UDN2916A stepper motor driver able to drive both windings of bipo- lar stepper motor output current up to 750ma each winding wide voltage range 10v to 50v half-step, full-step and microstepp- ing mode built-in protection diodes internal pwm current control low output saturation voltage designed for unstabilized motor supply voltage internal thermal shutdown description the UDN2916A is a bipolar monolithic integrated circuits intended to control and drive both winding of a bipolar stepper motor or bidirectionally con- trol two dc motors. the UDN2916A with a few external components form a complete control and drive circuit for ls- ttl or microprocessor controlled stepper motor system. the power stage is a dual full bridge capable of sustaining 50v and including four diodes for cur- rent recirculation. a cross conduction protection is provided to avoid simultaneous cross conduction during switching current direction. an internal pulse-width-modulation (pwm) con- trols the output current to 750ma with peak start- up current up to 1a. wide range of current control from 750ma (each bridge) is permitted by means of two logic inputs and an external voltage reference. a phase input to each bridge determines the load current direc- tion. a thermal protection circuitry disables the outputs if the chip temperature exceeds safe operating limits. notice. september 2003 ? powerdip 20+2+2 ordering number: UDN2916A block diagram 1/8
pin functions n name function 1;2 output a see pins 5;21 3;23 sense resistor connection to lower emitters of output stage for insertion of current sense resistor 4;22 comparator input input connected to the comparators. the voltage across the sense resistor is feedback to this input throught the low pass filter rc cc. the higher power transistors are disabled when the sense voltage exceeds the reference voltage of the selected comparator. when this occurs the current decays for a time set by r t c t (t off = 1.1 r t c t ). see fig. 1. 5;21 output b output connection. the output stage is a "h" bridge formed by four transistors and four diodes suitable for switching applications. 6;19 ground see pins 7;18 7;18 ground ground connection. with pins 6 and 19 also conducts heat from die to printed circuit copper. 8;20 input 0 see input 1 (pins 9;17) 9;17 input 1 these pins and pins 8;20 (input 0) are logic inputs which select the outputs of the comparators to set the current level. current also depends on the sensing resistor and reference voltage. see funcional description. 10;16 phase this ttl-compatible logic inputs sets the direction of current flow through the load. a high level causes current to flow from output a (source) to output b (sink). a schmitt trigger on this input provides good noise immunity and a delay circuit prevents output stage short circuits during switching. 11;15 reference voltage a voltage applied to this pin sets the reference voltage of the comparators, this determining the output current (also thus depending on r s and the two inputs input 0 and input 1). 12;14 rc a parallel rc network connected to this pin sets the off time of the higher power transistors. the pulse generator is a monostable triggered by the output of the comparators (t off = 1.1 r t c t ). 13 v ss - logic supply supply voltage input for logic circuitry 24 v s - load supply supply voltage input for the output stages. pin connection (top view) UDN2916A 2/8
absolute maximum ratings symbol parameter value unit v s supply voltage 50 v i o output current (peak) 1a i o output current (continuous) 0.75 a v ss logic supply voltage 7 v v in logic input voltage range -0.3 to +7 v v sense sense output voltage 1.5 v t j junction temperature +150 c t op operating temperature range 0 to 70 c t stg storage temperature range -55 to +150 c thermal data symbol description value unit r thj-case r thj-ambient thermal resistance junction-case thermal resistance junction-ambient max max 14 60 c/w c/w electrical characteristics (t amb = 25c, t tab 70c, v s = 50v, v ss = 4.75v to 5.25v, v ref = 5v; unless otherwise specified) see fig. 3. symbol parameter test condition min. typ. max. unit output drivers (out a or out b ) v s motor supply range 10 50 v i cex output leakage current v out = vs v out = 0 - - <1 <-1 50 -50 m a m a v ce(sat) output saturation voltage sink driver, i out = +500ma sink driver, i out = +750ma source driver, i out = -500ma source driver, i out = -750ma - - - - 0.3 0.7 1.1 1.3 0.6 1 1.4 1.6 v v v v i r clamp diode leakage current v r = 50v - <1 50 m a v f clamp diode forward voltage sink diode source diode i f =750ma 1 1 1.5 1.5 v v i s(on) driver supply current both bridges on, no load - 8 15 ma i s(off) driver supply current both bridges off - 6 10 ma control logic v in(h) input voltage all inputs 2.4 - - v v in(l) input voltage all inputs - - 0.8 v i in(h) input current v in = 2.4v - <1 20 m a i in(l) input current v in = 0.84v - -3 -200 m a v ref reference voltage operating 1.5 - 7.5 v i ss(on) total logic supply current i o = i 1 = 0.8v, no load - 54 64 ma i ss(off) total logic supply current i o = i 1 = 2.4v, no load - 10 14 ma comparators v ref / v sense current limit threshold (at trip point i o = i 1 = 0.8v 9.5 10 10.5 - i o = 2.4v, i 1 = 0.8v 13.5 15 16.5 - i o = 0.8v, i 1 = 2.4v 25.5 30 34.5 - t off cutoff time r t = 56k w c t = 820pf - 50 s t d turn off delay fig. 1 - 1 s m m UDN2916A 3/8
