ltc1981/ltc1982 1 applicatio s u descriptio u features the ltc ? 1981/ltc1982 are low-power, self-contained n-channel mosfet drivers. an internal voltage tripler allows gates to be driven without the use of any external components. internal regulation circuitry allows quies- cent current to drop to 10 m a per driver (20 m a for ltc1981) once the gates are charged. low quiescent current and low shutdown current (under 1 m a) make these parts ideal for battery and other power constrained systems. the wide input voltage range ac- commodates a variety of battery/input configurations. gate drive is internally clamped to 7.5v providing protec- tion to the external mosfet gate. the mosfets can be driven in either high side or low side mode. the ltc1981 single driver version also includes a gate drive ready pin and twice the drive current capacity of the dual driver ltc1982. the ltc1981 is available in a 5-pin sot-23. the ltc1982 is available in a 6-pin sot-23. n cellular telephones n portable pos terminal n handheld battery powered equipment , ltc and lt are registered trademarks of linear technology corporation. n no external components required n internal voltage triplers produce high side gate drive for logic level fets n ultralow power: 10 m a per driver on current (ltc1982) 20 m a on current (ltc1981) <1 m a shutdown current n v cc range: 1.8v to 5v n gate drive outputs driven to ground during shutdown n gate drive outputs internally clamped to 7.5v max n gate drive ready output (ltc1981) n ultrasmall application circuit n 5-pin sot-23 package (ltc1981) n 6-pin sot-23 package (ltc1982) single and dual micropower high side switch controllers in sot-23 v cc gate shdn gnd gdr ltc1981 load + 10 m f gate drive ready shdn v cc 1.8v to 5.0v 54 123 1981/82 ta01 100k q1 si3442dv v cc gate 1 gate 2 shdn 1 shdn 2 gnd ltc1982 load 1 load 2 + 10 m f shdn 1 shdn 2 v cc 1.8v to 5.0v 654 123 1981/82 ta02 q1 1/2 si6925dq q2 1/2 si6925dq typical applicatio n s u single high side switch controller dual high side switch controller
ltc1981/ltc1982 2 terminal voltage ltc1981: v cc , gate, shdn, gdr ........ C0.3v to 7.5v ltc1982: v cc , gate 1, gate 2, shdn 1, shdn 2 ................... C0.3v to 7.5v absolute axi u rati gs w ww u (notes 1, 2) electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v cc = 5v unless otherwise specified. c gate 1 = c gate 2 = c gate = 1000pf. symbol parameter conditions min typ max units v cc operating supply voltage l 1.8 5.5 v i cc supply current gate 1 and gate 2 outputs high l 17 30 m a gate 1 or gate 2 outputs high l 10 20 m a gate output high (ltc1981) l 17 30 m a i shdn shdn supply current shdn 1 and shdn 2 inputs low l 1 m a shdn input low (ltc1981) l 1 m a v gate gate drive output voltage v cc = 1.8v l 4.27 4.50 4.75 v v cc = 2.7v l 6.40 6.75 7.10 v v cc = 3.3v l 6.90 7.25 7.50 v v cc = 5v l 6.90 7.25 7.50 v f osc charge pump oscillator frequency measured with 10k resistor from output to gnd 600 khz t on turn-on time into 1000pf from shdn 1, shdn 2 going high to gate 1, gate 2 = v cc + 1v 110 m s from shdn going high to gate = v cc +1v (ltc1981) 85 m s t off turn-off time into 1000pf from shdn 1, shdn 2 going low to gate 1, gate 2 , gate = 100mv 12 m s v il shdn input low voltage v cc = 1.8v to 5.5v l 0.4 v v ih shdn input high voltage v cc = 1.8v to 5.5v l 1.6 v c in shdn input capacitance (note 4) 5 pf i in shdn input leakage current 1 m a order part number s6 part marking t jmax = 150 c, q ja = 230 c/w consult factory for parts specified with wider operating temperature ranges. ltpf ltc1982es6 package/order i for atio uu w operating temperature range ltc1981e/ltc1982e (note 3) ............ 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 s5 part marking t jmax = 150 c, q ja = 250 c/w ltsf ltc1981es5 4 gate 5 v cc shdn 3 gdr 1 top view s5 package 5-lead plastic sot-23 gnd 2 shdn 1 1 gnd 2 shdn 2 3 6 v cc 5 gate 1 4 gate 2 top view s6 package 6-lead plastic sot-23
