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1 ltc1255 dual 24v high-side mosfet driver the ltc1255 dual high-side driver allows using low cost n-channel fets for high-side industrial and auto- motive switching applications. an internal charge pump boosts the gate drive voltage above the positive rail, fully enhancing an n-channel mos switch with no external components. low power operation, with 12 m a standby current, allows use in virtually all systems with maximum efficiency. included on-chip is independent overcurrent sensing to provide automatic shutdown in case of short circuits. a time delay can be added to the current sense to prevent false triggering on high in-rush current loads. the ltc1255 operates from 9v to 24v supplies and is well suited for industrial and automotive applications. the ltc1255 is available in both an 8-pin dip and an 8-pin soic. s f ea t u re n fully enhances n-channel power mosfets n 12 m a standby current n operates at supply voltages from 9v to 24v n short circuit protection n easily protected against supply transients n controlled switching on and off times n no external charge pump components n compatible with standard logic families n available in 8-pin soic u s a o pp l ic at i n solenoid drivers n dc motor drivers n stepper motor drivers n lamp drivers/dimmers n relay drivers n low frequency h-bridge n p-channel switch replacement d u escriptio u a o pp l ic at i ty p i ca l 12v 1n4001 + 10 m f irlr024 24v 24v/0.5a solenoid v s ds2 ltc1255 in2 gnd ds1 in1 g1 g2 0.036 w 0.036 w irlr024 12v 1n4001 24v/0.5a solenoid from m p, etc. from m p, etc. ltc1255 ?ta01 standby supply current dual 24v high-side switch with overcurrent protection supply voltage (v) 0 0 supply current ( m a) 10 15 20 25 30 35 5 10 15 20 ltc1255 ?ta02 25 40 45 50 5 30 v in1 = v in2 = 0v t a = 25?
2 ltc1255 supply voltage ......................................... C 0.3v to 30v transient supply voltage (< 10ms) ......................... 40v input voltage ..................... (v s + 0.3v) to (gnd C 0.3v) gate voltage ...................... (v s + 20v) to (gnd C 0.3v) current (any pin) ................................................. 50ma a u g w a w u w a r b s o lu t exi t i s operating temperature range ltc1255c ............................................... 0 c to 70 c ltc1255i ........................................... C 40 c to 85 c storage temperature range ................ C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c wu u package / o rder i for atio order part number order part number t jmax = 100 c, q ja = 130 c/ w t jmax = 100 c, q ja = 150 c/w 1 2 3 4 8 7 6 5 top view ds1 gate 1 gnd in1 ds2 gate 2 v s in2 n8 package 8-lead plastic dip 1 2 3 4 8 7 6 5 top view ds2 gate 2 v s in2 ds1 gate 1 gnd in1 s8 package 8-lead plastic soic symbol parameter conditions min typ max units i q quiescent current off v s = 10v, v in = 0v (note 1) 12 40 m a v s = 18v, v in = 0v (note 1) 12 40 m a v s = 24v, v in = 0v (note 1) 12 40 m a quiescent current on v s = 10v, v gate = 22v, v in = 5v (note 2) 160 400 m a v s = 18v, v gate = 30v, v in = 5v (note 2) 350 800 m a v s = 24v, v gate = 36v, v in = 5v (note 2) 600 1200 m a v inh input high voltage l 2v v inl input low voltage l 0.8 v i in input current 0v v in v s l 1 m a c in input capacitance 5pf v sen drain sense threshold voltage 80 100 120 mv l 75 100 125 mv i sen drain sense input current 0v v sen v s l 0.1 m a v gate C v s gate voltage above supply v s = 9v l 7.5 10.5 12 v i gate gate output drive current v s = 18v, v gate = 30v l 520 m a v s = 24v, v gate = 36v l 523 m a e lectr ic al c c hara terist ics v s = 9v to 24v, t a = 25 c, unless otherwise noted. ltc1255cn8 ltc1255in8 s8 part marking ltc1255cs8 ltc1255is8 1255 1255i
