TYPICAL PERFORMANCE CURVES
(CONT)
At T
A
= +25°C, V
S
=
±15V,
unless otherwise noted.
NONLINEARITY vs INPUT VOLTAGE
1
1MHz FS Linearity Error (% of FSR)
NONLINEARITY vs FULL SCALE FREQUENCY
1
4MHz FS Linearity Error (% of FSR)
0.02
0.8
0.6
0.01
f
FS
= 4MHz
0
0.4
0.2
0
–0.2
Typical Nonlinearity (% of FSR)
0.1
–0.01
f
FS
= 1MHz
–0.02
0
1
2
3
4
5
6
7
8
9
10
–0.4
–0.6
–0.8
–1
0.01
0.001
10
4
Input Voltage (V)
10
5
10
6
10
7
Full Scale Frequency (Hz)
OPERATION
Figure 1 shows the connections required for operation at a
full-scale output frequency of 4MHz. Only power supply
bypass capacitors and an output pull-up resistor, R
PU
, are
required for this mode of operation. A 0V to 10V input
voltage produces a 0Hz to 4MHz output frequency. The
internal input resistor, one-shot and integrator capacitors set
the full-scale output frequency. The input is applied to the
summing junction of the integrator amplifier through the
25kΩ internal input resistor. Pin 14 (the non-inverting ampli-
fier input) should be referred directly to the negative side of
V
IN
. The common-mode range of the integrating amplifier is
limited to approximately –1V to +1V referred to analog
ground. This allows the non-inverting input to Kelvin-sense
the common connection of V
IN
, easily accommodating any
ground-drop errors. The input impedance loading V
IN
is
equal to the input resistor—approximately 25kΩ.
OPERATION AT LOWER FREQUENCIES
The VFC110 can be operated at lower frequencies simply by
limiting the input voltage to less than the nominal 10V full-
scale input. To maintain a 10V FS input and highest accu-
racy, however, external components are required (see Table
I). Small adjustments may be required in the nominal values
indicated. Integrator and one-shot capacitors are added in
parallel to internal capacitors. Figure 2 shows the connec-
tions required for 100kHz full scale output. The one-shot
capacitor, C
OS
, should be connected to logic ground. The
one-shot connection (pin 6) is not short-circuit protected.
Short-circuits to ground may damage the device.
+V
S
+15V
NC
1
12
11
10
8
2
14
0 to
+10V
V
IN
25kΩ*
50pF*
One-Shot
V
L
+5V
R
PU
680
Ω
f
OUT
0 to 4MHz
7 Logic Ground
5 NC
V
REF
4
–15V
* Nominal Values (±20%)
–V
S
13
3
NC
6
NC
Analog Ground
FIGURE 1. 4MHz Full-Scale Operation.
®
5
VFC110
BURR-BROWN [ BURR-BROWN CORPORATION ]