ltc1981/ltc1982 3 supply voltage, v cc (v) 1.5 gate drive voltage (v) 5.5 1982 g01 2.5 3.5 4.5 5.0 2.0 3.0 4.0 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 t a = 25 c gate drive voltage (v gs common source) gate drive ? cc (v gs source follower) supply voltage (v) 1.0 0 supply current ( a) 5 15 20 25 2.0 3.0 3.5 5.5 1982 g02 10 1.5 2.5 4.0 4.5 5.0 t a = 25 c ltc1981 or both channels on ltc1982 either channel on ltc1982 gate drive voltage (v) 0 gate drive current ( m a) 100 10 1 0.1 34 67 12 5 8 1982 g03 v cc = 3.3v v cc = 2.7v v cc = 1.8v t a = 25 c v cc = 5v shdn logic input voltage (v) 01 supply current ( a) 60 50 40 30 20 10 0 1981/82 g04 2 t a = 25 c v cc = 3v shdn1 tied to shdn2 shdn logic input voltage (v) 01 supply current ( a) 300 250 200 150 100 50 0 1981/82 g05 2 t a = 25 c v cc = 5v shdn1 tied to shdn2 symbol parameter conditions min typ max units v ol gdr output voltage low i sink = 100 m a, v cc = 1.8v l 0.05 0.4 v gate drive ready trip point gate voltage rising v cc = 1.8v l 3.85 4.05 4.25 v v cc = 2.7v l 5.78 6.08 6.38 v v cc = 3.3v l 6.17 6.5 6.82 v v cc = 5v l 6.17 6.5 6.82 v gdr hysteresis gate voltage falling 2 % gdr delay after gate is above the gdr trip threshold 2 m s 10k pull-up to v cc note 1 : absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: all voltage values are with respect to gnd. note 3: the ltc1982e is guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C40 c to 85 c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 4: guaranteed by design not subject to test. electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v cc = 5v unless otherwise specified. c gate 1 = c gate 2 = c gate = 1000pf. (ltc1981 only) typical perfor a ce characteristics uw supply current vs supply voltage gate drive voltage vs supply voltage gate drive current (ltc1982) i supply i supply
ltc1981/ltc1982 4 typical perfor a ce characteristics uw supply voltage (v) 2.0 turn-on time ( s) 1982 g06 1.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 400 350 300 250 200 150 100 50 0 c gate = 1000pf t a = 25 c v gs = 2v v gs = 1v supply voltage (v) 2.0 turn-off time ( s) 1982 g07 1.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 40 35 30 25 20 15 10 5 0 c gate = 1000pf t a = 25 c time for v gate < 0.1v temperature ( c) ?0 gate drive voltage (v) 7.50 7.45 7.40 7.35 7.30 7.25 7.20 7.15 7.10 7.05 7.00 ?0 20 40 1982 g08 ?0 0 60 80 100 v cc = 3.3v turn-off time (ltc1982) turn-on time (ltc1982) gate drive voltage vs temperature turn-on time (ltc1981) gate drive current (ltc1981) turn-off time (ltc1981) gate drive voltage (v) 01 100 10 1 0.1 2345678 gate drive current ( a) 1981/82 g09 v cc = 2.7v v cc = 1.8v v cc = 5v v cc = 3.3v supply voltage (v) 1.5 turn-on time ( s) 2.5 3.5 4.0 6.0 1981/82 g10 2.0 3.0 4.5 5.0 5.5 300 250 200 150 100 50 0 c gate = 1000pf t a = 25 c v gs = 2v v gs = 1v supply voltage (v) 1.5 0 turn-off time ( s) 5 15 20 25 2.5 3.5 4.0 6.0 1981/82 g11 10 2.0 3.0 4.5 5.0 5.5 c gate =1000pf t a = 25 c time for v gate < 0.1 pi n fu n ctio n s uuu ltc1981: gdr (pin 1): gate drive ready active high open drain output. used to indicate when the gate drive output is greater than 90% of its final value. gnd (pin 2): ground. shdn (pin 3): shdn active low input. used to shut down the part and force the gate output pin to ground. gate (pin 4): gate drive output to an external high side switch. fully enhanced by internal charge pump. con- trolled by the shdn input pin. output voltage on this pin will be approximately 2.5 times v cc or 7.25v, whichever is less. v cc (pin 5): input supply voltage. range from 1.8v to 5.5v. ltc1982: shdn 1 (pin 1): shdn 1 active low input. used to shut down the gate 1 charge pump and force the gate 1 output pin to ground. gnd (pin 2): ground. shdn 2 (pin 3): shdn 2 active low input. used to shut down the gate 2 charge pump and force the gate 2 output pin to ground.