3 ltc1255 symbol parameter conditions min typ max units t on turn-on time v s = 10v, c gate = 1000pf (note 3) time for v gate > v s + 2v 30 100 300 m s time for v gate > v s + 5v 75 250 750 m s v s = 18v, c gate = 1000pf (note 3) time for v gate > v s + 5v 40 120 400 m s time for v gate > v s + 10v 75 250 750 m s v s = 24v, c gate = 1000pf (note 3) time for v gate > v s + 10v 50 180 500 m s t off turn-off time v s = 10v, c gate = 1000pf, (note 3, 4) 10 24 60 m s v s = 18v, c gate = 1000pf, (note 3, 4) 10 21 60 m s v s = 24v, c gate = 1000pf, (note 3, 4) 10 19 60 m s t sc short-circuit turn-off time v s = 10v, c gate = 1000pf, (note 3, 4) 5 16 30 m s v s = 18v, c gate = 1000pf, (note 3, 4) 5 16 30 m s v s = 24v, c gate = 1000pf, (note 3, 4) 5 16 30 m s v s = 9v to 24v, t a = 25 c, unless otherwise noted. e lectr ic al c c hara terist ics the l denotes specifications which apply over the full operating temperature range. note 1: quiescent current off is for both channels in off condition. note 2: quiescent current on is per driver and is measured independently. the gate voltage is clamped to 12v above the rail to simulate the effects of protection clamps connected across the gate-source of the power mosfet. note 3: zener diode clamps must be connected across the gate-source of the power mosfet to limit v gs . 1n5242a (through hole) or mmbz5242a (surface mount) 12v zener diodes are recommended. all turn-on and turn-off tests are performed with a 12v zener clamp in series with a small-signal diode connected between v s and the gate output to simulate the effects of a 12v protection zener clamp connected across the gate-source of the power mosfet. note 4: time for v gate to drop below 1v. cc hara terist ics uw a t y p i ca lper f o r c e standby supply current gate voltage above supply supply current per driver (on) supply voltage (v) 0 0 v gate ?v s (v) 4 6 8 10 12 14 5 10 15 20 ltc1255 ?tpc03 25 16 18 20 2 30 v clamp = 12v supply voltage (v) 0 0 supply current (ma) 0.4 0.6 0.8 1.0 1.2 1.4 5 10 15 20 ltc1255 ?tpc02 25 1.6 1.8 2.0 0.2 30 one input = 0n other input = off t a = 25? supply voltage (v) 0 0 supply current ( m a) 10 15 20 25 30 35 5 10 15 20 ltc1255 ?tpc01 25 40 45 50 5 30 v in1 = v in2 = 0v t a = 25?
4 ltc1255 cc hara terist ics uw a t y p i ca lper f o r c e input threshold voltage short-circuit turn-off delay time turn-on time standby supply current supply current per channel (on) input on threshold gate clamp current drain sense threshold voltage turn-off time supply voltage (v) 0 0.4 input threshold voltage (v) 0.8 1.0 1.2 1.4 1.6 1.8 5 10 15 20 ltc1255 ?tpc04 25 2.0 2.2 2.4 0.6 30 v on v off supply voltage (v) 0 75 drain sense threshold voltage (v) 85 90 95 100 105 110 5 10 15 20 ltc1255 ?tpc05 25 115 120 125 80 30 t a = 25? supply voltage (v) 0 0 gate clamp current ( m a) 10 15 20 25 30 35 5 10 15 20 ltc1255 ?ta06 25 40 45 50 5 30 v clamp = 12v t a = 25? supply voltage (v) 0 0 turn-on time ( m s) 200 300 400 500 600 700 5 10 15 20 ltc1255 ?ta07 25 800 900 1000 100 30 c gate = 1000pf t a = 25? v gs = 5v v gs = 2v supply voltage (v) 0 0 turn-off time ( m s) 10 15 20 25 30 35 5 10 15 20 ltc1255 ?ta08 25 40 45 50 5 30 c gate = 1000pf time for v gate < 1v supply voltage (v) 0 0 turn-off time ( m s) 10 15 20 25 30 35 5 10 15 20 ltc1255 ?ta09 25 40 45 50 5 30 c gate = 1000pf time for v gate < 1v temperature (?) ?0 0 standby supply current ( m a) 10 15 20 25 30 35 ?5 0 25 50 ltc1255 ?ta10 75 40 45 50 5 100 v s = 10v v s = 18v v s = 24v temperature (?) ?0 0.4 input threshold voltage (v) 0.8 1.0 1.2 1.4 1.6 1.8 ?5 0 25 50 ltc1255 ?ta12 75 2.0 2.2 2.4 0.6 100 v s = 10v v s = 24v temperature (?) ?0 0 supply current (ma) 0.4 0.6 0.8 1.0 1.2 1.4 ?5 0 25 50 ltc1255 ?ta11 75 1.6 1.8 2.0 0.2 100 v s = 24v v s = 10v v s = 18v
