Diodes ZXCT1010 - Manual (Page 5)

ISSUE 10 - JULY 2007
S E M I C O N D U C T O R S
ZXCT1010
5
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
1
E.g.
A 1A current is to be represented by a 100mV output
voltage:
1)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
=> 0.1 ohms.
2)Choose R
out
to give V
out
= 100mV, when V
sense
=
100mV.
Rearranging
1
for R
out
gives:
R out = V out /(V sense x 0.01)
R
out
= 0.1 / (0.1 x 0.01) = 100 Ω
TYPICAL CIRCUIT APPLICATION
POWER DISSIPATION
The maximum allowable power dissipation of the
device for normal operation (Pmax), is a function of
the package junction to ambient thermal resistance
(
θja), maximum junction temperature (Tjmax), and
ambient temperature (Tamb), according to the
expression:
P max = (Tj max – T amb ) / θ
ja
The device power dissipation, P D is given by the
expression:
P
D
=I
out
.(V
in
-V
out
) Watts
Where R
load
represents any load including DC motors,
a charging battery or further circuitry that requires
monitoring, R
sense
can be selected on specific
requirements of accuracy, size and power rating.
APPLICATIONS INFORMATION