HV7802MG-G(2007) 查看數據表（PDF） - Supertex Inc
零件编号
产品描述 (功能)
生产厂家
HV7802MG-G Datasheet PDF : 5 Pages
| |||
HV7802
Block Diagram
VSENSE
ISENSE
► The current to be measured does not flow in a circuit
associated with ground.
RSENSE
RA
IN
RA
RP
(Optional,
see text)
LOAD
► The measurement at ground level can lead to ambiguity
due to changes in the grounding arrangement during
field use.
► The introduction of a sense resistor in the system ground
is undesirable due to issues with safety, EMI, or signal
degradation caused by common impedance coupling.
Principle of Operation
Bias
Circuits
The operational amplifier forces the voltage across RA to
track VSENSE, therefore, VRA = VSENSE. Transconductance gain
is equal to (1/RA).
HV7802
IRA flows from the OUT pin to low side circuitry. Current to
voltage conversion can be accomplished by a resistor, RB,
as shown in the block diagram, with a transimpedance gain
equal to RB.
GND OUT
RB
VOUT
Typically we would like to exploit the full current capability of
the transimpedance amplifier. A RA of 5kΩ will provide this
current, assuming a full scale sense voltage of 500mV and a
full scale sense current of 100µA.
Application Information
In a voltage output application, the output resistor RB is
determined by the desired overall voltage gain of (RB / RA).
For example, a RB of 10kΩ results in a voltage gain of two.
General
OUT Pin Loading Effects
The HV7802 high side current monitor IC features accurate
current sensing, small size, low component count, low power
consumption, exceptional input voltage range, ease of use
and low cost.
Typical use is measurement of line and load current for
purpose of overcurrent protection, metering and current
regulation.
High side current sensing, as opposed to ground referenced
or low side current sensing, is desirable or required when:
Note that the output is not buffered having an output
impedance equal to RB. Loading of the output causes voltage
gain to drop and rise and fall times to increase.
For example, assume a gain of one, using RA = RB = 5kΩ. In
this case the load resistance should exceed 5MΩ in order to
limit the gain drop to 1 part in 1000.
Assuming an output resistance of 5kΩ, a capacitive load of
20pF results in a load pole with a time constant of 100ns,
not enough to materially affect the output rise and fall time
(about 700ns).
3
Share Link: 