The PEL-2004 and PEL-2002 are multiple channel, programmable DC electronic loads with a modularized structure. The PEL-2000 Series is designed to meet the continuing shift toward high speed operation in today's semiconductor market. As the power supply units, DC-DC converters, and batteries that drive semiconductor circuits to follow this shift, power supply design, quality inspection, and characteristic certification using high-speed performance loads have become necessary. The PEL-2000 Series includes two types of mainframes and 4 types of load modules to accommodate users' requirements in a flexible manner. Any load module combination can be used with a mainframe to tailor a test system based on the number of channels, and the maximum load power, voltage and current of each channel. Multiple loads can be connected in parallel to provide a higher-power load to test higher power supply outputs. This flexibility significantly reduces the investment needed for future projects that have different power requirements. The PEL-2004 is a 4-slot mainframe with a master control unit to hold 4 load modules, while PEL-2002 is a 2-slot mainframe with master control unit to hold 2 load modules. When the PEL-2004 is configured with 4 load modules rated at 350W each, the PEL-2000 series is able to sink up to 1.4kVA of power.

For higher load capacities, mainframes can be linked together in parallel with standard MIL 20-pin connectors. A maximum of 5 mainframes, including one master and 4 slaves can be chained together to create a total load capacity of 7kW for high current and high power applications. Using 4 dual channel load modules, the PEL-2004 is able to test 8 power supply outputs simultaneously. The Sequence function allows each channel to change its load sink according to a predefined sequence at a rate of up to 100 s per step. Each sequence is able to run concurrently under the control of one clock. This is one of the most powerful features of the PEL-2000 Series as it is able to realistically simulate a multi-output power supply load. Under Dynamic mode, the load current or load resistance pulses between two preset levels at a pre-defined speed up to 25 s per step. This is often used as the standard test procedure to verify the response of a power supply to quick load changes. Most remarkably, multiple load channels can be connected in parallel to run Dynamic tests synchronously under a single clock. This Parallel Dynamic functionality gives the flexibility to perform dynamic tests for a high-power power supply without the need of another high-power load.

The PEL-2000 Series includes a number of protection modes: Over Current Protection (OCP), Over Voltage Protection (OVP), Over Power Protection (OPP), Reverse Voltage Protection (RVP), and Under Voltage Protection(UVP). The protection modes are useful to protect both the load modules and the DUT(s). A buzzer can be set when a protection setting has been tripped. When a protection mode has been tripped, the load unit will display an alarm and stop sinking current/voltage. When a load unit is operating in CR or CV mode, the unit may need Over Current Protection to prevent excessive current being sunk. Over Current Protection stops the load from sinking more current than its recommended limit and prevents the load from burn-out damage. Over Voltage Protection is used to limit the amount of voltage sink. If the OVP trips, the PEL-Series load will stop sinking voltage. Over Power Protection is used when the input power exceeds the specifications of the load. When OPP is tripped, the power will cease to be sunk. Reverse Voltage Protection prevents reverse voltage damage to the PEL-2000 Series up to the specified rating. When Reverse Voltage Protection has been tripped, an alarm tone will sound until the reverse voltage is removed. Under Voltage Protection will turn off the load when the voltage drops below a set limit. The Go/NoGo function is available to monitor test results all the time. When a test result goes beyond a preset limit range, a "No Go" indication will be shown on the display and a "No Go" signal can be sent out through the D-SUB interface for external device control. This Go/NoGo function is available for CC mode, CV mode, and CR mode. Under "Program" mode, 12 programs, each containing 10 panel setup memories, can be edited to create work routines for repetitive tests. After a program has been executed, the results of all test steps, along with the Go/NoGo judgments, will be shown on the screen. For external control and system configuration, the PEL series has USB and RS232 interfaces as standard and GPIB as an option. The LabView driver and Data Logging PC software are both supported for all the available interfaces. Each channel has an analog control/monitoring connector on the rear panel to externally turn a load on/off and to externally monitor load input current and voltage.

A. AUTOMATICALLY SEQUENCE FUNCTION

 The Sequence function allows each channel to change its load sink according to a predefined sequence at a rate of up to 100 s per step. Each sequence is able to run concurrently, under the control of one clock. This is one of the most powerful features of the PEL-2000 Series as it is able to realistically simulate a multi-output power supply load. Under Dynamic mode, the load current or load resistance pulses between two preset levels at a pre-defined speed up to 25 s per step. This is often used as the standard test procedure to verify the response of a power supply to quick load changes.

The picture above is an example of a sequence used as a load profile for a single output switching power supply. A load profile is programmed to simulate the current draw of a power supply load. By using a current probe to acquire a current waveform, the PEL-2000 is able to evaluate the performance of a power supply based on the load sequence that is programmed. An oscilloscope is then used to display the result.

B. MULTIPLE OPERATING MODE

C.C. ( Constant Current )
In Constant Current mode, a load unit will sink the amount of current programmed. Regardless of the voltage change, the current will stay the same. Two selectable ranges are available for constant current mode: High (HI) and low (LO) range. Low range has a higher resolution for high precision measurements. If the current exceeds the low range, high range must be used. The PEL-2000 Series offers the maximum rated power for the low measurement range. This unique feature enables high-resolution measurements at high voltage only if the load current doesn't exceed the rated low range level. Both static and dynamic modes are available for CC operation. Static mode can be used for stability tests and Dynamic mode can be used to test transient load performance of a power supply. Go/NoGo is supported for both high and low ranges as well as Static and Dynamic modes.

