tc500a Microchip Technology Inc., tc500a Datasheet - Page 15

• Manufacturer Part Number: tc500a
• Description: Precision Analog Front Ends
• Manufacturer: Microchip Technology Inc.

9.0
Refer to Figures 9-1 to 9-4.
EQUATION 9-1:
© 2006 Microchip Technology Inc.
Given:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Note:
Note:
DESIGN EXAMPLES
V
Microchip recommended capacitor:
Evox Rifa p/n: 5MR5 334K50J03L4.
Microchip recommended capacitor:
Evox Rifa p/n: 5MR5 224K50J02L4
Required Resolution: 16 bits (65,536
counts).
Maximum V
Power Supply Voltage: +5V
60 Hz System
Pick integration time (t
of the line frequency:
1/60 Hz = 16.6 msec. Use 4x line
frequency.
= 66 msec
Calculate R
R
= 100 k
Calculate C
integrator output swing.
C
= (.066) (20 x 10
= 0.32 F (use closest value: 0.33 F)
Choose C
conversion rate.
Conversions/sec:
= 1/(T
= 1/(66 msec +66 msec
= 3.7 conversions/sec
From which C
(see Table 7-1)
Calculate V
REF
INT
INT
+132 msec +2 msec)
=
=
------------------------------------------------------------- -
=
= V
= (t
AZ
---------------------------------------------------------- -
1.025
V
4.1 0.33 1
INT
IN(MAX)
+ T
S
REF
–
) (20 x 10
REF
INT
INT
IN
INT
0.9
2 0.66
: ±2V
AZ
and C
:
2 T
for maximum (4V)
:
+ 2 T
/20 A 2 /20 A
= C
–6
C
INT
INT
) / (4.1)
–
AZ
REF
INT
6
–6
INT
based on
) / (V
R
10
+ 2 msec)
= 0.22 F
) as a multiple
INT
5
S
- 0.9)
TC500/A/510/514
DS21428D-page 15