L6242 STMICROELECTRONICS | Alldatasheet
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OPERATES AT LOW VOLTAGES WITH LOW COIL RESISTANCE OF THE MOTOR LARGE COMMON MODE AND DIFFEREN- TIAL MODE RANGE LOW INPUT OFFSET VOLTAGE THERMAL SHUT-DOWN ENABLE FUNCTION INTERNAL CLAMP DIODES
DESCRIPTION
The L6242 is a monolithic integrated circuit in SO-20 package intended for use as a dual power opera- tional amplifier. It is particularly indicated for driv- ing inductive loads as linear motor, and finds ap- plication in Hard Disc, Compact-Disc, etc. The two power operational amplifiers are control- led by a common enable input. The high gain and output power capability provide superior performance whatever a power booster is required. November 1991 T is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice. PIN CONNECTION AND BLOCK DIAGRAM SO20 ORDERING NUMBER: L6242
Figure 1 shows the L6242 configurated as a tran- sconductance amplifier, in order to drive linear motors as Voice Coil (VCM). The L6242 provides the power section of the Transconductance Am- plifier. The two OP AMP are configurated one as inverting and the other as noninverting amplifier, with the same gain. Working in push-pull, they can be configurated as a bridge. The motor cur- rent can be controlled by means of the sense re- sistor (typical 1Ω ) in series with the motor. The current sense amplifier provides the feedback sig- nal, which is summed to the driving signal at the node which is the inverting input of the Error Am- plifier. R1 closes the control loop. R2 converts the input voltage signal, into a current signal. The snubber network provides the system stabil- ity, always required by the application. The net- work is directly connected to the output pins of the IC, OUT1 and OUT2, and in parallel with the load. R4 and C2 could be of different values, de- pending on the p.c.b. configuration and on the motor characteristics. The DC transfer function may be expressed as: gm = Iout/Vin = k• (R1/R2) where k = 1/(Rsense• Ad) and Ad = gain of the current sense amplifier. ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VS Supply Voltage 28 V Vi Input Voltage VS V Vi Differential Input Voltage ±VS V IO DC Output Current 1 A IP Peak Output Current (non repetitive) 1.5 A Ptot Maximum Power Dissipation at Tamb =8 5°C TCASE =7 5°C W W Tstg,TJ Storage and Junction Temperature Range -40 to 150 °C ELECTRICAL CHARACTERISTICS (VS = 12V, TJ =2 5°C unless otherwise specified) Symbol Parameter Test Condition Min. Typ. Max. Unit VS Supply Voltage 4 28 V IS Quiescent Drain Current V O =V S /2 10 15 mA Ib Input Bias Current 0.2 1 µA VOS Input Offset Voltage 15 mV IOS Input Offset Current 10 50 nA Sr Slew Rate 1.5 V/ µs R i Input Resistance 500 K Ω G V Open Loop Voltage Gain f = 100Hz 70 80 dB CMR Common Mode Rejection f = 100Hz 66 84 dB SVR Supply Voltage Rejection f = 100Hz R g = 10KΩ Vr = 0.5V 54 dB Vdrop High Drop Voltage I = 100mA I = 500mA 0.7 1 1.5 V V Vdrop Low Drop Voltage I = 100mA I = 500mA 0.3 0.6 1 V V Tsd Thermal Shutdown Junction Temperature 145 °C R p Internal Pull-up Resistor of the Enable Input 50 K Ω Ve Enable Low Voltage T J = 130°C -0.3 1.2 V Ieq Quiescent Drain Current En = L 2 5 mA Td Enable Delay 50 µs Iol Output Leakage Current 10 µA L6242
Optimizing a PC board layout involves to observe the following rules which in general can avoid ap- plication problems associated with ground loops and anomalous recirculation currents. The elec- trolytic capacitor for the power supply must be kept as close to the IC as possible. It is important that power grounds are close to each other on a wide enough. Copper side also, it is important to separate on the board the logic ground and the power ground in such a way that the ground traces for the logic signals and references do not cross the ground traces for the power signals. Logic ground and power ground must meet at one point on the board (startpoint grounding) far enough away from where the power ground traces terminate to ground (sense resistors and recirculation diodes). This is to avoid anomalous interface with the logic signals. It is generally a good idea to connect a non inductive capacitor (typically 100nF) between the pins VS and GND. In other cases it may be necessary to also place a by-pass capacitor between the pins Vref and GND. Figure 1:Voice Coil Motor Control Circuit L6242
SO20 PACKAGE MECHANICAL DATA DIM. mm inch A 2.65 0.104 a1 0.1 0.3 0.004 0.012 a2 2.45 0.096 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 12.6 13.0 0.496 0.512 E 10 10.65 0.394 0.419 e 1.27 0.050 e3 11.43 0.450 F 7.4 7.6 0.291 0.299 L 0.5 1.27 0.020 0.050 M 0.75 0.030 S 8 (max.) L6242
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. Specifications men- tioned 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 critical components in life support devices or systems without ex- press written approval of SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A. L6242