Designed for pulse-width modulated (PWM) current control of bipolar microstepping stepper motors, the A3972SB is capable of continuous output currents to ±1.5 A and operating voltages to 50 V. Internal fixed off-time PWM current-control timing circuitry can be programmed via a serial interface to operate in slow, fast, and mixed current-decay modes.
The desired load-current level is set via the serial port with two 6-bit linear DACs in conjunction with a reference voltage. The six bits of control allow maximum flexibility in torque control for a variety of step methods, from microstepping to full-step drive. Load current is set in 1.56% increments of the maximum value.
Synchronous rectification circuitry allows the load current to flow through the low rDS(on) of the DMOS output driver during the current decay. This feature will eliminate the need for external clamp diodes in most applications, saving cost and external component count, while minimizing power dissipation. Internal circuit protection includes thermal shutdown with hysteresis, transient-suppression diodes, and crossover-current protection. Special powerup sequencing is not required.
The A3972SB is supplied in a 24-lead plastic DIP with a copper batwing power tab. The power tab is at ground potential and needs no electrical isolation. The lead (Pb) free version has 100% matte tin leadframe plating.
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±1.5 A, 50 V Continuous Output Rating Low rDS(on) DMOS Output Drivers Optimized Microstepping via 6-Bit Linear DACs Programmable Mixed, Fast, and Slow Current-Decay Modes 4 MHz Internal Oscillator for Digital Timing Serial-Interface Controls Chip Functions Synchronous Rectification for Low Power Dissipation Internal UVLO and Thermal Shutdown Circuitry Crossover-Current Protection Precision 2 V Reference Inputs Compatible with 3.3 V or 5 V Control Signals Sleep and Idle Modes
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Load Supply Voltage, VBB ................ 50 V
Output Current, IOUT.................... ±1.5 A
Logic Supply Voltage, VDD................ 7.0 V
Logic Input Voltage Range,
VIN .......................... -0.3 V to VDD + 0.3 V
Reference Voltage, VREF ..................... 3 V
Sense Voltage (dc), VS ................. 500 mV
Package Power Dissipation,
PD ................................................... 3.1 W
Operating Temperature Range,
TA ................................. -20°C to +85°C
Junction Temperature, TJ ........... +150°C
Storage Temperature Range,
TS ............................... -55°C to +150°C
Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current rating or a junction temperature of 150°C.
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