ltc1981/ltc1982 5 operatio u charge pump to fully enhance the external n-channel switches, internal charge pumps are used to boost the output gate drive to approximately 2.5 times the supply voltage, or 7.25v, whichever is less. a feedback network is used to regulate the output gate drive. this keeps the supply current low in addition to providing a maximum output voltage limit. the reason for the maximum output voltage limit is to avoid switch gate source breakdown due to excessive gate overdrive. the gate drive outputs (gate 1, gate 2, or gate) are controlled by the shutdown input pins (shdn 1, shdn 2 or shdn). a logic high input on one of the shutdown input pins enables the corresponding charge pump and drives the related gate drive output pin high. a logic low input on one of the shutdown input pins disables the correspond- ing charge pump and drives the related gate drive output pin low. if shutdown input on the ltc1981 is low or both of the shutdown input pins on the ltc1982 are low, the part will be placed into a low current shutdown mode (<1 m a). gate drive ready (ltc1981 only) the gate drive ready pin (gdr) is used to indicate when the gate drive output (gate) is greater than 90% of its final value. this can be useful in applications that require knowledge of the state of the gate drive for initialization purposes or as fault detection should something be load- ing the gate drive down. block diagra s m w ltc1981 single high side switch driver ltc1982 dual high side switch driver regulating charge pump en + + gate gdr v cc ref shdn 1981/82 bd01 15k regulating charge pump 1 en gate 1 shdn 1 regulating charge pump 2 en gate 2 shdn 2 1981/82 bd02 30k 30k gate 2(pin 4): gate drive output to an external high side switch. fully enhanced by internal charge pump. con- trolled by the shdn 2 input pin. output voltage on this pin will be approximately 2.5 times v cc or 7.25v, whichever is less. gate 1 (pin 5): gate drive output to an external high side switch. fully enhanced by internal charge pump. con- trolled by the shdn 1 input pin. output voltage on this pin will be approximately 2.5 times v cc or 7.25v, whichever is less. v cc (pin 6): input supply voltage. range from 1.8v to 5.5v. pi n fu n ctio n s uuu
ltc1981/ltc1982 6 applicatio n s i n for m atio n wu u u figure 3. direct interface to 3.3v logic v cc gate 1 shdn 1 gnd 1/2 ltc1982 5v load 1981/82 f03 3.3v 5v si3442dv figure 1. powering a large capactive load figure 2. direct interface to 5v logic logic-level mosfet switches the ltc1981/ltc1982 are designed to operate with logic- level n-channel mosfet switches. although there is some variation among manufacturers, logic-level mosfet switches are typically rated with v gs = 4v with a maximum continuous v gs rating of 8v. rds (on) and maximum v ds ratings are similar to standard mosfets and there is generally little price differential. when operating at supply voltages of 5v or greater, care must be taken when selecting the mosfet. the ltc1981/ltc1982 limit the output voltage to between 6.9v and 7.5v. the v gs devel- oped for the mosfet may be too low to sufficiently turn on the mosfet. mosfets rated at 2.5v, or less, will be better suited for applications where the supply voltages ap- proach 5v. powering large capacitive loads electrical subsystems in portable battery-powered equip- ment are typically bypassed with large filter capacitors to reduce supply transients and supply induced glitching. if not properly powered however, these capacitors may themselves become the source of supply glitching. for example, if a 100 m f capacitor is powered through a switch with a slew rate of 0.1v/ms, the current during start-up is: i start = c( d v/ d t) = (100 ? 10 C6 )(1 ? 