5 ltc1255 pi fu ctio s u uu input pin the ltc1255 input pin is active high and activates all of the protection and charge pump circuitry when switched on. the ltc1255 logic and shutdown inputs are high impedance cmos gates with esd protection diodes to ground and supply and therefore should not be forced beyond the power supply rails. the input pin should be held low during the application of power to properly set the input latch. gate drive pin the gate drive pin is either driven to ground when the switch is turned off or driven above the supply rail when the switch is turned on. this pin is of relatively high impedance when driven above the rail (the equiva- lent of a few hundred k w ). care should be taken to minimize any loading of this pin by parasitic resistance to ground or supply. supply pin the supply pin of the ltc1255 serves two vital pur- poses. the first is obvious; it powers the input, gate drive, regulation and protection circuitry. the second purpose is less obvious; it provides a kelvin connection to the top of the drain sense resistor for the internal 100mv reference. the supply pin of the ltc1255 should never be forced below ground as this may result in permanent damage to the device . a 100 w resistor should be inserted in series with the ground pin if negative supply voltage transients are anticipated. the ltc1255 is designed to be continuously powered so that the gate of the mosfet is actively driven at all times. if it is necessary to remove power from the supply pin and then reapply it, the input pin should be cycled (low to high) a few milliseconds after the power is reapplied to reset the input latch and protection circuitry. also, the input pin should be isolated from the controlling logic by a 10k resistor if there is a possibility that the input pin will be held high after the supply has been removed. drain sense pin the drain sense pin is compared against the supply pin voltage. if the voltage at this pin is more than 100mv below the supply pin, the input latch will be reset and the mosfet gate will be quickly discharged. cycle the input to reset the short-circuit latch and turn the mosfet back on. this pin is also a high impedance cmos gate with esd protection and therefore should not be forced outside of the power supply rails. to defeat the overcurrent protection, short the drain sense pin to the supply pin. some loads, such as large supply capacitors, lamps or motors require high in-rush currents. an rc time delay can be added between the sense resistor and the drain sense pin to ensure that the drain sense circuitry does not false trigger during startup. this time constant can be set from a few microseconds to many seconds. however, very long delays may put the mosfet at risk of being destroyed by a short-circuit condition (see applications information section). operatio u the ltc1255 is a dual 24v mosfet driver with built-in protection and gate charge pump. the ltc1255 consists of the following functional blocks: ttl and cmos compatible inputs and latches the ltc1255 inputs have been designed to accommo- date a wide range of logic families. both input thresh- olds are set at about 1.3v with approximately 100mv of hysteresis. a low standby current regulator provides continuous bias for the ttl-to-cmos converter. the input/protection latch should be set after initial power-up, or after reapplication of power, by cycling the input low to high.
