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general description the max14870/max14872 motor drivers provide a small, low-power and simple solution for driving and controlling brushed dc motors and relays with voltages between 4.5v and 36v. very low driver on-resistance reduces power dissipation. these drivers feature a charge-pump-less design for reduced external components and low supply current. integrated fast-decay current regulation allows user- adjustable peak startup motor currents and requires mini - mal external components. a separate voltage-sense input (sns) reduces current sensing errors due to parasitic trace resistance. the max14870/max14872 features shoot-through protec - tion and internal free-wheeling diodes that absorb inductive motor currents. driver outputs are short-circuit-protected from shorts to ground, to the supply, and between m1 and m2. an active-low fault output signals thermal overload and overcurrents during fault conditions. the max14870 has pwm and direction-control inputs, while the max14872 has forward and reverse inputs for direction control. see the function tables . the max14870/max14872 are available in a 12-pin (3mm x 3mm) tdfn-ep package and operate over the -40c to +85c temperature range. benefts and features small package handles high power and reduces footprint circuit size ? up to 2.5a peak motor current ? space-saving tdfn-ep (3mm x 3mm) package ? flexible 4.5vC36v supply enables longer runtime on batteries low power consumption runs cooler and longer ? 280m w (typ) total bridge on-resistance ? 1ma (typ) supply current at 30khz/24v ? 10a (max) standby current at 12v simplified designs reduces time to market ? charge-pump-less architecture ? current regulation only requires a sense resistor ? current-sense input simplifes pcb layout integrated protection provides robust driving solution ? short-circuit-protected drivers ? thermal-shutdown undervoltage lockout ? diagnostic fault output ? -40c to +85c temperature range applications printers and scanners relay drivers vending and gaming machines ordering information appears at end of data sheet. 19-7062; rev 0; 9/14 driver v dd sns pwm + dir + max 14870 max 14872 gnd com m 1 m 2 en fault driver v dd v dd current regulation r sense c irq pwm gpo 24 v 3 . 3 v 3 . 3 v m + these pin names are for the max 14870 . on the max 14872 , these are the fwd and rev inputs . typical application circuit evaluation kit available max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers
(all voltages referenced to gnd) v dd ........................................................................ -0.3v to +40v m1, m2 ....................................................... -0.3v to (v dd +0.3v) pwm, dir, fwd, rev, fault , en , sns .................. -0.3v to +6.0v com ..................................................................... -0.3v to +0.3v continuous current into m1, m2 .......................................... 3a continuous power dissipation (t a = +70c) single-layer board (derate at 15.9mw/c above +70c) .......................................................... 1270mw multi-layer board (derate at 24.4mw/c above +70c) .......................................................... 1951mw operating temperature range ........................... -40c to +85c junction temperature ...................................................... +150oc storage temperature range ............................. -65oc to +150 c lead temperature (soldering, 10s ) ................................ +300 c solder temperature (reflow ) ......................................... +260 c junction-to-case thermal resistance ( jc ) tdfn-ep (single-layer board) .................................. 8.5c/w tdfn-ep (multi-layer board) .................................... 8.5c/w junction-to-ambient thermal resistance ( ja ) tdfn-ep (single-layer board) ................................... 63c/w tdfn-ep (multi-layer board) ..................................... 41c/w (note 1) (v dd = 4.5v to 36v, t a = t min to t max , unless otherwise noted. typical values are at v dd = 12v, t a = +25 c ) (note 2) parameter symbol conditions min typ max units power supply supply voltage v dd 4.5 36 v supply current i dd en = low, m1/m2 not connected f pwm/fwd = 50khz 1 ma no switching 0.5 1.2 shutdown supply current i shdn en = high, driver is in shutdown v dd = 12v 3.7 10 a v dd = 36v 10 20 undervoltage lockout threshold v uvlo v dd rising 3.3 3.8 4.3 v undervoltage lockout threshold hysteresis v uvlo_hyst 400 mv maxim integrated 2 note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to ab solute maximum rating conditions for extended periods may affect device reliability. package thermal characteristics electrical characteristics max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
