L6243DS 데이터 시트보기 (PDF) - STMicroelectronics
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L6243DS Datasheet PDF : 8 Pages
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L6243DS
ELECTRICAL CHARACTERISTICS (continued)
MONITORS AND CONTROL CIRCUIT
Symbol
Vt2
VtL
HVt2
HVtL
Vll
Ie
Ip
Venl
Venh
Vph
Vpl
Vpfl
Iprog
Ich
RF
Parameter
Threshold Voltage at Logic
Supply Sense
Threshold Voltage at Power Fail
Threshold Input
Hysteresis on Vt2
Hysteresis on Vt2
Low Level Voltage
Enable Input Current
Input Current at Park
Enable Low Input Voltage
Enable High Input Voltage
Parking Input High Voltage
Parking Input Low Voltage
Power Fail Low Output Voltage
Parking Voltage Program Current
Power On Reset Delay
Capacitor Charging
Equivalent Input Resistance at
5V Filter Input
Test Condition
Power on Reset = 2mA
Vi = 2.4V
Vi = 0.4V
Vi = 2.4V
Vi = 0.4V
Il = 2mA
Min. Typ. Max. Unit
4.2
4.5
V
1.375 1.4 1.435 V
50
mV
15
mV
250 500 mV
100
µA
–200 µA
100
µA
–200 µA
0.8
V
2
V
2
V
0.8
V
0.5
V
100
µA
5
µA
6.9
kΩ
FUNCTIONAL DESCRIPTION
The VCM Driver is controlled via two control sig-
nals, ENABLE, POWER ON RESET. An analog
input voltage, ERROR AMP IN, controls the polar-
ity 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.
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
BLOCK DESCRIPTION
OUTPUT STAGE
It consists of two Power Op Amps connected in
bridge configuration.
CURRENT SENSE AMPLIFIER
Differential amplifier whose inputs are connected
to the sense lines and whose output is accessible
externally. Closing the loop will transform the
differential voltage signal from the sense lines into
a current signal for the Error Amplifier.
ERROR AMPLIFIER
Error amplifier which drives the output stage. The
input and the output pins are accessible exter-
nally.
POWER SUPPLY MONITOR OPERATION
The circuit monitors the logic supply voltage input
(typ 5V) and activates Power on Reset output
when such a supply drops below the safe operat-
ing limit. After the logic supply voltage reaches its
nominal value a delay capacitor has to be
charged [Tdelay = 3x2x10e5 x C sec] before
Power on Reset output change from low to high
level. Falling edges of Power on Reset are de-
layed (typ 4µs) in order to disable the writing on
the disk before the Power on Reset is activated.
An additional supervisor circuit is present in the
4/8
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