5
Revision 5 / February 20, 2003 www.semtech.com
TEST AND MEASUREMENT PRODUCTS
Edge737
Circuit Description (continued)
HIZ
HIZ is a digital input which places the FORCE output into a
high impedance state, regardless of the operating mode
(forcing current or voltage.) This function allows the PMU
to be connected directly to the pin electronics without an
isolation relay while NOT adding any leakage current.
DISABLE
DISABLE is a digital input which places DUT L TH, DUT GTL,
I/V MONITOR, and P ASS/FAIL* into high impedance states.
Force Voltage / Measure Current Mode
In the FV / MI mode, VINP is a high input impedance,
analog voltage input that maps directly to the voltage forced
at the DUT (see Figure 1), where FORCE = VINP.
A current monitor is connected in series with the Op Amp
driving the FORCE voltage. This monitor generates a
voltage that is proportional to the current passing through
it, and its output is brought out to I/V MONITOR. The
monitor’s voltage may also be evaluated using the Window
Comparator whose operation is in accordance with the
FV/MI functional truth table (Table 6).
I/V MAX and I/V MIN are high impedance analog inputs
that establish the upper and lower thresholds for the
window comparator (see Table 4). In the FV / MI mode, a
maximum voltage input corresponds to at least a maximum
current output. Positive current is defined as current
flowing out of the PMU.
Table 4.
The voltage at I/V MONITOR follows the equation:
I(measured) = I/V MONITOR / (4.0 * REXT).
Nominally, the external resistors (RA, RB, RC, and RD)
should be chosen such that Imax * REXT = 2.0V.
Force Current / Measure Voltage Mode
In the FI / MV mode, IVIN is a high input impedance,
analog voltage input that is converted into a current (see
Table 5) using the following relationship:
FORCE = IVIN / (4.0 * REXT)
with positive current is defined as current flowing out of
the PMU.
Table 5.
The resulting DUT voltage is then tested via the SENSE
input by a window comparator , whose functional truth table
is shown in Table 7.
I/V MAX and I/V MIN are high impedance analog inputs
that establish the upper and lower thresholds for the win-
dow comparator. In the FI / MV mode, the reference in-
puts translate 1:1 to SENSE level thresholds.
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