AN7820 Ver la hoja de datos (PDF) - Fairchild Semiconductor
Número de pieza
componentes Descripción
Fabricante
AN7820 Datasheet PDF : 17 Pages
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Figure 11: Recommended Interfacing Circuit
CLK
FAST TTL
BUFFER
R1=100Ω
15
CLK
VIN
(±2V)
LIMITER
21
VIN
+5V
2 Vin IC1 Vout 6
+
(REF-03)
1µF
4
GND
5
Trim
10K
3
2 -5.2V
+5V
1
+-
IC2
4
10K
.01µF
8
.01µF
7
6
1µF
+
+2.5V
19
VFT
+
.01µF
C1
1µF
.01µF
20
VST
C2
30K
.01µF
22
VRM
30K
C3
.01µF
23
VSB
.01µF
C4
24
-2.5V
VFB
C5
16 27
17 26
.1µF
D1
C10
FB3
.1µF
C11
(ORB) D10 12
(MSB) D9 11
10
D8
9
D7
8
D6
7
D5
6
D4
5
D3
4
D2
3
D1
2
(LSB) D0
18 25 14 28
1 13
C8
.1µF
.01µF C6
C9
.1µF
.01µF C7
10 µF
+
10 µF
+
-5.2V AGND
+5V
(Analog)
DGND
+5V
LOGIC
5) Bypass all reference and power supply pinsas closely to
the device pin as possible (chip caps C1-11 are preferred):
0.1 µF for VCC and VEE, and 0.01µF for DVCC and Vref.
6 The top reference (VFT) driver must be current limited to
20 mA maximum if a different reference driver circuit is
used in place of the recommended circuit shown in fig-
ure 11.
Figure 12 : An Example of an Input Limiter
LIMITER
VIN
47 Ω
SK1
SK2
To ADC
VIN
7) The limiter is required if the maximum peak-to-peak volt-
age of the analog input exceeds ±2.5 V. Incorporate the
limiter within the analog input driver or use the circuit
shown in figure 12. Another option is to add a 100 Ω
resistor in series to current limited the input. This last
option adds another LSB error to both ± full scale com-
pared to only 1/2 LSB when using the circuit shown in
figure 12.
-+
+5 V
10 kΩ 10 kΩ
-5.2 V
SK1,2 = Fast recovery Schottkey diode:
RCA, P/N SK9091 or equivalent
AN7820/24
8
5/22/97
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