(v dd = 4.5v to 36v, t a = t min to t max , unless otherwise noted. typical values are at v dd = 12v, t a = +25 c ) (note 2) parameter symbol conditions min typ max units driver (m1, m2) driver output resistance (high-side + low-side) r on i m_ = 2.5a t j = 25c 280 395 m t j = 125c 410 580 driver overload current limit i m_ol 3 a m1, m2 leakage current i m_lkg en = high, v m1 = v m 2 = 0v or v dd -1 +1 a m1, m2 body diode forward-voltage v bf low-side diode, en = high, i f = 2.5a 1.5 v high-side diode, en = high, i f = 2.5a 1.5 current regulation (sns, com) sns current sense threshold v sns_th v sns rising (note 3) 94 100 110 mv sns input leakage current i sns_lkg v sns = 250mv -1 +1 a com leakage current i com_lkg en = high, v com = 250mv -1 +1 a logic signals (pwm, dir, fwd, rev, en , fault ) input logic-high voltage v ih fwd, rev, pwm, dir 2 v input logic-low voltage v il fwd, rev, pwm, dir 0.8 v en input logic-high voltage v en_ih 1.6 en input logic-low voltage v en_il 0.4 input leakage current i il pwm, dir, fwd, rev, en , v input = 5.5v or 0v -1 +1 a fault output low voltage v ol fault asserted, i sink = 5ma 0.5 v fault off leakage current i f_lkg fault deasserted, v fault = 5.5v -1 +1 a protection thermal-shutdown threshold t shdn temperature rising, fault asserted +160 c thermal-shutdown hysteresis t shdn_hyst 10 c maxim integrated 3 electrical characteristics (continued) max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
(v dd = 4.5v to 36v, t a = t min to t max , unless otherwise noted. typical values are at v dd = 12v, t a = +25 c ) (note 2) note 2: all units are production tested at t a = +25c. specifications over temperature are guaranteed by design. note 3: v sns_th is the threshold voltage to turn on current regulation. parameter symbol conditions min typ max units pwm frequency f sw en = low max14870, switching signal applied at pwm 50 khz max14872, switching signal applied at fwd or rev 50 dead time t dead 140 ns m1, m2 slew rate sr 200 v/s m1, m2 high-side propagation delay t pr r l = 1k, c l = 50pf, pwm/fwd/dir/rev rising, figure 1 620 ns m1, m2 low-side propagation delay t pf r l = 1k, c l = 50pf, pwm/fwd/dir/rev falling, figure 1 583 ns current regulation fixed off-time t off pwm/fwd = high, en = low, v sns > v sns_th 7.8 15 22 s current regulation minimum on-time t cr_bl pwm/fwd = high, en = low, v sns > v sns_th 2.5 s overcurrent blanking time t oc_bl m1/m2 is shorted to v dd or gnd, figure 2 1 s overcurrent autoretry timeout t oc_to pwm/fwd = high, en = low, i m or i m2 > i m_ol , figure 2 2 ms enable turn-on delay t en_on pwm/fwd = high, r l = 1k, c l = 50pf, en falling, m1/m2 rising to 10%, figure 3 23 s enable turn-off delay t en_off pwm/fwd = high, r l = 1k, c l = 50pf, en rising, m1/m2 falling to 90%, figure 3 50 s maxim integrated 4 ac electrical characteristics max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
figure 1. m1/m2 propagation delay figure 2. overcurrent autoretry timeout r l c l m 1 / m 2 t pr t pf 0 v v l v dd 0 v pwm / dir fwd / rev m 1 / m 2 1 v 1 v fault t oc _ bl v l 0 v i m 1 or i m 2 t oc _ to i m _ ol 0 a maxim integrated 5 test circuits/timing diagrams max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
figure 3. enable/disable delays r l c l m1/ m2 t en_on t en_off 0v v l v dd 0v en m1/m2 1.5v 1.5v 10% 90% maxim integrated 6 test circuits/timing diagrams (continued) max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
