A3950SLPTR-T IC

Technical Specifications of A3950SLPTR-T

Datasheet	A3950SLPTR-T datasheet
Category	Integrated Circuits (ICs)
Family	PMIC – Motor Drivers, Controllers
Manufacturer	Allegro MicroSystems, LLC
Series	–
Packaging	Tape & Reel (TR)
Part Status	Active
Motor Type – Stepper	–
Motor Type – AC, DC	Brushed DC
Function	Driver – Fully Integrated, Control and Power Stage
Output Configuration	Half Bridge (2)
Interface	Parallel
Technology	DMOS
Step Resolution	–
Applications	General Purpose
Current – Output	2.8A
Voltage – Supply	8 V ~ 36 V
Voltage – Load	8 V ~ 36 V
Operating Temperature	-20°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Package / Case	16-TSSOP (0.173″, 4.40mm Width) Exposed Pad
Supplier Device Package	16-TSSOP-EP

Introduction

The A3950SLPTR-T is a modular, high-performance integrated circuit developed for precise DC motor control. In this detailed article, we will delve into the A3950SLPTR-T’s characteristics, benefits, device operation, and application information, providing you with a thorough understanding of its capabilities and how to get the most out of this PWM motor driver IC.

Key Features and Benefits

Low RDS(on) Outputs

• The A3950SLPTR-T has low RDS(on) N-channel DMOS drivers, which reduce power dissipation and improve efficiency.

Overcurrent Protection

• In the event of an excessive current flow, this motor driver IC provides overcurrent protection to prevent harm to the attached motor or the IC itself.

Motor Lead Short-to-Supply Protection

• Built-in protection prevents motor lead short-circuits to the power supply, extending the life of your motor system.

Short-to-Ground Protection

• The A3950SLPTR-T also protects against ground shorts, increasing the safety of your motor-driven applications.

Sleep Function

• The IC incorporates a low current Sleep mode that disables unneeded internal circuitry to reduce power consumption while the driver is not in use.

Synchronous Rectification

• Internal synchronous rectification minimizes power consumption during PWM operation, resulting in greater overall efficiency.

Diagnostic Output

• The NFAULT pin provides a diagnostic tool for motor fault detection and troubleshooting by signaling any faults with the IC via an open drain output.

Internal Under voltage Lockout (UVLO)

• To ensure reliable functioning within specified voltage ranges, the IC has an under voltage lockout circuit.

Crossover-Current Protection

• Crossover-current protection aids in the prevention of IC damage during high-current conditions.

Device Operation

The A3950SLPTR-T is intended to control a single DC motor efficiently. It uses low RDS(on) N-channel DMOS drivers with internal synchronous rectification to reduce power dissipation. The PHASE and ENABLE inputs allow for simple two-wire motor control, and a MODE pin activates the braking function.

A Sleep mode is provided to reduce power consumption while the IC is not in use, and the IC provides protection against a variety of fault scenarios, including short circuits to earth, short circuits to the power supply, and thermal concerns.

● Logic Inputs

SLEEP, MODE, PHASE, and ENABLE are among the logic inputs on the IC. These inputs should not exceed a maximum voltage of 7 V, and high-value pull-up resistors should be used to limit current in the event of an overvoltage occurrence.

● VREG and Charge Pump

VREG provides power to the sink-side DMOS outputs and is internally monitored. For VREG, a decoupling capacitor (0.22 F) should be connected to ground. A charge pump also creates a supply above VBB to power the source-side DMOS gates. To ensure adequate pumping and to act as a reservoir, capacitors (0.1 F) should be connected between CP1 and CP2 and between VCP and VBB.

● Shutdown and Sleep Mode

In the event of excessive junction temperature, low voltage on VCP or VREG, or other fault conditions, the IC can shut down its outputs. Sleep mode reduces power usage by turning off various internal components. Allow a 1 ms gap after entering Sleep mode before applying PWM signals to allow the charge pump to settle.

● MODE and Braking

The MODE input switches between fast and slow decay modes. By using an enable chop command, slow decay mode is employed for braking. It is critical not to exceed device ratings, especially in high-speed and high-inertia braking circumstances.

● Diagnostic Output and TSD

The NFAULT pin is a diagnostic output that signals problems such as motor faults, undervoltage situations, or high die temperature. The IC can run to 160°C, but if the temperature rises over about 175°C, the full-bridge outputs will be disabled until the temperature drops below a hysteresis of 15°C.

Applications Information

● Power Dissipation.

To compute the A3950’s first-order power dissipation, first evaluate the full-bridge power consumption in each operation mode. During decay, synchronous rectification in the A3950 activates the low RDS(on) DMOS driver, shorting out the body diode. This significantly reduces full-bridge power dissipation. When both the source and sink drivers are turned on, the A3950 employs a 500 ns typical crossover delay to prevent shoot-through. The decay current path body diode carries current until the DMOS driver is turned on. This has an effect on power dissipation in high current, high ambient temperature applications. Motor specs and switching losses can potentially waste energy and degrade critical applications.

● SENSE Pin.

For current sensing, a low-value resistor can be connected between the SENSE pin and ground. The current sensing resistor should have an independent ground return to the star ground point to avoid ground-trace IR dips when detecting the output current level. This path should be as brief as feasible. The IR dips in the PCB can be severe for low value sense resistors and should be considered. When choosing a value for the sense resistor, keep in mind that the maximum voltage on the SENSE pin is 500 mV.

● Ground.

The location of a star ground should be as close to the A3950 as practicable. A ideal position for the star ground point is the copper ground plane just beneath the exposed thermal pad. For this purpose, the exposed pad might be linked to ground.

● Layout.

A strong ground plane should be used on the printed circuit board. The A3950 must be soldered directly onto the board for optimal electrical and thermal performance. A path for increased thermal dissipation is provided via an exposed pad on the underside of the A3950 package. The thermal pad should be soldered directly to the exposed surface of the PCB.

Thermal vias are used to transport heat from one layer of the PCB to another. The load supply pin, VBB, should be isolated as close to the device as possible with an electrolytic capacitor (typically 100 F) linked in parallel with a ceramic capacitor. To reduce lead inductance, the ceramic capacitors linked to VREG and between VCP and VBB, as well as CP1 and CP2, should be as close to the device’s pins as possible.

Conclusion

Finally, the A3950SLPTR-T is a powerful PWM motor driver IC with numerous functions and safeguards. Understanding its operation and application guidelines is critical for maximizing its potential in a variety of motor control applications. The A3950SLPTR-T can help you achieve precise and efficient motor control whether you’re creating robotics, automotive systems, or industrial machines.

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