UDQ2916EB Allegro Microsystems Inc, UDQ2916EB Datasheet - Page 6

• Manufacturer Part Number: UDQ2916EB
• Description: IC MOTOR DRIVER PWM DUAL 44PLCC
• Manufacturer: Allegro Microsystems Inc

Specifications of UDQ2916EB

• Applications: DC Motor Driver, Stepper Motor Driver
• Number Of Outputs: 2/1
• Current - Output: ±750mA
• Voltage - Load: 10 V ~ 45 V
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 44-LCC (J-Lead)
• Operating Current: 25mA
• Operating Temperature Classification: Industrial
• Package Type: PLCC
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.25V
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

2916
PWM CURRENT CONTROL
The UDx2916 dual bridges drive both windings of a bipolar
stepper motor. Output current is sensed and controlled
independently in each bridge by an external sense resistor, R
internal comparator, and monostable multivibrator.
When the bridge is turned on, current increases in the motor
winding and it is sensed by the external sense resistor until the
sense voltage, V
input:
The comparator then triggers the monostable, which turns off
the source driver of the bridge.
The actual load current peak will be slightly higher than the
trip point (especially for low-inductance loads) because of the
internal logic and switching delays. This delay, t
2 μs. After turn-off, the motor current decays, circulating
through the ground-clamp diode and sink transistor. The
source driver off-time (and therefore the magnitude of the
current decrease) is determined by the external RC timing
components of the monostable:
where:
The fi xed off-time should be short enough to keep the current
chopping above the audible range (< 46 μs) and long enough
to properly regulate the current. Because only slow-decay
current control is available, short off times (< 10 μs) require
additional efforts to ensure proper current regulation. Factors
that can negatively affect the ability to properly regulate the
current when using short off times include: higher motor-
supply voltage, light load, and longer than necessary blank
time.
When the source driver is re-enabled, the winding current (the
sense voltage) is again allowed to rise to the comparator’s
threshold. This cycle repeats itself, maintaining the average
motor winding current at the desired level.
Loads with high distributed capacitances may result in high
turn-on current peaks. This peak (appearing across R
attempt to trip the comparator, resulting in erroneous current
control or high-frequency oscillations. An external R
time delay should be used to further delay the action of the
comparator. Depending on load type, many applications will
not require these external components (SENSE connected to E).
R
C
T
T
= 20 to 100 kΩ, and
= 100 to 1000 pF.
SENSE
I
, reaches the level set at the comparator
TRIP
t
off
= V
= R
REF
T
C
/10 R
T
S
APPLICATIONS INFORMATION
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, is typically
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Dual Full-Bridge Motor Driver
+
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–
PWM OUTPUT CURRENT WAVE FORM
LOAD CURRENT PATHS
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 (508) 853-
5000
www.allegromicro.com
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5