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HV7801のメーカーはSupertexです、この部品の機能は「High Side Current Monitor」です。 |
部品番号 | HV7801 |
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部品説明 | High Side Current Monitor | ||
メーカ | Supertex | ||
ロゴ | |||
このページの下部にプレビューとHV7801ダウンロード(pdfファイル)リンクがあります。 Total 5 pages
Supertex inc.
HV7801
High Side Current Monitor
8.0 to 450V
Voltage Gain of 5
Features
►►Supply voltage 8V to 450V
►►Voltage output device
►►Typical gain 5.0±1%
►►Max VSENSE 500mV
►►Fast rise and fall time, 700ns to 2.0µs
►►Maximum quiescent current 50µA
Applications
►► SMPS current monitor
►► Battery current monitor
►► Motor control
General Description
The HV7801 high side current monitor IC transfers a high-
side current measurement voltage to its ground referenced
output with a voltage gain of five. The measurement voltage
typically originates at a current sense resistor which is located
in a “high side” circuit, such as the positive supply line.
This monitor IC features a very wide input voltage range, high
accuracy of transfer ratio, small size, low component count,
low power consumption, ease of use, and low cost. Offline,
battery, and portable applications can be served equally well
due to the wide input voltage range and the low quiescent
current.
Typical Application Circuit
8V to 450V Input
VSENSE
ISENSE
RSENSE
RP (optional)
VOUT = 5 • VSENSE
IN LOAD
HV7801
GND
OUT
VOUT
V
R
Doc.# DSFP-HV7801
A062813
Supertex inc.
www.supertex.com
1 Page Block Diagram
VSENSE
ISENSE
RSENSE
RP (Optional)
IN LOAD
RA
HV7801
Principle of Operation
The operational amplifier and MOSFET force the voltage
across RA to track VSENSE within the limit of the offset voltage
of the opamp, i.e. VRA = VSENSE.
The current through RA returns to ground through RB.
RA and RB are integrated, exhibiting tight matching and
excellent tracking. By design, RB is five times larger than RA.
Consequently, VRB is five times larger than VRA, thus resulting
in a voltage gain of 5.
Bias
Circuits
VOUT
RB
HV7801
GND
OUT
Application Information
General
The HV7801 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 or 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:
OUT Pin Loading Effects
Note that the OUT pin has a typical output resistance of
16.5kΩ. Loading the output causes the voltage gain to drop
and rise/fall time to increase.
For example, assuming output resistance is 16.5kΩ, the load
resistance should exceed 16.5MΩ in order to limit the drop in
gain to 1 part in 1000.
Again assuming output resistance is 16.5kΩ, capacitive
loading of 6pF results in a response pole with a time constant
of 100ns, not high enough to materially affect the output rise
and fall time (about 700ns).
Sense Resistor Considerations
Limit the sense resistor voltage to 500mV during normal
operating conditions. Limit the power dissipation in the sense
resistor to suit the application; a high sense voltage benefits
accuracy, but increases power dissipation.
Consider the use of Kelvin connections for applications
where considerable voltage drops may occur in the PCB
traces. A layout pattern which minimizes voltage across the
sense lines is shown below.
+ VSENSE -
►► The current to be measured does not flow in a circuit
associated with ground.
►► The measurement at ground level can lead to ambiguity
due to changes in the grounding arrangement during
field use.
►► 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.
IN LOAD
RSENSE
Choose a low inductance type sense resistor if preservation
of bandwidth is important. The use of Kelvin connections
helps by excluding the inductive voltage drop across the
traces leading to the sense resistor. The inductive voltage
drop may be substantial when operating at high frequencies.
A trace or component inductance of just 10nH contributes
an impedance of 6.2mΩ at 100kHz, which constitutes a 6%
error when using a 100mΩ sense resistor.
Doc.# DSFP-HV7801
A062813
Supertex inc.
3 www.supertex.com
3Pages | |||
ページ | 合計 : 5 ページ | ||
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PDF ダウンロード | [ HV7801 データシート.PDF ] |
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部品番号 | 部品説明 | メーカ |
HV7800 | High Side Current Monitor | Supertex |
HV7801 | High Side Current Monitor | Supertex |
HV7802 | High Side Current Monitor | Supertex |