Agamem Microelectronics Inc.
PRELIMINARY
■
APPLICATION CIRCUIT
AA1850
HIGH-SIDE CURRENT MONITOR
Vin
Rsense
2
1
Rload
3
Vout
Rout
Where R
LOAD
represents any load including DC motors, a charging battery or further
circuitry that requires monitoring, V
SENSE
can be selected on specific requirements of
accuracy, size and power rating.
The following lines describe how to scale a load current to an output voltage.
V
SENSE
=
V
IN
-
V
LOAD
V
OUT
= 0.01 x
V
SENSE
x
R
OUT
(E1)
E.g.
A 1A current is to be represented by a 100mV output voltage:
A. Choose the value of R
SENSE
to give 50mV > V
SENSE
> 500mV at full load.
For example V
SENSE
= 100mV at 1.0A. R
SENSE
= 0.1/1.0 => 0.1Ω.
B. Choose R
OUT
to give V
OUT
= 100mV, when V
SENSE
= 100mV.
Rearranging
E1
for
R
OUT
gives:
R
OUT
=
V
OUT
/(
V
SENSE
x 0.01)
R
OUT
= 0.1 / (0.1 x 0.01) = 100Ω
©Copyright
Agamem Microelectronics Inc.
4
www.agamem.com.tw
2008/4/8
AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER
NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT
ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED
HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
AGAMEM [ AGAMEM MICROELECTRONIC INC. ]
