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參數(shù)資料
| 型號(hào)： | ML4411 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Sensorless Spindle Motor Controller(無傳感器主軸電機(jī)控制器) |
| 中文描述： | 傳感器主軸電機(jī)控制器（無傳感器主軸電機(jī)控制器） |
| 文件頁數(shù)： | 8/14頁 |
| 文件大?。?/td> | 241K |
| 代理商： | ML4411 |
ML4411/ML4411A
8
REV. 1.0 10/10/2000
The motor will start more consistently and tolerate a wider
variation in open loop step rate if there is some damping
on the motor (such as head drag) during the open loop
modes.
The tolerance of the open loop step VCO acceleration
C2, and C
VCO
. For more optimum spin up times, these
variables can be digitally “calibrated” out by the
microprocessor using the following procedure:
1. Reset the IC by holding pin 16 low for at least 5
μ
s.
dF
dt
VCO
depends on the tolerances of K
VCO
, I
RAMP
, C1,
2. Go into open loop step mode with no current on
the motor and measure the difference between the
first two complete VCO periods with the PWM
signal at 50% duty cycle:
ENABLE E/A = (see below)
I
CMD
= 0V
PWM OUT = 50%
I(RAMP)
VCO/TACH OUT
PWM OUT
IN
MicroP
ML4411
Figure 7. Auto-Calibration of Open-Loop Step
Rate.
3. Compute a correction factor to adjust I
RAMP
current
by changing the PWM duty cycle from the
Micro (D.C.)
DC NEW
. .(
F
DESIRED
MEASURED
(
F
VCO
VCO
)
%
(
)
)
=
×
50
4. Use new computed duty cycle for open loop
stepping mode and proceed with a normal start-up
sequence.
If this auto calibration is used ENABLE E/A can be tied
permanently high, eliminating a line from the Micro.
Since there is offset associated with the Phase Detector
Error Amp (E/A), more current than is being injected by
I
RAMP
may be taken out of pin 20 if the offset is positive
(into pin 20) if the error amp were enabled during the
open loop stepping mode. In that case, V
VCO
would not
rise and the motor would not step properly. The effect of
E/A offset can also be canceled out by the auto calibration
algorithm described above allowing the E/A to be
permanently enabled.
A
sC
V
OTA
=
1 875 10
4
.
PWM AND LINEAR CURRENT CONTROL
To facilitate speed control, the ML4411 includes two
current control loops — linear and PWM (figure 9). The
linear control loop senses the motor current on the I
SENSE
terminal through R
SENSE
. An internal current sense
amplifier’s (A2) output modulates the gates of the 3 N-
channel MOSFET’s when OTA OUT is tied to OTA IN, or
can modulate a single MOSFET gate tied to OTA OUT.
When operated in this mode, OTA IN is tied to 12V, and
N1-N3 are saturated switches. This method produces the
lowest current ripple at the expense of an extra MOSFET.
The linear current control modulates the gates of the
external MOSFET drivers. Amplifier A2 is a
transconductance amplifier which amplifies the difference
between I
CMD
and I
SENSE
. The transconductance gain of
A2 is:
g
m
=
1 875 10
4
.
The current loop is compensated by C
OTA
which forms a
pole given by
ω
P
OTA
C
=
9 375 10
4
.
This time constant should be fast enough so that the
current loop settles in less than 10% of T
VCO
at the
highest motor speed to avoid torque ripple to V
TH
mismatch of the N-Channel MOSFETs.
The I
SENSE
input pin should be kept below 1V. If I
SENSE
goes above 1V, a bias current of about –300
μ
A will flow
out of pin 12 and the N outputs will be inhibited. Bringing
I
SENSE
below 0.7V removes the bias current to its normal
level. For this reason, the noise filter resistor on the I
SENSE
pin (1K
on Figure 10) should be less than 1.5K
.
The noise filter time constant should be great enough to
filter the leading edge current spike when the N-FETs turn
on but small enough to avoid excessive phase shift in the
I
SENSE
signal.
OUTPUT DRIVERS
The motor’s source drivers (P1 thru P3) are open-collector
NPN’s with internal 16K
pull-up resistors. N3is inhibited
until P3 is within 1.4V (typ) of V
CC2
on the ML4411A.
Drivers N1 through N3 are totem-pole outputs capable of
sourcing and sinking 10mA. Switching noise in the
external MOSFETs can be reduced by adding resistance in
series with the gates.
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PDF描述 |
|---|---|
| ML4423 | 1, 2, or 3-Phase Variable Speed AC Motor Controller(一、二或三相可變速交流電機(jī)控制器) |
| ML4425 | Sensorless BLDC Motor Controller |
| ML4425CP | Sensorless BLDC Motor Controller |
| ML4425CS | Sensorless BLDC Motor Controller |
| ML4425IP | Sensorless BLDC Motor Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4411ACS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ML4411CS | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Sensorless Spindle Motor Controller |
| ML44126N | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:FOR OPTICAL INFORMATION SYSTEMS |
| ML44126R | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:FOR OPTICAL INFORMATION SYSTEMS |
| ML4420 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:ENHANCED SENSORLESS BLDC MOTOR CONTROLLER |
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