Power Supplies Grundlagen und Anwendungen Thomas Giehm/ datatec
Agenda Grundlagen Kategorien Anwendungen Parameter Bauarten Eigenschaften DC Power Analyser N6705B Module Beispiele Portfolie Überblick Spezialformen von Power Supplies
Power Supply Categories Basic Supplies Manual or Programmable Used for setting bias, powering circuits, etc. Performance Supplies Faster, more accurate, higher power Typically used in system applications Modular Supplies Compact, flexible, mix-and-match Easily interconnected Specialty Supplies Battery Simulation Solar Array Simulation Page 3
What do People do with Power Supplies? Task Meaning Power Supply Required Basic DC Bias Set the output to one voltage or current to power the Device Under Test (DUT) Basic Power Supply (PS) Burn-in Lots of power or lots of channels Basic PS Margin Testing Turn-on and Inrush Testing Test DUT at a variety of points in DUT operating range Speed can be important if high throughput is required or if DUT is being tested at a lot of different points Multiple outputs must be sequenced Measure how much current is drawn when DC bias is first applied Basic PS or Performance PS Performance PS Depends on required speed or on required accuracy of V setting Characterization using Waveforms Parametric Testing of Devices Stimulate the DUT with a time varying voltage to test under dynamic test conditions Speed matters Characterize performance of transistors, diodes, resistors and capacitors Performance PS Precision Source Measure Unit Device/Parameter Analyzer Page 4 Page 4
Power Supply Output Characteristics Ripple and Noise Ideal output is free from any voltage variations; In practice, never the case Ripple = periodic variations, usually line related Noise = random variations Typically specified as either Vrms or Vp-p Vp-p shows the maximum variation away from the DC set point Programming Accuracy Measure of how closely the output will be to the setpoint Specified as a percent of output plus an offset Can determine if the power supply has the precision required Many power supplies have built-in voltmeters and ammeters to measure output Output Response When the set point or the load changes, it takes time for the output to change Slew rate is a result of the power supplies regulation and output bandwidth Typically specified for a voltage change from 10% to 90% of its rated output Also specified for a load change of 50% to 100% Page 5
DC Power Supply Topologies Linear or series-pass Advantages Low output ripple & noise Fast programming speed Fast transient recovery Disadvantages Low efficiency High weight/watt Physically large Applications Bench & laboratory Automated test Low power: < 500 W Note: Agilent's linear Power Supplies classically have fast programming speed which make them a good fit in test systems. Page 6
DC Power Supply Topologies Switched mode (SMPS) Advantages High power in small package High efficiency Disadvantages Moderate to high** ripple & noise Moderate programming speed Moderate transient recovery Applications Subassembly test Burn-in Bench & laboratory Electromechanical test **Note: Agilent's newest Switching Power Supplies have noise, slew rate, programming speed and transient performance nearly that of linear supplies Page 7
Key Power Supply Specs: Comparing Noise Typical PC Power Supply (not an instrument) Typical Switching (SMPS) Supply High Noise 100 mvpp 20 mvpp Hint Noise is very dependent on output voltage, so a 5V output will have much less noise than a 100 V output Agilent Switching Supply Typical Linear Supply Low Noise 10 mvpp 1 mvpp Agilent Low Noise Switching Supply Agilent Linear Supply Page 8
Controlling the Power Supply Computer Interfaces manual and/or computer control E.g. GPIB, USB, and LAN Analog Voltage Control Signal analog voltage control input acts as an amplifier Use case: Amplify the power of the input signal Track an analog voltage Page 9
Output Measurements built-in voltmeter and/or ampermeter - read back own output displayed on front panel or queried by remote interface accuracy is specified as a % of full scale plus an offset Page 10
Remote Sense (150 mv drop) Lead resistance can contribute a significant voltage drop between the output of the supply and the actual voltage presented at the load I =10 Amps (150 mv drop) The sense leads measure the voltage present at the load itself, and adjusts the output of the supply to compensate for the voltage drops in the leads 5.3 V High Z Input I =Zero Page 11
Remote Sensing Best Practice: Minimize Wiring Path Impedance Four steps to minimize path impedance: 1. Use larger gauge, twisted pair wire. 2. Reduce distance between power supply and DUT. 3. Minimize the use of relays / connectors. 4. Select relays / connectors to minimize contact resistance; consider initial and end of life specs. Beware of transient response issues for dynamic loads Use an adequate bypass capacitor at the DUT Consider a supply tailored for remote sensing with pulsed loads Page 12 Page
