Supertex inc.
HV7800
High Side Current Monitor
8.0 to 450V
Voltage Gain of 1
Features
General Description
Applications
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 of the HV7800.
►► Supply voltages from 8V to 450V
►► Voltage output device
►► Typical gain 1±1%
►► Max VSENSE 500mV
►► Fast rise and fall time, 700ns to 2.0µs
►► Maximum quiescent current 50µA
►► 5-Lead SOT-23 Package
►►
►►
►►
►►
The HV7800 high side current monitor IC transfers a highside current measurement voltage to its ground referenced
output with an accurate voltage gain of one. The measurement
voltage typically originates at a current sense resistor which
is located in a “high side” circuit, such as the positive supply
line.
SMPS current monitor
Battery current monitor
Motor controls
Telecom
Typical Application Circuit
VSENSE
8V to 450V Input
RSENSE
IN
V OUT = V SENSE
ISENSE
RP (optional)
LOAD
HV7800
GND
R
OUT
VOUT
V
Doc.# DSFP-HV7800
A062813
Supertex inc.
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HV7800
Pin Configuration
Ordering Information
Part Number
Package Option
Packing
HV7800K1-G
5-Lead SOT-23
2500/Reel
OUT
GND
5
4
-G denotes a lead (Pb)-free / RoHS compliant package
Absolute Maximum Ratings
Parameter
VIN, VLOAD 1
-0.5V to +10V
VSENSE 2
-0.5V to +5.0V
ILOAD
-40°C to +85°C
Operating junction temperature
-40°C to +125°C
Storage temperature
-65°C to +150°C
IN
5-Lead SOT-23
(top view)
Product Marking
±10mA
Operating ambient temperature
3
LOAD NC
-0.5V to +460V
VOUT 1
2
1
Value
Y = Last Digit of Year Sealed
W = Code for Week Sealed
= “Green” Packaging
7AYW
Package may or may not include the following marks: Si or
Absolute maximum ratings are those values beyond which damage to the device
may occur. Functional operation under these conditions is not implied. Continuous
operation of the device at the absolute rating level may affect device reliability. All
voltages are referenced to device ground.
5-Lead SOT-23
Typical Thermal Resistance
Notes:
1. Referenced to GND
2. VSENSE = VIN - VLOAD
Package
θja
5-Lead SOT-23
253OC/W
Note:
Thermal testboard per JEDEC JESD51-7
Electrical Characteristics (T = 25°C unless otherwise specified, V
A
Sym
IN
= 8V to 450V)
Parameter
Min
Typ
Max
Units
Conditions
VIN
Supply voltage
8.0
-
450
V
*
---
IQ
Quiescent supply current
-
-
50
µA
-
VIN = 8.0V to 450V, VSENSE = 0mV
-
3.6
-
kΩ
-
---
0
-
15
-
VSENSE = 0mV
79
-
121
-
VSENSE = 100mV
177
-
223
-
VSENSE = 200mV
470
-
530
-
VSENSE = 500mV
-
0.7
-
-
VSENSE step 5.0mV to 500mV
-
-
2.0
-
VSENSE step 0mV to 500mV
-
0.7
2.0
*
VSENSE step 500mV to 0mV
Supply
Input and Output
ROUT
VOUT
OUT pin output resistance
Output voltage
mV
Dynamic Characteristics
tRISE
Output rise time, 10% to 90%
tFALL
Output fall time, 90% to 10%
µs
µs
* Values apply over the full temperature range
Doc.# DSFP-HV7800
A062813
2
Supertex inc.
