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参数资料
| 型号： | DAC902U |
| 元件分类： | DAC |
| 英文描述： | PARALLEL, WORD INPUT LOADING, 0.03 us SETTLING TIME, 12-BIT DAC, PDSO28 |
| 封装： | SO-28 |
| 文件页数： | 3/16页 |
| 文件大小： | 216K |
| 代理商： | DAC902U |
11
DAC902
APPLICATION INFORMATION
THEORY OF OPERATION
The architecture of the DAC902 uses the current steering
technique to enable fast switching and a high update rate.
The core element within the monolithic D/A converter is an
array of segmented current sources, which are designed to
deliver a full-scale output current of up to 20mA (see
Figure 1). An internal decoder addresses the differential
current switches each time the DAC is updated and a
corresponding output current is formed by steering all
currents to either output summing node, IOUT or IOUT.
The complementary outputs deliver a differential output
signal, which improves the dynamic performance through
reduction of even-order harmonics, common-mode signals
(noise), and double the peak-to-peak output signal swing by
a factor of two, compared to single-ended operation.
The segmented architecture results in a significant reduc-
tion of the glitch energy, improves the dynamic perfor-
mance (SFDR), and DNL. The current outputs maintain a
very high output impedance of greater than 200k
.
The full-scale output current is determined by the ratio of
the internal reference voltage (1.24V) and an external
resistor, RSET. The resulting IREF is internally multiplied by
a factor of 32 to produce an effective DAC output current
that can range from 2mA to 20mA, depending on the value
of RSET.
The DAC902 is split into a digital and an analog portion,
each of which is powered through its own supply pin. The
digital section includes edge-triggered input latches and the
decoder logic, while the analog section comprises the cur-
rent source array with its associated switches, and the
reference circuitry.
DAC TRANSFER FUNCTION
The total output current, IOUTFS, of the DAC902 is the
summation of the two complementary output currents:
IOUTFS = IOUT + IOUT
(1)
The individual output currents depend on the DAC code and
can be expressed as:
IOUT = IOUTFS (Code/4096)
(2)
IOUT = IOUTFS (4095 - Code/4096)
(3)
where ‘Code’ is the decimal representation of the DAC data
input word. Additionally, IOUTFS is a function of the refer-
ence current IREF, which is determined by the reference
voltage and the external setting resistor, RSET.
IOUTFS = 32 IREF = 32 VREF/RSET
(4)
In most cases the complementary outputs will drive resistive
loads or a terminated transformer. A signal voltage will
develop at each output according to:
VOUT = IOUT RLOAD
(5)
VOUT = IOUT RLOAD
(6)
FIGURE 1. Functional Block Diagram of the DAC902.
PMOS
Current
Source
Array
LSB
Switches
Segmented
MSB
Switches
+1.24V Ref
Latches and Switch
Decoder Logic
12-Bit Data Input
D11...D0
DAC902
Full-Scale
Adjust
Resistor
Ref
Control
Amp
Ref
Buffer
BW
+V
D
+V
A
R
SET
2k
CLK
DGND
Ref
Input
0.1
F
INT/EXT
I
OUT
I
OUT
BYP
PD
20pF
50
50
20pF
1:1
V
OUT
0.1
F
400pF
0.1
F
+3V to +5V
Analog
Bandwidth
Control
+3V to +5V
Digital
FSA
REF
IN
AGND
Analog
Ground
Digital
Ground
Power Down
(internal pull-down)
Clock
Input
NOTE: Supply bypassing not shown.
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| DAC908E/2K5 | PARALLEL, 8 BITS INPUT LOADING, 0.03 us SETTLING TIME, 8-BIT DAC, PDSO28 |
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| DAT-3175-PN | 0 MHz - 2000 MHz RF/MICROWAVE VARIABLE ATTENUATOR, 2.1 dB INSERTION LOSS-MAX |
| DA | FEMALE; MALE, D SUBMINIATURE CONNECTOR, SOLDER |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DAC902U | 制造商:Texas Instruments 功能描述:12-BIT DIGITAL/ANALOG CONVERTER 12 RESO |
| DAC902U/1K | 功能描述:数模转换器- DAC 12-Bit 165MSPS SpeedPlus DAC 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 |
| DAC902U/1KG4 | 功能描述:数模转换器- DAC 12-Bit 165MSPS SpeedPlus DAC 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 |
| DAC902UG4 | 功能描述:数模转换器- DAC 12-Bit 165MSPS SpeedPlus DAC 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 |
| DAC904 | 制造商:BB 制造商全称:BB 功能描述:14-Bit, 165MSPS DIGITAL-TO-ANALOG CONVERTER |
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