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Ordering number: EN5505B
Monolithic Digital IC
LB1845
PWM Current Control Stepping Motor Driver
Overview
The LB1845 is a PWM current control type stepping motor driver that uses a bipolar drive scheme. It is particularly suitable for driving carriage and paper feed stepping motors in printers and similar products.
Package Dimensions
unit: mm 3147A-DIP28H
[LB1845]
Features
* * * * PWM current control (fixed off time scheme) Digital load current selection function Sustained output voltage: 45 V Built-in thermal shutdown circuit
SANYO: DIP28H
Specifications
Absolute Maximum Ratings at Ta = 25C
Parameter Motor supply voltage Peak output current Continuous output current Logic block supply voltage Logic input voltage range Emitter output voltage Allowable power dissipation Operating temperature Storage temperature Symbol VBB IOPEAK IOMAX VCC VIN VE Pd max1 Pd max2 Topr Tstg Independent IC With an arbitrarily large heat sink tW = 20 S Conditions Ratings 45 1.75 1.5 7.0 -0.3 to VCC 1.0 3.0 20.0 -20 to +85 -55 to +150 Unit V A A V V V W W C C
Recommended Operating Ranges at Ta = 25C
Parameter Motor supply voltage Logic block supply voltage Reference voltage Symbol VBB VCC VREF Conditions Ratings 10 to 44.5 4.75 to 5.25 1.5 to 7.5 Unit V V V
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TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
D3096HA (OT) No. 5505-1/7
LB1845 Electrical Characteristics at Ta = 25C, VBB = 38 V, VCC = 5 V, VREF = 5 V
Parameter [Output Block] Output stage supply voltage IBB ON IBB OFF VO(sat)1 Output saturation voltage 1 VO(sat)2 VO(sat)3 VO(sat)4 Output leakage current Sustained output voltage [Logic Block] Logic supply current ICC ON ICC OFF VIH VIL IIH IIL VREF/VSENSE TS VIH = 2.4 V VIL = 0.8 V I0 = 0.8 V, I1 = 0.8 V Current control threshold voltage I0 = 2.4 V, I1 = 0.8 V I0 = 0.8 V, I1 = 2.4 V Thermal shutdown temperature Note: *Design guaranteed value -10 9.5 13.5 25.5 10 15 30 170 10.5 16.5 34.5 C I0 = 0.8 V, I1 = 0.8 V I0 = 2.4 V, I1 = 2.4 V 2.4 0.8 10 19.5 15.5 25.3 20.1 mA mA V V A A IO(leak)1 IO(leak)2 V(sus) IO = +1.0 A sink IO = +1.5 A sink IO = -1.0 A source IO = -1.5 A source VO = VBB sink VO = 0 V source * -50 45 12 0.7 1.2 1.4 1.1 1.3 16 0.9 1.4 1.7 1.3 1.6 50 mA mA V V V V A A V Symbol Conditions Ratings min typ max Unit
Input voltage
Input current
Truth Table
ENABLE L L H PHASE H L -- OUT A H L OFF OUT B L H OFF
I0 L H L H
I1 L L H H
Output current VREF / (10 x RE) = IOUT VREF / (15 x RE) = IOUT x 2/3 VREF / (30 x RE) = IOUT x 1/3 0
Note: Outputs go off when ENABLE is high or in the I0 = I1 = high state.
Pin Assignment
No. 5505-2/7
LB1845
Block Diagram
Application Circuit Diagram
No. 5505-3/7
LB1845 Pin Functions
Pin no. 1, 14 2 13 3 12 4, 11 6 7 8 9 15 27 16 26 17 25 18 Pin VBB SENSE1 SENSE2 E1 E2 D-GND OUT 1B OUT 1A OUT 2B OUT 2A GND RC1 RC2 VREF1 VREF2 PHASE1 PHASE2 Ground Used to set the output off time for the switched output signal. The fixed off times are set by the capacitors and resistors connected to these pins. toff = CR. Output current settings The output current is determined by the voltage (in the range 1.5 to 7.5 V) input to these pins. Output phase switching inputs. High-level input: OUT A = high, OUT B = low Low-level input: OUT A = low, OUT B = high 24 19 ENABLE1 ENABLE2 Output on/off settings High-level input: output off Low-level input: output on 22, 23 21, 20 28 I01, I11 I02, I12 VCC Digital inputs that set the output current The output currents can be set to 1/3, 2/3, or full by setting these pins to appropriate combinations of high and low levels. Logic block power supply Internal diode anode connection Outputs Output stage power-supply voltage Set current detection pins. Connect these pins, fed back through noise filters, to E1 and E2. The set current is controlled by the resistors Re inserted between these pins and ground. Function
Timing chart for pin switching operations during PWM drive
Figure 1 Switching Waveforms
toff: Output off time. Determined by external capacitor and resistor Ct and Rt. (toff = Ct x Rt) td: Delay time between the point the set current is sensed at the SENSE pin and the point the output turns off.
