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参数资料
| 型号： | DAC7545JP |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | DAC |
| 英文描述： | PARALLEL, WORD INPUT LOADING, 2 us SETTLING TIME, 12-BIT DAC, PDIP20 |
| 封装： | PLASTIC, MS-001AD, DIP-20 |
| 文件页数： | 11/14页 |
| 文件大小： | 552K |
| 代理商： | DAC7545JP |
DAC7545
6
SBAS150A
www.ti.com
FIGURE 5. 8-Bit Processor Interface.
DAC7545
CS
DB
0
DB
7
WR
DB
8
DB
11
Latch
CS
WR
44
8
Q
1
(2)
8-Bit Data Bus
Q
0
(1)
Address Bus
Address
Decode
CPU
WR
DB
7
DB
0
A
15
A
0
NOTES: (1) Q
0 = decoded address for DAC.
(2) Q
1 = decoded address for latch.
FIGURE 4. Digitally Controlled Gain Block.
R
FB
DAC7545
AGND
DGND
OUT 1
DB
0-DB11
V
IN
WR
V
OUT
CS
16
+5V
NOTE: There must be
at least 1LSB loaded in
the DAC or the amp will
saturate due to the lack
of feedback.
OPA111
17
18
19
V
OUT =
–V
IN
DB
11
+
2
DB
10
+
4
DB
9
+ +
8
DB
0
4096
20
DIGITALLY-CONTROLLED GAIN BLOCK
Figure 4 shows a circuit for a digitally-controlled gain block.
The feedback for the op amp is made up of the FET switch
and the R-2R ladder. The input resistor to the gain block is
the RFB of the DAC7545. As the FET switch is in the
feedback loop, a zero code into the DAC will result in the op
amp having no feedback, and a saturated op amp output.
APPLICATION HINTS
CMOS DACs, such as the DAC7545, exhibit a code-depen-
dent out resistance. The effect of this is a code-dependent
differential nonlinearity at the amplifier output that depends on
the offset voltage, VOS, of the amplifier. Thus linearity depends
upon the potential of OUT 1 and AGND being exactly equal to
each other. Usually the DAC is connected to an external op
amp with the noninverting input connected to AGND. The op
amp selected should have a low input bias current and low VOS
and VOS drift over temperature. The op amp offset voltage
should be less than (25 10–6)(VREF) over operating conditions.
Suitable op amps are the OPA37 and the OPA627 for fixed
reference applications and low-bandwidth requirement; the
OPA37 has low VOS and does not require an offset trim. For
wide bandwidth, high slew rate, or fast-settling applications, the
OPA604 or 1/2 OPA2604 are recommended.
Unused digital inputs must be connected to VDD or to DGND,
this prevents noise from triggering the high impedance digital
input. It is suggested that the unused digital inputs also be
given a path to ground or VDD through a 1mW resistor to
prevent the accumulation of static charge if the PC card is
unplugged from the system. In addition, in systems where
the AGND to DGND connection is on a backplane, it is
recommended that two diodes be connected in inverse
parallel between AGND and DGND.
INTERFACING
TO MICROPROCESSORS
The DAC7545 can be directly interfaced to either an 8- or 16-
bit microprocessor through its 12-bit wide data latch using
the CS and WR controls.
An 8-bit processor interface is shown in Figure 5. It uses two
memory addresses: one for the lower 8 bits and one for the
upper 4 bits of data into the DAC via the latch.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DAC7545JU | 功能描述:数模转换器- DAC CMOS 12-Bit Multiplying RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube |
| DAC7545JUG4 | 功能描述:数模转换器- DAC CMOS 12-Bit Multiplying RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube |
| DAC7545KP | 制造商:Texas Instruments 功能描述:DAC SGL R-2R 12-BIT 24SSOP - Rail/Tube |
| DAC7545KU | 功能描述:数模转换器- DAC CMOS 12-Bit Multiplying RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube |
| DAC7545KU-1 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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