AA1850 Datasheet, PDF (4/6 Pages) Agamem Microelectronic Inc. – HIGH-SIDE CURRENT MONITOR

Agamem Microelectronics Inc.
AA1850
PRELIMINARY
HIGH-SIDE CURRENT MONITOR
■ APPLICATION CIRCUIT
Vin
Rsense
2
1
3
Rout
Vout
Rload
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.