6 ltc1255 operatio u internal voltage regulation the output of the ttl-to-cmos converter drives two regulated supplies which power the low voltage cmos logic and analog blocks. the regulator outputs are isolated from each other so that the noise generated by the charge pump logic is not coupled into the 100mv reference or the analog comparator. gate charge pump gate drive for the power mosfet is produced by an adaptive charge pump circuit which generates a gate voltage substantially higher than the power supply volt- age. the charge pump capacitors are included on-chip and therefore no external components are required to generate the gate drive. the charge pump is designed to drive a 12v zener diode clamp connected across the gate and source of the mosfet switch. (one channel) block diagra w drain current sense the ltc1255 is configured to sense the current flowing into the drain of the power mosfet in a high-side applica- tion. an internal 100mv reference is compared to the drop across a sense resistor (typically 0.002 w to 0.10 w ) in series with the drain lead. if the drop across this resistor exceeds the internal 100mv threshold, the input latch is reset and the gate is quickly discharged via a relatively large n-channel transistor. controlled gate rise and fall times when the input is switched on and off, the gate is charged by the internal charge pump and discharged in a controlled manner. the charge and discharge rates have been set to minimize rfi and emi emissions in normal operation. if a short circuit or current overload condition is encountered, the gate is discharged very quickly (typi- cally a few microseconds) by a large n-channel transistor. 100mv reference 10 m s delay low standby current regulator ttl-to-cmos converter voltage regulator analog digital input latch r s one shot oscillator and charge pump gate charge and discharge control logic fast/slow gate charge logic input gate drain sense analog section comp gnd v s ltc1255 ?bd
7 ltc1255 applicatio s i for atio w uu u mosfet and load protection the ltc1255 protects the power mosfet switch by removing drive from the gate as soon as an overcurrent condition is detected. resistive and inductive loads can be protected with no external time delay in series with the drain sense pin. lamp loads, however, require that the overcurrent protection be delayed long enough to start the lamp but short enough to ensure the safety of the mosfet. resistive loads loads that are primarily resistive should be protected with as short a delay as possible to minimize the amount of time that the mosfet is subjected to an overload condition. the drain sense circuitry has a built-in delay of approxi- mately 10 m s to eliminate false triggering by power supply or load transient conditions. this delay is sufficient to mask short load current transients and the starting of a small capacitor (< 1 m f) in parallel with the load. the drain sense pin can therefore be connected directly to the drain current sense resistor as shown in figure 1. v s ds1 1/2 ltc1255 g1 gnd in1 irfz24 12v 18v + 10 m f r load 18 w r sense 0.036 w c load 1 m f ltc1255 f01 figure 1. protecting resistive loads inductive loads loads that are primarily inductive, such as relays, sole- noids and stepper motor windings, should be protected with as short a delay as possible to minimize the amount of time that the mosfet is subjected to an overload condition. the built-in 10 m s delay will ensure that the overcurrent protection is not false triggered by a supply or load transient. no external delay components are required as shown in figure 2. large inductive loads (> 0.1mh) may require diodes con- nected directly across the inductor to safely divert the stored energy to ground. many inductive loads have these diodes included. if not, a diode of the proper current rating should be connected across the load, as shown in figure 2, to safely divert the stored energy. figure 2. protecting inductive loads capacitive loads large capacitive loads, such as complex electrical sys- tems with large bypass capacitors, should be powered using the circuit shown in figure 3. the gate drive to the power mosfet is passed through an rc delay network, r1 and c1, which greatly reduces the turn-on ramp rate of the switch. and since the mosfet source voltage follows the gate voltage, the load is powered smoothly and slowly from ground. this dramatically reduces the startup cur- rent flowing into the supply capacitor(s) which, in turn, reduces supply transients and allows for slower activation figure 3. powering large capacitive loads v s ds1 1/2 ltc1255 g1 gnd in1 irfz24 12v 12v + 100 m f 12v, 1a solenoid r sense 0.036 w 1n5400 ltc1255 f02 v s ds1 1/2 ltc1255 g1 gnd in1 mtp3055e 12v 15v + 470 m f r sense 0.036 w ltc1255 f03 c delay 0.01 m f r delay 100k d1 1n4148 r1 100k r2 100k c1 0.33 m f + c load 100 m f
