E4257ALPT Semtech, E4257ALPT Datasheet - Page 15

• Manufacturer Part Number: E4257ALPT
• Manufacturer: Semtech

Specifications of E4257ALPT

• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

Window Comparator
Each channel of the E42X7 features two comparators
connected in a “window comparator” topology. These
comparators can be used to provide two-bit measurement
range classification for go/no-go testing of devices. IVMAX
and IVMIN are high impedance analog voltage inputs that
establish the upper and lower thresholds for the window
comparator. DUTNH and DUTNL are LVTTL outputs that
indicate where a PPMU measured parameter lies in relation
to the IVMAX and IVMIN thresholds and are also used to
indicate when voltage clamping is taking place during
measurement as shown in Table 10.
Voltage Clamp
The integrated voltage clamp circuitry is controlled using
the HLV and LLV input pins. HLV and LLV are high
impedance analog voltage inputs that establish the “high”
and “low” clamp thresholds.
TEST AND MEASUREMENT PRODUCTS
Circuit Description (continued)
2005 Semtech Corp. / Rev. 5, 11/30/05
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a t
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Table 10. Comparator Output Truth Table
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measured parameter
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To PPMU
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IVMAX
IVMIN
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T
DUTNH
DUTNL
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The voltage clamp circuitry will constrain the DUT voltage
(V
LLV pins as follows:
As the voltage clamp circuitry uses the FORCE pin to sense
the DUT compliance voltage, applications that connect
the RF pin to the DUT (see Applications Information section)
must connect the FORCE pin to the RF pin for proper
voltage limiting functionality.
In the event of a voltage clamping condition, the DUTNL
and DUTNH comparator outputs are designed to “pull-
down” to logic “0” in order to indicate that the E42X7 is
clamping and may be influencing any measurement that
is being made (see Window Comparator section).
Current Limiting
The E42X7 features current limiting circuitry that limits
the amount of current that the device can delivery through
RF or FORCE pins. The amplitude of the short circuit
current is a function of the current range selected. The
maximum short-circuit current through the FORCE pin is
the sum of the force amp current limit and the voltage
clamp current limit if the voltage clamp is enabled and
engaged.
In the event that the voltage clamp is engaged, and the
FORCE pin voltage exceeds the HLV or LLV pin settings by
more than ~1.5V, the E42X7 will open all of the internal
switches connected to the FORCE and SENSE nodes in
order to protect internal PMU circuitry from damage.
compliance
15
where: V
) to within a range determined by the HLV and
V
V
min
min
max
E4237/E4257/E4287
= V
= V
V
compliance
LLV
HLV
specified Limit Accuracy
specified Limit Accuracy
V
max
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