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 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. BLOCK DIAGRAM 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) VCC(12V) 2 1 44 43 42 41 40 GND VREF 3 N.C. SENSE AMP OUTPUT 4 SENSE AMP INPUT B N.C. 5 OOUTPUT B N.C. 6 PARK POWER GND PLCC-44 GND 7 39 GND ERROR AMP INPUT 8 38 SENSE AMP INPUT A ERROR AMP OUTPUT 9 37 N.C. OP AMP -INPUT 10 36 GND OP AMP +INPUT 11 35 N.C. OP AMP OUTPUT 12 34 GND GND 13 33 N.C. WRITE DISABLE OUTPUT 14 32 N.C. POWER ON RESET OUTPUT 15 31 GND PARK VOLTAGE PROGRAM 16 30 ENABLE INPUT GND 17 29 GND 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 28 2 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 D96IN450 2/12 N.C. N.C. PARK INPUT 5V FILTER 1 OUTPUT A VCC (12V) LOGIC SUPPLY SENSE (5V) VCC SENSE OUTPUT POWER ON REST DELAY N.C. SO 24+2+2 POWER FAIL THRESHOLD 18 19 20 21 22 23 24 25 26 27 28 D96IN449 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) L6243-L6243D ABSOLUTE MAXIMUM RATINGS Symbol Parameter VS Supply Voltage Value Unit 18 V VIN Input Voltage VID Differential Input Voltage 0.3V to VS IO DC Output Current 2 A Ip Peak Output Current (non repetitive) 2.5 A Ptot Total Power Dissipation (Tamb = 70°C) for L6243 for L6243D 2 1.2 W W Tstg Storage and Junction Temperature -55 to +150 °C ±VS THERMAL DATA Symbol Description L6243 L6243D Unit R th j-pin Rth j-amb Rth j-amb 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 12 62 36 14 °C/W °C/W °C/W 50 PIN FUNCTIONS Name VCC Function Power supply. GND Common Ground. Vref Voltage Reference. ENABLE Input. Logic low will disable IC. PARK POWER Input Power supply for the parking circuit. CURRENT SENSE OUT Current sense operational amplifier output. 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 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. AMP– Inverting input of the additional op amp. AMP+ Non-inverting input of the additional op amp. AMPOUT Output of the additional op amp. 3/12 L6243-L6243D ELECTRICAL CHARACTERISTICS (VS = 12V, Tamb = 25°C; unless otherwise specified) Symbol Parameter Test Condition Min. Typ. 4.5 Max. 13.2 Unit VS Supply Range Id Quiescent Drain Current 20 mA V Tj Thermal Shutdown Junction Temperature 160 °C ERROR AMPLIFIER Ib Input Bias Current 1 µA IOS Input Offset Current 300 nA VOS Input Offset Voltage 5 mV Gv Large Signal Open Loop Voltage Gain 65 dB GBW Gain Bandwidth Gmin 3 MHz Minimum Voltage Gain IO+ Output Source Current 6 mA IO–- Output Sink Current 6 mA SR Slew-rate 2 V/µs 8 V/V 5 SENSE AMPLIFIER RIN, Vref Vref Input Impedance Ad Differential Gain SR GBW R in CMRR 9 KΩ Slew-rate 1 V/µs Gain Bandwidth Product 3 MHz Sense Input Impedance 1.5 KΩ Common Mode Rejection Ratio 55 dB POWER OP. AMP. GV Voltage Gain Vd Total Output Voltage Drop V off Offset Voltage on Sense Resistor BW Bandwidth on Resistive Load IO IO IO IO = 250mA = 500mA = 1A = 2A 26 dB 450 750 1.15 2.30 mV mV V V 1.5 2.5 5 mV 100 KHz GENERAL PURPOSE OP-AMP Ib Input Offset Current VOS Input Offset Voltage GV Large Signal Open Loop Voltage Gain GBW 4/12 Input Bias Current IOS 65 1 µA 300 nA 5 mV dB Gain Bandwidth Product 1 MHz IO+ Output Source Current 6 mA IO– Output Sink Current 6 mA SR Slew Rate 1 V/µs L6243-L6243D ELECTRICAL CHARACTERISTICS (continued) MONITORS AND CONTROL CIRCUIT Symbol Min. Typ. Max. Unit V t1 Threshold Voltage at Logic Supply Sense Parameter Test Condition 4.45 4.60 4.75 V V t2 Threshold Voltage at Power Fail Threshold Input 1.375 1.4 1.435 V HVt1 Hysteresis on Vt1 50 HVt2 Hysteresis