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L6243 L6243D
VOICE COIL MOTOR DRIVER
12V/5V OPERATION PARKING FUNCTION FOR HARD DISK HEAD ACTUATOR OUTPUT CURRENT UP TO 2A DC, 2.5A PEAK LOW SATURATION VOLTAGE LOGIC AND POWER SUPPLY MONITOR LINEAR CONTROL THERMAL PROTECTION ENABLE FUNCTION CURRENT SENSE RESISTOR CONNECTIONS DESCRIPTION The L6243/D is a Bipolar IC developed for use in Hard Disk Head Actuator positioning applications. The Power Op-Amp Output Bridge, Differential Amplifier, and Error Amplifier, are controlled by TTL/CMOS, input compatible, Digital Logic, and an Analog Current Control Voltage. A simple RC compensation network, tied to the output of the Error Amp, will configure the system to work BLOCK DIAGRAM
PLCC44 SO(24+2+2) ORDERING NUMBERS: L6243 L6243D
as a Transconductance Amplifier to drive a Voice Coil Motor in Linear Mode. Additional features include Power On Reset Delay, Enable and Park, as well as a general purpose Operational Amplifier. A logic low at the Park input activates the parking function. Holding the Enable input low will disable the device by forcing the outputs into a tristate mode. Power Fail Monitors for the logic and power supplies initiate an automatic parking sequence during a power failure. A resistor programmed parking voltage enables a constant velocity head retract.
July 1996
1/12
This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
L6243-L6243D
PIN CONNECTION (Top view) PLCC-44
SENSE AMP OUTPUT SENSE AMP INPUT B
PARK POWER
OOUTPUT B
VCC(12V)
VREF
GND
6 GND ERROR AMP INPUT ERROR AMP OUTPUT OP AMP -INPUT OP AMP +INPUT OP AMP OUTPUT GND WRITE DISABLE OUTPUT POWER ON RESET OUTPUT PARK VOLTAGE PROGRAM GND 7 8 9 10 11 12 13 14 15 16 17
5
4
3
2
1 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 GND SENSE AMP INPUT A N.C. GND N.C. GND N.C. N.C. GND ENABLE INPUT GND
18 19 20 21 22 23 24 25 26 27 28 POWER FAIL THRESHOLD LOGIC SUPPLY SENSE (5V) POWER ON REST DELAY VCC SENSE OUTPUT OUTPUT A PARK INPUT 5V FILTER VCC (12V) N.C. N.C. N.C.
D96IN449
SO 24+2+2
VREF N.C. N.C. N.C. ERROR AMP INPUT ERROR OUTPUT GND GND WRITE DISABLE OUTPUT POWER ON RESET OUTPUT PARK VOLTAGE PROGRAM POWER FAIL THRESHOLD VCC SENSE OUTPUT POWER ON RESET DELAY
1 2 3 4 5 6 7 8 9 10 11 12 13 14
28 27 26 25 24 23 22 21 20 19 18 17 16 15
SENSE AMP OUTPUT VCC PARK POWER OUTPUT B SENSE AMP INPUT B SENSE AMP INPUT A GND GND ENABLE PARK INPUT OUTPUT A 5V FILTER VCC LOGIC SUPPLY SENSE (5V)
D96IN450
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GND
N.C.
N.C.
N.C.
L6243-L6243D
ABSOLUTE MAXIMUM RATINGS
Symbol VS VIN VID IO Ip Ptot Tstg Supply Voltage Input Voltage Differential Input Voltage DC Output Current Peak Output Current (non repetitive) Total Power Dissipation (Tamb = 70C) for L6243 for L6243D Storage and Junction Temperature Parameter Value 18 0.3V to VS VS 2 2.5 2 1.2 -55 to +150 A A W W C Unit V
THERMAL DATA
Symbol R th j-pin Rth j-amb Rth j-amb Description Thermal Resistance Junction to pin Thermal Resistance Junction to pin floating in air Thermal Resistance Junction to pin 16 cm2 copper area on board heat sink L6243 12 62 36 L6243D 14 50 Unit C/W C/W C/W
PIN FUNCTIONS
Name VCC GND Vref ENABLE PARK POWER CURRENT SENSE OUT ERROR AMP IN ERROR AMP OUT SENSE IN OUT A, B PARK PARK VOLTAGE PROGRAM POWER FAIL THRESHOLD LOGIC SUPPLY SENSE 5V FILTER VCC SENSE OUT POR POR DELAY WRITE DISABLE AMP- AMP+ AMPOUT Power supply. Common Ground. Voltage Reference. Input. Logic low will disable IC. Input Power supply for the parking circuit. Current sense operational amplifier output. Error amplifier inverting input. Error amplifier output. Input for external sense resistors. Outputs of the two Power Operational Amplifiers Connections for Voice coil Motor. External input for parking. Low will activate the park procedure. Input to set the park voltage. Supply monitor threshold setting. Logic Supply Sense. Capacitor connection to filter the logic supply ripple. Power supply failure monitor output. Power on reset output. Low will signal to the controller the failure of the logic supply. Capacitor connection to set the power on reset delay. Output for write disable. Low will disable the writing mode. Inverting input of the additional op amp. Non-inverting input of the additional op amp. Output of the additional op amp. Function
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L6243-L6243D
ELECTRICAL CHARACTERISTICS (VS = 12V, Tamb = 25C; unless otherwise specified)
