ltc1555/ltc1556 sim power supply and level translator v in = 2.7v to 10v; step-up/step-down charge pump; 3v and 5v v out ltc1755 smart card interface v in = 2.7v to 6v; 24-pin ssop package; i q = 60 m a ltc1756 smart card interface v in = 2.7v to 6v; 16-pin ssop package; i q = 75 m a ltc1986 3v/5v sim power supply in sot-23 v in = 2.6v to 4.4v; i q = 14 m a gsm cellular telephone sim interface 12 3 4 5 6 7 8 1615 14 13 12 11 10 9 cinrin data ddrv dv cc n/cm1 m0 clkrst i/o v cc = 3v, 5v or v in i vcc = 10ma gnd clk rst i/o v cc v in c1 + c1 C gnd 0.1 m f 1 m f ltc1555l gsm controller sim v in 2.6v to 6v 1.425v to 4.4v 2.2 m f 1555l ta01a v cc package descriptio u dimensions in inches (millimeters) unless otherwise noted. gn package 16-lead plastic ssop (narrow 0.150) (ltc dwg # 05-08-1641) gn16 (ssop) 1098 * 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 12 3 4 5 6 7 8 0.229 C 0.244 (5.817 C 6.198) 0.150 C 0.157** (3.810 C 3.988) 16 15 14 13 0.189 C 0.196* (4.801 C 4.978) 12 11 10 9 0.016 C 0.050 (0.406 C 1.270) 0.015 0.004 (0.38 0.10) 45 0 C 8 typ 0.007 C 0.0098 (0.178 C 0.249) 0.053 C 0.068 (1.351 C 1.727) 0.008 C 0.012 (0.203 C 0.305) 0.004 C 0.0098 (0.102 C 0.249) 0.0250 (0.635) bsc 0.009 (0.229) ref downloaded from: http:///
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