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DS21Q55

31. JTAG-BOUNDARY-SCAN ARCHITECTURE AND TEST-ACCESS PORT

The DS21Q55 is an MCM consisting of 4 DS2155s. Each device has its on JTAG state machine and therefore is treated as 4 separate devices when testing. The following description refers to the DS2155 JTAG function.

The DS2155 IEEE 1149.1 design supports the standard instruction codes SAMPLE/PRELOAD, BYPASS, and EXTEST. Optional public instructions included are HIGH-Z, CLAMP, and IDCODE (Figure 21). The DS21Q55 contains the following as required by IEEE 1149.1 Standard Test-Access Port and Boundary-Scan Architecture:

§Test Access Port (TAP)

§TAP Controller

§Instruction Register

§Bypass Register

§Boundary Scan Register

§ Device Identification Register

The Test Access Port has the necessary interface pins: JTRST, JTCLK, JTMS, JTDI, and JTDO. See the pin descriptions for details.

JTAG FUNCTIONAL BLOCK DIAGRAM Figure 34-1

Boundary Scan

Register

Identification

Register

Bypass

Register

MUX

Instruction

Register

 

Test Access Port

Select

Output Enable

Controller

 

+V

+V

+V

10k

10k

10k

JTDI

JTMS

JTCLK

JTRST

JTDO

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Please contact telecom.support@dalsemi.com or search http://www.maxim-ic.com for updated

information.

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Maxim DS21Q55 specifications JTAG-BOUNDARY-SCAN Architecture and TEST-ACCESS Port, Jtag Functional Block Diagram Figure