( v dd = 12v, t a = +25c, unless otherwise noted.) 0 2 4 6 8 10 12 - 45 - 30 - 15 0 15 30 45 60 75 90 i shdn (a) temperature ( o c) shutdown supply current vs. temperature toc04 v dd = 4.5v v dd = 36v v dd = 24v 0 . 0 0 0 . 0 5 0 . 1 0 0 . 1 5 0 . 2 0 0 . 2 5 0 . 3 0 0 1 0 0 0 2 0 0 0 3 0 0 0 o n - r es i s t a nc e ( ? ) l o a d curr e n t ( m a ) h ig h -s i d e o n - r es i s t anc e vs . l o ad curr e n t t oc 01 v d d = 4 . 5 v v d d = 36 v 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 0 1 2 3 v bf ( v ) l o a d curr e n t ( a ) h i g h -s i d e m 1 / m 2 b o d y d i o d e f o r w ard -v o lta g e vs . l o a d t o c 0 7 t a = 2 5 c t a = 8 5 c t a = - 4 0 c 0 . 0 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 0 . 1 2 0 . 1 4 0 . 1 6 0 . 1 8 0 . 2 0 0 1 0 0 0 2 0 0 0 3 0 0 0 o n - r es i s t a nc e ( ? ) l o a d curr e n t ( m a ) l o w - s i d e o n - r es i s t anc e vs . l o ad curr e n t t oc 02 v dd = 4 . 5 v v dd = 36 v 0 5 10 15 20 25 30 35 40 45 50 55 100 150 200 250 300 350 400 450 500 t off (s) c off (pf) off - time vs c off capacitance toc08 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0 5 10 15 20 25 30 35 40 45 50 i cc (ma) data rate (khz) supply current vs. switching rate toc05 v dd = 5v v dd = 36v c l = 10pf on m1/m2 v dd = 24v v dd = 12v 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 0 1 2 3 v bf ( v ) l o a d curr e n t ( a ) l o w -s i d e m 1 / m 2 b o d y d i o d e f o r w ard -v o lta g e vs . l o a d t o c 0 6 t a = 2 5 c t a = 8 5 c t a = - 4 0 c maxim integrated 7 typical operating characteristics max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
pin name function max14870 max14872 1, 12 1, 12 com com current output. connect a sense resistor (r sense ) from com to gnd to use internal current regulation and/or external current control. connect both com pins together. 2 2 m1 motor driver output 1. see the function tables for more information. 3, 10 3, 10 v dd power supply input. bypass v dd to gnd with a 1f ceramic capacitor as close to the device as possible. connect both vdd pins together. 4 4 sns current sense input. connect sns to com to enable current regulation. to bypass current regulation, connect sns to gnd. 5 - pwm pwm control logic input. pwm and dir control m1 and m2 on the max14870. see the function tables for more information. 6 - dir direction control logic input. pwm and dir control m1 and m2 on the max14870. see the function tables for more information. - 5 fwd forward control logic input. fwd and rev control m1 and m2 on the max14872. see the function tables for more information. - 6 rev reverse control logic input. fwd and rev control m1 and m2 on the max14872. see the function tables for more information. tdfn-ep 3mm x 3mm * ep = exposed pad. connect to ground. max14870 m2 gnd en m1 sns pwm + 12 com com vdd vdd fault dir 11 10 9 8 7 1 2 3 4 5 6 *ep max14872 m2 gnd en m1 sns fwd + 12 com com vdd vdd fault rev 11 10 9 8 7 1 2 3 4 5 6 *ep top view maxim integrated 8 pin confguration pin description max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
pin name function max14870 max14872 7 7 fault open-drain active-low fault output. fault goes low during an overcurrent condition and thermal shutdown. 8 8 en active-low enable input. drive en low to enable the driver outputs. drive en high to tri-state the driver outputs. 9 9 gnd ground 11 11 m2 motor driver output 2. see the function tables for more information. - - ep exposed pad. connect to ground. inputs outputs operating mode en v sns pwm dir m1 m2 1 x x x high-impedance high-impedance shutdown 0 < v sns_th 0 x gnd gnd brake 0 < v sns_th 1 0 gnd v dd counterclockwise/reverse 0 < v sns_th 1 1 v dd gnd clockwise/forward 0 > v sns_th 1 0 switching switching current regulation 0 > v sns_th 1 1 switching switching current regulation inputs outputs operating mode en v sns fwd rev m1 m2 1 x x x high-impedance high-impedance shutdown 0 < v sns_th 0 0 gnd gnd brake 0 < v sns_th 1 0 v dd gnd forward 0 < v sns_th 0 1 gnd v dd reverse 0 < v sns_th 1 1 high-impedance high-impedance tri-state 0 > v sns_th 1 0 switching switching current regulation 0 > v sns_th 0 1 switching switching current regulation maxim integrated 9 pin description (continued) max14870 function table max14872 function table x = dont care x = dont care max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
driver vdd sns max 14870 gnd com m 1 m 2 en fault driver v dd v dd current regulation r sense dir pwm driver vdd sns max14872 gnd com m1 m2 en fault driver v dd v dd current regulation r sense fwd rev maxim integrated 10 functional diagrams max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
