TLC7528C, TLC7528E, TLC7528I
DUAL 8-BIT MULTIPLYING
DIGITAL-TO-ANALOG CONVERTERS
SLAS062B – JANUARY 1987 – REVISED MARCH 2000
APPLICATION INFORMATION
C3
47 pF
VI
DACA
(RS)
RFBA
AGND
OUTB
RFBB
–
A1
+
R4
R3
20
19
10 kΩ
+
–
30 kΩ
A2
High Pass
Out
Bandpass Out
DACA1 AND DACB1
C1
1000 pF
–
4
17
Data In
8 14 – 7
15
16
5
6
REFA
VDD
DB0 – DB7
CS
WR
DGND
DACA / DACB
DACA2 and DACB2
Circuit Equations:
C1 = C2, R1 = R2, R4 = R5
Q
DACB
(R2)
TLC7528
DACA
(R1)
OUTA
2
3
1
1000 pF
19
+
–
OUTB
RFBB
20
+
A3
C2
A4
4
17
Data In
8 14 – 7
15
16
5
6
REFA
VDD
OUTA
2
3
1
R5
30 kΩ
DB0 – DB7
TLC7528
CS
WR
DGND
DACA / DACB
DACB
(RF)
REFB 18
RFBA
AGND
Low Pass Out
REFB 18
+
R3
R
4
R
·
R
F
fb(DACB1)
Where:
R is the internal resistor connected between OUTB and RFBB
fb
R
G
– F
R
S
NOTES: A. Op-amps A1, A2, A3, and A4 are TL287.
B. CS compensates for the op-amp gain-bandwidth limitations.
256 (DAC ladder resistance)
C. DAC equivalent resistance equals
DAC digital code
+
Figure 10. Digitally Controlled State-Variable Filter
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
13
TI [ TEXAS INSTRUMENTS ]
