NTE1857
Integrated Circuit Stepper Motor Driver

Description:
The NTE1857 is designed to drive a two-phase stepper motor in the bipolar mode, The circuit of four input sections, a logic decoding/sequencing section, two driver-stages for the motor coils, and an output to indicate the Phase A drive state.

Features:
- Single Supply Operation: +7.2V to +16.5V
- 350mA/Coil Drive Capability
- Clamp Diodes Provided for Back-EMF Suppression
- Selectable CW/CCW and Full/Half Step Operation
- Selectable High/Low Output Impedance (Half Step Mode)
- TTL/CMOS Compatible Inputs
- Input Hysteresis: 400mV Min
- Phase Logic Can Be Initialized to Phase A
- Phase A Output Drive State Indication (Open-Collector)

Info as pdf-file
NTE-ECG replacement list as pdf-file
NTE-ECG diagrams

Absolute Maximum Ratings: (Note 1)
Supply Voltage, VM................................................................ +18V
Clamp Diode Cathode Voltage (Pin1), VD.........................................VM +5.0V
Driver Output Voltage (Pins 2, 3, 14, 15), VOD.....................................VM +6.0V
Driver Output Current/Coil, IOD...................................................±500mA
Input Voltage (Pins 7, 8, 9, 10), Vin.......................................... -0.5 to +7.0V
Bias/Set Current (Pin6), IBS.......................................................-10mA
Phase A Output Voltage (Pin11), VOA................................................ +18V
Phase A Sink Current (Pin11), IOA.................................................. 20mA
Junction Temperature, TJ.........................................................+150°C
Storage Temperature Range, Tstg.......................................... -65° to +150°C
Thermal Resistance, Junction-to-Ambient (No Heat Sink), RthJA.....................45°C/W

Note 1. “Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices should be operated at these limits. The “Electrical Characteristics” tables provide conditions for actual device operation.

Application Information:

General
The NTE1857 integrated circuit is designed to drive a stepper positioning motor in applications such as disk drives and robotics. The outputs can provide up to 350mA to each of two coils of a two-phase motor. The outputs change state with each low-to-high transition of the clock input, with the new output state depending on the previous state, as well as the input conditions on Pins 8, 9, and 10.

Outputs (Pins 2, 3, 14, 15)
The outputs (L1-L4) are high current outputs, which when connected to a two-phase motor, provide two full-bridge configurations. The polarities applied to the motor coils depend on which transistor (QH or QL) of each output is on, which in turn depends on the inputs and the decoding circuitry. The maximum sink current available at the outputs is a function of the resistor connected between Pin6 and GND (see section on Bias/Set operation). Whenever the outputs are to be in a high impedance state, both transistors (QH and QL) of each output are off.

VD (Pin1)
This pin allows for provision of a current path for the motor coil current during switching, in order to suppress back-EMF voltage spikes. Pin1 is normally connected to VM (Pin16) through a diode (zener or regular), a resistor, or directly. The peak instantaneous voltage at the outputs (Pins 2, 3, 14, and 15) must not exceed VM by more than 6 volts. The voltage drop across the internal clamping diodes must be included in design. Parasitic diodes across each QL of each output provide for a complete circuit path for the switched current.

Full/Half Step (Pin9)
When this input is at a Logic “0” (< 0.8 volts), the outputs change a full step with each clock cycle, with the sequence direction depending on the CW/CCW input (Pin10). There are four steps (Phase A,B,C,D) for each complete cycle of the sequencing logic. Current flows through both motor coils during each step.
When taken to a Logic “1” (> 2.0 volts), the outputs change a half step with each clock cycle, with the sequence direction depending on the CW/CCW input (Pin10). Eight steps (Phases A-H) result for each complete cycle of the sequencing logic. Phases A,C,E and G correspond (in polarity) to the phases A, B, C, and D, respectively, of the full step sequence. Phases B, D, F and H provide current to one motor coil, while de-energizing the other coil. The condition of the outputs of the de-energized coil depends on the OIC input (Pin8).

OIC (Pin8)
The output impedance control input determines the output impedance to the de-energized coil when operating in the half-step mode. When the outputs are in Phase B, D, F or H and this input is at a Logic “0” (< 0.8V), the two outputs to the de-energized coil are in a high-impedance condition-QL and QH of both outputs are off. When this input is at a Logic “1” (> 2.0V), a low impedance output is provided to the de-energized coil as both outputs have QH on (QL off). To complete the low impedance path requires connecting Pin1 (VD) to Pin16 (VM) as described elsewhere in this data sheet.


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