參數(shù)資料
型號(hào)： SAF7843HL
廠商： NXP Semiconductors N.V.
元件分類： 存儲(chǔ)器
英文描述： One chip CD audio device with integrated MP3-WMA decoder
封裝： SAF7843HL/M295<SOT486-1 (LQFP144)|<<http://www.nxp.com/packages/SOT486-1.html<1<Always Pb-free,;SAF7849HL/M245<SOT486-1 (LQFP144)|<<http://www.nxp.com/packages/SOT486-1.h
文件頁數(shù)： 48/93頁
文件大?。?/td> 396K
代理商： SAF7843HL
SAF784X_2
NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 May 2008
48 of 93
NXP Semiconductors
SAF784x
One chip CD audio device with integrated MP3/WMA decoder
6.5.10.7
Tacho
The tacho circuit accepts the tacho input on the tacho inputs T1, T2 and T3, coming from
the hall sensors on the spindle motor. The Tacho block measures the frequency of the
input pulses, and filters the measurements using a second-order low-pass filter to remove
noise on the tacho signal.
The measured tacho frequency can be read by the microprocessor, and can be used as a
frequency input to the motor control, and can be used to generate the tacho trip frequency
interrupt.
The relationship between the actual motor speed (in Hz) and the TachoFrequency[7:0]
value read back in register TACHO4, bit TACHOFREQUENCY is given by:
(7)
Where:
TachoFrequency[7:0] is the value read from register TACHO4; when doing CAV mode
motor control, it is compared to the motor frequency set point programmed in register
MotorFreqSet - an unsigned value
MotorFreq is the angular velocity in rounds per second (Hz)
Ktacho[7:0] is the gain value written to register TACHO1
2h: h is the number of hall sensors: 1 or 3, depending on motor and setting of bit
ONEPINMODE in register TACHO3
p is the number of motor pole-pairs, usually 1
f
s
is the sampling frequency of the filter; this can be configured via bit FSAMSEL in
register TACHO4
Tacho gain Ktacho:
The tacho gain, Ktacho[7:0] can be chosen so that the value read
from bit TACHOFREQUENCY in register TACHO2 is the motor frequency in Hz. However,
it is advisable to select Ktacho[7:0] such that a minimum amount of ripple is seen on the
measured tacho frequency. This must be tuned experimentally.
Tests have shown that with good selection of Ktacho[7:0] and TACHOSAMPLERATE, a
minimum amount of variation on the measured frequency can be obtained.
Fig 27. Tacho block diagram
001aag331
transition
detect
+
debounce
compare
to
motor loop
tacho
set
Ktacho
tacho
interrupt
T1
T2
T3
≥
TachoFrequency
7:0
[
]
------------------------------------------------------------------------------------------
s
p
=
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SAF7843HL/M295,557 功能描述:音頻 DSP IC AUD DECODER RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube
SAF7846HL/M210,557 功能描述:音頻 DSP 1 chip CD Audio Dev w/Integrated decoder RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube
SAF7847HL/M201,557 功能描述:音頻 DSP 1 chip CD Audio Dev w/Integrated decoder RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube
SAF7849HL/M245,557 功能描述:音頻 DSP IC AUD DECODER RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube
SAF7849HL/M295,557 功能描述:音頻 DSP IC AUD DECODER RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube
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