LMP8601MAEVAL/NOPB National Semiconductor, LMP8601MAEVAL/NOPB Datasheet - Page 16

• Manufacturer Part Number: LMP8601MAEVAL/NOPB
• Description: BOARD EVALUATION FOR LMP8601MA
• Manufacturer: National Semiconductor
• Series: LMP®r

Specifications of LMP8601MAEVAL/NOPB

• Channels Per Ic: 1 - Single
• Amplifier Type: Current Sense
• Output Type: Single-Ended
• Slew Rate: 0.83 V/µs
• Current - Output / Channel: 48mA
• Operating Temperature: -40°C ~ 125°C
• Current - Supply (main Ic): 1.1mA
• Voltage - Supply, Single/dual (±): 3 V ~ 5.5 V
• Board Type: Fully Populated
• Utilized Ic / Part: LMP8601
• Silicon Manufacturer: National
• Silicon Core Number: LMP8601, LMP8601Q
• Kit Application Type: Amplifier
• Application Sub Type: Current-Sense Amplifier
• Kit Contents: Board, Doc
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: LMP8601MAEVAL

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These figures can be used to estimate the disturbance that
will be caused when driving a switched capacitive load. To
FIGURE 6. Capacitive Load Response at 3.3V
FIGURE 7. Capacitive Load Response at 5.0V
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minimize the error signal introduced by the sampling that oc-
curs on the ADC input, an additional RC filter can be placed
in between the LMP8601/LMP8601Q and the ADC as illus-
trated in
The external capacitor absorbs the charge that flows when
the ADC sampling capacitor is connected. The external ca-
pacitor should be much larger than the sample and hold
capacitor at the input of the ADC and the RC time constant of
the external filter should be such that the speed of the system
is not affected.
LOW SIDE CURRENT SENSING APPLICATION
Figure 9
a low side driver. The power transistor is pulse width modu-
lated to control the average current flowing through the in-
ductive load which is connected to a relatively high battery
voltage. The current through the load is measured across a
shunt resistor R
transistor is on, current flows from the battery through the in-
ductive load, the shunt resistor and the power transistor to
ground. In this case, the common mode voltage on the shunt
is close to ground. When the power transistor is off, current
flows through the inductive load, through the shunt resistor
and through the freewheeling diode. In this case the common
mode voltage on the shunt is at least one diode voltage drop
above the battery voltage. Therefore, in this application the
common mode voltage on the shunt is varying between a
large positive voltage and a relatively low voltage. Because
the
LMP8601/LMP8601Q and because of the high AC common
mode rejection ratio, the LMP8601/LMP8601Q is very well
suited for this application.
large
FIGURE 8. Reduce Error When Driving ADCs
illustrates a low side current sensing application with
Figure
common
SENSE
8.
in series with the load. When the power
mode
voltage
range
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of
the