detailed description the max14870/max14872 dc brushed motor drivers provide a low-power and flexible solution for driving and controlling brushed motors with voltages between 4.5v and 36v. peak motor currents of up to 2.5a ensure large motor torque that is controllable by an external pwm signal and/or by autonomous internal current regulation. the max14870 has pwm and direction-control inputs, while the max14872 has forward and reverse inputs for direction control. see function tables . charge-pump-less design requires minimal external components and low supply current. integrated current regulation allows limiting peak start - up motor currents. shoot-through protection with a 140ns (typ) dead time ensures low operating current. internal free-wheeling diodes absorb inductive motor cur - rents. the fault output signals thermal overload and overcurrents. overcurrent protection the max14870/max14872 are protected against shorts on m1/m2 to any voltage between v dd and gnd, includ - ing shorts to gnd, v dd , and between m1 and m2 via overcurrent limiting. when a current above 6a (typ) flows through m1 or m2 for longer than 1s, an overcur - rent condition is detected and the h-bridge drivers are automatically disabled and the fault output asserts. if the overcurrent condition continues for longer than the overcurrent autoretry timeout (2ms (typ)) the max14870/ max14872 enters autoretry mode. in autoretry mode, the m1 and m2 outputs are re-enabled for 1s (typ) and fault goes high-impedance. the drivers are disabled again and fault is re-asserted if the overcurrent condi - tion persists. pwm control (max14870 only) the pwm input is used for motor speed/torque control. increasing or decreasing the duty cycle at pwm sets the effective (average) voltage across the motor terminals and allows first-order speed control. when pwm is logic-high, the motor is driven in the direc - tion defined by dir. when pwm is logic-low, the bridge is in brake mode. in brake mode, the motor current continues flowing and recirculates through the low-side transistors of the h-bridge driver, due to its inductive impedance and back emf. fwd/rev control (max14872 only) the fwd input is used to drive the motor forward/turn a relay on. the rev input reverses the m1 and m2 polarity, to drive the motor in reverse/turn a relay off. fwd/rev control can be optionally used to implement either bipolar motor control (with both m1 and m2 switch - ing) or unipolar control, where only m1 or m2 switches. slope control the max14871 drivers turn-on and turn-off with active slope-control during the m1/m2 transition times. the integrated slew rate-limiting reduces emc (like conducted and radiated emi) associated with high di/dt rates. thermal shutdown the max14870/max14872 include integrated protection against thermal overload. when the junction temperature exceeds 160c (typ), the h-bridge is tri-stated, m1 and m2 are disabled, and fault is asserted. i f the motor was spinning before thermal shutdown occurred, the motors inductance will push current through the internal m1 and m2 diodes, forcing the motor into fast decay, with a voltage across its terminals of v dd . m1 and m2 are automatically re-enabled when the junction temperature falls to 150c (typ). current sensing connect a sense resistor (r sense ) between com and gnd to monitor the motor current during operation. select r sense such that the voltage at com created by motor current flowing through the sense resistor is limited to within 250mv relative to gnd (-250mv v com +250mv). minimize series trace resistance from r sense to gnd to minimize voltage sense errors due to parasitic trace interconnect resistance. use a star ground connection between the max14870/max14872 gnd pins and the gnd-side of r sense . connect the voltage sense close to the r sense resistor and/or use differential voltage sensing. see figure 4 . maxim integrated 11 max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
