User manual JRC NJU39612E2

[. . . ] Data 7, TTL/CMOS level, input to set data bit 7 in data word. Data 6, TTL/CMOS level, input to set data bit 6 in data word. Data 5, TTL/CMOS level, input to set data bit 5 in data word. Data 4, TTL/CMOS level, input to set data bit 4 in data word. [. . . ] The address pin control data transfer to the two internal D-type registers. Data is transferred according to figure 7 and on the positive edge of the write signal. Output Output Output Actual Gain error Correct Endpoint non-linearity More than 2 bits Less than 2 bits Negative difference Positive difference Offset error Input Input Full scale Input Figure 3. Differential non-linearity of more than Differential non-linearity of less than 1 bit, output is non-monotonic. 1 bit, output is monotonic. Figure 5. Non-linearity, gain and offset errors. NJU39612 Current Direction, Sign1 & Sign2 These bits are transferred from D7 when writing in the respective DA register. A0 must be set according to the data transfer table in figure 7. DA1 and DA2 These are the two outputs of DAC1 and DAC2. Input to the DACs are internal data bus (Q61 . . . Reference Voltage VRef VRef is the analog input for the two DACs. Special care in layout, gives a very low voltage drop from pin to resistor. Any VRef between 0. 0 V and VDD can be applied, but output might be non-linear above 3. 0 V. Power-on Reset This function automatically resets all internal flip flops at power-on. This results in VSS voltage at both DAC outputs and all digital outputs. Reset If Reset is not used, leave it disconnected. Reset can be used to measure leakage currents from VDD. I2 [mA] T max T2 [mNm] Tnom Tmin I I1 [mA] T1 [mNm] Figure 6a. Assuming that torque is proportional to the current in resp. winding it is possible to draw figure 8b. Figure 6b. An example of accessible positions with a given torque deviation/fullstep. Note that 1:st µstep sets highest resolution. Data points are exaggerated for illustration purpose. TNom = code 127. CS 0 0 1 A0 0 1 X Data Transfer D7 --> Sign1, (D6--D0) --> (Q61--Q01) D7 --> Sign2, (D6--D0) --> (Q62--Q02) No Transfer Figure 7. Table showing how data is transfered inside NJU39612. NJU39612 s ABSOLUTE MAXIMUM RATINGS Parameter Pin no. [. . . ] The rotor and load inertia play a big role at higher speeds. Unlike the DC motor, the stepper motor is a synchronous motor and does not change its speed due to load variations. Examining a typical stepper motor's torque-versus-speed curve indicates a sharp torque drop-off for the "start-stop without error" curve. This can easily be accomplished and any two adjacent data will make up a microstep position. [. . . ]