NJM3774 New Japan Radio, NJM3774 Datasheet
NJM3774
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NJM3774 Summary of contents
Page 1
... GENERAL DESCRIPTION The NJM3774 is a switch-mode (chopper), constant- current driver with two channels: one for each winding of a two-phase stepper motor. The NJM3774 is equipped with a TTL level compatible Disable input to simplify half-stepping operation. The circuit is well suited for microstepping applications together with the matching dual DAC NJU39610 ...
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... Disable input (TTL level compatible) for channel 2. When HIGH, all four output transistors are turned 2 off, which results in a rapidly decreasing output current to zero Phase HIGH 2 HIGH. 2 NJM3774 Phase Phase GND GND 5 18 NJM ...
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... FUNCTIONAL DESCRIPTION Each channel of the NJM3774 consists of the following sections: an output H-bridge with four transistors, capable of driving up to 1000mA continuous current to the motor winding; a logic section that controls the output transistors; an S-R flip-flop; and a comparator. The clock-oscillator is common to both channels. Constant current control is achieved by switching the output current to the windings. This is done by sensing the peak current through the winding via a resistor, R turn-on period ...
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... Logic – 17 GND 820 NJM3774 Symbol Min - -1200 -55 stg ...
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... kohm Symbol Conditions Rth DIP package. J-GND Rth DIP package. Note 2. J-A Rth PLCC package. J-GND Rth PLCC package. Note 2. J-A 2 PCB copper area with free air convection 26.5 kHz. NJM3774 T +125 C. J Min Typ - mA 160 50 mV 1.4 2 ...
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... Increasing the time constant may result in unstable switching. The time constant should be adjusted by changing the C value 3300 pF GND (V CC Figure 6. Typical stepper motor driver application with NJM3774. input, the voltage control range can be increased 450 0 MM1 ...
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... It is not possible to use a motor that is rated for the same voltage as the actual supply voltage. Only rated current needs to be considered. Typical motors to be used together with the NJM3774 have a voltage rating while the supply voltage usually ranges from ...
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... Modifying the current levels must be done by bringing the reference voltage up (or down) from its nominal value correspondingly. This can be done by using DACs or simple resistor divider networks, as shown in figure 9. The NJM3774 is designed to handle about 1.4 times higher current in one channel on mode, for example 700 mA per winding in the full-step position, and 1000 mA in the half-step position. ...
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... V (V) CE Sat 1.2 1.0 0.8 0.6 0.4 0 0.20 0.40 0.60 0.80 I (A) M Figure 14. Typical upper transistor saturation voltage vs. output current NJM3774 V (V) CE Sat 1.2 1.0 0.8 0.6 0.4 0.2 150 0 0 0.20 0.40 0.60 I (A) M Figure 12. Typical lower transistor saturation voltage vs. output current The specifications on this databook are only given for information , without any guarantee as regards either mistakes or omissions ...