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Model 4225-RPM and Model 4225-RPM-LR 

Remote Pulse Module Instructions 

PA-1086 Rev. A October 2020 

*PPA-1086A*

Keithley Instruments

 

28775 Aurora Road 

 

Cleveland, Ohio 44139 

1-800-

833-9200

 

tek.com/keithley

Overview 

The Keithley Instruments Model 4225-RPM and 4225-RPM-LR Remote Preamplifier/Switch Modules are 

remote amplifiers and automatic switches. 

The 4225-RPM is a multiplexer switch that automatically switches between precision dc source-measure units 

(SMUs), C-V, and the ultra-fast pulsed I-V instruments. In addition, the Remot Preamplifier/Module (RPM) 

extends the low current measurement capability of the 4225-PMU Ultra-Fast Pulsed I-V Instrument Module. 

The Model 4225-RPM-LR is a lower output resistance version of the 4225-RPM. This lower output resistance 

allows for a more accurate RPM voltage output at higher currents than the 4225-RPM. Performance tradeoffs 

may result, especially when making measurements of high capacitive loads. 

Figure 1: 4225-RPM and 4225-RPM-LR 

Summary of Contents for 4225-RPM

Page 1: ...hat automatically switches between precision dc source measure units SMUs C V and the ultra fast pulsed I V instruments In addition the Remot Preamplifier Module RPM extends the low current measuremen...

Page 2: ...ve cap CAP 47 2 6 Triaxial caps for shielding not shorting CA 31 4 Not shown Support bracket 4200 322 1 Not shown Captive panel screw for support bracket FA 243 2 1 Not shown Allen socket head capscre...

Page 3: ...PMU and used by the PMU as well as the RPM modules Multi measurement Prober Cable Kit documents These are guides for the optional 4210 MMPC kits that are customized for various probers Switching and c...

Page 4: ...problems that may affect proper ranging and LLEC operation do not mix 4225 RPMs and 4225 RPM LRs in one system Use either all 4225 RPMS or all 4425 RPM LRs Connections from the 4225 PMU to an RPM The...

Page 5: ...ions PA 1086 Rev A October 2020 5 Connections to a 4 terminal device The following illustrates the connection to a 4 terminal device using the cabling and adapters that are included with either RPM or...

Page 6: ...PA 1086 Rev A October 2020 Typical 2 terminal connections The following figure illustrates the connections to 2 terminal devices using the optional MMPC cabling This figure shows two 4225 RPMs or 4225...

Page 7: ...225 RPM LR extends the lower current ranges of the 225 PMU This is especially important for devices like diodes or transistors that have I V curves that extend over several decades of current The auto...

Page 8: ...to be lower than the programmed source voltage The output resistance of a pulsing instrument causes this effect This resistance causes a reduction in output voltage at the test device when current fl...

Page 9: ...put but this is typically between 2 and 3 not including cable resistance It also exhibits the load line effect but to a much lesser degree than the 4225 RPM The following figure compares the load line...

Page 10: ...n these current ranges the RPM acts as a preamplifier for pulse current measurements Above the 10 mA range the RPM is bypassed and the current measurement occurs in the 4225 PMU which has 50 of output...

Page 11: ...may be connected to mains These instruments will be marked as category II or higher Unless explicitly allowed in the specifications operating manual and instrument labels do not connect any instrument...

Page 12: ...cumentation explains hazards that could damage the instrument Such damage may invalidate the warranty The CAUTION heading with the symbol in the user documentation explains hazards that could result i...

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