L6243 데이터 시트보기 (PDF) - STMicroelectronics
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L6243 Datasheet PDF : 12 Pages
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ELECTRICAL CHARACTERISTICS (continued)
MONITORS AND CONTROL CIRCUIT
Symbol
Vt1
Vt2
HVt1
HVt2
Vll
Ie
Ip
Rf
Venl
Ve nh
Vph
Vpl
Vpfl
Iprog
Ich
Td
Parameter
Test Condition
Threshold Voltage at Logic
Supply Sense
Threshold Voltage at Power Fail
Threshold Input
Hysteresis on Vt1
Hysteresis on Vt2
Low Level Voltage
Write Disable = 2mA
Power on Reset = 2mA
Enable Input Current
Vi = 2.4V
Input Current at Park
Equivalent Input Resistance at
5V Filter Input
Vi = 0.4V
Vi = 2.4V
Vi = 0.4V
Enable Low Input Voltage
Enable High Input Voltage
Parking Input High Voltage
Parking Input Low Voltage
Power Fail Low Output Voltage Il = 2mA
Parking Voltage Program Current
Power On Reset Delay
Capacitor Charging
Delay Between Write Disable
and Power on Reset Falling
Edges
L6243-L6243D
Min. Typ. Max. Unit
4.45 4.60 4.75
V
1.375 1.4 1.435 V
50
mV
15
mV
250 500 mV
250 500 mV
100
µA
–200 µA
100
µA
–200 µA
6.9
KΩ
0.8
V
2
V
2
V
0.8
V
0.5
V
100
µA
10
µA
4
10
µs
FUNCTIONAL DESCRIPTION
The VCM Driver is controlled via three control sig-
nals, ENABLE, POWER ON RESET, and WRITE
DISABLE. An analog input voltage, ERROR AMP
IN, controls the polarity and amplitude of the VCM
driving current.
Refer to figure two. This diagram is a repre-
sentation of the function of the VCM System.
Note that the signals with the bars represent the
”not true”, or ”non asserted” condition. From in -
itial power up, the system is held in the Park
Mode. Upon completion of the POWER UP RE-
SET DELAY the machine moves to Tristate Mode
or Run Mode, depending upon the condition of
the ENABLE input. If ENABLE is asserted, the
machine moves directly to Run Mode. If ENABLE
is not asserted, the machine moves to Tristate
Mode.
POWER ON RESET is an asynchronous output.
Additionally it affects the internal logic as a hard
wired reset and therefore if a supply failure occurs
during Tristate or Run state, the machine moves
directly back to the Park Mode. A WRITE DIS-
ABLE occurs a few to ten microseconds prior to
the POWER ON RESET in order for the system
to halt any read/write activity before a head re-
tract begins.
While in Tristate Mode, the assertion of ENABLE
will move the machine to the Run Mode. Run
Mode will typically be the steady running state.
The deassertion of the ENABLE signal causes
the machine to move into Tristate. If it is desired
to perform an active Parking function, the PARK
input must be driven low by the external hard-
ware, or the the VCM can be driven to the Park
position via the ERROR AMP IN control voltage
5/12
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