Monolithic MOS Technology External Compensation Capability High Voltage Operation : 350V Low Quiescent Current : 2mA Max. High Output Current : 60mA Min. No Secondary Breakdown High Speed : 40V/�S Typ. Low Cost
The MSK is an ultra high voltage monolithic MOSFET operational amplifier ideally suited for electrostatic transducer and electrostatic deflection applications. With a total supply voltage rating of 350 volts and 60mA of available output current, the MSK 164 is also an excellent low cost choice for high voltage piezo drive circuits. The MOSFET output frees the MSK 164 from secondary breakdown limitations and power dissipation is kept to a minimum with a quiescent current rating of only 2mA. The MSK 164 has user adjustable compensation pins and is packaged a 14 pin power dip with bolt down tabs.TYPICAL APPLICATIONS
Piezo Electric Positioning Electrostatic Deflection Computer to Vacuum Tube Interface Ultra High Voltage Op-Amp ApplicationsNC -Vcc +Vcc Output Drive Comp 1 Comp 2
Non-Inverting Input Inverting Input N/C Current Sense
VCC 2 �IOUT �IOUTP VIND VIN TJ Total Supply Voltage Output Current (within S.O.A.) Output Current Peak Input Voltage (Differential) Input Voltage (Common Mode) Junction Temperature
TST Storage Temperature TLD Lead Temperature TC Case Operating Temperature (MSK164B/E) (MSK164) RTH Thermal Resistance (DC) Junction to Case
Parameter STATIC Supply Voltage Range 4 9 Quiescent Current VIN=0V INPUT Offset Voltage Offset Voltage Drift 4 Offset Voltage vs �Vcc 4 Input Bias Current 4 Input Impedance 4 Input Capacitance 4 Common Mode Rejection 4 Noise OUTPUT Output Voltage Swing Output Current Power Bandwidth 4 Resistance 4 Settling Time 3 4 Capacitive Load 4 TRANSFER CHARACTERISTICS Slew Rate Open Loop Voltage Gain CC=Open F=15Hz RL=5K V/�S dB IOUT=�40mA Peak VOUT=MAX VOUT=280VPP No Load CC=10pF 10V Step V mA KHz VIN=0V VCM=0V (DC)
Unless otherwise noted CC=18pF, RC=2.2K, �VCC= �150VDC. Derate maximum supply voltage 0.5V/�C below TC=+25�C. No derating is needed above TC=25�C. AV=-10V/V measured in false summing junction circuit. Devices shall be capable of meeting the parameter, but need not be tested. Typical parameters are for reference only. Industrial grade and "E" suffix devices shall be tested to subgroups 1 and 4 unless otherwise requested. Military grade devices ('B' suffix) shall be 100% tested to subgroups 1,2,3 and 4. Subgroup 5 and 6 testing available upon request. Subgroup 1,4 TC=+25�C Subgroup 2,5 TC=+125�C Subgroup TA=-55�C 9 Electrical specifications are derated for power supply voltages less than �50VDC.Current limit resistor value can be calculated as follows:
The MOSFET output stage of this power operational amplifier has two distinct limitations: 1. The current handling capability of the die metallization. 2. The junction temperature of the output MOSFET's. NOTE: The output stage is protected against transient flyback. However, for protection against sustained, high energy flyback, external fast-recovery reverse biased diodes should be connected from the output to ground.
It is recommended that the user set up the value of current limit as close as possible to the maximum expected output current to protect the amplifier. The minumum value of current limit resistance is 33 ohms. The maximum practical value is 500 ohms. Current limit will vary with case temperature. Refer to the typical performance graphs as a guide. Since load current passes through the current limit resistor, a loss in output voltage swing will occur. The following formula approximates output voltage swing reduction: VR=IO * RCL When the device is in current limit, there will be spurious oscillations present on the negative half cycle. The frequency of the oscillation is application dependent and can not be predicted. Oscillation will cease when the device comes out of current limit.
Input protection circuitry within the MSK 164 will clip differential input voltages greater than 16 volts. The inputs are also protected against common mode voltages up to the supply rails as well as static discharge. There are 300 ohm current limiting resistors in series with each input. These resistors may become damaged in the event the input overload is capable of driving currents above 1mA. If severe overload conditions are expected, external input current limiting resistors are recommended.
A 100 ohm resistor and a 330pF capacitor connected in series from the output of the amplifier to ground is recommended for applications where load capacitance is less than 330pF. For larger values of load capacitance, the output snubber network may be omitted. If loop stability becomes a problem due to excessively high load capacitance, a 100 ohm resistor may be added between the output of the amplifier (the junction of RCL and pin 8) and the load. A small tradeoff with bandwidth must be made in this configuration. The graph below illustrates the effect of capacitive load on open loop gain. Note that the snubber capacitor must have a voltage rating greater than or equal to the total rail to rail power supply voltage.
The MSK 164 has sufficient phase margin when compensated for unity gain to be stable with capacitive loads of at least 10nF. However, it is recommended that the parallel sum of the input and feedback resistor be 1000 ohms or less for closed loop gains of ten or less to minimize phase shift caused by the R-C network formed by the input resistor, feedback resistor and input capacitance. The user can tailor the performance of the MSK 164 to their application using the external compensation pins. The graphs of small signal gain and phase as well as the graphs of slew rate and power response demonstrate the effect of various forms of compensation. The compensation capacitor must be rated at 350 volts working voltage if maximum power supply voltages are used. The compensation resistor and capacitor lead lengths must be kept as short as possible to minimize spurious oscillations. A high quality NPO capacitor is recommended for the compensation capacitor. External compensation is only necessary at gains 30V/V or less. For larger gains, the compensation resistor and capacitor may be omitted. An effective method of checking amplifier stability is to apply the worst case capacitive load to the output of the amplifier and drive a small signal square wave across it. If overshoot is less than 25%, the system will generally be stable. Rev. 6/02 3