E4237ALP Semtech, E4237ALP Datasheet - Page 16

• Manufacturer Part Number: E4237ALP
• Manufacturer: Semtech

Specifications of E4237ALP

• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

On-Chip “Termination” Mode
When the E42X7 is placed in FV mode and the internal
PMU is not selected (SELIPMU = 0), it can be placed in
“termination” mode by setting the HiZ input to logic “0”.
When configured in this manner, the E42X7 can be used
to provide an ~4.5K “pull-up” or “pull-down” resistor at
the FORCE pin to the termination voltage programmed by
V
outputs (i.e. open drain).
External PMU
The E42X7 features on-chip routing and switches for
connecting an external PMU to the FORCE and SENSE
pins of each channel.
The EPMUF pin is the “External PMU Force” input and is
connected to the FORCE pin through an on-chip 40 ,
40 mA switch.
The EPMUS pin is the “External PMU Sense” input and is
used to connect the external PMU’s sense line to the
E42X7’s SENSE pin through an on-chip high impedance
switch.
The on-chip switches used for routing the external PMU
are located in a separate on-chip well that can be
sepeartely powered from the core on-chip PMU circuitry
using SVCC. This allows the voltage range of the external
PMU to be greater than that of the core PMU without
increasing core PMU power dissipation.
NOTE: When using SVCC > VCC to extend the range
of the external PMU, care must be taken to ensure
that the RF pin voltage does NOT exceed VCC. This
can be accomplished by setting SELIPMU=0 to
disconnect the RF pin from FORCE, and will also
disconnect the internal sense circuitry from the
TEST AND MEASUREMENT PRODUCTS
Circuit Description (continued)
VINP
VINP
2005 Semtech Corp. / Rev. 5, 11/30/05
for testing devices with unipolar “open-element”
+
–
Force
Amp.
REXT
RF
~4.5K Typ.
FORCE
16
SENSE pin to protect it from over-voltage. The
internal PMU should be disabled (HiZ=1) in order to
prevent it from initiating pull-up mode.
REXT Selection
The E42X7 is designed for the full-scale voltage drop across
REXT (RA, RB, RC, RD) to be
Resistor values can be chosen that will enable the E42X7
to operate with full-scale current ranges other than those
specified provided the voltage swing across REXT does
not exceed 0.5V and the full-scale current for each range
does not exceed those specified in this datasheet.
Thermal Diode String
The E42X7 features an internal diode string connected
between the VC[0] and VC[1] pins that can be used to
perform device junction temperature measurements as
shown in the figure below.
100 A
External
Current
Source
Tj[˚C] =
E4237/E4257/E4287
(0.813 –
VC[0]
VC[1]
0.00162
VC[1] – VC[0]
3
0.5V.
SELC = 0
Temperature
Coefficient= –4.841mV/˚C
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