Symbol VS Id Tj Parameter Supply Range Quiescent Drain Current Thermal Shutdown Junction Temperature Test Condition Min. 4.5 20 160 Typ. Max. 13.2 Unit V mA C
ERROR AMPLIFIER
Ib IOS VOS Gv GBW Gmin IO+ IO-SR Input Bias Current Input Offset Current Input Offset Voltage Large Signal Open Loop Voltage Gain Gain Bandwidth Minimum Voltage Gain Output Source Current Output Sink Current Slew-rate 5 6 6 2 mA mA V/s 65 3 1 300 5 A nA mV dB MHz
SENSE AMPLIFIER
RIN, Vref Ad SR GBW R in CMRR Vref Input Impedance Differential Gain Slew-rate Gain Bandwidth Product Sense Input Impedance Common Mode Rejection Ratio 1.5 55 9 8 1 3 K V/V V/s MHz K dB
POWER OP. AMP.
GV Vd Voltage Gain Total Output Voltage Drop IO IO IO IO = 250mA = 500mA = 1A = 2A 26 450 750 1.15 2.30 5 100 dB mV mV V V mV KHz
1.5 2.5
V off BW
Offset Voltage on Sense Resistor Bandwidth on Resistive Load
GENERAL PURPOSE OP-AMP
Ib IOS VOS GV GBW IO+ IO- SR Input Bias Current Input Offset Current Input Offset Voltage Large Signal Open Loop Voltage Gain Gain Bandwidth Product Output Source Current Output Sink Current Slew Rate 65 1 6 6 1 1 300 5 A nA mV dB MHz mA mA V/s
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L6243-L6243D
ELECTRICAL CHARACTERISTICS (continued) MONITORS AND CONTROL CIRCUIT
Symbol V t1 V t2 HVt1 HVt2 Vll Ie Ip Rf V enl Venh V ph Vpl Vpfl Iprog Ich Td Parameter Threshold Voltage at Logic Supply Sense Threshold Voltage at Power Fail Threshold Input Hysteresis on Vt1 Hysteresis on Vt2 Low Level Voltage Enable Input Current Input Current at Park Equivalent Input Resistance at 5V Filter Input 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 Delay Between Write Disable and Power on Reset Falling Edges Il = 2mA 100 10 4 10 2 2 0.8 0.5 Write Disable = 2mA Power on Reset = 2mA Vi = 2.4V Vi = 0.4V Vi = 2.4V Vi = 0.4V 6.9 0.8 Test Condition Min. 4.45 1.375 Typ. 4.60 1.4 50 15 250 250 500 500 100 -200 100 -200 Max. 4.75 1.435 Unit V V mV mV mV mV A A A A K V V V V V A A s
FUNCTIONAL DESCRIPTION The VCM Driver is controlled via three control signals, 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 representation 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 RESET 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 DISABLE 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 retract 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 hardware, or the the VCM can be driven to the Park position via the ERROR AMP IN control voltage
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L6243-L6243D
FUNCTIONAL DESCRIPTION (continued)
Function VCC input POWER FAIL THRESH VCC SENSE OUT Output LOGIC SUPPLY SENSE input 5V FILTER input PARK POWER input This is the Power Supply input. Input for the VCC supply monitor. The Threshold can be externally set via a voltage divider. TTL compatible signal indicating the VCC supply has dropped below the POWER FAIL THRESHOLD. This input is used to monitor the Five Volt Logic Supply for the external control and other support IC's. The LOGIC SUPPLY SENSE operates independently of the 12V Power Supply. When a 5V supply failure is detected a POWER ON RESET is generated. This pin allows for the application of filter circuitry in order to avoid false triggering. This input is used during the Power Down/Power Fail Parking operation. When the supply goes down, a typical Spindle Driver Circuit automatically tristates its output stages. During this time the spindle motor spins freely and the stored energy is used to drive the VCM to the park position. The generated BEMF is rectified and filtered across an external PARKING CAPACITOR. Used to set the voltage applied to the VCM during an Automatic Parking Operation. Description
PROGRAMMABLE PARK VOLTAGE input PARK input POWER ON RESET output POWER ON RESET DELAY input
Logic signal asserted low, activates parking. Indicates an error condition to the external control and support circuitry. A Logic Supply Fail condition automatically initiates a POWER ON RESET. Internal 30k Pullup to LSS. The intent of this input is to provide a time delay at power up. During this time, the POWER ON RESET line will be asserted (low). A POWER ON RESET, will hold the system in the PARK mode. Once the delay has timed out, the POWER ON RESET will be removed to allow the external system to assume control. When applied in a Disk Drive Application, the POWER ON RESET DELAY will be required to have a minimum duration which will ensure that the Read/Write Heads