Download Supply Voltage Regulation

Technical Note 5
1 (1)
Supply Voltage Regulation
OBJECTIVE
To give recommendations on the power supply arrangements for VTI Technologies' inclination and
acceleration sensors.
DESCRIPTION OF THE PROBLEM
The output signal(s) of the sensors is (are) sensitive to the power supply arrangements. Unstable supply
voltage will effect the output signal(s) of the device.
The analogue output of the sensors is ratiometric. Therefore, any fluctuation in the supply voltage will directly
cause the analogue output to vary respectively. The ratiometric error may result a maximum error of 2%, i.e.
for 5V => 5±0.25V a maximum of 25mg in SCA61T - FA1H1G.
In some cases, the external circuitry can cause an overload in the analogue or digital outputs of the SCA61T,
SCA100T, SCA103T, or SCA1000 devices, and increase current consumption. In such cases, the supply
voltage may become unstable, thus causing the output of the device to fluctuate.
SOLUTION
The best performance for the sensors can be achieved by taking into account the following considerations.
1. Arrange a stable power supply voltage of 5V for the sensor. For best performance, the supply voltage
should be kept as 5V or at a stable voltage in the range of 4.75 … 5.25V.
2. For either the SCA100T, SCA103T or SCA1000, locate a supply filtering capacitor (min. 100 nF) between
pin 6 (Vss) and pin 12 (Vdd). The capacitor should be placed as close to pin 12 (Vdd) as possible. In case
of the SCA 61T, connect a min. 100nF capacitor between pin 4 (Vss) and pin 8 (Vdd).
3. Typical 7-30V supply voltage regulator circuitry that can be used is shown in Figure 1.
Figure 1. Typical supply voltage regulator circuitry
Please see also the product specific datasheets.
1 Sep 2005
VTI Technologies Oy
Myllynkivenkuja 6
P.O.Box 27
FIN-01621 Vantaa
Finland
Tel. +358 9 8791 81
Fax. +358 9 8791 8791
[email protected]
VTI Technologies reserves all rights to modify this document prior notice.
VTI Technologies Oy
Frankfurt Branch
Rennbahnstr. 72-74
D-60528 Frankfurt am Main
Germany
Tel. +49 69 6786 880
Fax +49 69 6786 8829
[email protected]
VTI Technologies, Inc.
One Park Lane Blvd.
Suite 804 - East Tower
Dearborn, MI 48126
USA
Tel. (313) 425 0850
Fax (313) 425 0860
[email protected]