Features and advantages

Low RDS (open) output

over current protection (OCP)

Protection

Motor Diversion Short -circuit Protection

Electric wires to protect the battery protection short circuit

low power standby mode [123 ]

Metable pulse wide adjustment current limit

synchronous rectification

internal under pressure lock (UVLO)

cross-current protection

A4950 K is AEC-Q100-level qualification

commercial temperature level (A4950E: –40 ° C to 85 ° C)

Automobile temperature level (A4950K: –40 ° C to 125 ° C)

Packaging: 8 -pin SOICN, with external dew pads (suffix Lj)

Explanation

A4950 Design pulse width modulation (PWM) control for DC motor, its peak output current can reach ± 3.5 A, work work The voltage can reach 40 V.

Provide input terminals to control the speed and direction of the DC motor using PWM control signals using external applications. Provide internal simultaneous rectifier control circuits to reduce the power consumption during the low pulse width adjustment operation.

Internal circuit protection includes over -current protection, short -circuit of motor lead to ground or power supply, lagging heat shutdown, VBB under voltage monitoring and cross -current protection.

For high -environment work temperature applications, automobile -level equipment (A4950K) is provided. The K -level device is tested within the extended temperature and voltage range to ensure that it meets the requirements in automotive or industrial applications.

A4950 uses a low section of 8 -needle SOICN packaging with naked hot pads (suffix LJ), without lead, 100%matte tin lead framework.

Function box diagram

Features

pulse width adjustment control time preface diagram

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Function description

Device operation

A4950 Design for operating DC motors. The output driver is low RDS (on), the N -channel DMOS driver, which has internal synchronous rectification functions to reduce power consumption. Output the current in the whole bridge through fixed closure of the time pulse width modulation (PWM) The control circuit is adjusted. IN1 and IN2 input allows dual -line control to the bridge.

The protection circuit includes internal heat shutdown to prevent short -circuit loads or short -circuit or power supply short circuits. The underwriting lock is prevented from damage, and the output is closed until the driver has enough voltage to work normally.

Standby mode

When the two input (INX) pins are as low as 1 milliseconds, the low -power standby mode is activated. Most internal circuits are disabled in low -power standby mode, including charge pumps and regulators. When the A4950 comes out of the standby mode, before sending any PWM command to the device, the charge pump should be allowed to reach its adjustment voltage (maximum delay 200 μs).

Internal PWM current control

Initially, the source of a pair of diagonal sources and the existence field effect tube output was enabled, the current flow through the motor winding, and the optional external current fluorine measurement resistor RS. When the voltage on the RS is equal to the comparator's trip value, the current influenza comparator resets the pulse width to modulate the lock memory. Then lock the memory to close the receiver and the source field effects transistor (hybrid attenuation mode).

VREF

Set the maximum restricted value by selecting the voltage of the RSX and VREF pin. The cross -guidance function is similar to the maximum value of the current limitation. The value is set by the following:

Among them, VREF is the input voltage on the VREF pin (V), and the input voltage on the VREF pin (V), RS is the resistance of the sensor (ω) on the LSS terminal.

Over -current protection

The current monitor will protect the damage caused by the short circuit of the IC. If the short circuit is detected, the IC will lock the fault and disable the output. The failure lock can only be removed by exiting the low -power standby mode or circulating the power supply to VBB. During the OCP incident, it may exceed the absolute maximum rated value in a short time before the device is locked.

Close

If the mold temperature increases to about 160 ° C, the output of the entire bridge will be disabled until the internal temperature drops below TTSDHYS. There is an internal UVLO on the VBB to prevent the output drive from opening when it is lower than the UVLO threshold.

braking

The braking function is achieved by enabling the chopping command (see the pulse width control and controlling the true value table), and the slow attenuation mode drives the device. Completed by high logic of two input applications. Because the DMOS switching two -way driving current can effectively make the BEMF short circuit generated by the motor, as long as the CHOP command is issued. The maximum current can be similar to VBEMF/RL. It should be noted that to ensure that the maximum rated value of the device will not exceed the device when the brake is worse: high -speed and high inertia load.

Synchronous rectification

When the internal fixed closing time cycle touchWhen a pulse width is sent to the closing cycle, the load current will be circulated again. The A4950 synchronizes rectifier function opens the appropriate DMOSFET during the current attenuation, and uses a low RDS (open) drive to effectively make the body diode short circuit. This significantly reduces power consumption. When the zero current level is detected, the synchronous rectifier will be closed to prevent the load current from reversing.

Mixed decay operation

These bridges work in a mixed decay mode. Refer to the bottom board below, when the trigger point is reached, the device enters the fast attenuation mode within a fixed closing time period of 50%. After this fast attenuation part, the device is switched to the slow attenuation mode at the remaining shutdown time. During the transition from fast decay to slow decay, the driver was forcibly closed due to cross -delay TCOD. Add this function to prevent shooting-mixed attenuation mode operations through the bridge. In this stagnation time " part