Multi-Site Concurrent JTAG/IJTAG test

By: Intellitech  09-12-2011
Keywords: Programming, Pcb

 

The PT100 Parallel Tester enables high throughput PCB digital test, on-board FLASH and CPLD programming while keeping up with modern production line rates of one PCB every 20 to 40 seconds.  The PT100 is a key element in any modern CM or EMS manufacturing line. As test time and in-system configuration times continue to increase, the PT100 can keep up with the fastest production line without sacrificing on product test quality or resorting to pre-programming non-volatile parts. The PT100 Parallel Tester is designed to off-load in-circuit testers and in-line programmers and optimize throughput of digital test and configuration of PCBs incorporating the IEEE 1149.1 standard.  It is ideal for testing large FPGA based PCBs with moderate to large amounts of FLASH memory or panelized PCBs with 8, 16, 32 or more circuits per panel.  

Each PT100 chassis can support up to 16 boundary-scan controllers all managed by a single production test software running on a PCI or PXI based PC.  Each PT100 chassis can be connected to as many other PT100 chassis that are necessary to optimize throughput and reduce overall programming and test times.

      Figure 1.   Traditional ICT focused flow

The traditional test flow for PCBs with FLASH and BGA devices is shown in figure 1.  Variations of this flow include pre-programming FLASH memory and CPLD devices then creating an storing in inventory rather than programming in-line.  In this flow, in-circuit testers such as Agilent and Teradyne perform boundary-scan (IEEE 1149.1) test with built-in software or a third party boundary-scan controller is incorporated into the in-circuit tester.   In the past when PCB digital test times were short, that is, roughly equivalent to the analog test time of a PCB, using boundary-scan on ICT was an efficient strategy.   However, non-volatile devices (FLASH, EEPROM, CPLDs, etc) continue to increase in size and use in the modern PCB.  These devices increase the digital test and configuration time of the PCB such that this creates a bottleneck on the in-circuit tester.  Even with direct physical access to FLASH memory, some devices can take as much as 45 seconds or longer to program.

  1. Typical boundary-scan test and configuration (programming CPLDs, FLASH etc) on a "C" size PCB can take 60-90 seconds.

  2. A Cisco PCB w/ boundary-scan test takes approximately 3 minutes to test  

  3. A 4 CPU network server takes roughly 3 minutes to execute 1149.1 tests and at-speed  memory tests

  4. A single Intel 28F128J3 StrataFLASH with full pin access takes ~144 seconds to program.  The latest Intel 28F128K3 StrataFLASH takes ~78 seconds to program.

As digital test times have increased, the utilization of the ICT during the testing has dropped, in many cases the ICT is just supplying power while a independent boundary-scan controller applies test and configuration data.

  Figure 2. Optimized Flow for new generation PCBs

 As digital test times have increased, assembly test flow can be optimized by testing more UUTs in parallel.  On-board programming of FLASH through 1149.1 has received much attention, however, on many PCBs the FLASH configuration times over a single 1149.1 controller is unacceptable, forcing pre-programming or in-line FLASH programming equipment.  ISP (In-system programming) of CPLDs is also desired, but adds to the digital test time. 

New high-speed technologies and at-speed structural test (testing IC to IC connections with 1149.1 at there rated speed) require testing connections without pogo-pins.

+FPGAs with gigabit serial interfaces from Altera and Xilinx

+SDRAM, FCRAM, DDRAM memories require at-speed testing

+ AC coupled connections (when a capacitor exists betwen boundary-scan connections) require precise timing to test over 1149.1 or the 1149.6 standard

+ IBIST - Interconnect Built-in Self-Test or 'at-speed' interconnect testing

Figure 2 shows the optimized flow of testing the modern PCB.  Parallel 1149.1 test enables testing and configuration of the largest PCBs within the beat rate of the production line with a minimal of capital equipment.  

Environmental test

Environmental testing (exercising the system or PCB over temperature and humidity) typically is the longest test process of any product.  Since the tester can test many PCBs in parallel, it is an attractive alternative for testing large number of PCBs in an environmental chamber when the Intellitech embedded test products (SystemBIST) cannot be used. The PT100 sets a new price point enabling lower cost, high-volume products to be tested over temperature that typically could not be justified.

PT100 expandable architecture

The tester itself is not a traditional tester with a back plane and fixed number of test channels, but a collection of self-contained 'parallel tester card' building blocks that connect together over flexible ribbon cable.   The PT100 Parallel Tester cards are housed in a 19" 3U height rack mountable box with room for 16 plug-able cards, each one supporting 24 re-configurable tester channels and one IEEE 1149.1 controller.  Each 19" rack of 16 parallel tester cards can then be connected to another 19" rack of PT100 tester cards, expanding the tester channels as physical space and AC power permits. 

The physical flexibility of the tester enables it to interface with a variety of UUTs from small cell phones to large telecom blades.  The 24 tester channels and 1149.1 interface have a programmable logic high output level from .8v to 5V with a current drive of up to 84ma.  The IEEE 1149.1 interface can deliver and test boundary-scan data to and from the UUT at 64 Megabits per second on each tester card simultaneously.  Each tester card also has a high-speed clock channel that supports a clock rate up to 500Mhz for use with at-speed Built-In Self Test on the UUT. 

The tester cards are controlled from a single PC console using either Intellitech's PXI or PCI card interface and Intellitech's Scan Executive manufacturing software. The software comes standard with integrated support for adding PXI, GPIB or VISA instruments and power-supplies needed for testing the UUTs.   A secondary connector exists with auxiliary I/O that support integrating the parallel test process with automated board handlers and external fixturing.  Test development and debug is done with the Eclipse Test Development Environment.  All the tests developed for testing a single PCB can be exported without modification to the Intellitech Parallel Test environment.

Benefits

  • Maximizes PCB configuration and test throughput for production or environmental test

  • Users can parallelize PCB test and FLASH programming and not parallelize production lines

  • Provides a solution for matching PCB test and configuration throughputs to the beat rate of the production line.

  • Designed to off-load in-circuit testers and in-line programmers using patent-pending parallel test methods.

  • Reduces costs by eliminating complex line balancing and duplication of capital equipment.

  • Enables the balancing of test and configuration time with UUT handling time.

  • Enables structural test during burn-in testing for high volume products

  • Enables higher fault coverage tests without sacrificing test throughput

Keywords: Pcb, Programming

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