MP7680JE EXAR [Exar Corporation], MP7680JE Datasheet - Page 8

• Manufacturer Part Number: MP7680JE
• Description: 5 V CMOS 12-Bit Quad Double-Buffered Multiplying Digital-to-Analog Converter
• Manufacturer: EXAR [Exar Corporation]

THEOR Y OF OPERA TION
Digital
Figure 3.
controls the writing of the input latches and the one that
controls the DAC latches are completely separated. It is
easy to understand how the MP7680/80A works by
understanding each basic operation.
MP7680
DB11-DB4
A1 (MSB)
DB3-DB0
A0 (LSB)
Rev. 3.10
(MSB)
B1/B2
(LSB)
WR1
Interface
CS
shows the internal control logic. The logic that
DB11-
DB8
Disable-B1
Decoder
Address
Latch
0
1
MUX
Enable A
Enable B
Enable C
Enable D
Figure
8
4
8
4
8
4
8
4
3. Latches
INPUT LA TCHES
D
E
D
E
D
E
D
E
D
E
D
E
D
E
D
E
8
Latch
Latch
Latch
Latch
Latch
Latch
Latch
Latch
B1
B2
B1
B2
B1
B2
B1
B2
W riting to Input Latches
By keeping B1/B2 = high, a 12-bit bus has direct access to
the 12 bits of the input latches. The condition CS = WR1 =
0 loads the values contained in the data bus DB11-DB0
into the input latch addresses by A
Table 1.
Control
Q
Q
Q
Q
Q
Q
Q
Q
LA11 - LA0
8
8
8
8
4
4
4
4
XFER
).
Logic
WR2
Transfer
DAC LA TCHES
D
E
D
E
D
E
D
E
Q
Q
Q
Q
DA11 - DA0
DB11 - DB0
DC11 - DC0
DD11 - DD0
12
12
12
12
DAC
DAC
DAC
DAC
1
, A
0
(
Figure 4.
R
I
I
V
R
I
I
V
R
I
I
V
R
I
I
V
OUT1A
OUT2A
OUT1B
OUT2B
OUT1C
OUT2C
OUT1D
OUT2D
REFA
REFB
REFC
REFD
FBA
FBB
FBC
FBD
,