AD8215(Rev0) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
AD8215 Datasheet PDF : 16 Pages
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AD8215
APPLICATIONS INFORMATION
HIGH-SIDE CURRENT SENSING WITH A LOW-SIDE
SWITCH
In such load control configurations, the PWM-controlled
switch is ground referenced. An inductive load (solenoid) is tied
to a power supply. A resistive shunt is placed between the switch
and the load (see Figure 28). An advantage of placing the shunt on
the high side is that the entire current, including the recirculation
current, can be measured because the shunt remains in the loop
when the switch is off. In addition, diagnostics can be enhanced
because shorts to ground can be detected with the shunt on the
high side. In this circuit configuration, when the switch is
closed, the common-mode voltage moves down to near the
negative rail. When the switch is opened, the voltage reversal
across the inductive load causes the common-mode voltage to
be held one diode drop above the battery by the clamp diode.
5V
BATTERY
INDUCTIVE
LOAD
CLAMP
DIODE
SHUNT
SWITCH
8
7
6
5
IN+ NC V+ OUT
AD8215
IN– GND NC NC
14
2
3
54
Figure 28. Low-Side Switch
HIGH-SIDE CURRENT SENSING
In this configuration, the shunt resistor is referenced to the
battery. High voltage is present at the inputs of the current sense
amplifier. In this mode, the recirculation current is again measured
and shorts to ground can be detected. When the shunt is battery
referenced, the AD8215 produces a linear ground-referenced
analog output. An AD8214 can also be used to provide an over-
current detection signal in as little as 100 ns (see Figure 29).
This feature is useful in high current systems where fast
shutdown in over-current conditions is essential.
OVERCURRENT
DETECTION (<100ns)
5
6
7
8
OUT GND NC –IN
AD8214
NC VREG +IN VS
4
3
2
1
5V
5
6
7
8
OUT V+ NC IN+
AD8215
NC NC GND IN–
4
3
2
15
SHUNT
CLAMP
DIODE
INDUCTIVE
LOAD
BATTERY
SWITCH
Figure 29. Battery-Referenced Shunt Resistor
LOW-SIDE CURRENT SENSING
In systems where low-side current sensing is preferred, the
AD8215 provides an integrated solution with great accuracy.
Ground noise is rejected, CMRR is typically higher than 90 dB,
and output linearity is not compromised, regardless of the input
differential voltage.
5V
5
6
7
8
OUT V+ NC IN+
AD8215
NC NC GND IN–
4
3
2
51
INDUCTIVE
LOAD
CLAMP
DIODE
SWITCH
BATTERY
SHUNT
Figure 30. Ground-Referenced Shunt Resistor
Rev. 0 | Page 12 of 16
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