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參數(shù)資料
| 型號： | TDF5242 |
| 廠商： | NXP Semiconductors N.V. |
| 英文描述： | Brushless DC motor drive circuit |
| 中文描述： | 無刷直流電動機(jī)驅(qū)動電路 |
| 文件頁數(shù)： | 7/20頁 |
| 文件大?。?/td> | 108K |
| 代理商： | TDF5242 |
1997 Sep 12
7
Philips Semiconductors
Preliminary specification
Brushless DC motor drive circuit
TDF5242T
T
HE TIMING CAPACITOR
(CAP-TI)
Capacitor CAP-TI is used for timing the successive steps
within one commutation period; these steps include some
internal delays.
The most important function is the watchdog time in which
the motor EMF has to recover from a negative diode-pulse
back to a positive EMF voltage (or vice versa). A watchdog
timer is a guarding function that only becomes active when
the expected event does not occur within a predetermined
time.
The EMF usually recovers within a short time if the motor
is running normally (<<1 ms). However, if the motor is
motionless or rotating in the reverse direction, the time can
be longer (>>1 ms).
A watchdog time must be chosen such that it is long
enough for a motor without detectable EMF, however, it
must be short enough to detect reverse rotation. If the
watchdog time is made too long, then the motor may run in
the wrong direction (with little torque).
The capacitor is charged with a current of 57
μ
A from
0.2 to 0.3 V. Above this level, it is charged with a current of
5
μ
A up to 2.2 V only if the selected motor EMF remains in
the wrong polarity (watchdog function). At the end, or, if the
motor voltage becomes positive, the capacitor is
discharged with a current of 28
μ
A. The watchdog time is
the time taken to charge the capacitor, with a current of
5
μ
A, from 0.3 to 2.2 V.
To ensure that the internal delays are covered CAP-TI
must have a minimum value of 2 nF. For the watchdog
function a value for CAP-TI of 10 nF is recommended.
To ensure a good start-up and commutation, care must be
taken that no oscillations occur at the trailing edge of the
flyback pulse. Snubber networks at the outputs should be
critically damped.
Typical voltage waveforms are illustrated by Fig.4.
Miscellaneous functions
In addition to start-up and commutation control, the
TDF5242T provides the following functions:
Generation of the tacho signal FG
General purpose Operational Transconductance
Amplifier (OTA)
Possibilities of motor control
Direction function and brake function
High current and temperature protection.
T
HE
O
PERATIONAL
T
RANSCONDUCTANCE
A
MPLIFIER
(OTA)
The OTA is an uncommitted amplifier with a high output
current (40 mA) that can be used as a control amplifier or
as a level converter in a Switched Mode Power Supply
(SMPS). The common mode input range includes ground
(GND) and rises to V
P
1.7 V. The high sink current
enables the OTA to drive a power transistor directly in an
analog control amplifier or in a SMPS driver.
Although the gain is not extremely high (0.3 S), care must
be taken with the stability of the circuit if the OTA is used
as a linear amplifier as no frequency compensation is
provided.
Fig.4 Typical CAP-TI and V
MOT1
voltage waveforms in normal running mode.
If the chosen value of CAP-TI is too small, oscillations can occur in certain positions of a blocked rotor. If the chosen value is too large, then it is possible
that the motor may run in the reverse direction (synchronously with little torque).
handbook, full pagewidth
MGG994
VSWH
VMOT1
voltage
on CAP-TI
VSWM
VSWL
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相關(guān)代理商/技術(shù)參數(shù) |
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| TDF5242T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Brushless DC motor drive circuit |
| TDF685K35CB | 制造商:SHARMA 制造商全稱:Sharma Electro Components,Inc 功能描述:Tantalum Capacitors |
| TDF8530TH/N1,512 | 功能描述:音頻放大器 ClassAB 45W 65dB RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TDF8530TH/N1,518 | 功能描述:音頻放大器 ClassAB 45W 65dB RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TDF8530TH/N2,112 | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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