Physical Characteristics Physical size / Form Factor Half rack width or full rack width, some vendors offer ¼ rack width Height ranges from 1U to 4U (1.75 in to 7.00 in). Half rack width is generally better for bench applications Full rack width works well in system racks Front or Rear Output Terminals System and high current power supplies have their outputs located on the rear panel Bench and some low current power supplies have their outputs on the front Number of Outputs Multiple output power supplies can save space on the bench or in a rack
DC Power Supply Capabilities Constant voltage (CV) mode Output sensing V Set CV I Constant current (CC) mode V CC I Set Page 14
Output Characteristics Rectangular V max P max V max P max Dual-range P max I max I max Autoranging V max Maximum power range I max
Special Capabilities Protecting the Device Under Test Over Voltage Protection (OVP) Over Current Protection (OCP) Discrete Fault Indicator (DFI) / Remote Inhibit (RI) Protecting the Power Supply Over Temperature Protection (OTP) Output Disconnect Relay Output Polarity Reversal Page 16
Output protection features Inhibit (INH) / FAULT (FLT) Power Supply A Daisy-Chain of Three Power Supplies for Emergency Shutdown Power Supply B Power Supply C Load A +S + - -S Load B +S + - -S Load C +S + - -S 1 FLT 2 3 INH 4 1 FLT 2 3 INH 4 1 FLT 2 3 INH 4 For multiple bias input subassemblies, if one bias supply senses a failure, all should be shut down TTL Input/Output Fault definition defined by system controller at set-up Page 17 Page
Unique Feature: Down Programming Capacitors discharge slowly under light loads Static voltage source: no problem Varying voltage levels: slow tests Down programming Rapidly decrease the output voltage Reducing discharge times by hundreds of ms Page 18
Remote sense leads Remote sense leads compensate for voltage drops in load leads Allows power supply to regulate set voltage right at user s load +Sense +Out Power Supply Output - Out - Sense Iout + - - + Vload User s Load With remote sensing: Vload = Vset (the set voltage) Without remote sensing: Vload < Vset (due to voltage drop in wire resistance)
N6705A Remote sense: called 4 Wire Sense Access from Source Settings screen Illuminates a green 4 wire LED on front panel for each output with 4 Wire Sense turned on Setting is stored in non-volatile memory CAUTION: If you do not have sense wires connected, turn 4 Wire Sense off. Otherwise, output will regulate slightly higher than setting (a few %).
Parallel and Series Safety Precautions SERIES CONNECTION Never exceed the floating voltage rating of any of the supplies. Never subject any of the power supplies to negative voltages. Program each power supply independently. If two supplies are used, program each one for 50% of the total output voltage. If three supplies are used, program each supply for about 33% of the total output voltage. Set the current limit of each supply to the maximum that the load can safely handle. PARALLEL CONNECTION One unit must operate in constant voltage (CV) mode and the other(s) in constant current (CC) mode. The output load must draw enough current to keep the CC unit(s) in CC mode. Program the current limit of each unit to its maximum value and program the output voltage of the CV unit to a value slightly lower than the CC unit(s). The CC units supply the maximum output current that they have been set to and drop their output voltage until it matches the voltage of the CV unit, which supplies only enough current to fulfill the total load demand.
DC Power Analyzer N6705B has sourcing and measurement capability Sourcing functions Simple DC bias Arbitrary waveform generator-like functions Sequencing outputs Measurement functions DC measurements Oscilloscope-like functions Datalogger function
Agilent N6705 Sourcing Capabilities Output sequencing Output waveforms V V DC bias V pulse t Module 1 Module 2 Module 3 Module 4 t V V OUTPUT ON t Step turnon Trapezoid Delay 2 Delay 3 Delay 4 t V t Ramp turnon V V dropout t V V Slew t Staircase turn-on t AC + DC offset V1 V2 V3 V t Exponential turn-on V User defined t V4
Agilent N6705A DC Power Analyzer Measure/Source control Keypad/menu entry/control Output select, V & I set knobs Emergency stop: All outputs off USB memory stick connector LCD display: Metering Scope Datalogger Menu AC line switch Display control knobs: V, I, & Time / division Offsets for each Markers Trigger level Auto-scale 4 power supply outputs, each with: Output On/Off +/- Sense +/- Output
N6705A Rear View Trigger In/Out Digital port USB, LAN, GPIB (LXI Class C)