8 ltc1255 of sensitive electrical loads. (resistor r2, and the diode d1, provide a direct path for the ltc1255 protection circuitry to quickly discharge the gate in the event of an overcurrent condition.) the rc network, r delay and c delay , in series with the drain sense input should be set to trip based on the expected characteristics of the load after startup, i.e., with this circuit, it is possible to power a large capacitive load and still react quickly to an overcurrent condition. the ramp rate at the output of the switch as it lifts off ground is approximately: dv/dt = (v gate C v th )/(r1 c1) therefore, the current flowing into the capacitor during startup is approximately: i startup = c load dv/dt using the values shown in figure 3, the startup current is less than 100ma and does not false trigger the drain sense circuitry which is set at 2.7a with a 1ms delay. lamp loads the in-rush current created by a lamp during turn-on can be 10 to 20 times greater than the rated operating current. the circuit shown in figure 4 shifts the current limit threshold up by a factor of 11:1 (to 30a) for a short period of time while the bulb is turned on. the current limit then drops down to 2.7a after the in-rush current has subsided. applicatio s i for atio w uu u v s ds1 1/2 ltc1255 g1 gnd in1 vn2222ll 9.1v 12v + 470 m f r sense 0.036 w ltc1255 f04 12v/1a bulb 10k 100k 1m 0.1 m f mtp3055el figure 4. lamp driver with delayed protection selecting r delay and c delay figure 5 is a graph of normalized overcurrent shutdown time versus normalized mosfet current. this graph is used to select the two delay components, r delay and c delay , which make up a simple rc delay between the drain sense input and the drain sense resistor. the y axis of the graph is normalized to one rc time constant. the x axis is normalized to the set current. (the set current is defined as the current required to develop 100mv across the drain sense resistor.) note that the shutdown time is shorter for increasing levels of mosfet current. this ensures that the total energy dissipated by the mosfet is always within the bounds established by the manufacturer for safe opera- tion. (see mosfet data sheet for further s.o.a. information.) normalized mosfet current (1 = set current) 0.1 0.01 normalized delay time (1 = rc) 0.1 1 10 1 10 100 ltc1255 ?f05 figure 5. normalized delay time vs mosfet current using a speed-up diode another way to reduce the amount of time that the power mosfet is in a short-circuit condition is to bypass the delay resistor with a small signal diode as shown in figure 6. the diode will engage when the drop across the drain sense resistor exceeds about 0.7v, providing a direct path to the sense pin and dramatically reducing the amount of time the mosfet is in an overload condition. the drain sense resistor value is selected to limit the maximum dc current to 4a.
9 ltc1255 applicatio s i for atio w uu u v s ds1 1/2 ltc1255 g1 gnd in1 irf530 12v 18v + 100 m f r sense 0.036 w ltc1255 f06 c delay 0.01 m f r delay 100k 1n4148 load figure 6. using a speed-up diode the large output capacitors on many switching regula- tors, on the other hand, may be able to hold the supply pin of the ltc1255 above 3.5v sufficiently long that this extra filtering is not required. because the ltc1255 is micropower in both the standby and on state, the voltage drop across the supply filter is very small (typically < 6mv) and does not signifi- cantly alter the accuracy of the drain sense threshold voltage which is typically 100mv. automotive applications reverse battery protection the ltc1255 can be protected against reverse battery conditions by connecting a resistor in series with the ground lead as shown in figure 8. the