80960KB datasheet(15/39 Pages) INTEL

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80960KB

2.5.

Test Load Circuit

Figure 12 illustrates the load circuit used to test the

80960KB’s three-state pins; Figure 13 shows the load

circuit used to test the open drain outputs. The open

drain test uses an active load circuit in the form of a

matched diode bridge. Since the open-drain outputs

sink current, only the IOL legs of the bridge are

necessary and the IOH legs are not used. When the

80960KB driver under test is turned off, the output pin

is pulled up to VREF (i.e., VOH). Diode D1 is turned off

and the IOL current source flows through diode D2.

When the 80960KB open-drain driver under test is

on, diode D1 is also on and the voltage on the pin

being tested drops to VOL. Diode D2 turns off and IOL

flows through diode D1.

Figure 12. Test Load Circuit for Three-State Output Pins

Figure 13. Test Load Circuit for Open-Drain Output Pins

THREE-STATE OUTPUT

CL = 50 pF for all signals

OPEN-DRAIN OUTPUT

IOL

IOL Tested at 25 mA

VREF = VCC

D1 and D2 are matched

CL = 50 pF for all signals

80960KB 数据表(PDF) 15 Page - Intel Corporation