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HV7800
Typical Performance Characteristics
VOUT
2000
mV
VOUT
2000
TAMB = 25°C
mV
VSENSE = 1500mV
1500
VIN = 10V
1500
VIN = 5.0V
VSENSE = 1000mV
1000
VIN = 4.0V
VSENSE = 800mV
1000
VIN = 3.5V
VSENSE = 500mV
500
0
0.5
0.4
500
VSENSE = 200mV
VSENSE = 100mV
1
10
100
0
1000
0
1000
2000
3000
4000
5000
VSENSE
∆VOUT
%
TAMB = 25°C
mV
V
VIN
VIN = 3.0V
Minimum VIN
3.5
V
VSENSE = 500mV
0.3
VSENSE = 500mV
3.4
0.2
0.1
3.3
0
-1.0
3.2
-2.0
-3.0
3.1
-4.0
-5.0
-60
C
O
0
40
80
120
3.0
-60
140
Curve represents level of VIN
which causes a 1% drop in VOUT
0
40
Temperature
C
O
80
120
140
Temperature
Maximum VOUT
2500
TAMB = 25°C
mV
2000
1500
1000
VSENSE = VOUT +250mV
500
0
Doc.# DSFP-HV7800
A062813
V
1
10
VIN
3
100
1000
Supertex inc.
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HV7800
Typical Performance Characteristics (cont.)
IIN
40
IIN
40
µA
µA
TAMB = 25°C
30
30
20
20
Top Curve: VIN = 400V
Bottom Curve: VIN = 10V
10
10
VSENSE = 0mV
VSENSE = 0mV
0
1
V
10
100
C
O
0
-60
1000
-40
-20
0
20
VIN
60
80
100
120
140
Temperature
VOUT/VSENSE (Gain)
40
40
VIN/VOUT (PSRR)
120
dB
TAMB = 25°C
100
20
TAMB = 25°C
dB
80
0
VSENSE = 500mV
60
-20
40
VSENSE = 500mV
Top Curve: VIN = 400V
Bottom Curve: VIN = 10V
-40
-60
20
Top Curve: VIN = 400V
Bottom Curve: VIN = 10V
0
-80
-20
Hz
-100
103
10
10
4
10
5
Frequency
7
DIV
DIV
VSENSE
200mV/DIV
10
107
6
VIN = 8V
500mV
6
VSENSE
200mV/DIV
4
4
+ 10mV
-10mV
VOUT
200mV/DIV
VOUT
200mV/DIV
2
2
0
10
5
Step Response (from neg 10mV)
8
VIN = 8V
500mV
6
10
4
Frequency
Step Response (from pos 10mV)
8
Hz
-40
103
10
6
µs
0
Doc.# DSFP-HV7800
A062813
2
4
Time
6
8
0
10
4
µs
0
2
4
Time
6
8
10
Supertex inc.
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HV7800
Block Diagram
Principle of Operation
VSENSE
R SENSE
IN
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.
ISENSE
RP (optional)
The current through RA returns to ground through RB. RA and
RB are integrated, exhibiting tight matching and excellent
tracking. By design, RA and RB have the same resistance.
Consequently, VRA is equal to VRB, resulting in a voltage gain
of 1.
LOAD
RA
OUT Pin Loading Effects
Note that the OUT pin has a typical output resistance of
3.6kΩ. Loading the output causes the voltage gain to drop
and rise/fall time to increase.
Bias
Circuits
For example, assuming an output resistance of 3.6kΩ, the
load resistance should exceed 3.6MΩ in order to limit the
drop in gain to 1 part in 1000.
VOUT
OUT
RB
Again assuming an output resistance of 3.6kΩ, capacitive
loading of 30pF results in a response pole with a time
constant of 100ns, not yet high enough to materially affect
the output rise and fall time (about 700ns).
HV7800
GND
Application Information
Sense Resistor Considerations
Choose a sense resistor that will not exceed 500mV during
normal operating conditions. Limit the power dissipation in
the sense resistor to whatever is practical; a high sense
voltage benefits accuracy, but increases power dissipation.
General
The HV7800 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.
Consider the use of Kelvin connections for applications
where considerable voltage drops may occur in the PCB
traces that carry the current to be measured to the sense
resistor. A layout pattern that minimizes voltage across the
sense lines is shown below.