resistor limits the supply current to less than 120ma with C 12v applied. since the ltc1255 draws very little current while in normal operation, the drop across the ground resistor is minimal. the 5v m p (or controlling logic) is protected by the 10k resistors in series with the input. figure 7. supply filter for current limited supplies v s ds1 1/2 ltc1255 g1 gnd in1 mtp12n06e 12v 14v + 10 m f r sense 0.036 w ltc1255 f08 load 100 w 28v 10k m p or control logic 5v figure 8. reverse battery protection transient overvoltage protection a common scheme used to limit overvoltage transients on a 14v nominal automotive power bus is to clamp the supply to the module containing the high-side mosfet switches with a large transient suppressor diode, d1 in figure 9. this diode limits the supply voltage to 40v under worse case conditions. the ltc1255 is designed to survive short (10ms) 40v transients and return to normal operation after the transient has passed. current limited power supplies the ltc1255 requires at least 3.5v at the supply pin to ensure proper operation. it is therefore necessary that the supply to the ltc1255 be held higher than 3.5v at all times, even when the output of the switch is short circuited to ground. the output voltage of a current limited regulator may drop very quickly during short circuit and pull the supply pin of the ltc1255 below 3.5v before the shutdown circuitry has had time to respond and remove drive from the gate of the power mosfet. a supply filter should be added as shown in figure 7 which holds the supply pin of the ltc1255 high long enough for the overcurrent shutdown cir- cuitry to respond and fully discharge the gate. linear regulators with small output capacitors are the most difficult to protect as they can switch from a voltage mode to a current limited mode very quickly. v s ds1 1/2 ltc1255 g1 gnd in1 mtp12n06e 12v 15v + 10 m f r sense 0.1 w ltc1255 f07 0.01 m f 100k 1n4148 10 w * + 47 m f* + 10 m f 12v/2a regulator short circuit *supply filter component
10 ltc1255 the switches can either be turned off by the controlling logic during these transients or latched off above 30v by holding the drain sense pin low as shown in figure 9. switch status can be ascertained by means of an xnor gate connected to the input and switch output through 100k current limiting resistors (see typical applications section for more detail on this scheme). the switch is reset after the overvoltage event by cycling the input low and then high again. the power mosfet switch should be selected to have a breakdown voltage sufficiently higher than the 40v supply clamp voltage to ensure that no current is conducted to the load during the transient. applicatio s i for atio w uu u figure 9. overvoltage transient protection typical applicatio s u dual automotive high-side switch with overvoltage protection, xnor status and 12 m a standby current v s ds1 1/2 ltc1255 g1 gnd in1 irf530 12v 1n5242b 14v r sense 0.036 w ltc1255 f09 load 100 w 10k 1k* d1 mr2535l 30v* 1n5256b from m p, etc. + 1 m f 50v *optional overvoltage (30v) latch-off components v s ds2 ltc1255 in2 gnd ds1 in1 g1 g2 mtd3055e 1n5400 14v mr2535l* 0.036 w ltc1255 ta03 10k** 12v mmbz5242b 100k 10k fault to m p from m p, etc. 100 w + 1 m f 50v fault to m p from m p, etc. 10k 100k 1n5400 12v mmbz5242b 10k** mtd3055e 14v/1a solenoid 0.036 w 14v/1a solenoid 1/4 74c266 ? limits v s transients to <40v. see manufacturer data sheet for further detail. optional open load detection requires 10k pull-up resistors. (ultra low standby quiescent current is sacrificed) power from 5v logic supply. * ** ? in 0 1 0 1 out 0 0 1 1 condition switch off overcurrent open load** switch on fault 1 0 0 1 truth table 1/4 74c266 ?
11 ltc1255 typical applicatio s u automotive motor direction and speed control with stall-current shutdown v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 0.1 m f 100k 30k 30k 12v mmbz5242b mtd3055e 100 w 0.1 m f 14v dc motor 12v mmbz5242b mtd3055e mtd3055el motor speed and direction control logic or m p direction direction pwm 2 pwm 1 mtd3055el + 10 m f 50v mr2535l 14v 0.02 w 5v ltc1255 ?ta05 10 to 12 cell battery switch and 5v ramped load switch with 12 m a standby current and optional 3a overcurrent shutdown v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 100k m p or control logic v logic 10k 10k 2n2222 0.22 m f* 100k* 18v to 30v from battery charger 9.1v mmbz5239bl 0.033 w * 1n5400 10 to 12 cell battery pack irfr024 12v mmbz5242bl irfr024 + 100 m f high ? efficiency switching regulator v in + 100 m f 5v/1a switched battery 5v/1a (switched) mtd3055el v out 100k 1k 0.1 m f *optional 3a overcurrent shutdown ? see ltc1149 data sheet for circuit details ltc1255 ?ta04 1n4148
