S1L35000 Datasheet, PDF (84/106 Pages) Epson Company – GATE ARRAY

Chapter 8: Test Pattern Generation
(1) The input terminals are all in a fixed state.
(2) The bi-directional terminals are given “H” level or “L” level inputs or are in an
output state.
(3) There are no oscillators or operating functions within the circuit.
(4) None of the internal 3-state buffers (internal bus) are in a floating or a contention
state.
(5) The RAM, the ROM, and the megacells are not in states wherein current is
flowing.
(6) An “H” level input is applied to input terminals which have pull-up resistors.
(7) Bi-directional terminals with pull-up resistors attached are either given “H” level inputs
or are producing “H” level outputs.
(8) Bi-directional terminals with pull-down resistors are either in an input state or are pro-
ducing “L” level outputs.
(c) The Input Current Test
The input current test measures the inputs to the input buffer. The test items include meas-
urements of input leakage current and of pull-up/pull-down currents. The tests for these
measurement items are performed by applying a V_DD level or V_SS level voltage to the termi-
nal being measured, and measuring the current which flows. In other words, the test is per-
formed by applying either an “H” level or a “L” level voltage to the terminal being measured.
For example, when a V_DD (“H” level) signal is applied during the test to a terminal being
measured and which is in a state having an “L” level, then there is the potential for this to
cause the state to change from “L” to “H” in the terminal being measured, and the potential
that this will cause the LSI to function incorrectly.
In order to measure the input current tests, a test where a V_DD level is applied at an event
where there is an “H” input to the terminal being measured in the test pattern, and a test is
performed where a V_SS level is applied in the event where a “L” is applied. Because of this, it
is not possible to perform these tests when the terminals being measured are not in these
states in the test pattern.
The input current tests are further broken down into the following classifications.
(1) Input Leakage Current Test (I_LH. I_LL)
Measurements are performed regarding the input current of the input buffers which
have no pull-up/pull-down resistors.
The current which flows when an “H” level voltage is applied to the input buffer is
called I_LH, and its Max. current value is guaranteed. In order to perform this test there
must be an event in the test pattern which causes the input terminal to be measured to
have an “H” level input. Bi-directional terminals must have “H” level inputs in the input
state.
The current which flows when a “L” level voltage is applied to the input buffer is called
I_LL, and its Max. value is guaranteed. In order to perform this test there must be an
event in the test pattern which causes the input terminal to be measured to have a “L”
level input. Bi-directional terminals must have “L” level inputs in the input state.
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