Datasheet

DS21352/DS21552

98 of 137

The DS21352/552 are enhanced versions of the DS2152 and are backward pin-compatible. The JTAG

feature uses pins that had no function in the DS2152. When using the JTAG feature, be sure FMS (pin

76) is tied LOW enabling the newly defined pins of the DS21352/552. Details on Boundary Scan

Architecture and the Test Access Port can be found in IEEE 1149.1-1990, IEEE 1149.1a-1993, and IEEE

1149.1b-1994.

The Test Access Port has the necessary interface pins; JTRST, JTCLK, JTMS, JTDI, and JTDO. See the

pin descriptions for details.

Figure 19-1 JTAG FUNCTIONAL BLOCK DIAGRAM

Boundary Scan

Identification

Bypass

Instruction

JTDI JTMS JTCLK

JTRST JTDO

+V +V

Test Access Port

Controller

MUX

10K 10K 10K

Select

Output Enable