The UDN2916B , UDN2916EB, and UDN2916LB motor drivers are designed to drive the two windings of a bipolar stepper motor or bidirectionally control two DC motors. Both bridges are capable of sustaining 45v and include internal pulse width modulation (PWM) to control the output current to 750ma. The output has been optimized for low output saturation voltage drop (less than 1.8v total supply plus 500mA sink). For PWM current control, the maximum output current is determined by user selection of the reference voltage and sense resistor. Two logic level inputs select output current limits of 0, 33, 67, or 100 % of maximum level. The phase input of each bridge determines the direction of the load current. These bridges include ground clamps and flyback diodes to prevent induced transients. An internally generated delay prevents cross currents when switching current directions. No special power-up sequence is required. Thermal protection circuitry disables the output if the die temperature exceeds the safe operating limit. The UDN2916B utilizes a 24-pin dual-in-line plastic batwing assembly with a copper leadframe and heatsink for improved power dissipation. The UDN2916EB is supplied by a 44 lead power supply PLCC for surface mount applications. The UDN2916LB is a 24-lead surface mount SOIC. Their batwing construction provides maximum package power dissipation in the smallest possible build. The UDN2916B/EB/LB can be used for -40°C to +85°C operation. To order, change the prefix from "UDN" to "UDQ". These devices are also available on special order for operation at +105°C. The LB package is available in a lead-free version (100% matte tin leadframe). Features: 750mA continuous output current; 45V output holding voltage; internal clamp diode; internal PWM current control; low output saturation voltage; internal thermal shutdown circuit; similar to dual PBL377, UC3770

The PWM current controlled UDN2916B/EB/LB dual bridge is designed to drive both windings of a bipolar stepper motor. The output current is sensed and controlled independently in each bridge by an external sense resistor (RS), an internal comparator, and a monostable multivibrator. When the bridge opens, the current in the motor windings increases and is sensed by the external sense resistor until the sensed voltage (VSENSE) reaches the level set at the comparator input: ITRIP=VREF/10 RS The comparator then triggers a single steady state, thereby turning off the source driver of the bridge. Due to internal logic and switching delays, the actual load current peak will be slightly above the trip point (especially for low inductance loads). This delay (td) is typically 2 microseconds. After shutdown, the motor current decays and circulates through the ground clamp diode and receiver transistor. The off time of the source driver (and therefore the magnitude of the current reduction) is determined by the external RC timing component of the monostable, where toff = RTCT in the range of 20 kΩ to 100 kΩ and 100 pF to 1000 pF. The fixed off time should be short enough to keep current chopping above the audible range (<46 microseconds) and long enough to properly regulate the current. Since only slow decay current control is available, short off-times (<10 μs) require extra effort to ensure proper current regulation. Factors that can negatively impact the ability to properly regulate current when using short circuit time include: higher motor supply voltages, light loads, and longer than necessary blank times. When the source driver is re-enabled, the winding current (induced voltage) is again allowed to rise to the comparator's threshold. This cycle repeats to keep the average current in the motor windings at the desired level. Loads with high distributed capacitance can cause high on-current peaks. This spike (appearing on RS) will try to trip the comparator, causing incorrect current control or high frequency oscillation. An external RCCC delay should be used to further delay the action of the comparator. Depending on the load type, many applications do not require these external components (sensing connected to E).

Logic control of the two logic level inputs (L0 and I1) of the output current allows digital selection of the motor winding current at 100%, 67%, 33% or 0% of the maximum level of the meter. The 0% output current condition turns off all drivers in the bridge and can be used as an output enable function. Current Control Truth Table l0 I1 Output Current LLV REF/10 RS=ITRIP HLV REF/15 RS=2/3 ITRIP LHV REF/30 RS=1/3 ITRIP H 0 These logic stage inputs greatly enhance the μP control drive format accomplish. During half-step operation, l0 and l1 allow the μP to control the motor with constant torque between all positions in eight steps typical of the application sequence. This is done by digitally selecting 100% drive current when only one phase is on and 67% drive current when both phases are on. A logic high on l0 and l1 turns off all drivers to allow fast current decay when switching phases. This helps ensure proper operation of the motor at high step rates. A logic control input can also be used to select a reduced current level (and reduced power consumption) for "hold" conditions and/or increased current (and available torque) for start-up conditions. Generally speaking, the phase input of each bridge determines the direction of motor winding current flow. An internally generated dead time (about 2 μs) prevents cross currents that can occur when switching phase inputs. All four drivers in the bridge output can be turned off between two steps (l0=l1 382 ; 2.4v), resulting in fast current decay through the internal output clamp and flyback diode. In half-step and high-speed applications, fast current decay is required. The phase, l0, and I1 inputs float high. Changing the reference voltage (VREF) provides continuous control of peak load current for microstepping applications. Thermal protection circuitry shuts down all drivers when the junction temperature reaches +170°C. It is only used to protect the device from faults caused by excessive junction temperature and should not be meant to allow output short circuits. The output drivers are re-enabled when the junction temperature drops to +145°C. The UDN2916B/EB/LB output drivers are optimized for low output saturation voltages of less than 1.8 V (source plus sink) total output voltage at 500 mA. Under normal operating conditions, when combined with the excellent thermal performance of the batwing assembly design, this allows both bridges to operate simultaneously and continuously at 500 mA.

UDN2916B dimension unit: inches (control dimension)

Allegro MicroSystems, Inc. reserves the right to deviate from detailed specifications at any time to improve the design of its products. The information contained herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use or for any infringement of patents or other rights of third parties that may result from its use.
Note: 1. Mesh lead frame. The indicated wires are internally integrated. 2. Lead spacing tolerances are non-cumulative. three. Within the limits shown, the exact body and lead configuration is selected by the supplier.