The part typically performs the measurement of line or
load current for overcurrent protection, metering or current
regulation.
+ VSENSE -
High side current sensing, as opposed to ground referenced
or low side current sensing, is desirable or required when:
►► 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.
IN
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.
►► 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.
Doc.# DSFP-HV7800
A062813
LOAD
5
Supertex inc.
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HV7800
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.
shows the orientation of this diode. The Zener diode provides
clamping at 5.0V for a positive VSENSE and at 600mV for a
negative VSENSE.
Transient Protection
Under worst case conditions, limit the Zener current to 10mA.
A 100kΩ resistor limits the Zener diode current to 4.5mA
when VSENSE is 450V, whether positive or negative. Note that
the protection resistor may affect the bandwidth. The resistor
forms a RC network with the trace and pin capacitance at the
LOAD pin. A capacitance of 5.0pF results in a time constant
of 500ns.
Add a protection resistor (RP) in series with the LOAD pin
if VSENSE can exceed 5.0V in a positive sense or 600mV in
a negative sense, whether in a steady state or in transient
conditions.
A large VSENSE may occur during system startup or shutdown
due to the charging and discharging of bulk storage
capacitors. VSENSE may be large due to fault conditions, such
as a short circuit condition, or a broken or missing sense
resistor.
The protection resistor may cause an offset due to bias
current at the LOAD input. Under worst case bias current
(1.0nA), a 100kΩ protection resistor could cause an offset
of 100µV or 0.2% of full scale. Note that the bias current
is nominally zero as the LOAD is a high impedance CMOS
input.
An internal 5.0V Zener diode with a current rating of 10mA
protects the sense amplifier inputs. The block diagram
Pin Description
Pin #
Pin Name
1
LOAD
2
NC
No connect. This pin must be left floating for proper operation.
3
IN
Sense amplifier input and supply.
4
GND
Supply return.
5
OUT
Output with a nominal output resistance of 3.6kΩ. Preservation of accuracy may require
an external buffer amplifier to prevent excessive loading.
Doc.# DSFP-HV7800
A062813
Description
Sense amplifier input. High impedance input with Zener diode protection. Add an external
protection resistor in series with LOAD if VSENSE exceeds the range of -600mV to +5V.
6
Supertex inc.
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HV7800
5-Lead SOT-23 Package Outline (K1)
2.90x1.60mm body, 1.45mm height (max), 0.95mm pitch
θ1
D
e1
5
Note 1
(Index Area
D/2 x E/2)
E1 E
Gauge
Plane
L2
1
L
e
b
θ
L1
Top View
View B
Seating
Plane
View B
A
A
A2
Seating
Plane
A1
Side View
View A - A
A
Note:
1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or
a printed indicator.
Symbol
MIN
Dimension
NOM
(mm)
MAX
A
A1
A2
b
0.90*
0.00
0.90
0.30
-
-
1.15
-
1.45
0.15
1.30
0.50
D
E
E1
2.75* 2.60* 1.45*
2.90
2.80
1.60
3.05* 3.00* 1.75*
e
0.95
BSC
e1
1.90
BSC
L
0.30
0.45
0.60
L1
0.60
REF
L2
0.25
BSC
θ
θ1
0O
5O
4
O
10O
8O
15O
JEDEC Registration MO-178, Variation AA, Issue C, Feb. 2000.
* This dimension is not specified in the JEDEC drawing.
Drawings not to scale.
Supertex Doc. #: DSPD-5SOT23K1, Version A041309.
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information 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 them for use in such applications unless it receives
an adequate “product liability indemnification insurance agreement.” Supertex inc. 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 and inaccuracies. Circuitry and
specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com)
Supertex inc.
©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited.
Doc.# DSFP-HV7800
A062813
7
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: 408-222-8888
www.supertex.com
