MAX22211

The MAX22211 is a dual 36V, 3.8AMAX H-bridge. It can be used to drive two brushed DC motors or a single stepper motor. The H-bridge FETs have very low impedance resulting in high driving efficiency and low heat generation. The typical total R_ON (high-side + low-side) is 0.25Ω. Each H-bridge can be individually pulse-width modulation (PWM)-controlled using three logic inputs (DIN1, DIN2, EN).

The MAX22211 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 user configurable threshold (I_TRIP). When the bridge current exceeds the I_TRIP threshold, 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 bulky external power resistors which are normally required for this function resulting in a dramatic space and power saving compared with mainstream applications using external sense resistors.

The internally measured current of the two full bridges are mirrored on pins ISENA and ISENB. By connecting external resistors to these pins to GND, voltages proportional to the motor currents are generated. The voltage across these external resistors can be used as inputs to analog-to-digital converters (ADCs) of an external motor controller if the motion control algorithm requires the load current or torque information.

In addition, two open-drain output pins (CDRA, CDRB) are asserted every time the internal current regulation takes control of the driver. This allows the external controller to monitor the activity of the internal current loop.

The maximum user configurable current regulation threshold (I_{TRIP_MAX}) can be set up to 3.8A and is limited by the Overcurrent Protection (OCP). The ITRIP current thresholds can be set independently for the two full bridges by connecting external resistors from pins REFA and REFB to GND. Because of thermal considerations, the recommended maximum RMS current for standard four-layer PCBs is 2A_RMS per H-bridge.

The MAX22211 features 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 TSD and UVLO events, the driver is three-stated until normal operations are restored.

APPLICATIONS

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