zxct1009t8 Zetex Semiconductors plc., zxct1009t8 Datasheet - Page 5

• Manufacturer Part Number: zxct1009t8
• Description: High-side Current Monitor
• Manufacturer: Zetex Semiconductors plc.

ISSUE 10 - JULY 2007
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
( ja), maximum junction temperature (Tjmax), and
ambient temperature (Tamb), according to the
expression:
P
The device power dissipation, P
expression:
P
max
D
=I
out
= (Tj
.(V
in
max
-V
out
– T
) Watts
amb
) /
SOT23
SM8
ja
D
is given by the
5
APPLICATIONS INFORMATION
The following lines describe how to scale a load
current to an output voltage.
E.g.
A 1A current is to be represented by a 100mV output
voltage:
1)Choose the value of R
> 500mV at full load.
For example V
0.1/1.0 => 0.1 ohms.
2)Choose R
100mV.
Rearranging
R
R
TYPICAL CIRCUIT APPLICATION
Where R
a charging battery or further circuitry that requires
monitoring, R
requirements of accuracy, size and power rating.
out
out
= V
= 0.1 / (0.1 x 0.01) = 100
out
load
out
V
/(V
out
1
represents any load including DC motors,
for R
sense
to give V
sense
sense
V
= 0.01 x V
sense
out
x 0.01)
= 100mV at 1.0A. R
can be selected on specific
gives:
= V
sense
out
in
sense
= 100mV, when V
- V
to give 50mV > V
S E M I C O N D U C T O R S
load
x R
ZXCT1009
out
1
sense
sense
sense
=
=