functional description the circuit is intended to drive both windings of a bipolar stepper motor. the peak current control is generated through switch mode regulation. there is a choice of three different current levels with the two logic inputs i 01 - i 11 for winding 1 and i 02 - i 12 for winding 2. the current can also be switched off completely input logic (i 0 and i 1 ) the current level in the motor winding is selected with these inputs. (see fig. 2) if any of the logic inputs is left open, the circuit will treat it has a high level input. i o i 1 current level h l h l h h l l no current low current 1/3 i o max medium current 2/3 i o max maximum current i o max phase this input determines the direction of current flow in the windings, depending on the motor connec- tions. the signal is fed through a schmidt-trigger for noise immunity, and through a time delay in order to guarantee that no short-circuit occurs in the output stage during phase-shift. high level on the phase input causes the motor current flow from out a through the winding to out b current sensor this part contains a current sensing resistor (r s ), a low pass filter (r c , c c ) and three comparators. only one comparator is active at a time. it is acti- vated by the input logic according to the current level chosen with signals i o and i 1 . the motor current flows through the sensing re- sistor r s . when the current has increased so that the volt- age across r s becomes higher than the refer- ence voltage on the other comparator input, the comparator goes high, which triggers the pulse generator. the max peak current i max can be defined by: i max = v ref 10 r s figure 1 electrical characteristics (continued) symbol parameter test condition min. typ. max. unit protection t j thermal shutdown temperature - 170 - c UDN2916A 4/8
single-pulse generato r the pulse generator is a monostable triggered on the positive going edge of the comparator output. the monostable output is high during the pulse time, t off , which is determined by the time compo- nents r t and c t . t off = 1.1 r t c t the single pulse switches off the power feed to the motor winding, causing the winding current to decrease during t off . if a new trigger signal should occur during t off , it is ignored. output stage the output stage contains four darlington transis- tors (source drivers) four saturated transistors (sink drivers) and eight diodes, connected in two h bridge. the source transistors are used to switch the power supplied to the motor winding, thus driving a constant current through the winding. it should be noted however, that is not permitted to short circuit the outputs. internal circuitry is added in order to increse the accuracy of the motor current particularly with low current levels. figure 2: principle operating sequence UDN2916A 5/8
v s , v ss , v ref the circuit will stand any order of turn-on or turn- off the supply voltages v s and v ss . normal dv/dt values are then assumed. preferably, v ref should be tracking v ss during power-on and power-off if v s is established. application informations (note 1) some stepper motors are not designed for contin- uous operation at maximum current. as the circuit drives a constant current through the motor, its temperature might increase exceedingly both at low and high speed operation. also, some stepper motors have such high core losses that they are not suited for switch mode current regulation. unused inputs should be connected to proper voltage levels in order to get the highest noise im- munity. as the circuit operates with switch mode current regulation, interference generation problems might arise in some applications. a good measure might then be to decouple the circuit with a 100nf capacitor, located near the package between power line and ground. the ground lead between r s , and circuit gnd should be kept as short as possible. a typical application circuit is shown in fig. 3. note that c t must be npo type or similar else. to sense the winding current, paralleled metal film resistors are recommended (r s ) note 1 - other information is available as "smart power development system": hwpc2916a. figure 3: typical application circuit. UDN2916A 6/8
dim. mm inch min. typ. max. min. typ. max. a 4.320 0.170 a1 0.380 0.015 a2 3.300 0.130 b 0.410 0.460 0.510 0.016 0.018 0.020 b1 1.400 1.520 1.650 0.055 0.060 0.065 c 0.200 0.250 0.300 0.008 0.010 0.012 d 31.62 31.75 31.88 1.245 1.250 1.255 e 7.620 8.260 0.300 0.325 e 2.54 0.100 e1 6.350 6.600 6.860 0.250 0.260 0.270 e1 7.620 0.300 l 3.180 3.430 0.125 0.135 m 0? min, 15? max. powerdip 24 a1 b e b1 d 13 12 24 1 l a e1 a2 c e1 sdip24l m outline and mechanical data UDN2916A 7/8
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