on Vt2 15 Vll Low Level Voltage Write Disable = 2mA 250 Power on Reset = 2mA 250 Ie Enable Input Current Vi = 2.4V Vi = 0.4V –200 µA Vi = 2.4V 100 µA Ip Input Current at Park Rf Equivalent Input Resistance at 5V Filter Input Vi = 0.4V mV mV 500 mV 500 mV 100 µA –200 6.9 µA KΩ V enl Enable Low Input Voltage Venh Enable High Input Voltage 2 V ph Parking Input High Voltage 2 Vpl Parking Input Low Voltage Vpfl Power Fail Low Output Voltage Iprog Parking Voltage Program Current 100 µA Ich Power On Reset Delay Capacitor Charging 10 µA Td Delay Between Write Disable and Power on Reset Falling Edges 4 0.8 V V 0.8 Il = 2mA 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. V 0.5 10 V V µs 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 5/12 L6243-L6243D FUNCTIONAL DESCRIPTION (continued) Function VCC input POWER FAIL THRESH Description This is the Power Supply input. Input for the VCC supply monitor. The Threshold can be externally set via a voltage divider. VCC SENSE OUT Output TTL compatible signal indicating the VCC supply has dropped below the POWER FAIL THRESHOLD. LOGIC SUPPLY SENSE input 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. 5V FILTER input This pin allows for the application of filter circuitry in order to avoid false triggering. PARK POWER input 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. PROGRAMMABLE PARK VOLTAGE input PARK input Used to set the voltage applied to the VCM during an Automatic Parking Operation. Logic signal asserted low, activates parking. POWER ON RESET output 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. POWER ON RESET DELAY input 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. WRITE DISABLE output Becomes asserted a few microseconds prior to the assertion of POWER ON RESET. Internal 30k Pullup to LSS. ENABLE 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. input V REF input ERROR AMP IN input 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 AMP OUT output Error amplifier output pin. OUTPUT A power output Voice Coil power output. OUTPUT B power output Voice Coil power output. SENSE AMP IN A/B signal input Sense amplifier input pins. The sense resistor is connected across these pins. SENSE AMP OUT signal output Output pin of sense amplifier. AMPOUT Output of an internal op-amp for general application. 6/12 output AMP+ input General purpose op-amp non inverting input. AMP- input General purpose op-amp inverting input. 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 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 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=100µA 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) 7/12 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 9/12 L6243-L6243D PLCC44 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 17.4 17.65 0.685 0.695 B 16.51 16.65 0.650 0.656 C 3.65 3.7 0.144 0.146 D 4.2 4.57 0.165 0.180 d1 2.59 2.74 0.102 0.108 d2 E 0.68 14.99 0.027 16 0.590 0.630 e 1.27 0.050 e3 12.7 0.500 F 0.46 0.018 F1 0.71 0.028 G 10/12 inch 0.101 0.004 M 1.16 0.046 M1 1.14 0.045 L6243-L6243D SO28 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. A inch MAX. MIN. TYP. 2.65 MAX. 0.104 a1 0.1 0.3 0.004 0.012 b 0.35 0.49 0.014 0.019 b1 0.23 0.32 0.009 0.013 C 0.5 0.020 c1 45° (typ.) D 17.7 18.1 0.697 0.713 E 10 10.65 0.394 0.419 e 1.27 0.050 e3 16.51 0.65 F 7.4 7.6 0.291 0.299 L 0.4 1.27 0.016 0.050 S 8° (max.) 11/12 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. 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. 12/12