E4257ALPT-T データシートの表示（PDF） - Semtech Corporation
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E4257ALPT-T Datasheet PDF : 39 Pages
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E4237/E4257/E4287
TEST AND MEASUREMENT PRODUCTS
Circuit Description
Circuit Overview
E42X7 is a family of dual channel parametric test and
measurement units, each of which can:
• Force Voltage/Measure Current
• Force Current/Measure Voltage
• Force Voltage/Measure Voltage
• Force Current/Measure Current
Each PMU channel can force or measure voltage over a
16.25V range and force or measure current over four
distinct ranges:
E4257, E4287
± 40 µA
± 400 µA
± 4 mA
± 40 mA
E4237
± 40 µA
± 4 mA
The E42X7 also features integrated voltage clamp/over-
voltage detection circuitry that provides over-voltage
protection to the DUT (Device Under Test) during normal
operation. Short-circuit protection circuitry protects the
E42X7 by limiting the maximum output current to a
specified value over the full-scale current for a particular
range. The E4287 features an integrated analog MUX
that is intended to be used to toggle the “driver high level”
supplied to a pin electronics driver between normal logic
levels and a super voltage level which is suitable for
programming devices that require a “third-level” such as
FLASHTM.
Also included with the E42X7 are a number of integrated
switches that allow the device to be configured to:
• Connect a central “system” PMU to the
DUT through the FORCE and SENSE pins
of the E42X7.
• Provide a ~4.5KΩ pull-up resistor to the
programmed force voltage level, which
allows devices with unipolar open-element
outputs (i.e., open drain) to be tested without
providing a designated pull-up or pull-down
on a load board.
PPMU Functionality
The trapezoid in Figure 1 describes the V/I functionality of
the E42X7’s internal PMU when a DUT is connected to
the FORCE or RF pins (a functional schematic of the E42X7
can be viewed in Figure 2).
Output Voltage [V]
VCC – 2V
VCC – 4V
–100%
Output Current
+100% [% Full-Scale Range]
The E4287 also features a pin (per channel), GUARD,
which can be used to drive the guard traces of a FORCE/
SENSE pair. By surrounding FORCE and SENSE traces
with guard traces which connect to the GUARD pin, an
effective method to achieve minimal leakage can be
achieved.
The E42X7 also includes a test head ground (DUTGND)
referencing features which allow the force voltage function
to be referenced to a separate ground reference other
than the ground (GND) power used for the device.
VEE + 4V
VEE + 2V
FORCE Pin, Range D (E4257, E4287)
FORCE Pin, Range C (E4237)
RF Pin, All Ranges
FORCE Pin, Ranges A,B,C (E4257, E4287)
Figure 1. PMU Functionality/Range at the
FORCE and RF Pins
2005 Semtech Corp. / Rev. 5, 11/30/05
10
www.semtech.com
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