12 ltc1255 typical applicatio s u low frequency (f o = 100hz) pwm motor speed control with current limit and 22v overvoltage shutdown dual automotive lamp dimmer with controlled rise and fall times and short-circuit protection v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 + 22v mmbz5251bl 100k 10k 10k 0.47 m f 100 w 0.1 m f 50v lmc555 0.01 m f 3 5 2 6 8 4 22v mmbz5251bl mr750 0.01 w 10 m f 50v irfr024 ltc1255 ?ta06 + 1 m f 5.6v 9.1k mr2535l 14v 1 0.1 m f 1k 1n4148 fast 15k med 30k slow 60k off 1n4148 14v motor v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 100 w lmc555 0.01 m f 3 5 2 6 8 4 + 10 m f 5.6v 9.1k 1 0.1 m f 1n4148 1n4148 100k 1k pulse width adjust + 10 m f 50v mr2535l 14v 0.1 m f 0.1 m f 30k 0.1 m f 0.05 w 100k 30k 12v mmbz5242b #53 14v bulbs mtd3055e 12v mmbz5242b mtd3055e 0.05 w 100k ltc1255 ?ta06
13 ltc1255 typical applicatio s u 18v to 32v operation with overcurrent shutdown and optional overvoltage shutdown bootstrapped gate driver (100hz < f o < 10khz) high-side switch with thermal shutdown (ptc thermistor) v s ds1 1/2 ltc1255 gnd in1 g1 + 10 m f *keystone rl2006-100-100-30-pt load irf530 from m p, etc. 9v to 24v ltc1255 ?ta10 ptc* thermistor (100?) 12v 1n5242b 100k v s ds1 1/2 ltc1255 g1 gnd in1 + 10k 2n3904 1k 2n3906 36v* 1n5258b r sen 0.10 w 1w (i max = v be /r sen ) 10k 12v 1n5242b irf530 from m p, etc. 24v 1n5252b 1 m f 50v 18v to 32v load 1k 18v to 32v *optional 36v overvoltage shutdown ltc1255 ?ta08 v s ds1 1/2 ltc1255 gnd in1 g1 + 10 m f 2n2222 12v 1n5242b *v gs = v s ?0.6v (clamped at 12v) rise and fall times are beta times faster * 1n4148 load 2n3906 irfz44 0.1 m f from m p, etc. 9v to 24v 0.036 w ltc1255 ?ta09
14 ltc1255 typical applicatio s u h-bridge dc motor driver (direction and on/off control) v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 100k 1n4148 1n4148 100k 12v mmbz5242b 0.036 w mtd3055e 12v mmbz5242b mtd3055e dc motor 1n4148 100k mtd3055el 1n4148 100k mtd3055el 5v 1/4 74c02 1/4 74c02 1/4 74c02 disable direction 9v to 24v 0.33 m f 100k 10 m f 50v + ltc1255 ?ta11 high-side dc motor driver with electronic braking and stalled motor shutdown 30k 30k + 100 m f v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 1/4 74c02 5v 1/4 74c02 run/coast brake 18v 0.47 m f 100k 12v 1n5242b irfz34 0.02 w 1 w * irfz34 12v 1n5242b 1n5400 18v dc motor *size resistor to dissipate energy regenerated by motor during braking. ltc1255 ?ta12
15 ltc1255 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. typical applicatio s u stepper motor driver with overcurrent protection v s ds1 ltc1255 g2 gnd in2 g1 ds2 in1 0.01 m f 100k 12v mmbz5242bl irfr024 0.036 w irfr024 12v mmbz5242bl v s ltc1255 in2 gnd ds1 g2 g1 in1 ds2 0.01 m f 100k 0.036 w 12v mmbz5242bl 12v mmbz5242bl irfr024 stepper motor windings 12v 1n4001 1n4001 1n4001 1n4001 ac bd stepper motor control logic 5v 100 m f + a b c d ltc1255 ta13 irfr024
16 ltc1255 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7487 (408) 432-1900 l fax : (408) 434-0507 l telex : 499-3977 package descriptio u dimensions in inches (millimeters) unless otherwise noted. n8 package 8-lead plastic dip s8 package 8-lead soic n8 0393 0.045 ?0.015 (1.143 ?0.381) 0.100 ?0.010 (2.540 ?0.254) 0.065 (1.651) typ 0.045 ?0.065 (1.143 ?1.651) 0.130 ?0.005 (3.302 ?0.127) 0.020 (0.508) min 0.018 ?0.003 (0.457 ?0.076) 0.125 (3.175) min 12 3 4 87 6 5 0.250 ?0.010 (6.350 ?0.254) 0.400 (10.160) max 0.009 ?0.015 (0.229 ?0.381) 0.300 ?0.320 (7.620 ?8.128) 0.325 +0.025 0.015 +0.635 0.381 8.255 () ? linear technology corporation 1993 lt/gp 0493 10k rev 0 1 2 3 4 0.150 ?0.157 (3.810 ?3.988) 8 7 6 5 0.189 ?0.197 (4.801 ?5.004) 0.228 ?0.244 (5.791 ?6.197) 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 8?typ 0.008 ?0.010 (0.203 ?0.254) so8 0393 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) bsc

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