- 您现在的位置：买卖IC网 > PDF目录43901 > L7250 (STMICROELECTRONICS) VOICE COIL MOTOR CONTROLLER, PQFP64 PDF资料下载
参数资料
| 型号： | L7250 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 运动控制电子 |
| 英文描述： | VOICE COIL MOTOR CONTROLLER, PQFP64 |
| 封装： | TQFP-64 |
| 文件页数： | 31/46页 |
| 文件大小： | 478K |
| 代理商： | L7250 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页当前第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页
37/46
L7250
3.8.5 Constant Voltage Unload operation at POWER ON
The same costant voltage retract operation can be activated via software (during a power on phase). In that
case no actions are implemented to the spindle motor; the spindle motor will continue to mantain its running
status.
Again in power on condition if the bit ‘b3b2b1’ of the REG. 01H are set to 000 or 111 only one step costant volt-
age retract is activated as in power off condition with the difference that when the ‘End unload threshold’ is
reached the retract voltage is mantained applied to the motor until a different programmation is asserted via se-
rial port by the microcontroller.
In all the others ‘b3b2b1’ combination as the timer1 is elapsed the VCM is put in tristate condition.
NOTE: In case of Hard Disk application with CSS operation (no Ramp Loading), the polarity of the VCM connection must be re-
versed. In this way the active brake and the constant voltage unload operations will force the heads in the inner position
of the disks.
3.9 10 bit AD converter
The L7250 device includes a 10 bit analog to digital converter (hereafter ADC).
The ADC uses a two complement output code.
The ADC converts one of four different channels on demand, through SPI, and result of conversion can be read
from SPI too. The uC tells the ADC which channel must be converted, gives a start signal, reads the conversion
result; all this happens through the SPI.
The ADC convertion frequency, then its conversion time, could be changed using two bits into the serial port
(Reg 06H -> b1,b2). Setting these two bit to the configuration 00 the ADC can be disabled entering a sleep mode
status.
Hereafter is listed the recommended sequence of operations to obtain a conversion from ADC:
A)
C selects which channel must be converted, writing the ADC_CH_ADDR field in SPI (Reg 0CH -> b1,b2);
C selects the ADC input range writing the ADCRange bit (Reg 0CH -> b3);
C writes high the ADC_START bit (Reg 0CH ->b0) in SPI (end of required conversion automatically resets it);
B) now
C can read the conversion result from the SPI registers;
C) a new conversion can be required.
The
C isn't allowed to require a conversion start when the ADC is already running; the start bit can be written
anyway, but ADC logic ignores it and continues the current conversion. If the uC avoids modifies over the
ADC_START bit, it can be used as a flag to state the end of the conversion.
The result of conversion is ten bits wide, larger than the 8 bits SPI registers, so it has been spanned over two
registers; if allowed by the precision required for the application, only the 8 msbits can be read with a single SPI
read operation, saving some time.
A new conversion can be required after the end of the previous one but before the read-back of the result, i.e.
swapping the order of (B) and (C) points listed before; working this way, it's possible to convert values closer in
time than with the previous sequence.
SPI includes an additional read-only field (2bits) that contains the channel number related to the present con-
version result.
相关PDF资料 |
PDF描述 |
|---|---|
| L7980A | 3.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| L7980 | 3.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| L7980TR | 3.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| L7981ATR | SWITCHING REGULATOR, DSO8 |
| L7981TR | SWITCHING REGULATOR, DSO8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| L7250E1.2 | 功能描述:电源开关 IC - 配电 DSD POWER RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| L7252E2.6 | 功能描述:电源开关 IC - 配电 DSD POWER RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| L725MAG | 制造商:Apex Tool Group 功能描述:TAPE, 1 IN. X 25 FT, 700 SERIES, MAGNETIC END HOOK 制造商:Lufkin 功能描述:TAPE MEASURE, MAGNETIC END HOOK 25FT 1IN; Tape Measure Type:Manual; Measuring Range Max:25ft; Blade Width:1"; Case Color:Orange; Tool Body Material:ABS; Blade Finish:Yellow Clad; Blade Length:25ft ;RoHS Compliant: NA |
| L728 | 制造商:BURNDY 功能描述:L-DIE |
| L7290 | 制造商:CIPS 功能描述:CUTTER OBLIQUE SEMI FLUSH 109MM |
发布紧急采购，3分钟左右您将得到回复。