Module Dependent The Agilent N6705A DC Power Analyzer Key Specifications Number of outputs: Total output power: Max current per output: Max voltage per output: Available power per output: Ammeter accuracy: Scope: Arb bandwidth: Datalogger sample interval: Datalogger maximum log size: Internal memory: Takes 1 to 4 DC Power Modules 600 W (= sum of 4 outputs) 20 A (binding post limit) 100 V; can put in series for higher V 50 W, 100 W, 300 W Up to 0.03 % + 15 µa (Precision module) Up to 0.10 % + 20 ma (Hi-Performance module) 50 khz digitizer, 4096 pts, up to 18 bits Up to 4500 Hz (Hi-Perf), up to 260 Hz (Basic) 1 ms minimum, 1 minute maximum 500 Million readings 64 MB, non-volatile (=16 Million readings)
Flexible: Mix and Match Power Modules N6705A DC Power Analyzer, 600W Holds up to 4 modules, below, in any combination 50 W DC Power Modules (6 models up to 100 V or 10 A) 100 W DC Power Modules (6 models up to 100 V or 20 A) 300 W DC Power Modules (4 models up to 100 V or 15 A) For basic DUT or fixture power 50 W High-Performance, Autoranging DC Power Module 100 W High-Performance, Autoranging DC Power Module 300 W High-Performance, Autoranging DC Power Module For applications where power supply plays key role as source and measurement instrument 50 W Precision DC Power Module 100 W Precision DC Power Module For semiconductor testing and applications requiring precision in the milli- and microampere region
7 New High Power Modules, 300 & 500 Watts Brings the N6700 family total to 33 modules N6755A N6756A 20V, 50A 60V, 17A N675x N6751A 50V, 5A 50W Max N6752A 50V, 10A 100W Max N6753A 20V, 50A 300W Max N6754A 60V, 20A 300W Max 500W Max $2800 REF 500W Max $2800 REF High Performance Series N6763A N6764A N6765A N6766A 20V, 50A 60V, 20A 20V, 50A 60V, 17A N676x N6761A 50V, 1.5A 50W Max N6762A 50V, 3A 100W Max 300W Max $3500 REF 300W Max $3500 REF 500W Max $3900 REF 500W Max $3900 REF Precision Series N6777A 150V, 2A N677x N6773A 20V, 15A 300W N6774A 35V, 8.5A 300W N6775A 60V, 5A 300W N6776A 100V, 3A 300W 300W $1350 REF Basic Series
New N6700 Series SMU Products - Applications 2-Quadrant SMU for Battery Drain Analysis 20W 20V +1A / 6V +3A 2-Quadrant SMU for Functional Test 20W 20V +1A / 6V +3A 4-Quadrant SMU for General Purpose 20W +20V +1A / +6V +3A Application N6781A N6782A N6784A Battery drain logging and analysis Battery run-down logging & analysis Chip set test PMU test Active device test Semiconductor test Discrete device test Passive device test
N6781A 2-Quadrant Source/Measure Unit for Battery Drain Analysis Voltage Source Current Source Electronic Load Glitch free sourcing and measurement Multiple measurement ranges Excellent transient response to GSM pulse Stable with capacitive loads up to 150 µf Programmable output resistance: -40mΩ to +1Ω Auxiliary voltage measurement input for battery rundown test Measurement Built-in digitizer of 200,000 samples/second +6V -3A -1A +20V +1A +6V +3A Introduced in 2010 14585A Software
Making Measurements Battery Rundown Test N6781A only Battery Rundown Test (Single reading, Scope or Data log) Zero-burden ammeter mode --plus-- Aux input voltage measurement to measure battery voltage Gives most realistic assessment of DUT operation under battery power Your power source _ Battery Current Drain 0 Volts Ammeter + DUT Aux In Voltage Measurement on N6781A Up to 4
Example Application: Helping to solve an ABS module manufacturing problem Problem: At automotive body & assembly plant, during final assembly, as battery connector was slid onto battery post, intermittent power was briefly applied to ABS module causing ABS light to erroneously come on Testing requirement: Quality Engineers needed a way to simulate intermittent power to the ABS module to test it on the bench
Example Application: Helping to solve an ABS module manufacturing problem (continued) Solution: N6705A arbitrary waveform generator was used to create a variety of power drop-outs to look for problems and evaluate margin after design changes were made Arb definition: User defined voltage Only part of arb shown above Voltage bouncing between 0V & 14.4V Experiment with time settings & number of dropouts to try to create problem Scope view 200ms/div Shows simulated intermittent battery connection
Ic = C x dv/dt Effect of Output Capacitor on Current Measurements Each module measures its output current here Ic = cap current User s current Note: Ic flows only when Vout is changing
5000V/s slew rate Compensate current measurements during voltage transients setting 25V step N6762A, no load The only difference
14585A Control and Analysis Software for the DC Power Analyzer Works with N6705A/B, N6715A/B mainframes only Simultaneously control up to 4 mainframes; Up to 16 power supplies Advanced features made easy, such as record & playback Works with all N6700 modules $1,240 per mainframe license (after 30 day free trial) www.agilent.com/find/14585
