rdc19220 ETC-unknow, rdc19220 Datasheet - Page 6

• Manufacturer Part Number: rdc19220
• Description: 16-bit Monolithic Tracking Resolver Lvdt -to-digital Converters
• Manufacturer: ETC-unknow

Data Device Corporation
www.ddc-web.com
4) The BIT output which is active low is activated by an error of
5) This device has several high impedance amplifier inputs (+C,
6) Setup of bandwidth and velocity scaling for the optimized crit-
Note: DDC has software available to perform the previous calcu-
approximately 100 LSBs. During normal operation for step
inputs or on power up, a large error can exist.
-C, +S, -S, -VCO and -VSUM). These nodes are sensitive to
noise and coupling components should be connected as
close as possible.
ically damped case should proceed as follows:
Calculate component values for a 16-bit converter with 100Hz
bandwidth, a tracking rate of 10RPS and a full scale velocity
lations. Contact DDC to request software or visit our web-
site at www.ddc-web.com to download software.
TABLE 3. TRACKING/BW RELATIONSHIP
RPS (MAX)/BW
0.125
0.45
0.25
- Rv =
- Compute C
- Compute R
- Select the desired f
- Select f carrier
- Select the applications tracking rate (in accordance with TABLE 3),
- Compute Rv =
- Compute C
- Where Fs = 67 kHz for R CLK = 30 K
- Compute R
- Compute
1
system dynamics.
and use appropriate values for R SET and R CLK
As an example:
10 rps x 2
of 4 volts.
C
BW
B
BW
100 kHz for R CLK = 20 K
125 kHz for R CLK = 15 K
B
10
BW
=
=
(pF) =
(pF) =
21955 x 10
Tracking Rate (rps) x 2
16
C
3.5f
BW
x 50 pF x 1.25 V
4 V
BW
0.9
BW
3.2 x 67 kHz x 10
x f
97655 x 100 Hz
3.2 x Fs (Hz) x 10
(closed loop) based on overall
BW
0.9
Rv x (f
Full Scale Velocity Voltage
-12
x 100 Hz
BW
)
= 97655
2
RESOLUTION
2
resolution
8
8
= 410 k
= 21955 pF
10
12
14
16
x 50 pF x 1.25 V
6
7) Selecting a f
8) For RDC-19222 & RDC-19224; package’s only.
Note: When using the highest BW and Tracking Rates, using
HIGHER TRACKING RATES AND CARRIER FREQUENCIES
Tracking rate (nominally 4 V) is limited by two factors: velocity
voltage saturation and maximum internal clock rate (nominally
1,333,333 Hz). An understanding of their interaction is essential
to extending performance.
The General Setup Considerations section makes note of the
selection of R
cation tracking rate can create a spin-around condition in
which the converter never settles. The relationship to insure
against
This version is capable of +5V only operation. It accomplish-
es this with a charge pump technique that inverts the +5V
supply for use as -5V, hence the +5V supply current doubles.
The built-in -5 V inverter can be used by connecting pin 2 to
26, pin 17 to 22, a 10 µF/10 Vdc capacitor from pin 23 (nega-
tive terminal) to pin 25 (positive terminal), and a 47 µF/10 Vdc
capacitor from -5 V to GND. The current drain from the +5 V
supply doubles. No external -5 V supply is needed (SEE FIG-
URE 5).
When using the -5 V inverter, the max. tracking rate should be
scaled for a velocity output of 3.5 V max. Use the following equa-
tion to determine tracking rate used in the formula on page 5:
TR (required) x (4.0) = Tracking rate used in calculation
(3.5)
.01uF
the -5 V inverter is not recommended.
(-5c) -5V
FIGURE 5. -5V BUILT-IN INVERTER
v
+
spin-around
RDC-19222/4
for the desired velocity scaling. R
BW
47uF
that is too low relative to the maximum appli-
.01uF
(+5c) +5V
is
as
+
47uF
+CAP
follows
-CAP
RDC-19220 SERIES
v
is the input resis-
(TABLE
R-12/05-0
10uF
3):