C.V. ( Constant Voltage )
In Constant Voltage mode the load unit will sink current whilst keeping the voltage constant. Under CV mode, single channel load modules support two levels of voltage (A Value, B Value) with a preset cut-off current limit. An A / B button is available on the load module front panels to switch the Constant Voltage between A Value and B Value for power supply load regulation testing. Dual channel load modules only support A Value for CV mode. To accommodate the response of a power supply, response rates during voltage transitions can be set to fast or slow under static test mode.

C.V.+C.C. ( Constant Voltage + Constant Current )
When using CV mode, a current limit can be set for CV+CC mode. If the input voltage is greater than the preset CV limit, the channel will operate in CV mode if the input current is less than the preset CC limit. When the input current exceeds the current limit, the channel will operate in CC mode.

C.R. ( Constant Resistance )
In Constant Resistance mode the load units will linearly sink current and voltage to match a set resistance. Two different CR values and two different rising and falling slew rates can be set under CR Mode for single channel load modules. Like CC mode, Constant Resistance mode supports both dynamic and static loads. As with the other modes, Go/No Go is also supported.

C. PARALLEL DYNAMIC LOADING

 All the load channels in a PEL-2000 mainframe can be connected in parallel to perform any combination of static or dynamic loading. Under Dynamic mode, the load current or load resistance pulses between two preset levels at a predefined speed of up to 25 s per step. When the channels are connected in parallel, dynamic tests are synchronously clocked. The ability to perform parallel dynamic loading gives you the flexibility to perform dynamic tests to highpower power supplies without the need for a dedicated high power electronic load.

D. FRAME LINK

 The PEL-2000 Series allows multiple mainframes to be linked together with standard MIL 20-pin connectors to provide higher power load capacity. A maximum of 5 mainframes maximum, including one master and 4 slaves, can be chained together to give a 7kW load capacity for high current and high power applications

E. RUN PROGRAM

 Under "Program" mode, up to 12 programs each with 10 panel setup memories, can be edited to create work routines for repetitive tests. After a program has completed, the results of all test steps, including the Go/NoGo judgments will be shown on the screen. Up to 12 programs with a total of up to 120 panel-setup memories can be chained together to be run one after the other.

F. PROTECTION MODES

 The PEL-2000 Series includes a number of protection modes: Over Current Protection (OCP), Over Voltage Protection (OVP), Over Power Protection (OPP), Reverse Voltage Protection (RVP), and Under Voltage Protection (UVP). The protection modes are useful to protect both the load modules and the DUT(s). A buzzer can be set for when a protection setting has been tripped. When a protection mode has been tripped, the load unit will display an alarm and stop sinking current/voltage. When a load unit is operating in CR or CV mode, the unit may need Over Current Protection to prevent excessive current being sunk. Over Current Protection stops the load from sinking more current than its recommended limit and prevents the load from burn-out damage. Over Voltage Protection is used to limit the amount of voltage sunk. If the OVP trips, the PEL-Series load will stop sinking voltage. Over Power Protection is used when the input power exceeds the specifications of the load. When OPP is tripped, the power will cease to be sunk. Reverse Voltage Protection prevents reverse voltage damage to the PEL-2000 Series up to the specified rating. When Reverse Voltage Protection has been tripped, an alarm tone will sound until the reverse voltage is removed. Under Voltage Protection will turn off the load when the voltage drops below a set limit.

G. Von VOLTAGE SETTINGS

 Von Voltage is the voltage limit at which the load will start to sink current. The Von Voltage setting is necessary for some kinds of power supply if a heavy load is connected during load on. There are two operation modes for Von Voltage: Latch ON and Latch OFF. When Von Latch is set to ON, the load starts to sink current when input voltage exceeds Von, and will continue to sink current even if the voltage drops below the Von Voltage later. When Von Latch is set to OFF, the load starts to sink current when input voltage exceeds Von, but will stop sinking current when the voltage drops below the Von voltage setting. This is to prevent the power supply from running into oscillation when the output voltage goes below certain level.

H. EXTERNAL CHANNEL CONTROL

 A six-pin analog control connector is available on the rear panel to externally turn a load on/off and to externally monitor the load input status of each channel, including input current, input voltage, and CC current or CV settings. The Voltage Monitor Output (VMON) and Current Monitor Output (IMON) output the load input voltage and load input current as a percentage of rating current/voltage. Where 0 volts = 0% rating and 10 volts = 100% load input rating voltage or current. The voltage monitor output is across pins 1 & 3, and the current monitor output is across pins 1 & 2. Below shows the pin configuration of the voltage and current monitor outputs.

To turn a load on, an active low voltage (0-1V) must be applied across Load On (pin 5) and GND (pin 1), similarly an active high voltage (4-5V) must be applied to turn a load off. The Load On input must be TTL.