參數(shù)資料
型號: 2917
廠商: Allegro MicroSystems, Inc.
元件分類: 基準(zhǔn)電壓源/電流源
英文描述: DUAL FULL-BRIDGE PWM MOTOR DRIVER
中文描述: 雙全橋PWM電機驅(qū)動
文件頁數(shù): 4/8頁
文件大?。?/td> 178K
代理商: 2917
2917
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
+
0
Dwg. WM-003-1A
V
PHASE
I
OUT
t
d
t
off
I
APPLICATIONS INFORMATION
PWM CURRENT CONTROL
The UDN2917EB dual bridge is designed
to drive both windings of a bipolar stepper
motor. Output current is sensed and con-
trolled independently in each bridge by an
external sense resistor (R
S
), internal com-
parator, 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
SENSE
) reaches the level set
at the comparator
s input:
I
TRIP
= V
REF
/10 R
S
The comparator then triggers the mon-
ostable which turns off the source driver of
the bridge. The actual load current peak will
be slightly higher than the trip point (espe-
cially for low-inductance loads) because of
the internal logic and switching delays. This
delay (t
d
) is typically 2
μ
s. After turn-off, the
motor current will normally decay, circulating
through the ground clamp diode and sink
transistor. The source driver
s off time (and
therefore the magnitude of the current de-
crease) is determined by the monostable
s
external RC timing components, where t
off
=
R
T
C
T
within the range of 20 k
to 100 k
and
200 pF to 500 pF.
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.
Special circuitry has been included to
prevent runaway current control when the
fixed off time (t
off
) is set too short. This
circuitry prevents the source driver from being
re-enabled until the load current has decayed
to below the I
TRIP
level.
PWM OUTPUT CURRENT WAVEFORM
LOAD CURRENT PATHS
Dwg. EP-006-1
RS
BB
V
BRIDGE ON
SOURCE OFF
ALL OFF
相關(guān)PDF資料
PDF描述
2918 DUAL FULL-BRIDGE PWM MOTOR DRIVER
2919 DUAL FULL-BRIDGE PWM MOTOR DRIVER
2920 20 MHz BIPOLAR LOGARITHMIC AMPLIFIER
2927 DUAL FULL-BRIDGE PWM MOTOR DRIVER
292A Low Cost Single and Multichannel Isolation Amplifier
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