L6243DS VOICE COIL MOTOR DRIVER 5-12V OPERATION PARKING FUNCTION FOR HARD DISK HEAD ACTUATOR OUTPUT CURRENT UP TO 1A DC, 1.2A PEAK LOW SATURATION VOLTAGE LOGIC AND POWER SUPPLY MONITOR LINEAR CONTROL THERMAL PROTECTION ENABLE FUNCTION CURRENT SENSE RESISTOR CONNECTIONS SO24 ORDERING NUMBER: L6243DS to work as a Transconductance Amplifier to drive a Voice Coil Motor in Linear Mode. Additional features include Power On Reset Delay, Enable and Park. 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. DESCRIPTION The L6243DS is a Bipolar IC developed for use in Mass Storage 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 BLOCK DIAGRAM SNUBBER VIN Cf VOICE COIL R1 Rsense R2 Rf OUT A GND VDD B PARK VOLTAGE PROGRAM POWER FAIL THRESHOLD (12V) SENSE IN B BRIDGE POWER STAGE VDD A PARK POWER OUT B SENSE IN A SENSE OUT ERROR IN - - + + ERROR OUT VREF PARK VOLTAGE GENERATOR THERMAL PROTECTION VCC + PARK + LOGIC SUPPLY SENSE ENABLE + INTERNAL VOLTAGE REFERENCE LOGIC SUPPLY FILTER February 1998 VCC SENSE OUT FALL TIME DELAY POR DELAY POR D96IN469 1/8 L6243DS PIN CONNECTION (Top view) LOGIC SUPPLY SENSE 1 24 POR DELAY VDDA 2 23 VDD SENSE OUT OUTA 3 22 POWER FAIL THRESHOLD PARK 4 21 PARK VOLTAGE PROG ENABLE 5 20 POR GND 6 19 GND GND 7 18 GND SENSE IN A 8 17 ERROR OUT LOGIC SUPPLY FILTER 9 16 ERROR IN SENSE IN B 10 15 VREF OUT B 11 14 SENSE OUT PARK POWER 12 13 VDD B D96IN467 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit 14 V VS Supply Voltage VIN VID Input Voltage Differential Input Voltage ±VS IO Ip DC Output Current Peak Output Current (non repetitive) 1 1.2 A A Total Power Dissipation (Tamb = 70°C) 1.2 W W -55 to +150 °C Ptot Tstg 0.3V to VS Storage and Junction Temperature PIN FUNCTIONS Name Power supply. GND Vref Common Ground. Voltage Reference. ENABLE PARK POWER Input. Logic low will disable IC. Input Power supply for the parking circuit. CURRENT SENSE OUT Current sense operational amplifier output. ERROR AMP IN ERROR AMP OUT SENSE IN Α/Β OUT A, B PARK PARK VOLTAGE PROGRAM POWER FAIL THRESHOLD LOGIC SUPPLY SENSE POR POR DELAY LOGIC SUPPLY FILTER 2/8 Function VDD 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. Sense the logic supply level 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. Capacitor connection to filter the logic supply ripple L6243DS THERMAL DATA Symbol Rth j-amb Description Thermal Resistance Junction - Ambient Value Unit 77 to 97 °C/W ELECTRICAL CHARACTERISTICS (VS = 12V, Tamb = 25°C; unless otherwise specified) Symbol Parameter Test Condition Min. Typ. 4.5 Max. 13.2 Unit VS Id Supply Range Quiescent Drain Current 20 mA V Tj Thermal Shutdown Junction Temperature 160 °C ERROR AMPLIFIER Ib IOS Input Bias Current Input Offset Current VOS Input Offset Voltage -5 Gv Large Signal Open Loop Voltage Gain 65 GBW Gmin Gain Bandwidth Minimum Voltage Gain IO+ IO–SR 1 µA 300 nA +5 mV dB 3 MHz Output Source Current 6 mA Output Sink Current Slew-rate 6 2 mA V/µs 5 SENSE AMPLIFIER RIN, Vref Vref Input Impedance Ad Differential Gain Slew-rate 8 1 V/V V/µs Gain Bandwidth Product Sense Input Impedance 3 1.5 MHz KΩ Common Mode Rejection Ratio 55 dB SR GBW Rin CMRR 9 KΩ POWER OP. AMP. GV Vd Voff BW Voltage Gain Total Output Voltage Drop Offset Voltage on Sense Resistor Bandwidth on Resistive Load IO = 250mA IO = 500mA IO = 1A 26 dB 450 750 1.15 mV mV V 1.5 5 mV 100 KHz 3/8 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 Typ. Max. 4.5 Unit V 1.375 1.4 1.435 V 50 15 250 Power on Reset = 2mA Vi = 2.4V Vi = 0.4V Vi = 2.4V Vi = 0.4V 100 5 mV mV mV µA µA µA µA V V V V V µA µA 6.9 kΩ 500 100 –200 100 –200 0.8 2 2 0.8 0.5 Il = 2mA FUNCTIONAL DESCRIPTION The VCM Driver is controlled via two control signals, ENABLE, POWER ON RESET. 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 initial 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. 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 4/8 Min. 4.2 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 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 = 3x2x10e5 x C sec] before Power on Reset output change from low to high level. Falling edges of 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 L6243DS FUNCTIONAL DESCRIPTION (continued) Function VDD input POWER FAIL THRESH VCC SENSE OUT Output Description 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. LOGIC SUPPLY SENSE input This pin allows the monitoring of 5V supply. When a low voltage is detected POR is asserted 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. Used to set the voltage applied to the VCM during an Automatic Parking Operation. PROGRAMMABLE PARK VOLTAGE input PARK input 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. ENABLE input 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. VREF input ERROR AMP IN input ERROR AMP OUT output 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. OUTPUT A power output OUTPUT B power output Voice Coil power output. SENSE AMP IN A/B signal input SENSE AMP OUT signal output Sense amplifier input pins. The sense resistor is connected across these pins. LOGIC SUPPLY FILTER Error amplifier output pin. Open collector output. Voice Coil power output. Output pin of sense amplifier. Capacitor connection to avoid false triggering 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. 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. 5/8 L6243DS Figure 1: Application Circuit VDD 13K 5V 1 22 2K 24 (*) 6,7,18,19 3 VCM 0.1µF 1.8nF 11 5K 16 8 100 VIN 17 0.5 1.5K 10 9 21 14 D96IN468 (*) VALUES TO BE SET IN APPLICATION (*) (*) Figure 2: Application Circuit LOGIC SUPPLY SENSE POWER ON DELAY INPUT POWER ON RESET td POWER ON RESET DELAY D96IN470 6/8 1.5K L6243DS SO24 PACKAGE MECHANICAL DATA mm DIM. MIN. inch TYP. MAX. MIN. TYP. MAX. A 2.35 2.65 0.093 0.104 A1 0.10 0.30 0.004 0.012 A2 2.55 0.100 B 0.33 0.51 0.013 0.0200 C 0.23 0.32 0.009 0.013 D 15.20 15.60 0.598 0.614 E 7.40 7.60 0.291 0.299 e 1.27 0,050 H 10.0 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 k 0° (min.), 8° (max.) L 0.40 1.27 0.016 0.050 0.10mm B e A A2 h x 45? A1 K A1 L .004 C H Seating Plane D 13 1 12 E 24 SO24 7/8 L6243DS 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. SGSTHOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. © 1998 SGS-THOMSON Microelectronics – Printed in Italy – All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. 8/8