10 5 ) = 10a obviously, this is too much current for the regulator (or output capacitor) to supply and the output will glitch by as much as a few volts. the start up current can be substantially reduced by limiting the slew rate at the gate of an n-channel as shown in figure 1. the gate drive output of the ltc1981/ltc1982 have an internal 30k resistor (15k ltc1981) in series with each of the output gate drive pins (see functional block diagram). therefore, it only needs an external 0.1 m f capacitor (0.22 m f for the ltc1981) to create enough rc delay to substantially slow the slew rate of the mosfet gate to approximately 0.6v/ms. since the mosfet is operating as a source follower, the slew rate at the source is essentially the same as that at the gate, reducing the startup current to approximately 60ma which is easily managed by the system regulator. r1 is required to eliminate the possibility of parasitic mosfet oscillations during switch transitions. it is a good practice to isolate the gates of paralleled mosfets with 1k resistors to decrease the possibility of interaction between switches. mixed 5v/3v systems because the input esd protection diodes are referenced to the gnd pin instead of the supply pin, it is possible to drive the ltc1981/ltc1982 inputs from 5v cmos or ttl logic even though the ltc1981/ltc1982 is powered from a 3.3v supply as shown in figure 2. likewise, because the input threshold voltage high is never greater than 1.6v, the reverse situation is true. the ltc1981/ltc1982 can be driven with 3v cmos or ttl even when the supply to the device is as high as 5v as shown in figure 3. v cc gate 1 shdn 1 gnd 1/2 ltc1982 + lt1129-3.3 + v in on/off 3.3 m f r1 1k c1 0.1 m f c l 100 m f 3.3v load 1981/82 f01 3.3v si3442dv v cc gate 1 shdn 1 gnd 1/2 ltc1982 3.3v load 1981/82 f02 3.3v si3442dv 5v
ltc1981/ltc1982 7 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. package descriptio u dimensions in inches (millimeters) unless otherwise noted. s5 package 5-lead plastic sot-23 (ltc dwg # 05-08-1633) applicatio n s i n for m atio n wu u u s6 package 6-lead plastic sot-23 (ltc dwg # 05-08-1634) 0.95 (0.037) ref 1.50 ?1.75 (0.059 ?0.069) 0.35 ?0.55 (0.014 ?0.022) 0.35 ?0.50 (0.014 ?0.020) five places (note 2) s5 sot-23 0599 2.80 ?3.00 (0.110 ?0.118) (note 3) 1.90 (0.074) ref 0.90 ?1.45 (0.035 ?0.057) 0.90 ?1.30 (0.035 ?0.051) 0.00 ?0.15 (0.00 ?0.006) 0.09 ?0.20 (0.004 ?0.008) (note 2) 2.60 ?3.00 (0.102 ?0.118) 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) 0.95 (0.037) ref 1.50 ?1.75 (0.059 ?0.069) 0.35 ?0.55 (0.014 ?0.022) 0.35 ?0.50 (0.014 ?0.020) six places (note 2) s6 sot-23 0898 2.80 ?3.00 (0.110 ?0.118) (note 3) 1.90 (0.074) ref 0.90 ?1.45 (0.035 ?0.057) 0.90 ?1.30 (0.035 ?0.051) 0.00 ?0.15 (0.00 ?0.006) 0.09 ?0.20 (0.004 ?0.008) (note 2) 2.6 ?3.0 (0.110 ?0.118) 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) figure 4. reverse battery protection v cc gate shdn gnd gdr ltc1981 load 1981/82 f04 3v v bat (1.8v to 5v) si3442dv 10k 10k 0.1 f 1 2 3 5 4 150 gate drive ready reverse battery protection the ltc1981/ltc1982 can be protected against reverse battery conditions by connecting a 150 w resistor in series with the supply pin as shown in figure 4. the resistor limits the supply current to less than 24ma with C3.6v applied. because the ltc1981/ltc1982 draw very little current while in normal operation, the drop across the resistor is minimal. control logic can be protected by adding 10k resistors in series with the input pins.
ltc1981/ltc1982 8 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com ? linear technology corporation 2000 19812f lt/lcg 1200 4k ? printed in usa related parts part number description comments ltc1153/ltc1154 single high side micropower mosfet drivers circuit breaker with auto reset ltc1155/ltc1255 dual high side micropower mosfet drivers latchoff current limit ltc1163/ltc1165 triple 1.8v to 6v high side mosfet driver three mosfet drivers in 8-lead so package ltc1623 smbus dual high side switch controller uses external switches, two three-state address pins ltc1710 smbus dual monolithic high side switch uses internal switches, one three-state address pin driving both high side and low side switches u typical applicatio shdn 1 gnd shdn 2 ltc1982 gate 1 gate 2 v cc shdn 1 shdn 2 high side load low side load 10 m f 0.1 m f 0.1 m f 1k 1k q1 si6954dq q2 si6954dq v cc 1.8 to 5.0v v ext (30v max) 1981/82 ?ta03 1 2 3 6 5 4
|
