DS04-13508-2E
FUJITSU SEMICONDUCTOR
DATA SHEET
Linear IC Converter
CMOS
D/A Converter for Digital Tuning
(24-channel, 8-bit, on-chip OP amp)
MB88345
s
DESCRIPTION
The MB88345 incorporates twenty-four 8-bit D/A converter modules.
It also contains an output amplifier, allowing driving at large current.
Since the inputs data in serial mode, it requires only three control lines for data input and can be cascaded.
The MB88345 is suitable for applications such as electronic volume controls and replacement of semi-fixed
resistors in tuning systems.
s
FEATURES
Ultra-low power consumption (1.1 mW/ch : typical)
Compact space-saving package (QFP-32)
Contains 24-channel R-2R type 8-bit D/A converter
On-chip analog output amps (sink current max. 1.0 mA, source current max. 1.0 mA)
Analog output range : 0 V to V
CC
Two separate power supply/ground lines for MCU interface block/operational amplifier output buffer block and
D/A converter block
Serial data input : maximum operating speed 2.5 MHz
CMOS process
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PACKAGE
32-pin Plastic QFP
(FPT-32P-M21)
MB88345
2
s
PIN ASSIGNMENT
s
PIN DESCRIPTION
* : DI, CLK, LD pins should be fixed with "Low"level while no data are transferred.
Pin No.
Pin name
I/O
Description
27
DI*
I
Serial data input pin. This pin inputs serial data with a data length of 14 bits.
24
DO
O
This pin outputs the MSB data in the 14-bit shift register.
26
CLK*
I
Shift clock input pin. The input signal from the DI pin enters the 14-bit shift
register at the rising edge of the shift clock pulse.
25
LD*
I
When the LD pin inputs the High-level signal, shift register value is loaded to
the decoder and the D/A output register.
30 to 32
1 to 11
14 to 23
AO1 to AO3
AO4 to AO14
AO15 to AO24
O
8-bit D/A output with OP-amp.
13
V
CC
MCU interface and OP-amp power-supply pin
28
GND
MCU interface and OP-amp GND pin
12
V
DD
D/A converter power-supply pin
29
V
SS
D/A converter GND pin
(TOP VIEW)
(FPT-32P-M21)
25
26
27
28
29
30
31
32
LD
CLK
DI
GND
V
SS
AO1
AO2
AO3
16
15
14
13
12
11
10
9
AO17
AO16
AO15
V
CC
V
DD
AO14
AO13
AO12
24 23 22 21 20 19 18 17
DO
AO24
AO23
AO22
AO21
AO20
AO19
AO18
AO4
AO5
AO6
AO7
AO8
AO9
AO10
AO11
1 2 3 4 5 6 7 8
INDEX
MB88345
3
s
BLOCK DIAGRAM
DI
CLK
DO
LD
V
DD
V
SS
V
CC
GND
AO1
AO2
AO24
+
-
+
-
+
-
D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13
Channel decoder
8
24
1
24
1
2
24
8-bit register
8-bit register
8-bit register
R-2R type
8-bit D/A
converter
R-2R type
8-bit D/A
converter
R-2R type
8-bit D/A
converter
14-bit shift register
MB88345
4
s
DATA CONFIGURATION
The MB88345 has a 14-bit shift register for chip control.
The 14-bit shift register must be used to set up data in the configuration shown below.
Note : The data configuration has a total of 14 bits, six for channel selection and eight for D/A data output.
D/A converter control signals
V
REF
=
V
DD
-
V
SS
Channel selection signals
: Don't Care
Input data signal
D/A converter output voltage
D0
D1
D2
D3
D4
D5
D6
D7
0
0
0
0
0
0
0
0
:= V
SS
1
0
0
0
0
0
0
0
:= V
REF
/
255
1
+
V
SS
0
1
1
1
1
1
1
1
:= V
REF
/
255
254
+
V
SS
1
1
1
1
1
1
1
1
:= V
DD
Input data signal
Channel selection
D8
D9
D10
D11
D12
D13
0
0
0
0
0
Deselected
0
0
0
0
1
AO1 Selection
0
0
0
1
0
AO2 Selection
1
0
1
1
1
AO23 Selection
1
1
0
0
0
AO24 Selection
1
1
0
0
1
Deselected
1
1
0
1
0
1
1
1
1
0
1
1
1
1
1
Last
LSB
First
MSB
D/A output bits
Channel selection bits
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
MB88345
5
s
TIMING CHART
s
ANALOG OUTPUT VOLTAGE RANGE
DI
CLK
LD
D/A
output
MSB
D13
D12
D11
D10
D2
D1
D0
LSB
V
DD
V
CC
R-2R ladder output
OP amp. output
V
AOH
(V
CC
)
V
AOL
(GND)
D/A output range
(linear area)
V
SS
GND
V
CC
=
V
DD
GND
=
V
SS
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