cat515 Catalyst Semiconductor, cat515 Datasheet - Page 7

• Manufacturer Part Number: cat515
• Description: 8-bit Quad Digital Pot With Independent Reference Inputs
• Manufacturer: Catalyst Semiconductor

CONTROL
& DATA
CONTROL
& DATA
setting is reloaded into the DAC control register. Since
this value is the same as that which had been there
previously no change in the DAC’s output is noticed.
Had the value held in the control register been different
from that stored in EEPROM then a change would occur
at the read cycle’s conclusion.
TEMPORARILY CHANGE OUTPUT
The CAT515 allows temporary changes in DAC’s output
to be made without disturbing the settings retained in
EEPROM memory. This feature is particularly useful
when testing for a new output setting and allows for user
adjustment of preset or default values without losing the
original factory settings.
Figure 3 shows the control and data signals needed to
effect a temporary output change. DAC settings may be
changed as many times as required and can be made to
any of the four DACs in any order or sequence. The
temporary setting(s) remain in effect long as CS remains
high. When CS returns low all four DACs will return to the
output values stored in EEPROM memory.
When it is desired to save a new setting acquired using
this feature, the new value must be reloaded into the
DAC control register prior to programming. This is be-
cause the CAT515’s internal control circuitry discards
from the programming register the new data two clock
cycles after receiving it if no PROG signal is received.
APPLICATION CIRCUITS
+5V
+5V
V DD
OPT 505
CAT515
GND
V DD
OPT 505
GND
CAT515
Buffered DAC Output
V
V
REF
V i
REF
V
V
REF
REF
H
L
H
L
V
OUT
R
For R =
V
= V
V
I
OUT
OUT
DAC
–
+
+15V
-15V
I R F
= 2V
=
V DAC
OP 07
–
+
+15V
-15V
DAC
OP 07
(
R
-V
R + I
F
I
V OUT
R I
Bipolar DAC Output
R F
) -V
V
I
OUT
R F
7
RDY/BSY
OUTPUT
Figure 3. Temporary Change in Output
PROG
DAC
CONTROL
& DATA
MSB
1111
1000
0111
0000
0000
DO
CS
DI
DAC INPUT
1111
0000
1111
0001
0000
LSB
t
o
1
1
2
—— (.98 V
—— (.98 V
—— (.98 V
—— (.98 V
—— (.98 V
V
V
V
255
255
128
255
127
255
255
255
+5V
A0
DAC
FS
ZERO
1
0
V DD
OPT 505
CAT515
GND
3
A1
= 0.99 V
NON-VOLATILE
Amplified DAC Output
4
DAC VALUE
= ——— (V
CURRENT
D0
D0
= 0.01 V
CODE
255
5
REF
REF
REF
REF
REF
D1
D1
DAC OUTPUT
REF
6
V
V
NEW DAC DATA
CURRENT DAC DATA
D2
D2
REF
REF
) + .01 V
) + .01 V
) + .01 V
) + .01 V
) + .01 V
REF
7
D3
D3
FS
H
L
8
- V
D4
D4
REF
REF
REF
REF
REF
9
ZERO
V
D5
D5
OUT
10
R
= .990 V
= .502 V
= .498 V
= .014 V
= .010 V
D6
D6
I
11
) + V
= (1 + –––) V
D7
D7
12
Doc. No. 25077-00 2/98 M-1
ZERO
REF
REF
REF
REF
REF
DAC VALUE
VOLATILE
R F
R I
NEW
–
+
+15V
-15V
N
DAC
V
V
V
V
V
R
OP 07
V
R = R
OUT
ANALOG
OUT
OUT
OUT
OUT
OUTPUT
N+1 N+2
F
REF
NON-VOLATILE
CAT515
I
DAC VALUE
CURRENT
= +4.90V
= +0.02V
= -0.02V
= -4.86V
= -4.90V
= 5V
F
V OUT