HV7800K1-G [SUPERTEX]
High Side Current Monitor; 高压侧电流监视器
| 型号： | HV7800K1-G |
| 厂家： | 
Supertex, Inc |
| 描述： | High Side Current Monitor |
| 文件： | 总6页 (文件大小：363K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Supertex inc.
HV7800
Initial Release
High Side Current Monitor
Features
General Description
The HV7800 is a high side current monitor IC, which
senses the voltage across an external current sense
resistor located in the power or “high” side of the circuit
and translates this voltage to a ground referenced circuit
at a gain of one.
ꢀ 450V Maximum supply voltage
ꢀ Voltage output device
ꢀ 1% Typical gain accuracy
ꢀ 500mV Maximum VSENSE
ꢀ Fast response: 700ns rise and fall time
ꢀ 50µA Quiescent current (max.)
The HV7800 has a wide operating range of 3V-450VDC,
which enables its use in DC power systems of 12V/24V/
48V, and in AC systems operating at voltages from 85VAC
to 265VAC.
Applications
ꢀ LED driver current monitor
ꢀ SMPS current monitor
ꢀ Battery current monitor
ꢀ Motor controls
The fast response time of the HV7800 allows use of this
current monitor in the feedback loop of a switching power
supply or in LED driver applications.
Typical Application Circuit
ILOAD
VSENSE
400VDC Input
RSENSE
3
2
1
LOAD
HV7800
4
5
VOUT = ILOAD • RSENSE
NR031306
Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: (408) 222-8888 FAX: (408) 222-4895 www.supertex.com
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HV7800
Ordering Information
DEVICE
Package Options
HV7800K1-G
5-Lead SOT-23
-G indicates package is RoHS compliant (‘Green’)
Absolute Maximum Ratings
Pinout
Parameter
Value
−0.5V to +450V
−0.5V to +450V
−0.5V to +10V
−40°C to +85°C
−40°C to +125°C
−65°C to +150°C
260 K/W
IN
1
2
3
5
4
OUT
LOAD
LOAD
N/C
IN
OUT
GND
Operating Ambient Temperature1
Operating Junction Temperature
Storage Temperature
SOT23-5 Package Thermal Resistance
HV7800K1
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent
damage to the device. These are stress ratings only, and functional operation of the device
at these or any other conditions beyond those indicated in the operational sections of the
specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
1 Limited by package dissipation.
Electrical Characteristics
(Voltages referenced to GND, VIN = 10V, TA = 25°C, unless otherwise noted. Values of parameters marked with a • apply over the full temperature range.)
Symbol
Parameter
Min
Typ
Max
Units Conditions
ESD Characteristics, IN, LOAD
ESD
Supply
VIN
Human body model
-
2.0
-
kV
1.5kΩ, 100pF
Supply voltage
10
10
-
-
450
50
•
•
V
---
IQ
Quiescent supply current
μA
VIN = 400V, VSENSE = 0mV
Input and Output Characteristics
ILOAD
ROUT
Input current to LOAD pin
OUT pin output resistance
-1.0
2.60
0
-
1.0
4.0
nA
kΩ
VSENSE = 500mV
---
3.30
5.0
VSENSE = 0mV
VSENSE = 100mV
VSENSE = 200mV
VSENSE = 500mV
94
106
207
510
VOUT
Output Voltage
-
mV
193
490
Dynamic Characteristics
tRISE Output rise time, 10% to 90%
tFALL Output fall time, 90% to 10%
-
-
700
700
-
-
ns
ns
VSENSE step 0mV to 500mV
VSENSE step 500mV to 0mV
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HV7800
Typical Performance Characteristics
0
-20
-40
-60
160
120
80
40
0
-40
10m
0.1
10
100
1K
10K
100K
1M
10M
1.0M
1.0
10m
0.1
1
10
100
1K
10K
100K
1M
10M
Frequency (Hz)
Frequency (Hz)
Gain
vs Frequency
Common Mode Rejection Ratio
vs Frequency
0.5
0.4
VSENSE = 500mV
VSENSE = 400mV
VSENSE = 300mV
VSENSE = 200mV
0.5
0.4
0.3
0.2
0.3
0.2
VSENSE = 5mV-500mV
0.1
0
0.1
0
VSENSE = 100mV
0
2
4
6
8
10
2
4
6
8
10
12
VIN Voltage(V)
time (μs)
Output Characteristics
(VOUT vs VIN)
Step Response
(5.0mV to 500mV)
NR031306
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HV7800
Block Diagram
ILOAD
RSENSE
LOAD
IN
1
3
RA
BIAS
CKTS
5
OUT
RB
4
GND
Pin Description
Pin Name Description
This pin is an input sense pin that connects to the negative (-) side of sense resistor, RSENSE. The
negative side denotes the system load end of the sense resistor.
