MAX22212

The MAX22212 integrates a high current 36V, 7.6A_MAX H-Bridge to drive one Brushed DC motor or one half of a stepper motor. The H-Bridge FETs feature very low impedance, resulting in high driving efficiency and low heat generation. The typical total R_ON (high-side + low-side) is 0.125Ω. The H-Bridge can be PWM controlled by using three logic inputs (DIN1, DIN2, and EN).

The MAX22212 features an accurate current drive regulation (CDR), which can be used to limit the start up current of a brushed DC motor or to control the phase current for stepper operation. The bridge output current is sensed by a non-dissipative integrated current sensing (ICS) and it is then compared with a user configurable set point (ITRIP). When the bridge current exceeds the setpoint, the device enforces the decay for a fixed OFF-time (t_OFF). Four different decay methods are supported (Slow Decay, Fast Decay, and two Mixed Decay modes). The non-dissipative ICS eliminates the bulky external power resistors normally required for this function resulting in a dramatic space and power saving compared with mainstream applications based on the external sense resistor.

A current proportional to the internally-sensed motor current is output to the external pins (ISENA, ISENB). By connecting an external resistor from these pins to GND, a voltage proportional to the motor current is generated. The voltage across this resistor can be used as inputs to ADCs of an external motor controller if motion control algorithm requires the current/torque information.

In addition, one open-drain output (CDR pin) is asserted every time the internal current regulation takes control of the driver so that the activity of the internal current loop can be monitored.

The maximum user configurable full-scale current (I_{FS_MAX}) can be set up to 7.6A limited by the overcurrent protection (OCP). An external resistor connected from REF to GND sets the full-scale current (I_FS) threshold. An integrated sinusoidal 4-bit DAC allows the user to dynamically modify the current regulation set-point (I_TRIP) from zero to IFS. Because of thermal considerations, the recommended maximum RMS current on a standard 4-layers PCB is 4A_RMS.

In applications in which the requirement of maximum full-scale current is less than 3.8A and high current control accuracy is desired, the half full scale (HFS) logic input pin can be set high to halve the current rating and double the low-side FET R_ON. This results in better current control loop accuracy in the bottom end of the current range. The MAX22212 features overcurrent protection (OCP), thermal shutdown (TSD), and undervoltage lockout (UVLO) protection. An open-drain active low FAULT pin is activated every time a fault condition is detected. During thermal shutdown and undervoltage lockout events, the driver is disabled until normal operations are restored.

The MAX22212 is available into a small TQFN32 5mm x 5mm package or in a TSSOP28 4.4mm x 9.7mm package.

APPLICATIONS

• Stepper-Motor Driver
• Brushed DC Motor Driver
• Solenoid Driver
• Latched Valves