Dynamic Battery Test Examples Examples of dynamic battery drain: GSM phone current during a phone call Digital camera current during a picture Google G1 phone current during boot process (turn on) Dynamic battery drain reproduced using N6781A as an electronic load: All screenshots are of 14585A Control & Analysis Software for the DC Power Analyzer www.agilent.com/find/14585
Agilent Basic DC Power Supply Family Programmable (All have GPIB -- some include RS-232 or USB + LAN/LXI) E3640A-45A Single Output 30 W - 80 W E3646A-49A Dual Output 60 W - 100 W E3631A Triple Output 80 W E3632A-34A Single Output 120 W - 200 W 500 37 models 4200 Non-programmable (for Labs and Low-cost Manufacturing) N5700/N8700 Single Output 750 W 5000 W U8000A 90 W, 150 W E3610A-17A 30 W - 60 W E3620A 50 W E3630A 35 W 200 Single output 11 models Multiple Output 480
Multiple Output N6700 Low-Profile Modular Power System Agilent Performance DC Power Supply Family 5500 13 900 2700 10 500 N6705B DC Power Analyzer 4100 13 900 66000 Modular Power System 8 x 150 W, for legacy systems Single Output DC, GPIB, Ideal for ATE, Accurate, Low Noise 6610 6630 6640 6650 6670 6680 6690 50 W 100 W, 2Q 200 W 500 W 2000 W 5000 W 6600 W 1400 33 models 5600
Agilent N6700 Modular Power System Small Flexible 4 Outputs, 1U Modular Mix-and-Match Up to 4 outputs at up to 500 W per output Select any combo of 34 output power and performance levels Open Connectivity: LAN, USB, and GPIB all standard Certified LXI Class C Fast Command Processing Time < 1 millisecond Market leader in speed to maximize system throughput Built-in output sequencing Built-in scope-like digitizer (optional)
The N5700 System DC Power Supplies Easy test system integration High power density (1U) Affordable basic power Product Highlights 24 models: 750 W & 1500 W Output up to 600V and up to 180A Built-in voltage and current measurement Parallel up to 4 units for higher power USB, LAN (LXI C), and GPIB interfaces standard
Agilent N8700 System DC Power Supplies All the same benefits of the N5700 Series but with up to 8x more power Basic power and a lot of it 21 models: 3300 W and 5000 W Up to 600 V and up to 400 A High density 2 U, full-rack package Full DUT protection: OV, OC, UVL Built-in measurements Parallel up to 4 units for higher power USB, LAN (LXI C), & GPIB all standard
For ALL general-purpose sourcing/measurement applications B2900A However, there are a few situations where the N6784A SMU might be a better choice: If there is already an N6700 or N6705 mainframe and a need for SMU capabilities If the DUT is dynamic and fast transient response is required If there is a need to create dynamic waveforms (sourcing or sinking) If the DUT has capacitance greater than 50µF If there is a need to do long-term data logging
Agilent N3300 Modular Electronic Loads Automatically execute stored command sequences N3300 6 slot mainframe N3301 2 slot mainframe Programmable delay allows for either simultaneous or sequential load changes Digitize measurements into 4096 pt buffer Control rising and falling slew rates separately Test high current power supplies Measure with all loads simultaneously 1800W total power
Electronic Loads in Solar Testing High power handling capability in a compact unit: the 1,800-W N3300A is a full-rack unit and the 600-W N3301A is a half-rack unit Simultaneous channel measurements and simultaneous current, voltage, and power measurements from a single channel for high-throughput testing Built-in digitizer can make measurements of current or voltage vs. time Temperature coefficient specifications make calculating accuracy for outdoor testing easy High input stability to prevent oscillations in test setup High-impedance external sense capability
Solar Array Simulation Difficult to implement and control during test Sun Solar module DC Microinverter AC AC power grid Easy to implement and control during test Agilent Technologies E4360A Solar Array Simulator DC Microinverter AC AC power grid 46
Solar cell characteristics I Photovoltaic I-V Characteristics R sh Decreasing Light Intensity Decreasing R sh Increasing Temperature Increasing R s R s V Photovoltaic Cell DC Equivalent Circuit Illuminated I d I R s + V R sh - Photovoltaic Cell DC Equivalent Circuit when Dark Photovoltaic Cell AC Equivalent Circuit Illuminated Agilent Solar Array Simulators act like a real solar array + V - R s R sh
Specialty Products: AC Power Source/Analyzers Simulates the AC power for testing devices that plug into the wall Can add disturbances, like dropouts, surges, sags, etc Test power supplies, UPS devices Perform AC-mains CE-mark testing Integrated source, measurement and AC power analysis 6811B = 375 VA 6812B = 750 VA 6813B = 1750 VA
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