No. 5505-4/7
LB1845 Usage Notes 1.External diode Since this IC adopts a system based on lower side transistor switching drive, an external diode for the regenerative current that occurs during switching is required between VBB and VOUT. Use a Schottky barrier diode with a low feedthrough current. 2.Noise filters Since spike noise (see Figure 1) occurs when switching to the on state due to the external diode's feedthrough current, applications must remove noise from the SENSE pin with a noise filter (Cc, Rc) between the E pin and the SENSE pin. However, note that if the values of Cc and Rc are too large, the SENSE voltage rise will be slowed, and the current setting will be shifted towards a higher current level. 3.VREF pin It is possible to change the output current continuously by continuously changing the VREF pin voltage. However, this voltage cannot be set to 0 V. The VREF pin input impedance is 26 k (30%) when VREF is 5 V. Since this pin is used to set the output current, applications must be designed so that noise does not appear on this pin's input. 4.GND pin Since this IC switches large currents, care must be taken to avoid ground loops when the IC is mounted in the application. The section of the PCB that handles large currents should be designed with a low-impedance pattern, and must be separated from the small signal sections of the circuit. In particular, the ground for the sense resistor Re must be as close as possible to the IC ground. 5.Operation in hold mode There are cases where a current somewhat larger than the current setting may flow in hold mode (light load mode). Since this IC adopts a lower side switching, lower side sense system, the emitter voltage falls and the sense voltage goes to 0 when the switching state goes to off. The circuit then always turns the output on after the toff period has elapsed. At this time, due to the light load, the existence of the time td, and the fact that the output goes on even if the output current is higher than the set current, the output current will be somewhat higher than the set current. Applications should set the current setting somewhat lower than required if this occurs. 6.Function for preventing the upper and lower outputs being on at the same time This IC incorporates a built-in circuit that prevents the through currents that occur when the phase is switched. The table lists the output on and off delay times when PHASE and EANBLE are switched.
Sink side On delay time When PHASE is switched Off delay time On delay time When ENABLE is on Off delay time 10 s 1.5 s 9 s 1.5 s Source side 9 s 3 s 9 s 6.5 s
7.1-2 phase excitation and the double 1-2 phase excitation control sequence To reduce the vibration that occurs when the motor turns, this IC supports 1-2 phase excitation and double 1-2 phase excitation by using the output current setting digital input pins I0 and I1 without changing the VREF pin voltage. Tables 1 and 2 list that control sequence, and Figure 2 and Figure 3 present the composite vector diagram for this sequence.2. Noise filters Table 1 [1-2 phase excitation] 1/2 step
ENABLE1 = ENABLE2 = 0 Phase A No. 0 1 2 3 4 5 6 7 PH1 0 0 * 1 1 1 * 0 I11 0 0 1 0 0 0 1 0 I01 0 1 1 1 0 1 1 1 Current value 1 2/3 0 2/3 1 2/3 0 2/3 PH2 * 0 0 0 * 1 1 1 I12 1 0 0 0 1 0 0 0 Phase B I02 1 1 0 1 1 1 0 1 Current value 0 2/3 1 2/3 0 2/3 1 2/3
No. 5505-5/7
LB1845 Table 2 [Double 1-2 phase excitation] about 1/4 step
ENABLE1 = ENABLE2 = 0 Phase A No. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 PH1 0 0 0 0 * 1 1 1 1 1 1 1 * 0 0 0 I11 0 0 0 1 1 1 0 0 0 0 0 1 1 1 0 0 I01 0 0 1 0 1 0 1 0 0 0 1 0 1 0 1 0 Current value 1 1 2/3 1/3 0 1/3 2/3 1 1 1 2/3 1/3 0 1/3 2/3 1 PH2 * 0 0 0 0 0 0 0 * 1 1 1 1 1 1 1 I12 1 1 0 0 0 0 0 1 1 1 0 0 0 0 0 1 Phase B I02 1 0 1 0 0 0 1 0 1 0 1 0 0 0 1 0 Current value 0 1/3 2/3 1 1 1 2/3 1/3 0 1/3 2/3 1 1 1 2/3 1/3
Composite Vector Diagram
Figure 2 Composite Vector Diagram for the Sequence in Table 1 (1/4 cycle)
Figure 3 Composite Vector Diagram for the Sequence in Table 2 (1/4 cycle)
No. 5505-6/7
LB1845
s No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury, death or property loss. s Anyone purchasing any products described or contained herein for an above-mentioned use shall: Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated with such use: Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally. s Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of December, 1996. Specifications and information herein are subject to change without notice. No. 5505-7/7

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