can be fully parked. Becomes asserted a few microseconds prior to the assertion of POWER ON RESET. Internal 30k Pullup to LSS. This signal originates at the external controller and, when asserted, allows the VCM Drivers to operate. When deasserted the VCM Driver is forced into Tristate mode. During a POWER ON RESET condition however, the parking operation is automatic and takes priority over the ENABLE function. Only at the end of the POWER ON RESET DELAY will the ENABLE input become active. If active parking is desired, it will be accomplished under control of the VIN signal, otherwise it is an automatic function at power down. The reference voltage input is basically that voltage, at which the output current is zero. Inverting input of error amplifier. The non inverting one is internally tied to Vref. Open collector output. Error amplifier output pin. Voice Coil power output. Voice Coil power output. Sense amplifier input pins. The sense resistor is connected across these pins. Output pin of sense amplifier. Output of an internal op-amp for general application. General purpose op-amp non inverting input. General purpose op-amp inverting input.
WRITE DISABLE output ENABLE input
V REF input ERROR AMP IN input ERROR AMP OUT output OUTPUT A power output OUTPUT B power output SENSE AMP IN A/B signal input SENSE AMP OUT signal output AMPOUT output AMP+ input AMP- input
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L6243-L6243D
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 externally. POWER SUPPLY MONITOR OPERATION The circuit monitors the logic supply voltage input (typ 5V) and activates Power on Reset and Write Disable output when such a supply drops below the safe operating limit. After the logic supply voltage reaches its nominal value a delay capacitor has to be charged [Tdelay=3x10e5 x C sec] before Power on Reset and Write Disable outputs change from low to high level. Falling edges of Write Disable and Power on Reset are delayed (typ 4s) in order to disable the writing on the disk before the Power on Reset is activated. An additional supervisor circuit is present in the IC with a programmable threshold, which is set by an external resistive divider. The TTL compatible output can be used separately or connected to Park input in order to park the head. The VCC sense output pin can also be connected to 5V filter input in order to implement a POWER ON RESET function sensitive both to 5V and VCC. PARKING CIRCUIT OPERATIONT The voice coil driver is switched into the parking condition when Power on Reset output or Park input are low. In such a condition a fixed voltage is superimposed on the load and the value of such a voltage is set by connecting an external resistor between Park Voltage Program input and ground: (Vpark=Rext x Iref, Iref=100A typ). Connecting ENABLE input to GND the driver will be disabled (outputs in high impedance mode). THERMAL SHUTDOWN It will disable the IC when the junction temperature exceeds the threshold value above which the device could be damaged.
Figure 1: Application Circuit (The pinout refers to the L6243)
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L6243-L6243D
Figure 2: Waveforms
8/12
L6243-L6243D
THERMAL CHARACTERISTICS Figure 3: Rth (j-amb) vs. Dissipated Power Figure 4: Rth (j-amb) vs. Dissipated Power
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L6243-L6243D
PLCC44 PACKAGE MECHANICAL DATA
DIM. MIN. A B C D d1 d2 E e e3 F F1 G M M1 1.16 1.14 14.99 1.27 12.7 0.46 0.71 0.101 0.046 0.045 17.4 16.51 3.65 4.2 2.59 0.68 16 0.590 0.050 0.500 0.018 0.028 0.004 mm TYP. MAX. 17.65 16.65 3.7 4.57 2.74 MIN. 0.685 0.650 0.144 0.165 0.102 0.027 0.630 inch TYP. MAX. 0.695 0.656 0.146 0.180 0.108
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L6243-L6243D
SO28 PACKAGE MECHANICAL DATA
DIM. MIN. A a1 b b1 C c1 D E e e3 F L S 7.4 0.4 17.7 10 1.27 16.51 7.6 1.27 8 (max.) 0.291 0.016 18.1 10.65 0.1 0.35 0.23 0.5 45 (typ.) 0.697 0.394 0.050 0.65 0.299 0.050 0.713 0.419 mm TYP. MAX. 2.65 0.3 0.49 0.32 0.004 0.014 0.009 0.020 MIN. inch TYP. MAX. 0.104 0.012 0.019 0.013
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L6243-L6243D
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as criticalcomponents in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. (c) 1996 SGS-THOMSON Microelectronics - Printed in Italy - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A.
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