SP9604DS/03 SP9604 Quad, 12-Bit, Low Power Voltage Output D/A Converter
Copyright 2000 Sipex Corporation
6
A
1
A
0
CS
WR1
B1/B2
WR2
XFER
CLR
FUNCTION
0
0
0
0
1
1
1
1
X
X
X
0
0
1
1
0
0
1
1
X
X
X
1
0
1
0
1
0
1
0
X
X
X
1
1
1
1
1
1
1
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1
Address DAC 1 and load input register
Address DAC 1 and load 4 LSBs
Address DAC 2 and load input register
Address DAC 2 and load 4 LSBs
Address DAC 3 and load input register
Address DAC 3 and load 4 LSBs
Address DAC 4 and load input register
Address DAC 4 and load 4 LSBs
Transfer data from input registers to DAC registers
Sets all DAC output voltages to 0V
Temporarily force all DAC output voltages to 0V,
while CLR is low
Invalid state with any other control line active
Invalid state with any other control line active
**
X
1
**
X
1
1
0
0
X
X
X
X
1
X
X
1
X
X
X
X
X
X
X
X
X = Don’t care; ** = Don’t care; however, CS and WR1 = 1 will inhibit changes to the input registers.
To load a 12-bit word to the input register of
each DAC, using an 8-bit data bus, the sequence
is as follows:
1) Set XFER=1, B1/B2=1, CLR=1, WR1=1,
WR2=1, CS=1.
2) Set D11 through D4 to the 8 MSB’s of the
desired digital input code.
3) Load the 8 MSB’s of the digital word to
the selected input register by cycling WR1
and CS through the “1” — “0” — “1”
sequence.
4) Reset B1/B2 from “1” —— “0”
5) Set D11 (MSB) through D8 to the 4 LSB’s
of the digital input code.
6) Load the 4 LSB’s by cycling WR1 and CS
through the “1” — “0” — “1” sequence.
7) Repeat sequence for each input register.
DAC
3 TO 7
DECODE
&
5 BITS
LATCH
8–BIT
LATCH
4-BIT
LATCH
DB11 - DB8
DB7 - DB4
Ref In
–
+
VOUT
4
4
4
4
4
MUX
4
4
4
12
DB3 - DB0
INPUT
REGISTER
DAC
REGISTER
40 K
40 K
Figure 1. Detailed Block Diagram (only one DAC shown)
USING THE SP9604 WITH
DOUBLE-BUFFERED INPUTS
Loading Data
To load a 12-bit word to the input register of
each DAC, using a 12-bit data bus, the sequence
is as follows:
1) Set XFER=1, B1/B2=1, CLR=1, WR1=1,
WR2=1, CS=1.
2) Set A
and A
(the DAC address) to the
desired DAC — 0,0 = DAC
1
; 0,1 = DAC
2
1,0 = DAC
; 1,1 = DAC
.
3) Set D11 (MSB) through D0 (LSB) to the
desired digital input code.
4) Load the word to the selected DAC by
cycling WR1 and CS through the follow-
ing sequence:
“1” — “0” — “1”
5) Repeat sequence for each input register.
Table 2. Control Logic Truth Table