current regulation the max14870/max14872 features internal current regulation to limit the startup current. regulation is set when the motor current (i m ) exceeds the current limit defined by the sense resistor (r sense ): i m_max = 0.1v/r sense when the motor current exceeds the maximum threshold, the h-bridge drive is reversed for fast decay for a fixed time (t off = 15s). the h-bridge is turned back to normal operation after t off . fast decay mode when the motor current exceeds the set threshold, the h-bridge polarity is reversed during the 15s (typ) t off period. this results in faster motor current decay since Cv dd is applied across the motors terminals. the motor current decrease is first order with an l/r time constant and proportional to (v dd + v emf ). note that if t off is larger than the motors l/r electrical time constant, the motor current can reverse direction, causing the motor to not start. during fast decay, the motors inductive current recircu - lates through the external v dd supply, which charges up the v dd bypass capacitor. therefore, the voltage seen across r sense is negative during the t off delay. applications information layout considerations connect duplicate pins (com pins and v dd pins) togeth - er with low-resistance traces. see the current sensing section for further layout recommendations. power considerations the max14870/max14872 driver can generate more power than the package for the device can safely dissi - pate. total power dissipation for the device is calculated using the following equation: p total = p driver + p sw + p d the power dissipated inside of the driver is calculated as: p driver = i m 2 x r on figure 4. layout example for accurate current sensing ep m1 m2 to sns com com r sense gnd gnd gnd gnd gnd gnd maxim integrated 12 max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
where i m is the motor current and r on is the on-resis - tance of the high and low-side fets. p sw is the power generated by the driver during the rise/ fall times in switching and includes both arms of the bridge. calculate p sw using the following equation: p sw = i m x 2 x v ds = i m x 2 x (1/2 x v dd x f sw x t r ) where i m is the motor current, t r is the 200ns (typ) rise or fall time of the driver output, and f sw is the switching frequency. the internal diodes dissipate power during switching, as well. calculate the power dissipated in the diodes as: p d = i m x 2 x v bf x t dead x f sw operation without current regulation to operate the max14870/max14872 without internal or external current regulation, connect sns directly to gnd. no sense resistor is required for this configuration. operation with external current regulation the motor current can be controlled by external pwm regulation using sense resistor feedback in a control loop. to disable the internal current regulation circuitry of the max14870/max14872 and use external regulation, con - nect sns directly to ground. note that, if fast decay control is used, the com voltage pulses negatively when the h-bridge direction is inverted. use of external capacitors maxim does not recommend using external capacitors across the motor terminals. added capacitance between h-bridge outputs increases the power dissipated in the h-bridge by: p d = v dd 2 x c x f sw where c is the capacitance across m1/m2 and f sw is the m1/m2 switching frequency. this power is dissipated without good reason. figure 5. operation with external current regulation v uvlo driver vdd sns pwm + dir + max14870 max14872 gnd com m1 m2 en fault driver v dd v dd current regulation r sense c irq pwm gpo adc 9v 3.3v 3.3v m a + these pin names are for the max14870. on the max14872, these are the fwd and rev inputs. maxim integrated 13 max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
package information for the latest package outline information and land patterns (foot - prints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 12 tdfn-ep td1233+1 21-0664 90-0397 ordering information part temp range pin-package max14870 etc+ -40c to +85c 12 tdfn-ep max14872 etc+ -40c to +85c 12 tdfn-ep +denotes a lead(pb)-free/rohs-compliant package. *ep = exposed pad maxim integrated 14 chip information process: bicmos max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers www.maximintegrated.com
revision history revision number revision date description pages changed 0 9/14 initial release ? 2014 maxim integrated products, inc. 15 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max14870/max14872 compact 4.5v to 36v full-bridge dc motor drivers for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.

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