1
2
3
4
5
LOAD
N/C
IN
No Connection
Positive supply. Input voltage range is 3.0 to 450V. This pin is an input sense pin that connects to
the positive (+) side of sense resistor, RSENSE
.
GND This pin is connected to the GND or return of the system.
Output Voltage referenced to GND terminal. The voltage at OUT will be equal to VSENSE. The output
impedance of this pin is typically 3.3 kΩ.
OUT
1
2
3
5
4
OUT
GND
LOAD
N/C
IN
HV7800K1
NR031306
4
HV7800
Application Information
General
ILOAD
RSENSE
The HV7800 offers high side current sensing featuring
accuracy, small size, low component count, low power
consumption, ease of use and low cost. The input voltage
rating of 450V extends the use to off-line applications.
LOAD
IN
HV7800
The HV7800 allows measurement of line or load current
for purpose of overcurrent protection, current metering and
current regulation.
GND
OUT
ROUT = 3.3k
Ω
30%
High side current sensing, as opposed to ground or low-side
sensing, is desirable or required when:
•
The current to be measured does not flow in a circuit
associated with ground.
R
LOAD CLOAD
•
The addition of resistance in the grounding system
will cause issues with safety, EMI, or will lead to
signal degradation due to common impedance
coupling.
Sense Resistor Considerations
The choice of value of the sense resistor entails a trade-
off between power dissipation from the sense resistor and
accuracy. Power dissipation from the sense resistor is
equal to (VSENSE • ILOAD). It is generally desirable to maximize
diSsEsNiSpEation from the sense resistor becomes objectionable.
Principle of Operation
The operational amplifier and associated MOSFET, as
shown in the block diagram, force a current through resistor
RA such that VRA is equal to VSENSE. The current through RA
flows to ground through RB and develops an output voltage
VOUT, which is equal to VSENSE, given that RA and RB have
equal resistance.
V
to enhace accuracy, but not to the extent that power
Consider the use of Kelvin connections for applications with
a large load current. Atypical layout pattern, which minimizes
voltage drops across the sense lines is shown below:
Note that the output is not buffered, having an output
resistance of 3.3kΩ nominal. Loading of the output will affect
gain accuracy and / or bandwidth.
Assume in the following that ROUT = 4kΩ.
To limit gain error to say 1 part in 1000, the external load
impedance should exceed 4MΩ.
Capacitive loading forms a load pole. The break frequency
follows from:
Sense
Resistor
1
f =
τ = RB // RLOAD •C
where
(
)
LOAD
VSENSE
2 •π •τ
Preservation of bandwidth requires careful attention to trace
layout and choice of sense resistor. Note that the resistance
of the sense resistor is typically small, and that both the
impedence of printed circuit board traces and the equivalent
series inductance of the sense resistance can be a major part
of the total sense/impedence at high frequency operation.
An inductance of just 1nH contributes an impedence of 3mΩ
at 500kHz.
E.g. let R
= ∞ and C
= 1nF, then the load pole is
located atL3O8AD.8kHz, givingLrOisADe and fall times of 8.8us.
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HV7800
Protection of the LOAD input
In situations where the sense voltage can significantly An excessive sense voltage might occur when line or load
exceed 500mV, the LOAD input to the differential amplifier current is significantly larger during the startup or shutdown
should be protected by the addition of a protection resistor event, or during overcurrent or short circuit events. A large
and two diodes as shown below:
differential voltage can also exist if the sense resistor fails
open, or is inadvertently not installed.
ISURGE
RSENSE
RPROTECT
IN
LOAD
HV7800
OUT
GND
5-Lead SOT-23 (K1) Package Outline
2.80
3.05
2.60
3.00
1.50
1.75
All dimensions are in millimeters
Legend: min
max
Pin 1
0.95ref
1.90ref
Top View
0.90
1.30
0.90
1.45
0.30
0.55
0.09
0.20
0.30
0.50
0.00
0.15
Front View
Side View
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline informa-
tion go to http://www.supertex.com/packaging.html.)
Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell its products for use in such applications, unless it receives an adequate
"product liability indemnification insurance agreement". Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of the devices
determined defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest
product specifications, refer to the Supertex website: http//www.supertex.com.
©2006 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited.
Supertex inc.
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 222-8888 / FAX: (408) 222-4895
Doc.# DSFP - HV7800
NR031306
www.supertex.com
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